Tax Evasion and Inequality

DEFF Research Database (Denmark)

Alstadsæter, Annette; Johannesen, Niels; Zucman, Gabriel

2017-01-01

.01% of the wealth distribution, a group that includes households with more than $45 million in net wealth. A simple model of the supply of tax evasion services can explain why evasion rises steeply with wealth. Taking tax evasion into account increases the rise in inequality seen in tax data since the 1970s......This paper attempts to estimate the size and distribution of tax evasion in rich countries. We combine random audits—the key source used to study tax evasion so far—with new micro-data leaked from large offshore financial institutions—HSBC Switzerland (“Swiss leaks”) and Mossack Fonseca (“Panama...... Papers”)—matched to population-wide wealth records in Norway, Sweden, and Denmark. We find that tax evasion rises sharply with wealth, a phenomenon random audits fail to capture. On average about 3% of personal taxes are evaded in Scandinavia, but this figure rises to close to 30% in the top 0...

Tax evasion: a game countermeasure

Directory of Open Access Journals (Sweden)

David Carfi'

2015-08-01

Full Text Available We propose a game-theoretic model analyzing the interaction between the State and any possible relative taxpayer, by using a realistic probability (frequency approach to the checking evasion strategy. Starting from Allingham and Sandmo's model (1972, we study a possible measure to prevent tax evasion and we also propose a ``honesty-award'' for Taxpayers declaring their entire income by using two Kalai-Smorodinsky solutions. This methodology leaves room for further development of the model, leading to a self-identification by tax evaders and honest citizens.

Prey aggregation is an effective olfactory predator avoidance strategy

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Asa Johannesen

2014-05-01

Full Text Available Predator–prey interactions have a major effect on species abundance and diversity, and aggregation is a well-known anti-predator behaviour. For immobile prey, the effectiveness of aggregation depends on two conditions: (a the inability of the predator to consume all prey in a group and (b detection of a single large group not being proportionally easier than that of several small groups. How prey aggregation influences predation rates when visual cues are restricted, such as in turbid water, has not been thoroughly investigated. We carried out foraging (predation experiments using a fish predator and (dead chironomid larvae as prey in both laboratory and field settings. In the laboratory, a reduction in visual cue availability (in turbid water led to a delay in the location of aggregated prey compared to when visual cues were available. Aggregated prey suffered high mortality once discovered, leading to better survival of dispersed prey in the longer term. We attribute this to the inability of the dead prey to take evasive action. In the field (where prey were placed in feeding stations that allowed transmission of olfactory but not visual cues, aggregated (large groups and semi-dispersed prey survived for longer than dispersed prey—including long term survival. Together, our results indicate that similar to systems where predators hunt using vision, aggregation is an effective anti-predator behaviour for prey avoiding olfactory predators.

Optimal predator risk assessment by the sonar-jamming arctiine moth Bertholdia trigona.

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Aaron J Corcoran

Full Text Available Nearly all animals face a tradeoff between seeking food and mates and avoiding predation. Optimal escape theory holds that an animal confronted with a predator should only flee when benefits of flight (increased survival outweigh the costs (energetic costs, lost foraging time, etc.. We propose a model for prey risk assessment based on the predator's stage of attack. Risk level should increase rapidly from when the predator detects the prey to when it commits to the attack. We tested this hypothesis using a predator--the echolocating bat--whose active biosonar reveals its stage of attack. We used a prey defense--clicking used for sonar jamming by the tiger moth Bertholdia trigona--that can be readily studied in the field and laboratory and is enacted simultaneously with evasive flight. We predicted that prey employ defenses soon after being detected and targeted, and that prey defensive thresholds discriminate between legitimate predatory threats and false threats where a nearby prey is attacked. Laboratory and field experiments using playbacks of ultrasound signals and naturally behaving bats, respectively, confirmed our predictions. Moths clicked soon after bats detected and targeted them. Also, B. trigona clicking thresholds closely matched predicted optimal thresholds for discriminating legitimate and false predator threats for bats using search and approach phase echolocation--the period when bats are searching for and assessing prey. To our knowledge, this is the first quantitative study to correlate the sensory stimuli that trigger defensive behaviors with measurements of signals provided by predators during natural attacks in the field. We propose theoretical models for explaining prey risk assessment depending on the availability of cues that reveal a predator's stage of attack.

Optimal Predator Risk Assessment by the Sonar-Jamming Arctiine Moth Bertholdia trigona

Science.gov (United States)

Corcoran, Aaron J.; Wagner, Ryan D.; Conner, William E.

2013-01-01

Nearly all animals face a tradeoff between seeking food and mates and avoiding predation. Optimal escape theory holds that an animal confronted with a predator should only flee when benefits of flight (increased survival) outweigh the costs (energetic costs, lost foraging time, etc.). We propose a model for prey risk assessment based on the predator's stage of attack. Risk level should increase rapidly from when the predator detects the prey to when it commits to the attack. We tested this hypothesis using a predator – the echolocating bat – whose active biosonar reveals its stage of attack. We used a prey defense – clicking used for sonar jamming by the tiger moth Bertholdia trigona– that can be readily studied in the field and laboratory and is enacted simultaneously with evasive flight. We predicted that prey employ defenses soon after being detected and targeted, and that prey defensive thresholds discriminate between legitimate predatory threats and false threats where a nearby prey is attacked. Laboratory and field experiments using playbacks of ultrasound signals and naturally behaving bats, respectively, confirmed our predictions. Moths clicked soon after bats detected and targeted them. Also, B. trigona clicking thresholds closely matched predicted optimal thresholds for discriminating legitimate and false predator threats for bats using search and approach phase echolocation – the period when bats are searching for and assessing prey. To our knowledge, this is the first quantitative study to correlate the sensory stimuli that trigger defensive behaviors with measurements of signals provided by predators during natural attacks in the field. We propose theoretical models for explaining prey risk assessment depending on the availability of cues that reveal a predator's stage of attack. PMID:23671686

Tax evasion between fraud and legality

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Opreţ Laura-Anca

2017-12-01

Full Text Available This paper focuses on detailing the general coordinates regarding tax evasion and the necessity of creating a common unitary European legal framework. Accounting information might mirror erroneously in a certain measure the micro to macroeconomic tendency of fraud by showing a gross image of available resources. It is of the utmost importance to become fully aware of causes for illicit practices, ways to fight any fraud attempts and to evaluate the accounting mechanism that both creates and identifies tax evasion.

TAX EVASION THROUGH FICTITIOUS ECONOMIC OPERATIONS, OBSTACLE TO SUSTAINABLE DEVELOPMENT

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SERGIU-BOGDAN CONSTANTIN

2016-06-01

Full Text Available Tax evasion means the avoidance of declaring and paying taxes. The purpose of the research is to identify ways and mechanisms of tax evasion through fictitious economic operations and how this kind o tax evasion can influence sustainable development. The principal methods are researching tax evasion cases investigated by the Romanian authorities responsible for combating this phenomenon, court trials on tax evasion and using the bibliographic references in the field. The data used are obtained through open sources of the authorities specialized in combating tax evasion for the cases made public, the media and also from specialised literature. The principal results are that this type of tax evasion is manifested through transactions with “ghost companies”, with offshore companies and transactions between associated enterprises. The main causes of this problem are: high taxation, corruption, inefficient government and tax authorities, no fiscal education and very hard tax legislation. The consequences are that the state budget is affected, the companies that do business legally are affected and also the final consumers, so Romania will not have economic growth and the quality of life will not improve. The main conclusion is that in order to have sustainable development, tax evasion in general and this kind of tax evasion in particular must be eradicated. The measures that have to be taken are to prevent tax evasion and to tighten controls but without violating taxpayers rights and without making abuses

15 CFR 760.4 - Evasion.

Science.gov (United States)

2010-01-01

... 15 Commerce and Foreign Trade 2 2010-01-01 2010-01-01 false Evasion. 760.4 Section 760.4 Commerce... BOYCOTTS § 760.4 Evasion. (a) No United States person may engage in any transaction or take any other... the coverage and intent of the exceptions set forth in this part do not constitute evasion regardless...

Deciding on Tax Evasion

DEFF Research Database (Denmark)

Boll, Karen

2015-01-01

Purpose – The purpose of this paper is to analyse everyday reasoning in public administration. This is done by focusing on front line tax inspectors’ decisions about tax evasion. Design/methodology/approach – The paper presents ethnography of bureaucracy and field audits. The material stems from...... fieldwork conducted in the Central Customs and Tax Administration. Findings – The paper shows that the tax inspectors reason about tax evasion in a casuistic manner. They pay attention to similar cases and to particular circumstances of the individual cases. In deciding on tax evasion, the inspectors do...

Steering and evasion assist

NARCIS (Netherlands)

Dang, T.; Desens, J.; Franke, U.; Gavrila, D.; Schäfers, L.; Ziegler, W.; Eskandarian, A.

2012-01-01

Steering and evasion assistance defines a new and future class of driver assistance systems to avoid an impending collision with other traffic participants. Dynamic and kinematic considerations reveal that an evasive steering maneuver has high potential for collision avoidance in many driving

The Tax Evasion in Ukraine: Causes and Methods of Countering

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Parfentii Liudmyla A.

2018-03-01

Full Text Available The essence of the concept of tax evasion is researched; reasons of occurrence and development of this phenomenon are analyzed; proposals on the main directions of prevention and countering tax evasion have been developed. Analyzing, systematizing and generalizing the scientific works of many scholars, it was found that there is no unified approach to interpretation of the essence of this phenomenon in the context of legality and awareness of relevant actions in the scientific literature. As a result of the research the factors of tax evasion with the allocation of moral, political, economic, technical, and legal reasons have been systematized. The preconditions of tax evasion in Ukraine are analyzed, the most common schemes are indicated, resulting from which the budget of Ukraine suffers the greatest losses. Methods of countering tax offenses have been researched and necessity of development and implementation of measures on prevention and countering tax evasion at the State level has been substantiated. Prospects for further researches in this direction are studying of foreign experience of countering tax evasion and detailed analyzing of the tax minimization schemes prevalent in Ukraine with the purpose of identifying ways of elimination of possibility of their use.

Tax Evasion in a Model of Endogenous Growth

OpenAIRE

Been-Lon Chen

2003-01-01

This paper integrates tax evasion into a standard AK growth model with public capital. In the model, the government optimizes the tax rate, while individuals optimize tax evasion. It studies tax rate, tax evasion and economic growth, and compares them with otherwise identical economies except those without tax evasion. It inquires into the effects of three government policies on tax rate, tax evasion, and economic growth. It finds that an increase in both unit cost of tax evasion and punishme...

TAX EVASION BETWEEN FRAUD AND OPTIMIZATION

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Emilia Cornelia STOICA

2017-05-01

Full Text Available Tax optimization, often called legal tax evasion is the use of methods and techniques that are within the law, in order to reduce or even cancel the tax liability. To achieve such an approach, the taxpayer or his advisers must know in depth the tax law - and by extension, the financial and administrative law - and, moreover, must be functional tax jurisdictions which allow the use of appropriate assemblies. The recent leasks, as WikiLeaks, LuxLeaks, SwissLeaks, Panama Papers etc. on financial flows to tax havens highlight the far-reaching unprecedented evasion and tax fraud, both in the amounts involved - trillions of dollars - and sophisticated assemblies used primarily by multinational companies to the detriment of the public finances of Member territory headquarters and branches which are located and, therefore, detrimental economic and social life of those countries. Tax evasion is based on legal mechanisms which, combined together in the montages of increasingly complex, allowing operators, mostly multinational legal entities to circumvent national tax law and not pay the taxes due. The border between tax optimization, tax evasion and fraud is very thin, optimization using various legal methods to reduce the tax owed, whereas tax evasion using illegal means, which covered crime. Tax evasion reveals either optimize or fraud. There is a significant international dimension of tax evasion because it is favored by multinational corporations operating conditions.

Antelope Predation by Nigerian Forest Baboons: Ecological and Behavioural Correlates.

Science.gov (United States)

Sommer, Volker; Lowe, Adriana; Jesus, Gonçalo; Alberts, Nienke; Bouquet, Yaëlle; Inglis, David M; Petersdorf, Megan; van Riel, Eelco; Thompson, James; Ross, Caroline

2016-01-01

Baboons are well studied in savannah but less so in more closed habitats. We investigated predation on mammals by olive baboons (Papio anubis) at a geographical and climatic outlier, Gashaka Gumti National Park (Nigeria), the wettest and most forested site so far studied. Despite abundant wildlife, meat eating was rare and selective. Over 16 years, baboons killed 7 bushbuck (Tragelaphus scriptus) and 3 red-flanked duiker (Cephalophus rufilatus), mostly still-lying 'parked' infants. Taking observation time into account, this is 1 predation per group every 3.3 months - far lower than at other sites. Some features of meat eating resemble those elsewhere; predation is opportunistic, adult males monopolize most prey, a targeted killing bite is lacking and begging or active sharing is absent. Carcass owners employ evasive tactics, as meat is often competed over, but satiated owners may tolerate others taking meat. Other features are unusual; this is only the second study site with predation records for bushbuck and the only one for red-flanked duiker. The atypical prey and rarity of eating mammals probably reflects the difficulty of acquiring prey animals when vegetation cover is dense. Our data support the general prediction of the socioecological model that environments shape behavioural patterns, while acknowledging their intraspecific or intrageneric plasticity. © 2016 S. Karger AG, Basel.

Tax evasion and the law in Nigeria

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Enya Matthew Nwocha

2017-12-01

Full Text Available This paper has dealt with the incidence of tax evasion and how the law in Nigeria has tackled the problem. It came against the background of massive tax evasion in the country which has resulted in the loss of needed revenue for development. Most individuals eligible to pay tax are not usually amenable to doing so willingly thereby resulting in tax evasion and tax avoidance. Neglect or refusal to pay tax invariably attracts various ranges of punishment. All of these issues have been discussed in this paper under introduction, conceptual framework, grounds for imposition of tax, statutory provisions on tax evasion, reasons for and implications of tax evasion, recommendations and conclusion. The paper in discussing the subject has focused on the principal tax legislations in the country, namely, the Personal Income Tax Act, Companies Income Tax Act, and the Federal Inland Revenue Service Act.

VAT EVASION INLEBANON: CASES AND MAIN CAUSES

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Rana Ismail

2012-07-01

Full Text Available The Value Added Tax (VAT is a very important source oftreasuryrevenuesinLebanon. It was initially introduced inLebanon in order to reduce the budgetdeficit and help contain the debt. However, VAT evasion growth inLebanon isleading to significant VAT revenue losses because of its size and frequency.In this paper, we will highlight the contribution of VAT to the treasury revenue. Inaddition, our research has led to figure out the most significant VAT evasion casesand the way tax payers evade paying their required VAT or try to have an illegalrefund. From these tax evasion cases, we will pinpoint the main causes of suchevasions and propose solutions to limit as much as possible VAT evasion inLebanon.

Infrared tomographic PIV and 3D motion tracking system applied to aquatic predator–prey interaction

International Nuclear Information System (INIS)

Adhikari, Deepak; Longmire, Ellen K

2013-01-01

Infrared tomographic PIV and 3D motion tracking are combined to measure evolving volumetric velocity fields and organism trajectories during aquatic predator–prey interactions. The technique was used to study zebrafish foraging on both non-evasive and evasive prey species. Measurement volumes of 22.5 mm × 10.5 mm × 12 mm were reconstructed from images captured on a set of four high-speed cameras. To obtain accurate fluid velocity vectors within each volume, fish were first masked out using an automated visual hull method. Fish and prey locations were identified independently from the same image sets and tracked separately within the measurement volume. Experiments demonstrated that fish were not influenced by the infrared laser illumination or the tracer particles. Results showed that the zebrafish used different strategies, suction and ram feeding, for successful capture of non-evasive and evasive prey, respectively. The two strategies yielded different variations in fluid velocity between the fish mouth and the prey. In general, the results suggest that the local flow field, the direction of prey locomotion with respect to the predator and the relative accelerations and speeds of the predator and prey may all be significant in determining predation success. (paper)

TAX EVASION THROUGH FICTITIOUS ECONOMIC OPERATIONS, OBSTACLE TO SUSTAINABLE DEVELOPMENT

OpenAIRE

SERGIU-BOGDAN CONSTANTIN

2016-01-01

Tax evasion means the avoidance of declaring and paying taxes. The purpose of the research is to identify ways and mechanisms of tax evasion through fictitious economic operations and how this kind o tax evasion can influence sustainable development. The principal methods are researching tax evasion cases investigated by the Romanian authorities responsible for combating this phenomenon, court trials on tax evasion and using the bibliographic references in the field. The data used...

Study of seismological evasion. Part III. Evaluation of evasion possibilities using codas of large earthquakes

International Nuclear Information System (INIS)

Evernden, J.F.

1976-01-01

The seismological aspects of various proposed means of obscuring or hiding the seismic signatures of explosions from a surveillance network are discussed. These so-called evasion schemes are discussed from the points of view of both the evader and the monitor. The analysis will be conducted in terms of the USSR solely because that country is so vast and the geological/geophysical complexities of the country are so great that the complete spectrum of hypothesized evasion schemes requires discussion. Techniques appropriate for use when the seismic noise problem is interference due to codas of P and surface waves from earthquakes are described, and the capabilities of several seismological networks to restrain use of such codas for effective evasion are analyzed

Pursuit-evasion differential games

CERN Document Server

Yavin, Y

1987-01-01

Twenty papers are devoted to the treatment of a wide spectrum of problems in the theory and applications of dynamic games with the emphasis on pursuit-evasion differential games. The problem of capturability is thoroughly investigated, also the problem of noise-corrupted (state) measurements. Attention is given to aerial combat problems and their attendant modelling issues, such as variable speed of the combatants, the three-dimensionality of physical space, and the combat problem, i.e. problems related to 'role determination'.

Tax Evasion Dynamics in Romania Reflected by Fiscal Inspection Activities

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CORINA-MARIA ENE

2010-06-01

Full Text Available The paper aims to provide a panoramic view of the dynamics of tax evasion in Romania, reflected in terms of fiscal inspection activities. The author used the official data published by the institutions with attributions on the line of identification and fighting against tax evasion (National Agency of Fiscal Administration and Financial Guard with the view to reflect the real situation concerning the number of inspections, quantify and sanction tax evasion for 2003-2008 periods. Although the number of fiscal inspections and the number of tax payers who have violated the rules of fiscal discipline decreased compared with 2003, the frequency of tax evasion remained. At the same time, based on the data referring to the level and dynamics of the tax dodger phenomenon appreciations have been made regarding the fiscal discipline of the Romanian tax payer and to the attitude of the qualified institutions in discovering and sanctioning the fraudulent tax evasion. In this respect, the author observed that the level of willingness of tax legislation in relation to the Romanian tax payer has not changed considerably.The level of identified tax evasion reported to real GDP increased slightly. This situation can be interpreted as a success of institutions in charge of identification and fighting of tax evasion, a result of the increase of fiscal inspection number and detection probability, but also a result of GDP growth at a rate lower than the identified tax evasion. The author has also tried to find a causality relation between the option for tax evasion and corruption. The author found that a corrupt environment facilitates the decision to evade depending on detection probability, penalty system and bribery level as discouraging factors for tax evasion. The level of identified tax evasion is smaller than the real level of entire tax evasion, an important part being impossible to determine because of corruption.

The Hidden Costs of Tax Evasion: Collaborative Tax Evasion in Markets for Expert Services

OpenAIRE

Balafoutas, Loukas; Beck, Adrian; Kerschbamer, Rudolf; Sutter, Matthias

2015-01-01

We experimentally examine the impact of tax evasion attempts on the performance of credence goods markets, where contractual incompleteness results from asymmetric information on the welfare maximizing quality of the good. Our results suggest that tax evasion attempts – independently of whether they are successful or not – lead to efficiency losses in the form of too low quality and less frequent trade. Thus, shadow economies may reduce welfare not only by inducing agents to incur costs to hi...

Tax evasion, social norms and economic growth

OpenAIRE

Bethencourt, Carlos; Kunze, Lars

2013-01-01

This paper proposes a theoretical model to account for the most relevant micro- and macroeconomic empirical facts in the tax evasion literature. To do so, we integrate tax morale into a dynamic overlapping generations model of capital income tax evasion. Tax morale is modeled as a social norm for tax compliance. It is shown that accounting for such nonpecuniary costs of evasion may not only explain (i) why some taxpayers never evade even if the gamble is profitable, and (ii) how a higher tax ...

THE DETERMINANTS PERCEPTION OF TAX EVASION ETHICS

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Ningsih D.N.C.

2018-01-01

Full Text Available This study aimed to examine the determinants perception of tax evasion ethics, and combined three models based on the research of McGee et al (2012, Lau et al (2013, Lemvora et al (2013. Data collection used survey method on 148 auditors who worked at Public Accountant Office (KAP Big Ten. The result of this study showed that the justice and taxation systems affect significantly negative toward the perception of tax evasion ethics. Religiosity strengthened the effect of justice, taxation systems, and discrimination on the perception of tax evasion ethics.

Forms of Manifestation regarding Tax Evasion: New Approaches

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Alia Gabriela DUŢĂ

2015-09-01

Full Text Available Tax evasion has existed, exists and will exist as long as the state and the tax will continue to exist, but the forms and ways of achievement are perfectly in time. In terms of how can be committed, the ratio that exists between this phenomenon and the current legislation, tax evasion, there are two manifestations: the lawful tax avoidance (performed at the shelter law; unlawful tax evasion (fraudulent or fraud. In terms of space can be identified: tax evasion and tax avoidance at national and international level. In recent years circumvention actions are transferred, increasingly more inside from national tax systems across state borders, action driven by trends economic globalization, political and social.

FORMS OF TAX EVASION IN ROMANIA. ANALYTICAL PERSPECTIVE

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PETRE BREZEANU

2011-01-01

Full Text Available This study brings to the fore an analysis of the phenomenon of tax evasion in Romania. The perspective is broad, with a descriptive substrate, originally founded by highlighting the dimensions that define this phenomenon; later, the perspective is materialized by the presentation of tax evasion schemes that often takes the form of real complex fiscal and also financial engineering. The purpose of this work consists in the awareness of practitioners, academics and the public of the tax evasion forms useful in order to identify precise modalities to combat it. Since the volume of funds subject to the phenomenon of tax evasion is greater, the negative effects of macroeconomic environment.

Cigarette tax avoidance and evasion: findings from the International Tobacco Control Policy Evaluation Project

Science.gov (United States)

Guindon, G. Emmanuel; Driezen, Pete; Chaloupka, Frank J.; Fong, Geoffrey T.

2014-01-01

Background Decades of research have produced overwhelming evidence that tobacco taxes reduce tobacco use and increase government tax revenue. The magnitude and effectiveness of taxes at reducing tobacco use provide an incentive for tobacco users, manufacturers and others, most notably criminal networks, to devise ways to avoid or evade tobacco taxes. Consequently, tobacco tax avoidance and tax evasion can reduce the public health and fiscal benefit of tobacco taxes. Objectives First, this study aims to document, using data from the International Tobacco Control Policy Evaluation Project (ITC), levels and trends in cigarette users’ tax avoidance and tax evasion behaviour in a sample of sixteen low-, middle- and high-income countries. Second, this study explores factors associated with cigarette tax avoidance and evasion. Methods We use data from ITC surveys conducted in 16 countries to estimate the extent and the type of cigarette tax avoidance/evasion between countries and across time. We use self-reported information about the source of a smoker’s last purchase of cigarettes or self-reported packaging information, or similar information gathered by the interviewers during face-to-face interviews to measure tax avoidance/evasion behaviours. We use generalized estimating equations (GEE) to explore individual-level factors that may affect the likelihood of cigarette tax avoidance or evasion in Canada, United States, United Kingdom and France. Findings We find prevalence estimates of cigarette tax avoidance/evasion vary substantially between countries and across time. In Canada, France and the United Kingdom, more than 10% of smokers report last purchasing cigarettes from low or untaxed sources while in Malaysia, some prevalence estimates suggest substantial cigarette tax avoidance/evasion. We also find important associations between household income and education and the likelihood to engage in tax avoidance/evasion. These associations, however, vary both in

Estimation of tax evasion and the effectiveness of tax collection for Thailand

OpenAIRE

Janbunjong, Pichit

2009-01-01

ABSTRACT Low tax revenue is an acute problem for the Thai Government, one which causes a lack of funds for much needed economic and social development. The cause of the low tax revenue is ineffective tax administration. Thus the purpose of this research was to measure the tax effectiveness in Thailand. The review presents the popular Tanzi’s monetary approach for estimating the level of tax evasion and it has resulted in the hypothesis that tax evasion generally increases ...

Adversarial Feature Selection Against Evasion Attacks.

Science.gov (United States)

Zhang, Fei; Chan, Patrick P K; Biggio, Battista; Yeung, Daniel S; Roli, Fabio

2016-03-01

Pattern recognition and machine learning techniques have been increasingly adopted in adversarial settings such as spam, intrusion, and malware detection, although their security against well-crafted attacks that aim to evade detection by manipulating data at test time has not yet been thoroughly assessed. While previous work has been mainly focused on devising adversary-aware classification algorithms to counter evasion attempts, only few authors have considered the impact of using reduced feature sets on classifier security against the same attacks. An interesting, preliminary result is that classifier security to evasion may be even worsened by the application of feature selection. In this paper, we provide a more detailed investigation of this aspect, shedding some light on the security properties of feature selection against evasion attacks. Inspired by previous work on adversary-aware classifiers, we propose a novel adversary-aware feature selection model that can improve classifier security against evasion attacks, by incorporating specific assumptions on the adversary's data manipulation strategy. We focus on an efficient, wrapper-based implementation of our approach, and experimentally validate its soundness on different application examples, including spam and malware detection.

Cytomegalovirus immune evasion of myeloid lineage cells.

Science.gov (United States)

Brinkmann, Melanie M; Dağ, Franziska; Hengel, Hartmut; Messerle, Martin; Kalinke, Ulrich; Čičin-Šain, Luka

2015-06-01

Cytomegalovirus (CMV) evades the immune system in many different ways, allowing the virus to grow and its progeny to spread in the face of an adverse environment. Mounting evidence about the antiviral role of myeloid immune cells has prompted the research of CMV immune evasion mechanisms targeting these cells. Several cells of the myeloid lineage, such as monocytes, dendritic cells and macrophages, play a role in viral control, but are also permissive for CMV and are naturally infected by it. Therefore, CMV evasion of myeloid cells involves mechanisms that qualitatively differ from the evasion of non-CMV-permissive immune cells of the lymphoid lineage. The evasion of myeloid cells includes effects in cis, where the virus modulates the immune signaling pathways within the infected myeloid cell, and those in trans, where the virus affects somatic cells targeted by cytokines released from myeloid cells. This review presents an overview of CMV strategies to modulate and evade the antiviral activity of myeloid cells in cis and in trans.

Profit Tax Evasion Under Oligopoly With Endogenous Market Structure

OpenAIRE

Goerke, Laszlo; Runkel, Marco

2006-01-01

This note investigates the impact of profit tax evasion on firms' output decisions in a Cournot oligopoly setting in which the market structure is determined endogenously. It is shown that tax evasion intensifies market entry and raises aggregate output, while production of each incumbent firm decreases. Therefore, tax evasion choices affect activity decisions and an evadable profit tax distorts the market outcome.

Cultural Norms, the Persistence of Tax Evasion, and Economic Growth

OpenAIRE

Dimitrios Varvarigos

2015-01-01

I study the effects of tax evasion on economic growth by focusing on the cultural aspects of tax compliance and their effect on the extensive margin of tax evasion. A cultural norm that determines the contemptibility of tax dodging practices links the past incidence of tax evasion with the tax payers’ current incentives to conceal sources of income. This dynamic complementarity may lead to multiple equilibria in the evolution of tax evasion. Due to the latter’s effect on capital accumulation,...

Cigarette tax avoidance and evasion: findings from the International Tobacco Control Policy Evaluation (ITC) Project.

Science.gov (United States)

Guindon, G Emmanuel; Driezen, Pete; Chaloupka, Frank J; Fong, Geoffrey T

2014-03-01

Decades of research have produced overwhelming evidence that tobacco taxes reduce tobacco use and increase government tax revenue. The magnitude and effectiveness of taxes in reducing tobacco use provide an incentive for tobacco users, manufacturers and others, most notably criminal networks, to devise ways to avoid or evade tobacco taxes. Consequently, tobacco tax avoidance and tax evasion can reduce the public health and fiscal benefit of tobacco taxes. First, this study aims to document, using data from the International Tobacco Control Policy Evaluation Project (ITC), levels and trends in cigarette users' tax avoidance and tax evasion behaviour in a sample of 16 low-, middle- and high-income countries. Second, this study explores factors associated with cigarette tax avoidance and evasion. We used data from ITC surveys conducted in 16 countries to estimate the extent and type of cigarette tax avoidance/evasion between countries and across time. We used self-reported information about the source of a smoker's last purchase of cigarettes or self-reported packaging information, or similar information gathered by the interviewers during face-to-face interviews to measure tax avoidance/evasion behaviours. We used generalised estimating equations to explore individual-level factors that may affect the likelihood of cigarette tax avoidance or evasion in Canada, the USA, the UK and France. We found prevalence estimates of cigarette tax avoidance/evasion vary substantially between countries and across time. In Canada, France and the UK, more than 10% of smokers reported last purchasing cigarettes from low or untaxed sources, while in Malaysia some prevalence estimates suggested substantial cigarette tax avoidance/evasion. We also found important associations between household income and education and the likelihood to engage in tax avoidance/evasion. These associations, however, varied both in direction and magnitude across countries.

Determination of mercury evasion in a contaminated headwater stream.

Science.gov (United States)

Maprani, Antu C; Al, Tom A; Macquarrie, Kerry T; Dalziel, John A; Shaw, Sean A; Yeats, Phillip A

2005-03-15

Evasion from first- and second-order streams in a watershed may be a significant factor in the atmospheric recycling of volatile pollutants such as mercury; however, methods developed for the determination of Hg evasion rates from larger water bodies are not expected to provide satisfactory results in highly turbulent and morphologically complex first- and second-order streams. A new method for determining the Hg evasion rates from these streams, involving laboratory gas-indexing experiments and field tracer tests, was developed in this study to estimate the evasion rate of Hg from Gossan Creek, a first-order stream in the Upsalquitch River watershed in northern New Brunswick, Canada. Gossan Creek receives Hg-contaminated groundwater discharge from a gold mine tailings pile. Laboratory gas-indexing experiments provided the ratio of gas-exchange coefficients for zero-valent Hg to propane (tracer gas) of 0.81+/-0.16, suggesting that the evasion mechanism in highly turbulent systems can be described by the surface renewal model with an additional component of enhanced gas evasion probably related to the formation of bubbles. Deliberate field tracer tests with propane and chloride tracers were found to be a reliable and practical method for the determination of gas-exchange coefficients for small streams. Estimation of Hg evasion from the first 1 km of Gossan Creek indicates that about 6.4 kg of Hg per year is entering the atmosphere, which is a significant fraction of the regional sources of Hg to the atmosphere.

Intraguild predation reduces redundancy of predator species in multiple predator assemblage.

Science.gov (United States)

Griffen, Blaine D; Byers, James E

2006-07-01

1. Interference between predator species frequently decreases predation rates, lowering the risk of predation for shared prey. However, such interference can also occur between conspecific predators. 2. Therefore, to understand the importance of predator biodiversity and the degree that predator species can be considered functionally interchangeable, we determined the degree of additivity and redundancy of predators in multiple- and single-species combinations. 3. We show that interference between two invasive species of predatory crabs, Carcinus maenas and Hemigrapsus sanguineus, reduced the risk of predation for shared amphipod prey, and had redundant per capita effects in most multiple- and single-species predator combinations. 4. However, when predator combinations with the potential for intraguild predation were examined, predator interference increased and predator redundancy decreased. 5. Our study indicates that trophic structure is important in determining how the effects of predator species combine and demonstrates the utility of determining the redundancy, as well as the additivity, of multiple predator species.

Tax design-tax evasion relationship in Serbia: New empirical approach to standard theoretical model

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Ranđelović Saša

2015-01-01

Full Text Available This paper provides evidence on the impact of the change in income tax rates and the degree of its progressivity on the scale of labour taxes evasion in Serbia, using the tax-benefit microsimulation model and econometric methods, on 2007 Living Standard Measurement Survey data. The empirical analysis is based on novel assumption that individual's tax evasion decision depends on a change in disposable income, which is captured by the variation in their Effective Marginal Tax Rates (EMTR, rather than on a change in after-tax income. The results suggest that the elasticity of tax evasion to EMTR equals -0.3, confirming the Yitzhaki's theory, while the propensity to evade is decreasing in the level of wages and increasing in the level of self-employment income. The results also show that introduction of revenue-neutral, progressive taxation of labour income would lead to increase in labour tax evasion by 1 percentage point.

Tax Evasion and the Shadow Economy

OpenAIRE

Oliver Reimers

2015-01-01

Leading scholars examine recent evidence from theoretical and empirical research on tax compliance and tax evasion, and provide an in-depth analysis of underlying methods. Strategies to fight tax evasion are evaluated and the motivations behind it are explored, as are the impact and size of the shadow economy in Europe. As well as promoting a better understanding of the issues, this book intends to stimulate further debate and, in so doing, broaden the exchange of ideas and concepts.

A Stochastic Growth Model with Income Tax Evasion: Implications for Australia

OpenAIRE

Ratbek Dzhumashev; Emin Gahramanov

2009-01-01

In this paper we develop a stochastic endogenous growth model augmented with income tax evasion. Our model avoids some existing discrepancies between empirical evidence and theoretical predictions of traditional tax evasion models. Further, we show that: i) productive government expenditures play an important role in affecting economy's tax evasion rate; ii) the average marginal income tax rate in Australia come close to the optimal; and iii) the phenomenon of tax evasion is not an excuse for...

Small Business Tax Evasion, is There a Case of Internal Finance?

Directory of Open Access Journals (Sweden)

Ilirjan Lipi

2017-04-01

Full Text Available As long as there are taxes, the incentive for evasion will exist as well. Studies for tax evasion are of interest in different fields like that of economics, public finance, personal finance, business administration, business finance, financial accounting, in the banking system etc. However, there are only a few studies about the internal causes and financial incentives that oblige decision-makers of small firms towards tax evasion. When we refer to business tax evasion, always brings to mind sensational cases of large businesses that evade taxes, but business tax evasion is a widespread phenomenon even to small firms. To be more competitive, small business must have a consistently entrepreneurial orientation, but limited financing prevents this, therefore the business savings from tax evasion is believed to be an internally funding path. The restrictions on small firms financing often make them orientate more toward internal generation of funds, which also has few alternatives. As a way to internal saving, firms often find tax evasion, which is not only a deviant and unethical behavior, but also puts firms into many difficulties in the long run. Consequently, the study aims to discuss the phenomenon of tax evasion in the managerial practice of small business in an Albanian region, as well as its financial cause as is perceived by the small business. The study findings report that the deviant behavior of businesses from taxes considers the need for internal financing as an important reason. The study concluded that savings from tax evasion is an alternative of internal financing primarily for small and early-staged firms, and that if entrepreneurs are capable of a good business model and competitive strategy, they will not need to make evasion.

Evasion of added isotopic mercury from a northern temperate lake

Science.gov (United States)

Southworth, G.; Lindberg, S.; Hintelmann, H.; Amyot, M.; Poulain, A.; Bogle, M.; Peterson, M.; Rudd, J.; Harris, R.; Sandilands, K.; Krabbenhoft, D.; Olsen, M.

2007-01-01

Isotopically enriched Hg (90% 202Hg) was added to a small lake in Ontario, Canada, at a rate equivalent to approximately threefold the annual direct atmospheric deposition rate that is typical of the northeastern United States. The Hg spike was thoroughly mixed into the epilimnion in nine separate events at two-week intervals throughout the summer growing season for three consecutive years. We measured concentrations of spike and ambient dissolved gaseous Hg (DGM) concentrations in surface water and the rate of volatilization of Hg from the lake on four separate, week-long sampling periods using floating dynamic flux chambers. The relationship between empirically measured rates of spike-Hg evasion were evaluated as functions of DGM concentration, wind velocity, and solar illumination. No individual environmental variable proved to be a strong predictor of the evasion flux. The DGM-normalized flux (expressed as the mass transfer coefficient, k) varied with wind velocity in a manner consistent with existing models of evasion of volatile solutes from natural waters but was higher than model estimates at low wind velocity. The empirical data were used to construct a description of evasion flux as a function of total dissolved Hg, wind, and solar illumination. That model was then applied to data for three summers for the experiment to generate estimates of Hg re-emission from the lake surface to the atmosphere. Based on ratios of spike Hg to ambient Hg in DGM and dissolved total Hg pools, ratios of DGM to total Hg in spike and ambient Hg pools, and flux estimates of spike and ambient Hg, we concluded that the added Hg spike was chemically indistinguishable from the ambient Hg in its behavior. Approximately 45% of Hg added to the lake over the summer was lost via volatilization. ?? 2007 SETAC.

L'evasione in Italia e nei paesi OCSE: evidenze empiriche, determinanti ed effetti economici (Evasion in Italy and in OECD countries: empirical evidence, determinants and economic effects

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M. MARÈ

2013-10-01

Full Text Available The paper analyses evasion in terms of size and its main determinants, and discusses some of the measures to reduce its extension. Instead of attempting a new estimate of evasion, the author uses the many existing estimates and compares them, highlighting their strengths and weaknesses. The available data on the underground economy and fiscal evasion in Italy and in major OECD countries is shown. Then, after recalling its effects on public budgets, the other economic effects of evasion are discussed. Some determinants of tax evasion, in particular those that appear most significant for our country, are then analysed. Finally, major issues of economic policy and measures to reduce tax evasion are discussed.JEL: H26

Issues, Challenges and Problems with Tax Evasion: The Institutional Factors Approach

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Mohd Rizal Palil

2016-08-01

Full Text Available Tax evasion, particularly in developing countries is a debatable issue. Evasion is a disease and needs to be minimized so that the black economy or hidden economy can be mitigated. This paper attempts to reveal the determinants of tax evasion from the institutional perspectives. The objective of this study is to identify the determinants of tax evasion a decade after the introduction of a Self-Assessment System (SAS. Three institutional perspectives of the determinants of tax evasion were examined, namely the probability of being detected, the role of the tax authority and the complexity of the tax system. The results suggested that the complexity of the system, and the probability of being detected had a significant impact on tax evasion. The results of this study could possibly contribute to the body of knowledge in lieu of combating tax evasion, as well as being an input to tax administrators and policymakers into which ways the determinants can affect compliance. The findings also provide an indicator for tax administrators of the relative importance of the tax system in assisting with the design of tax education programs, simplifying tax systems and developing a wider understanding of taxpayers’ behavior.

Conic surveillance evasion

NARCIS (Netherlands)

Lewin, J.; Olsder, G.J.

1979-01-01

A surveillance-evasion differential game of degree with a detection zone in the shape of a two-dimensional cone is posed. The nature of the optimal strategies and the singular phenomena of the value function are described and correlated to subsets of the space of all possible parameter combinations,

Identifying Bacterial Immune Evasion Proteins Using Phage Display.

Science.gov (United States)

Fevre, Cindy; Scheepmaker, Lisette; Haas, Pieter-Jan

2017-01-01

Methods aimed at identification of immune evasion proteins are mainly rely on in silico prediction of sequence, structural homology to known evasion proteins or use a proteomics driven approach. Although proven successful these methods are limited by a low efficiency and or lack of functional identification. Here we describe a high-throughput genomic strategy to functionally identify bacterial immune evasion proteins using phage display technology. Genomic bacterial DNA is randomly fragmented and ligated into a phage display vector that is used to create a phage display library expressing bacterial secreted and membrane bound proteins. This library is used to select displayed bacterial secretome proteins that interact with host immune components.

Pursuit/evasion in orbit

Science.gov (United States)

Kelley, H. J.; Cliff, E. M.; Lutze, F. H.

1981-01-01

Maneuvers available to a spacecraft having sufficient propellant to escape an antisatellite satellite (ASAT) attack are examined. The ASAT and the evading spacecraft are regarded as being in circular orbits, and equations of motion are developed for the ASAT to commence a two-impulse maneuver sequence. The ASAT employs thrust impulses which yield a minimum-time-to-rendezvous, considering available fuel. Optimal evasion is shown to involve only in-plane maneuvers, and begins as soon as the ASAT launch information is gathered and thrust activation can be initiated. A closest approach, along with a maximum evasion by the target spacecraft, is calculated to be 14,400 ft. Further research to account for ASATs in parking orbit and for generalization of a continuous control-modeled differential game is indicated.

Rank dependent expected utility models of tax evasion.

OpenAIRE

Erling Eide

2001-01-01

In this paper the rank-dependent expected utility theory is substituted for the expected utility theory in models of tax evasion. It is demonstrated that the comparative statics results of the expected utility, portfolio choice model of tax evasion carry over to the more general rank dependent expected utility model.

America’s Underground Economy: Measuring the Size, Growth and Determinants of Income Tax Evasion in the U.S

OpenAIRE

Feige, Edgar L.; Cebula, Richard

2011-01-01

Abstract This study empirically investigates the extent of non compliance with the tax code and the determinants of federal income tax evasion in the U.S. Employing the most recent data we find that 18-19% of total reportable income is not properly reported to the IRS, giving rise to a “tax gap” approaching $500 billion dollars. Three time periods are studied, 1960-2008, 1970-2008, and 1980-2008. It is found across study periods that income tax evasion is an increasing function of the av...

Value added tax evasion and excise duty fraud on fuel market in the Czech Republic

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Pavel Semerád

2012-01-01

Full Text Available This paper deals with analysis of current problems in the motor fuel market. It analyzes bottlenecks in setting the legislative changes in value added tax, excise tax and the legislation concerning fuels. The biggest problem is tax evasions that favor one group of business entities at the expense of another, and also cause that the state loses revenues mainly from indirect taxes. Therefore, attention is directed to quality control of fuels as a means of consumer protection and prevention of tax evasion and ways to combat tax evasion in import, distribution and storage of mineral oils. The examples are the most common errors found in fraudulent companies. Based on the data collected the possible ultimate evasion was estimated. Therefore, I propose that value added tax law should be amended and some other measures to improve supervision by public authorities like tax authorities and customs administration offices should be taken.

Predation on rose galls: parasitoids and predators determine gall size through directional selection.

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Zoltán László

Full Text Available Both predators and parasitoids can have significant effects on species' life history traits, such as longevity or clutch size. In the case of gall inducers, sporadically there is evidence to suggest that both vertebrate predation and insect parasitoid attack may shape the optimal gall size. While the effects of parasitoids have been studied in detail, the influence of vertebrate predation is less well-investigated. To better understand this aspect of gall size evolution, we studied vertebrate predation on galls of Diplolepis rosae on rose (Rosa canina shrubs. We measured predation frequency, predation incidence, and predation rate in a large-scale observational field study, as well as an experimental field study. Our combined results suggest that, similarly to parasitoids, vertebrate predation makes a considerable contribution to mortality of gall inducer larvae. On the other hand, its influence on gall size is in direct contrast to the effect of parasitoids, as frequency of vertebrate predation increases with gall size. This suggests that the balance between predation and parasitoid attack shapes the optimal size of D. rosae galls.

Predator-induced changes in metabolism cannot explain the growth/predation risk tradeoff.

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Ulrich K Steiner

2009-07-01

Full Text Available Defence against predators is usually accompanied by declining rates of growth or development. The classical growth/predation risk tradeoff assumes reduced activity as the cause of these declines. However, in many cases these costs cannot be explained by reduced foraging effort or enhanced allocation to defensive structures under predation risk. Here, we tested for a physiological origin of defence costs by measuring oxygen consumption in tadpoles (Rana temporaria exposed to predation risk over short and long periods of time. The short term reaction was an increase in oxygen consumption, consistent with the "fight-or-flight" response observed in many organisms. The long term reaction showed the opposite pattern: tadpoles reduced oxygen consumption after three weeks exposure to predators, which would act to reduce the growth cost of predator defence. The results point to an instantaneous and reversible stress response to predation risk. This suggests that the tradeoff between avoiding predators and growing rapidly is not caused by changes in metabolic rate, and must be sought in other behavioural or physiological processes.

Tax Rates and Tax Evasion: Evidence from "Missing Imports" in China.

Science.gov (United States)

Fisman, Raymond; Wei, Shang-Jin

2004-01-01

Tax evasion, by its very nature, is difficult to observe. We quantify the effects of tax rates on tax evasion by examining the relationship in China between the tariff schedule and the "evasion gap," which we define as the difference between Hong Kong's reported exports to China at the product level and China's reported imports from Hong…

Fiscal Policy under Indeterminacy and Tax Evasion

DEFF Research Database (Denmark)

Busato, Francesco; Chiarini, Bruno; Marchetti, Enrico

This paper shows under indeterminacy and tax evasion, an increase in corporate,labor or income tax rates pushes the economy into an expansionary pattern.These effects are reversed when the steady state is saddle-path stable.......This paper shows under indeterminacy and tax evasion, an increase in corporate,labor or income tax rates pushes the economy into an expansionary pattern.These effects are reversed when the steady state is saddle-path stable....

Tax Evasion and Economic Growth in an Endogenous Growth Model

OpenAIRE

加藤, 秀弥; KATO, Hideya

2004-01-01

This paper presents an endogenous growth model with tax evasion where government expenditures affect production. An individual evades a tax so as to maximize his or her utility, the tax authority controls the detection probability to maximize net tax revenue, and the government chooses the income tax rate to maximize individuals’ utility. The main conclusions are as follows. First, the optical income tax rate with tax evasion is higher than that without tax evasion. Second, the rise in a ...

International capital tax evasion and the foreign tax credit puzzle

OpenAIRE

Kimberley A. Scharf

2001-01-01

This paper examines the role of international tax evasion for the choice of an optimal foreign tax credit by a capital exporting region. Since a foreign tax credit raises the opportunity cost of concealing foreign source income, it can be employed to discourage evasion activity. The existence of international tax evasion possibilities could thus help rationalize a choice of tax credit in excess of a deduction-equivalent credit level. Our analysis shows that, in general the optimal credit will...

CONTROVERSIAL ASPECTS REGARDING TAX EVASION

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Mircea-Constantin SINESCU

2018-05-01

Full Text Available Throughout the paper, we have highlighted some controversial aspects regarding the crime of tax evasion, referring to some important decisions of the High Court of Cassation and Justice and also of the Bucharest Court of Appeal. Debating upon the impunity provision stated by art. 10 of Law no. 241/2005, the study also sheds light upon the issue of the perspective of the judicial organs regarding the juridical regime of the tax due for dividends. The main focus of the paper leads to the situations when there is legal ground for the tax due for dividends to be considered part of the damage caused by tax evasion crime. The study includes a short analysis of some relevant provisions of the Romanian Fiscal Code and also some aspects deriving from decisions issued by the Administrative and Tax Litigation Chamber of The High Court of Cassation and Justice concerning the legal regime of dividends. Consequently, the authors are presenting both perspectives of the interpretation of the issue regarding the tax due for dividends to be considered part of the damage caused by tax evasion crime, resulting from two decisions of the two Criminal Sections of The Bucharest Court of Appeal, also arguing in favour of the most solid interpretation among them

Staphylococcal Immune Evasion Proteins: Structure, Function, and Host Adaptation.

Science.gov (United States)

Koymans, Kirsten J; Vrieling, Manouk; Gorham, Ronald D; van Strijp, Jos A G

2017-01-01

Staphylococcus aureus is a successful human and animal pathogen. Its pathogenicity is linked to its ability to secrete a large amount of virulence factors. These secreted proteins interfere with many critical components of the immune system, both innate and adaptive, and hamper proper immune functioning. In recent years, numerous studies have been conducted in order to understand the molecular mechanism underlying the interaction of evasion molecules with the host immune system. Structural studies have fundamentally contributed to our understanding of the mechanisms of action of the individual factors. Furthermore, such studies revealed one of the most striking characteristics of the secreted immune evasion molecules: their conserved structure. Despite high-sequence variability, most immune evasion molecules belong to a small number of structural categories. Another remarkable characteristic is that S. aureus carries most of these virulence factors on mobile genetic elements (MGE) or ex-MGE in its accessory genome. Coevolution of pathogen and host has resulted in immune evasion molecules with a highly host-specific function and prevalence. In this review, we explore how these shared structures and genomic locations relate to function and host specificity. This is discussed in the context of therapeutic options for these immune evasion molecules in infectious as well as in inflammatory diseases.

The role of auditing in detecting tax evasion

Directory of Open Access Journals (Sweden)

Vržina Stefan

2016-01-01

Full Text Available Forthcoming paper opens questions about new area of audit operations and a new practical challenge for audit profession - detecting tax frauds. A growing problem of tax evasion, expressed as an act of illegal reduction of tax liabilities, points out to the inability of state authorities to reduce or neutralize tax evasion volume. Created as a consequence of previous fact, forthcoming paper has an objective to examine whether, and in which way, auditing financial statements could contribute to initial signalizing of tax evasion through expressing opinion about veracity and objectivity of accounting statements. Special focus is put on related-party transactions with entities registered in offshore zones. As they progress more and more, these transaction become materially significant, thus becoming a subject of audit examination.

The tax havens between measures of economic stimulation and measures against tax evasion

Directory of Open Access Journals (Sweden)

Manea, A. C.

2010-11-01

Full Text Available In the literature but also in the legal language there are ever-increasingly met the current economic notions of tax havens, offshore companies, offshore law or double taxation. These concepts are encountered, however, in legislative efforts of combating domestic and international business and tax evasion, because such tax havens, although offering financial benefits to individuals or legal residents, make it virtually impossible to control, by the national tax services, the level of imposed income tax and the fees payable by the taxpayer, and all these through operations under the legislation of the States where there are these tax havens. The terminology of tax havens is replaced in recent years with the more discreet terms. of center of international finance or financial haven.

Aspects of random geometric graphs : Pursuit-evasion and treewidth

NARCIS (Netherlands)

Li, A.

2015-01-01

In this thesis, we studied two aspects of random geometric graphs: pursuit-evasion and treewidth. We first studied one pursuit-evasion game: Cops and Robbers. This game, which dates back to 1970s, are studied extensively in recent years. We investigate this game on random geometric graphs, and get

Morphological selection and the evaluation of potential tradeoffs between escape from predators and the climbing of waterfalls in the Hawaiian stream goby Sicyopterus stimpsoni.

Science.gov (United States)

Blob, Richard W; Kawano, Sandy M; Moody, Kristine N; Bridges, William C; Maie, Takashi; Ptacek, Margaret B; Julius, Matthew L; Schoenfuss, Heiko L

2010-12-01

Environmental pressures may vary over the geographic range of a species, exposing subpopulations to divergent functional demands. How does exposure to competing demands shape the morphology of species and influence the divergence of populations? We explored these questions by performing selection experiments on juveniles of the Hawaiian goby Sicyopterus stimpsoni, an amphidromous fish that exhibits morphological differences across portions of its geographic range where different environmental pressures predominate. Juvenile S. stimpsoni face two primary and potentially opposing selective pressures on body shape as they return from the ocean to freshwater streams on islands: (1) avoiding predators in the lower reaches of a stream; and (2) climbing waterfalls to reach the habitats occupied by adults. These pressures differ in importance across the Hawaiian Islands. On the youngest island, Hawai'i, waterfalls are close to shore, thereby minimizing exposure to predators and placing a premium on climbing performance. In contrast, on the oldest major island, Kaua'i, waterfalls have eroded further inland, lengthening the exposure of juveniles to predators before migrating juveniles begin climbing. Both juvenile and adult fish show differences in body shape between these islands that would be predicted to improve evasion of predators by fish from Kaua'i (e.g., taller bodies that improve thrust) and climbing performance for fish from Hawai'i (e.g., narrower bodies that reduce drag), matching the prevailing environmental demand on each island. To evaluate how competing selection pressures and functional tradeoffs contribute to the divergence in body shape observed in S. stimpsoni, we compared selection imposed on juvenile body shape by (1) predation by the native fish Eleotris sandwicensis versus (2) climbing an artificial waterfall (∼100 body lengths). Some variables showed opposing patterns of selection that matched predictions: for example, survivors of predation had

Analysis of Driver Evasive Maneuvering Prior to Intersection Crashes Using Event Data Recorders.

Science.gov (United States)

Scanlon, John M; Kusano, Kristofer D; Gabler, Hampton C

2015-01-01

Intersection crashes account for over 4,500 fatalities in the United States each year. Intersection Advanced Driver Assistance Systems (I-ADAS) are emerging vehicle-based active safety systems that have the potential to help drivers safely navigate across intersections and prevent intersection crashes and injuries. The performance of an I-ADAS is expected to be highly dependent upon driver evasive maneuvering prior to an intersection crash. Little has been published, however, on the detailed evasive kinematics followed by drivers prior to real-world intersection crashes. The objective of this study was to characterize the frequency, timing, and kinematics of driver evasive maneuvers prior to intersection crashes. Event data recorders (EDRs) downloaded from vehicles involved in intersection crashes were investigated as part of NASS-CDS years 2001 to 2013. A total of 135 EDRs with precrash vehicle speed and braking application were downloaded to investigate evasive braking. A smaller subset of 59 EDRs that collected vehicle yaw rate was additionally analyzed to investigate evasive steering. Each vehicle was assigned to one of 3 precrash movement classifiers (traveling through the intersection, completely stopped, or rolling stop) based on the vehicle's calculated acceleration and observed velocity profile. To ensure that any significant steering input observed was an attempted evasive maneuver, the analysis excluded vehicles at intersections that were turning, driving on a curved road, or performing a lane change. Braking application at the last EDR-recorded time point was assumed to indicate evasive braking. A vehicle yaw rate greater than 4° per second was assumed to indicate an evasive steering maneuver. Drivers executed crash avoidance maneuvers in four-fifths of intersection crashes. A more detailed analysis of evasive braking frequency by precrash maneuver revealed that drivers performing complete or rolling stops (61.3%) braked less often than drivers

Object and subject of evasion of taxes and other compulsory payments

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Koval L.

2014-01-01

Full Text Available The paper is devoted to such topical issue of Criminal Law as Object and Subject of Evasion of Taxes and Other Compulsory Payments. There are analyzed researched crime determination problems, which are connected with subject and object of tax and other compulsory payments evasion. In the course of the research, the author has made the conclusions that the object of the evasion of taxes and other compulsory payments group is the national economic interests. The direct object is the national economic interests in the sphere of state revenues or the national fiscal interests. While analyzing the law and regulations it is concluded that the subject of the evasion of taxes and other compulsory payments is the tax base (income, property, expenses and consumption, taxes, state and local government fees, as well as other payments determined by the State. The author has also concluded that the subject of the evasion of taxes and other compulsory payments does not include increase in the tax principal debt, fine and late charge, which are covered by the financial responsibility. The subject of the evasion of taxes and other compulsory payments may not include also income from illegal activity or proceeds resulting from criminal offences.

The economic approach to the problem of tax evasion and recommendations for Serbia

Directory of Open Access Journals (Sweden)

Milosavljević Valentina

2016-01-01

Full Text Available Tax evasion is a global problem and it has severe consequences for every country, regardless of differences in socio-economic and political structure. The basis for tax criminal offenses is embodied in different manifestations of tax evasion, especially when taking into account that tax evasion is also the most important form of informal economy. Since the taxation achieves not only fiscal, but also objectives in the field of economic and social policy, tax evasion has consequences on the economic and socio-political level. After introductory considerations, the paper shows the topicality of this issue, then the analysis of theoretical and practical features of tax evasion, as the basic fiscal criminal offense in the new Criminal Law of the Republic of Serbia, while the economic approach to the problem of tax evasion is based on an analysis of individual behavior of taxpayers.

IMPACT OF TAX EVASION ON THE ECONOMIC GROWTH IN THE EUROPEAN UNION

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FLORIN BOȘTINĂ

2017-12-01

Full Text Available The relevance of the research topic emerges from the fact that an important part of the fiscal revenues is lost annually through activities of fiscal planning, fiscal circumvention and tax evasion, undertaken by the private sector. In this respect, the aim of the paper is to estimate, by using the econometric analysis, the impact of tax evasion on the economic growth in the European Union for the period 1997-2010 for which the data was available. For the tax evasion it have been used index as a proxy that optimizes by maximum. Thus the main hypothesis (that the index tax evasion positively influences the economic growth was not rejected, even after including some specific control variables in the regressive models. In other words, as tax evasion is increased the economic growth is likely to decrease.

International Tax Evasion in the Current Geopolitical Context

OpenAIRE

Constantin Sergiu-Bogdan

2014-01-01

Tax evasion means the avoidance of declaring and paying the tax obligations. Through the manifestation of this phenomenon, the state incomes are reduced, the governments not being capable of complying with their tasks. As the economic globalization progresses, tax evasion becomes international thanks to the tax havens which usually are small states that provide various tax facilities to those who want to carry out their activity through their agency, especially through offshore companies. It ...

Equilibrium Implications of Fiscal Policy with Tax Evasion

DEFF Research Database (Denmark)

Busato, Francesco; Chiarini, Bruno; Rey, Guido M.

This paper studies equilibrium effects of fiscal policy disturbances within a dynamic general equilibrium model where tax evasion and underground activities are explicitly incorporated. There are three mainresults. (i) The underground sector mitigates the distortionary impact of fiscal policies......, while lesseningthe drop (and the rise) of aggregate production after restrictive (expansionary) tax shocks. (ii) Taxevasion and underground economy can rationalize expansionary response to contractionary fiscal policies;(iii) A dynamic general equilibrium with tax evasion gives a rational justification...

Android Rooting: An Arms Race between Evasion and Detection

Directory of Open Access Journals (Sweden)

Long Nguyen-Vu

2017-01-01

Full Text Available We present an arms race between rooting detection and rooting evasion. We investigate different methods to detect rooted device at both Java and native level and evaluate the counterattack from major hooking tools. To this end, an extensive study of Android rooting has been conducted, which includes the techniques to root the device and make it invisible to the detection of mobile antimalware product. We then analyze the evasion loopholes and in turn enhance our rooting detection tool. We also apply evasion techniques on rooted device and compare our work with 92 popular root checking applications and 18 banking and finance applications. Results show that most of them do not suffice and can be evaded through API hooking or static file renaming. Furthermore, over 28000 Android applications have been analyzed and evaluated in order to diagnose the characteristics of rooting in recent years. Our study shows that rooting has become more and more prevalent as an inevitable trend, and it raises big security concerns regarding detection and evasion. As a proof of concept, we have published our rooting detection application to Google Play Store to demonstrate the work presented in this paper.

Evasion of Neutrophil Extracellular Traps by Respiratory Pathogens.

Science.gov (United States)

Storisteanu, Daniel M L; Pocock, Joanna M; Cowburn, Andrew S; Juss, Jatinder K; Nadesalingam, Angalee; Nizet, Victor; Chilvers, Edwin R

2017-04-01

The release of neutrophil extracellular traps (NETs) is a major immune mechanism intended to capture pathogens. These histone- and protease-coated DNA structures are released by neutrophils in response to a variety of stimuli, including respiratory pathogens, and have been identified in the airways of patients with respiratory infection, cystic fibrosis, acute lung injury, primary graft dysfunction, and chronic obstructive pulmonary disease. NET production has been demonstrated in the lungs of mice infected with Staphylococcus aureus, Klebsiella pneumoniae, and Aspergillus fumigatus. Since the discovery of NETs over a decade ago, evidence that "NET evasion" might act as an immune protection strategy among respiratory pathogens, including group A Streptococcus, Bordetella pertussis, and Haemophilus influenzae, has been growing, with the majority of these studies being published in the past 2 years. Evasion strategies fall into three main categories: inhibition of NET release by down-regulating host inflammatory responses; degradation of NETs using pathogen-derived DNases; and resistance to the microbicidal components of NETs, which involves a variety of mechanisms, including encapsulation. Hence, the evasion of NETs appears to be a widespread strategy to allow pathogen proliferation and dissemination, and is currently a topic of intense research interest. This article outlines the evidence supporting the three main strategies of NET evasion-inhibition, degradation, and resistance-with particular reference to common respiratory pathogens.

Tänapäevased liikursuurtükid / Anna Kern

Index Scriptorium Estoniae

Kern, Anna

2013-01-01

Riigikaitse arengukavas (a. 2013-2022) on ette nähtud võimalused 1. jalaväebrigaadile hankida tänapäevased liikursuurtükid. Ülevaade liikursuurtükkide loomisest, kasutamisest sõdades ja tänapäevase liikursuurtüki iseloomustus. Näiteid erinevtest liikursuurtükkidest: Archer (Rootsi), Panzerhaubitze 2000 (Saksamaa), Caesar (Prantsusmaa), M777 (USA). Lisatud tabel tehniliste andmetega

White-tailed deer age ratios as herd management and predator impact measures in Pennsylvania

Science.gov (United States)

Rosenberry, Christopher S.; Norton, Andrew S.; Diefenbach, Duane R.; Fleegle, Jeannine T.; Wallingford, Bret D.

2011-01-01

A review of the Pennsylvania Game Commission's (PGC) deer management program and public concern about predator impacts on deer (Odocoileus virginianus) populations compelled the PGC to investigate the role of age ratios in developing management recommendations. Age ratios, such as proportion of juveniles in the antlerless harvest, may provide an index to population productivity and predator impacts. We estimated proportion of juveniles in the antlerless harvest from hunter-killed deer, population trends using the Pennsylvania (USA) sex–age–kill model, and reproduction from road-killed females. Using these estimates and a simulation model, we concluded that no single age-ratio value would serve as a reliable measure of population status. Wildlife Management Unit-specific trends in proportion of juveniles in the antlerless harvest and population trends provided the most relevant management information. We also provide an example decision chart to guide management actions in response to declining age ratios in the harvest. Although predator management activities and juvenile survival studies are often desired by the public, our decision-chart example indicated a number of deer management options exist before investing resources in predator management activities and juvenile survival studies.

Ultrasonic predator-prey interactions in water-convergent evolution with insects and bats in air?

Science.gov (United States)

Wilson, Maria; Wahlberg, Magnus; Surlykke, Annemarie; Madsen, Peter Teglberg

2013-01-01

Toothed whales and bats have independently evolved biosonar systems to navigate and locate and catch prey. Such active sensing allows them to operate in darkness, but with the potential cost of warning prey by the emission of intense ultrasonic signals. At least six orders of nocturnal insects have independently evolved ears sensitive to ultrasound and exhibit evasive maneuvers when exposed to bat calls. Among aquatic prey on the other hand, the ability to detect and avoid ultrasound emitting predators seems to be limited to only one subfamily of Clupeidae: the Alosinae (shad and menhaden). These differences are likely rooted in the different physical properties of air and water where cuticular mechanoreceptors have been adapted to serve as ultrasound sensitive ears, whereas ultrasound detection in water have called for sensory cells mechanically connected to highly specialized gas volumes that can oscillate at high frequencies. In addition, there are most likely differences in the risk of predation between insects and fish from echolocating predators. The selection pressure among insects for evolving ultrasound sensitive ears is high, because essentially all nocturnal predation on flying insects stems from echolocating bats. In the interaction between toothed whales and their prey the selection pressure seems weaker, because toothed whales are by no means the only marine predators placing a selection pressure on their prey to evolve specific means to detect and avoid them. Toothed whales can generate extremely intense sound pressure levels, and it has been suggested that they may use these to debilitate prey. Recent experiments, however, show that neither fish with swim bladders, nor squid are debilitated by such signals. This strongly suggests that the production of high amplitude ultrasonic clicks serve the function of improving the detection range of the toothed whale biosonar system rather than debilitation of prey.

Ultrasonic predator-prey interactions in water– convergent evolution with insects and bats in air?

Directory of Open Access Journals (Sweden)

Maria eWilson

2013-06-01

Full Text Available Toothed whales and bats have independently evolved biosonar systems to navigate and locate and catch prey. Such active sensing allows them to operate in darkness, but with the potential cost of warning prey by the emission of intense ultrasonic signals. At least six orders of nocturnal insects have independently evolved ears sensitive to ultrasound and exhibit evasive maneuvers when exposed to bat calls. Among aquatic prey on the other hand, the ability to detect and avoid ultrasound emitting predators seems to be limited to only one subfamily of Clupeidae: the Alosinae (shad and menhaden. These differences are likely rooted in the different physical properties of air and water where cuticular mechanoreceptors have been adapted to serve as ultrasound sensitive ears, whereas ultrasound detection in water have called for sensory cells mechanically connected to highly specialized gas volumes that can oscillate at high frequencies. In addition, there are most likely differences in the risk of predation between insects and fish from echolocating predators. The selection pressure among insects for evolving ultrasound sensitive ears is high, because essentially all nocturnal predation on flying insects stems from echolocating bats. In the interaction between toothed whales and their prey the selection pressure seems weaker, because toothed whales are by no means the only marine predators placing a selection pressure on their prey to evolve specific means to detect and avoid them.Toothed whales can generate extremely intense sound pressure levels, and it has been suggested that they may use these to debilitate prey. Recent experiments however, show that neither fish with swim bladder, nor squid are debilitated by such signals. This strongly suggests that the production of high amplitude ultrasonic clicks serve the function of improving the detection range of the toothed whale biosonar system rather than debilitation of prey.

Novel Evasion Mechanisms of the Classical Complement Pathway.

Science.gov (United States)

Garcia, Brandon L; Zwarthoff, Seline A; Rooijakkers, Suzan H M; Geisbrecht, Brian V

2016-09-15

Complement is a network of soluble and cell surface-associated proteins that gives rise to a self-amplifying, yet tightly regulated system with fundamental roles in immune surveillance and clearance. Complement becomes activated on the surface of nonself cells by one of three initiating mechanisms known as the classical, lectin, and alternative pathways. Evasion of complement function is a hallmark of invasive pathogens and hematophagous organisms. Although many complement-inhibition strategies hinge on hijacking activities of endogenous complement regulatory proteins, an increasing number of uniquely evolved evasion molecules have been discovered over the past decade. In this review, we focus on several recent investigations that revealed mechanistically distinct inhibitors of the classical pathway. Because the classical pathway is an important and specific mediator of various autoimmune and inflammatory disorders, in-depth knowledge of novel evasion mechanisms could direct future development of therapeutic anti-inflammatory molecules. Copyright © 2016 by The American Association of Immunologists, Inc.

Large Lakes Dominate CO2 Evasion From Lakes in an Arctic Catchment

Science.gov (United States)

Rocher-Ros, Gerard; Giesler, Reiner; Lundin, Erik; Salimi, Shokoufeh; Jonsson, Anders; Karlsson, Jan

2017-12-01

CO2 evasion from freshwater lakes is an important component of the carbon cycle. However, the relative contribution from different lake sizes may vary, since several parameters underlying CO2 flux are size dependent. Here we estimated the annual lake CO2 evasion from a catchment in northern Sweden encompassing about 30,000 differently sized lakes. We show that areal CO2 fluxes decreased rapidly with lake size, but this was counteracted by the greater overall coverage of larger lakes. As a result, total efflux increased with lake size and the single largest lake in the catchment dominated the CO2 evasion (53% of all CO2 evaded). By contrast, the contribution from the smallest ponds (about 27,000) was minor (evasion at the landscape scale.

Predictive Virtual Infection Modeling of Fungal Immune Evasion in Human Whole Blood

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Maria T. E. Prauße

2018-03-01

Full Text Available Bloodstream infections by the human-pathogenic fungi Candida albicans and Candida glabrata increasingly occur in hospitalized patients and are associated with high mortality rates. The early immune response against these fungi in human blood comprises a concerted action of humoral and cellular components of the innate immune system. Upon entering the blood, the majority of fungal cells will be eliminated by innate immune cells, i.e., neutrophils and monocytes. However, recent studies identified a population of fungal cells that can evade the immune response and thereby may disseminate and cause organ dissemination, which is frequently observed during candidemia. In this study, we investigate the so far unresolved mechanism of fungal immune evasion in human whole blood by testing hypotheses with the help of mathematical modeling. We use a previously established state-based virtual infection model for whole-blood infection with C. albicans to quantify the immune response and identified the fungal immune-evasion mechanism. While this process was assumed to be spontaneous in the previous model, we now hypothesize that the immune-evasion process is mediated by host factors and incorporate such a mechanism in the model. In particular, we propose, based on previous studies that the fungal immune-evasion mechanism could possibly arise through modification of the fungal surface by as of yet unknown proteins that are assumed to be secreted by activated neutrophils. To validate or reject any of the immune-evasion mechanisms, we compared the simulation of both immune-evasion models for different infection scenarios, i.e., infection of whole blood with either C. albicans or C. glabrata under non-neutropenic and neutropenic conditions. We found that under non-neutropenic conditions, both immune-evasion models fit the experimental data from whole-blood infection with C. albicans and C. glabrata. However, differences between the immune-evasion models could be

Predictive Virtual Infection Modeling of Fungal Immune Evasion in Human Whole Blood.

Science.gov (United States)

Prauße, Maria T E; Lehnert, Teresa; Timme, Sandra; Hünniger, Kerstin; Leonhardt, Ines; Kurzai, Oliver; Figge, Marc Thilo

2018-01-01

Bloodstream infections by the human-pathogenic fungi Candida albicans and Candida glabrata increasingly occur in hospitalized patients and are associated with high mortality rates. The early immune response against these fungi in human blood comprises a concerted action of humoral and cellular components of the innate immune system. Upon entering the blood, the majority of fungal cells will be eliminated by innate immune cells, i.e., neutrophils and monocytes. However, recent studies identified a population of fungal cells that can evade the immune response and thereby may disseminate and cause organ dissemination, which is frequently observed during candidemia. In this study, we investigate the so far unresolved mechanism of fungal immune evasion in human whole blood by testing hypotheses with the help of mathematical modeling. We use a previously established state-based virtual infection model for whole-blood infection with C. albicans to quantify the immune response and identified the fungal immune-evasion mechanism. While this process was assumed to be spontaneous in the previous model, we now hypothesize that the immune-evasion process is mediated by host factors and incorporate such a mechanism in the model. In particular, we propose, based on previous studies that the fungal immune-evasion mechanism could possibly arise through modification of the fungal surface by as of yet unknown proteins that are assumed to be secreted by activated neutrophils. To validate or reject any of the immune-evasion mechanisms, we compared the simulation of both immune-evasion models for different infection scenarios, i.e., infection of whole blood with either C. albicans or C. glabrata under non-neutropenic and neutropenic conditions. We found that under non-neutropenic conditions, both immune-evasion models fit the experimental data from whole-blood infection with C. albicans and C. glabrata . However, differences between the immune-evasion models could be observed for the

Complement evasion by Bordetella pertussis: implications for improving current vaccines.

Science.gov (United States)

Jongerius, Ilse; Schuijt, Tim J; Mooi, Frits R; Pinelli, Elena

2015-04-01

Bordetella pertussis causes whooping cough or pertussis, a highly contagious disease of the respiratory tract. Despite high vaccination coverage, reported cases of pertussis are rising worldwide and it has become clear that the current vaccines must be improved. In addition to the well-known protective role of antibodies and T cells during B. pertussis infection, innate immune responses such as the complement system play an essential role in B. pertussis killing. In order to evade this complement activation and colonize the human host, B. pertussis expresses several molecules that inhibit complement activation. Interestingly, one of the known complement evasion proteins, autotransporter Vag8, is highly expressed in the recently emerged B. pertussis isolates. Here, we describe the current knowledge on how B. pertussis evades complement-mediated killing. In addition, we compare this to complement evasion strategies used by other bacterial species. Finally, we discuss the consequences of complement evasion by B. pertussis on adaptive immunity and how identification of the bacterial molecules and the mechanisms involved in complement evasion might help improve pertussis vaccines.

A evasão no ensino superior brasileiro Higher education institutions' evasion

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Roberto Leal Lobo e Silva Filho

2007-12-01

Full Text Available Neste trabalho a evasão nas instituições de educação superior no Brasil é estudada com base em dados oficiais, em que se incluem análises regionais dos índices da evasão anual média e da evasão por tipo de instituição. Verifica-se uma correlação negativa entre os índices de evasão e a demanda por curso. Com vistas a possibilitar comparações, são apresentados dados internacionais que indicam que a evasão no Brasil não difere muito das médias internacionais.In this work, evasion in institutions of higher education is studied, based on official data, including regional analyses of annual mean evasion rates and evasion rates by type of institution. It was verified that there is a negative correlation between evasion rates an demand for undergraduate courses. Comparisons with international data are presented, pointing out that the evasion rates in Brazil do not differ a lot from those of other countries.

Complex pattern of immune evasion in MSI colorectal cancer.

Science.gov (United States)

Ozcan, Mine; Janikovits, Jonas; von Knebel Doeberitz, Magnus; Kloor, Matthias

2018-01-01

Mismatch repair (MMR)-deficient cancers accumulate multiple insertion/deletion mutations at coding microsatellites (cMS), which give rise to frameshift peptide neoantigens. The high mutational neoantigen load of MMR-deficient cancers is reflected by pronounced anti-tumoral immune responses of the host and high responsiveness towards immune checkpoint blockade. However, immune evasion mechanisms can interfere with the immune response against MMR-deficient tumors. We here performed a comprehensive analysis of immune evasion in MMR-deficient colorectal cancers, focusing on HLA class I-mediated antigen presentation. 72% of MMR-deficient colorectal cancers of the DFCI database harbored alterations affecting genes involved in HLA class I-mediated antigen presentation, and 54% of these mutations were predicted to abrogate function. Mutations affecting the HLA class I transactivator NLRC5 were observed as a potential new immune evasion mechanism in 26% (6% abrogating) of the analyzed tumors. NLRC5 mutations in MMR-deficient cancers were associated with decreased levels of HLA class I antigen expression. In summary, the majority of MMR-deficient cancers display mutations interfering with HLA class I antigen presentation that reflect active immune surveillance and immunoselection during tumor development. Clinical studies focusing on immune checkpoint blockade in MSI cancer should account for the broad variety of immune evasion mechanisms as potential biomarkers of therapy success.

Cheating, Emotions, and Rationality: An Experiment on Tax Evasion

OpenAIRE

Giorgio Coricelli; Mateus Joffily; Claude Montmarquette; Marie Claire Villeval

2010-01-01

International audience; The economics-of-crime approach usually ignores the emotional cost and benefit of cheating. In this paper, we investigate the relationships between emotions, deception, and rational decision-making by means of an experiment on tax evasion. Emotions are measured by skin conductance responses and self-reports. We show that the intensity of anticipated and anticipatory emotions before reporting positively correlates with both the decision to cheat and the proportion of ev...

Tax Evasion in Romania: New Approaches

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Sebastian George Perpelea

2016-11-01

Full Text Available Tax evasion has existed and will exist, and moreover, it will always be "creative and active" and will represent a current problem for any state. With the emergence of taxes also the phenomenon of "escape" from their path emerged, since the taxes determine the individuals to adopt an avoidance behavior or, at the best, to mitigate them. This phenomenon occurs in all the countries, obviously to varying degrees, starting from the level of individuals, to the level of large companies, it being favored by the legislative hiatuses, sometimes it being even encouraged by legislation, which legislation is drafted and voted by very the people. Thus, in our approach we will try to emphasize the actual causes of tax evasion and the consequences of this phenomenon on the society and the economy.

Defensive responses by a social caterpillar are tailored to different predators and change with larval instar and group size

Science.gov (United States)

McClure, Melanie; Despland, Emma

2011-05-01

Gregariousness in animals is widely accepted as a behavioral adaptation for protection from predation. However, predation risk and the effectiveness of a prey's defense can be a function of several other factors, including predator species and prey size or age. The objective of this study was to determine if the gregarious habit of Malacosoma disstria caterpillars is advantageous against invertebrate natural enemies, and whether it is through dilution or cooperative defenses. We also examined the effects of larval growth and group size on the rate and success of attacks. Caterpillars of M. disstria responded with predator-specific behaviors, which led to increased survival. Evasive behaviors were used against stinkbugs, while thrashing by fourth instar caterpillars and holding on to the silk mat by second instar caterpillars was most efficient against spider attacks. Collective head flicking and biting by groups of both second and fourth instar caterpillars were observed when attacked by parasitoids. Increased larval size decreased the average number of attacks by spiders but increased the number of attacks by both stinkbugs and parasitoids. However, increased body size decreased the success rate of attacks by all three natural enemies and increased handling time for both predators. Larger group sizes did not influence the number of attacks from predators but increased the number of attacks and the number of successful attacks from parasitoids. In all cases, individual risk was lower in larger groups. Caterpillars showed collective defenses against parasitoids but not against the walking predators. These results show that caterpillars use different tactics against different natural enemies. Overall, these tactics are both more diverse and more effective in fourth instar than in second instar caterpillars, confirming that growth reduces predation risk. We also show that grouping benefits caterpillars through dilution of risk, and, in the case of parasitoids, through

A synthesis of rates and controls on elemental mercury evasion in the Great Lakes Basin

International Nuclear Information System (INIS)

Denkenberger, Joseph S.; Driscoll, Charles T.; Branfireun, Brian A.; Eckley, Chris S.; Cohen, Mark; Selvendiran, Pranesh

2012-01-01

Rates of surface-air elemental mercury (Hg 0 ) fluxes in the literature were synthesized for the Great Lakes Basin (GLB). For the majority of surfaces, fluxes were net positive (evasion). Digital land-cover data were combined with representative evasion rates and used to estimate annual Hg 0 evasion for the GLB (7.7 Mg/yr). This value is less than our estimate of total Hg deposition to the area (15.9 Mg/yr), suggesting the GLB is a net sink for atmospheric Hg. The greatest contributors to annual evasion for the basin are agricultural (∼55%) and forest (∼25%) land cover types, and the open water of the Great Lakes (∼15%). Areal evasion rates were similar across most land cover types (range: 7.0–21.0 μg/m 2 -yr), with higher rates associated with urban (12.6 μg/m 2 -yr) and agricultural (21.0 μg/m 2 -yr) lands. Uncertainty in these estimates could be partially remedied through a unified methodological approach to estimating Hg 0 fluxes. - Highlights: ► Considerable variability exists across spatial/temporal scales in Hg 0 evasion rates. ► Methodological approaches vary for estimating and reporting gaseous Hg 0 fluxes. ► Hg 0 evasion from the Great Lakes Basin is estimated at 7.7 Mg/yr (10.2 μg/m 2 -yr). ► Hg flux estimates suggest region is a net sink for atmospheric Hg. ► 95% of Hg 0 evasion in the region is from agriculture, forest, and the Great Lakes. - A synthesis of Hg evasion was conducted and this information was used to develop an estimate of Hg evasion for the Great Lakes Basin.

Seeing Themselves through Borrowed Eyes: Asian Americans in Ethnic Ambivalence/Evasion.

Science.gov (United States)

Tse, Lucy

1998-01-01

Focuses on the second stage of ethnic identity development, Ethnic Ambivalence/Evasion, experienced by Asian Americans through 39 personal narratives. Ethnic Ambivalence/Evasion, one of four identified stages that culminate with ethnic identity incorporation, typically occurs during the years of childhood and adolescence, and so is a stage…

Toward Simulating Realistic Pursuit-Evasion Using a Roadmap-Based Approach

KAUST Repository

Rodriguez, Samuel

2010-01-01

In this work, we describe an approach for modeling and simulating group behaviors for pursuit-evasion that uses a graph-based representation of the environment and integrates multi-agent simulation with roadmap-based path planning. We demonstrate the utility of this approach for a variety of scenarios including pursuit-evasion on terrains, in multi-level buildings, and in crowds. © 2010 Springer-Verlag Berlin Heidelberg.

The underground economy in the U.S.A.: preliminary new evidence on the impact of income tax rates (and other factors on aggregate tax evasion 1975-2008

Directory of Open Access Journals (Sweden)

Richard J. Cebula

2014-12-01

Full Text Available This empirical study seeks to identify determinants of the underground economy in the U.S. in the form of aggregate federal personal income tax evasion over the period 1975-2008, with a specific focus upon the impact of higher federal income tax rates on tax evasion. In this study, we use the most recent data available on aggregate personal income tax evasion, data that are derived from the General Currency Ratio Model and measured in the form of the ratio of unreported AGI to reported AGI. Most other studies of federal income tax evasion for the U.S. do not use data this current. It is found that the impact of increases in the federal income tax rate on aggregate personal income tax evasion may, on balance, be ambiguous, possibly suggesting that the income effect is negative and outweighs the positive substitution effect for the representative taxpayer. It is also found that the degree of aggregate personal income tax evasion may be an increasing function of the percentage of federal personal income tax returns characterized by itemized deductions and a decreasing function of the Tax Reform Act of 1986 (during the first two years of implementation, the ratio of the tax free interest rate yield on high grade municipals to the interest rate yield on ten year Treasury notes, and higher audit rates of filed federal income tax returns (as a measure of risk from tax evasion by IRS personnel. Finally, unpopular wars may provide a secondary benefit for and therefore act as an inducement for greater tax evasion.

Herpesvirus Evasion of Natural Killer Cells.

Science.gov (United States)

De Pelsmaeker, Steffi; Romero, Nicolas; Vitale, Massimo; Favoreel, Herman W

2018-06-01

Natural killer (NK) cells play an important role in the host response against viral infections and cancer development. They are able to kill virus-infected and tumor cells, and they produce different important cytokines that stimulate the antiviral and antitumor adaptive immune response, particularly interferon gamma. NK cells are of particular importance in herpesvirus infections, which is illustrated by systemic and life-threatening herpesvirus disease symptoms in patients with deficiencies in NK cell activity and by the myriad of reports describing herpesvirus NK cell evasion strategies. The latter is particularly obvious for cytomegaloviruses, but increasing evidence indicates that most, if not all, members of the herpesvirus family suppress NK cell activity to some extent. This review discusses the different NK cell evasion strategies described for herpesviruses and how this knowledge may translate to clinical applications. Copyright © 2018 American Society for Microbiology.

Establishing the link between money laundering and tax evasion

OpenAIRE

Storm, Ansia

2013-01-01

No clear link has yet been made between tax evasion and money laundering although many (or all) of the professionals in this field may have already assumed the relation. The aim of the research that was conducted for the purposes of this article was to explore whether there is a clear link between tax evasion and money laundering. This was done by studying the relevant literature available on both subjects. The findings, that there is a clear link between these two offences, we...

Corruption and Tax Evasion = Yolsuzluk ve Vergi Kaçakçılığı

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Sacit Hadi AKDEDE

2006-06-01

Full Text Available Corruption and tax evasion problems have been investigated separately before. Tax evasion is also considered to be a corrupt behavior itself. However, in this paper, corruption is taken to be a bribe taken by a government official and tax evasion is defined as an illegal act to avoid paying taxes by violating tax laws. An interesting research question would be to see whether corruption can induce tax evasion in individuals ? It is found in the paper that the size of bribe can negatively affect tax evasion. It is shown that when a bribe is sufficiently large, taxpayers prefer to pay their taxes voluntarily, not to evade taxes.

A Tax Evasion - Bribery Game: Experimental Evidence from Ukraine

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Volodymyr Bilotkach

2006-06-01

Full Text Available This paper examines the issue of tax evasion by enterprises through underreporting activity. We develop a view of this phenomenon as an equilibrium of the game between a businessman and an imperfectly monitored supervising official, in which a businessman can hide part of his profit and offer bribe to official. We determine conditions under which such tax evasion and bribery become wide-spread in the society, resulting in shadow economy. The game is put into an experimental setting in Kiev, Ukraine, with the emphasis of spreading of the tax evasion and bribery activity in the laboratory setting. We find that once it becomes known that substantial share of subjects playing the role of supervising officials agree to accept bribes from subjects playing the role of businessmen, the latter offer bribes more aggressively. Yet, this in turn does not affect the behavior of subjects playing the role of supervising officials.

Predators

Science.gov (United States)

Young, Donald D.; McCabe, Thomas R.; Ambrose, Robert E.; Garner, Gerald W.; Weiler, Greg J.; Reynolds, Harry V.; Udevitz, Mark S.; Reed, Dan J.; Griffith, Brad; Douglas, David C.; Reynolds, Patricia E.; Rhode, E.B.

2002-01-01

Calving caribou (Rangifer tarandus) of the Central Arctic herd, Alaska, have avoided the infrastructure associated with the complex of petroleum development areas from Prudhoe Bay to Kuparuk (Cameron et al. 1992, Nellemann and Cameron 1998, and Section 4 of this document). Calving females of the Porcupine caribou herd may similarly avoid any oil field roads and pipelines developed in areas traditionally used during the calving and post-calving periods. This may displace the caribou females and calves to areas east and south of the 1002 Area of the Arctic National Wildlife Refuge.Increased calf mortality could occur if calving caribou are displaced into areas that have a higher density of predators, higher rates of predation, or where a higher proportion of the predators regularly use caribou as a food source (Whitten et al. 1992).Our study assessed predation risks to caribou calving in the 1002 Area versus calving in potential displacement areas. Due to funding constraints, our research focused on grizzly bears (Ursus arctos), with wolves (Camus lupus) and golden eagles (Aquila chrysaetos) receiving only cursory attention. Our research objectives were 1) to compare relative abundance of predators within the 1002 Area with that in adjacent peripheral areas, 2) to determine factors affecting predator abundance on the calving grounds, and 3) to quantify the use of caribou as a food source for predators and the importance of caribou to the productivity of predator populations using the coastal plain of the Arctic National Wildlife Refuge.

Evasion Mechanisms Used by Pathogens to Escape the Lectin Complement Pathway

DEFF Research Database (Denmark)

Rosbjerg, Anne; Genster, Ninette; Pilely, Katrine

2017-01-01

the level of activity. The result is a pro-inflammatory response meant to combat foreign microbes. Microbial elimination is, however, not a straight forward procedure; pathogens have adapted to their environment by evolving a collection of evasion mechanisms that circumvent the human complement system....... Complement evasion strategies features different ways of exploiting human complement proteins and moreover features different pathogen-derived proteins that interfere with the normal processes. Accumulated, these mechanisms target all three complement activation pathways as well as the final common part...... of the cascade. This review will cover the currently known lectin pathway evasion mechanisms and give examples of pathogens that operate these to increase their chance of invasion, survival and dissemination....

The Effect of Tax Rates on Fiscal Evasion and Avoidance

OpenAIRE

Mentor Gashi; Halil Kukaj

2016-01-01

Abstract:In order to findelements that destimulate fiscal evasion or avoidance, we have submitted six elements, through the questionnaire, to determine which elements are that destimulate the fiscal evasion and avoidance, and evaluate their impact.This paper is focused in customs duty avoidance.The elements that we have submitted to evaluate their power, are: Powerful control during customs clearance, more efficient post clearance control, probability of subject investigation, higher fines, l...

Asymmetric Information, Tax Evasion and Alternative Instruments of Government Revenue

OpenAIRE

Rangan Gupta

2005-01-01

Using a pure-exchange overlapping generations model, characterized with tax evasion and information asymmetry between the government (the social planner) and the financial intermediaries, we try and seek for the optimal tax and seigniorage plans, derived from the welfare maximizing objective of the social planner. We show that irrespective of whether the economy is characterized by tax evasion, or asymmetric information, a benevolent social planner, maximizing welfare and simultaneously finan...

Evasion in the plane

Science.gov (United States)

Leitmann, G.; Liu, H. S.

1977-01-01

Dynamic systems were considered subject to control by two agents, one of whom desires that no trajectory of the system emanating from outside a given set, intersects that set no matter what the admissible actions of the other agent. Constructive conditions sufficient to yield a feedback control for the agent seeking avoidance were employed to deduce an evader control for the planar pursuit-evasion problem with bounded normal accelerations.

Influence of predator density on nonindependent effects of multiple predator species.

Science.gov (United States)

Griffen, Blaine D; Williamson, Tucker

2008-02-01

Interactions between multiple predator species are frequent in natural communities and can have important implications for shared prey survival. Predator density may be an important component of these interactions between predator species, as the frequency of interactions between species is largely determined by species density. Here we experimentally examine the importance of predator density for interactions between predator species and subsequent impacts on prey. We show that aggressive interactions between the predatory shore crabs Carcinus maenas and Hemigrapsus sanguineus increased with predator density, yet did not increase as fast as negative interactions between conspecifics. At low density, interactions between conspecific and heterospecific predators had similar inhibitory impacts on predator function, whereas conspecific interference was greater than interference from heterospecifics at high predator density. Thus the impact of conspecific interference at high predator density was sufficient in itself that interactions with a second predator species had no additional impact on per capita predation. Spatial and temporal variability in predator density is a ubiquitous characteristic of natural systems that should be considered in studies of multiple predator species.

A VAR Analysis Regarding Tax Evasion and Tax Pressure in Romania

Directory of Open Access Journals (Sweden)

Boștină Florin

2017-01-01

The main aim of the paper is to identify the relationship that exists between tax evasion and tax pressure in Romania, between 2000 and 2013, using an autoregressive vector type of analysis. The VAR model with 3 lags can be considered as representative in order to describe autoregressive links between tax evasion and fiscal pressure in Romania.

General Consideration on Legal Tax Evasion vs. Tax Fraud

Directory of Open Access Journals (Sweden)

Octavia-Daniela Steriopol

2010-12-01

Full Text Available The article is a brief overview of tax evasion as a complex social and economicphenomenon, of utmost importance, that today’s states confront with; its consequences seek to limitas much as possible, by legal and fiscal means, the eradication, which, at this point, is virtuallyimpossible. Tax evasion can be analysed from two points of view, the legal and the illegal aspect ofthe phenomenon or the fiscal fraud. The “fiscal paradises” had a very important role in the last years’activity.

A note on the neutrality of profit taxes with tax evasion and tax avoidance

OpenAIRE

Che-chiang Huang; Horn-in Kuo

2014-01-01

Traditional literature exploring the relationship between production and tax evasion ignores the impact of other activities on these two decisions. This paper incorporates firms' tax avoidance activities into the model of tax evasion. In contrast to conventional results, we find that profit tax is not necessarily neutral. In addition, the independency or separability of tax evasion and production decisions may not hold either whenever tax avoidance is present.

Complex Immune Evasion Strategies in Classical Hodgkin Lymphoma.

Science.gov (United States)

Wein, Frederik; Weniger, Marc A; Höing, Benedikt; Arnolds, Judith; Hüttmann, Andreas; Hansmann, Martin-Leo; Hartmann, Sylvia; Küppers, Ralf

2017-12-01

The cellular microenvironment in classical Hodgkin lymphoma (cHL) is dominated by a mixed infiltrate of inflammatory cells with typically only about 1% Hodgkin and Reed/Sternberg (HRS) tumor cells. T cells are usually the largest population of cells in the cHL microenvironment, encompassing T helper (Th) cells, regulatory T cells (Tregs), and cytotoxic T cells. Th cells and Tregs presumably provide essential survival signals for HRS cells. Tregs are also involved in rescuing HRS cells from antitumor immune responses. An understanding of the immune evasion strategies of HRS cells is not only relevant for a characterization of the pathophysiology of cHL but is also clinically relevant, given the current treatment approaches targeting checkpoint inhibitors. Here, we characterized the cHL-specific CD4 + T-cell infiltrate regarding its role in immune evasion. Global gene expression analysis of CD4 + Th cells and Tregs isolated from cHL lymph nodes and reactive tonsils revealed that Treg signatures were enriched in CD4 + Th cells of cHL. Hence, HRS cells may induce Treg differentiation in Th cells, a conclusion supported by in vitro studies with Th cells and cHL cell lines. We also found evidence for immune-suppressive purinergic signaling and a role of the inhibitory receptor-ligand pairs B- and T-cell lymphocyte attenuator-herpesvirus entry mediator and CD200R-CD200 in promoting immune evasion. Taken together, this study highlights the relevance of Treg induction and reveals new immune checkpoint-driven immune evasion strategies in cHL. Cancer Immunol Res; 5(12); 1122-32. ©2017 AACR . ©2017 American Association for Cancer Research.

Phenotypic plasticity in anti-intraguild predator strategies: mite larvae adjust their behaviours according to vulnerability and predation risk.

Science.gov (United States)

Walzer, Andreas; Schausberger, Peter

2013-05-01

Interspecific threat-sensitivity allows prey to maximize the net benefit of antipredator strategies by adjusting the type and intensity of their response to the level of predation risk. This is well documented for classical prey-predator interactions but less so for intraguild predation (IGP). We examined threat-sensitivity in antipredator behaviour of larvae in a predatory mite guild sharing spider mites as prey. The guild consisted of the highly vulnerable intraguild (IG) prey and weak IG predator Phytoseiulus persimilis, the moderately vulnerable IG prey and moderate IG predator Neoseiulus californicus and the little vulnerable IG prey and strong IG predator Amblyseius andersoni. We videotaped the behaviour of the IG prey larvae of the three species in presence of either a low- or a high-risk IG predator female or predator absence and analysed time, distance, path shape and interaction parameters of predators and prey. The least vulnerable IG prey A. andersoni was insensitive to differing IGP risks but the moderately vulnerable IG prey N. californicus and the highly vulnerable IG prey P. persimilis responded in a threat-sensitive manner. Predator presence triggered threat-sensitive behavioural changes in one out of ten measured traits in N. californicus larvae but in four traits in P. persimilis larvae. Low-risk IG predator presence induced a typical escape response in P. persimilis larvae, whereas they reduced their activity in the high-risk IG predator presence. We argue that interspecific threat-sensitivity may promote co-existence of IG predators and IG prey and should be common in predator guilds with long co-evolutionary history.

Partitioning mechanisms of predator interference in different habitats.

Science.gov (United States)

Griffen, Blaine D; Byers, James E

2006-01-01

Prey are often consumed by multiple predator species. Predation rates on shared prey species measured in isolation often do not combine additively due to interference or facilitation among the predator species. Furthermore, the strength of predator interactions and resulting prey mortality may change with habitat type. We experimentally examined predation on amphipods in rock and algal habitats by two species of intertidal crabs, Hemigrapsus sanguineus (top predators) and Carcinus maenas (intermediate predators). Algae provided a safer habitat for amphipods when they were exposed to only a single predator species. When both predator species were present, mortality of amphipods was less than additive in both habitats. However, amphipod mortality was reduced more in rock than algal habitat because intermediate predators were less protected in rock habitat and were increasingly targeted by omnivorous top predators. We found that prey mortality in general was reduced by (1) altered foraging behavior of intermediate predators in the presence of top predators, (2) top predators switching to foraging on intermediate predators rather than shared prey, and (3) density reduction of intermediate predators. The relative importance of these three mechanisms was the same in both habitats; however, the magnitude of each was greater in rock habitat. Our study demonstrates that the strength of specific mechanisms of interference between top and intermediate predators can be quantified but cautions that these results may be habitat specific.

Tax Evasion, Information Reporting, and the Regressive Bias Prediction

DEFF Research Database (Denmark)

Boserup, Simon Halphen; Pinje, Jori Veng

2013-01-01

evasion and audit probabilities once we account for information reporting in the tax compliance game. When conditioning on information reporting, we find that both reduced-form evidence and simulations exhibit the predicted regressive bias. However, in the overall economy, this bias is negated by the tax......Models of rational tax evasion and optimal enforcement invariably predict a regressive bias in the effective tax system, which reduces redistribution in the economy. Using Danish administrative data, we show that a calibrated structural model of this type replicates moments and correlations of tax...

Take-over performance in evasive manoeuvres

NARCIS (Netherlands)

Happee, R.; Gold, Christian; Radlmayr, Jonas; Hergeth, Sebastian; Bengler, Klaus

2017-01-01

We investigated after effects of automation in take-over scenarios in a high-end moving-base driving simulator. Drivers performed evasive manoeuvres encountering a blocked lane in highway driving. We compared the performance of drivers 1) during manual driving, 2) after automated driving with

THE LINK BETWEEN ACCOUNTING AND FISCAL EVASION

Directory of Open Access Journals (Sweden)

Silvia Lăzărescu (Marinescu

2008-12-01

Full Text Available In the literature, controversies have arisen concerning the link between accounting and fiscal evasion, which are the object of debates among specialists from different specialized organizations from many countries. Under the term of “creative accounting”, the American and European tax systems have made up an ensemble of accounting mechanisms and also of fiscal manipulation which increased the interest and involvement of the states in the mitigation of such fraud risks and fiscal subterfuges whose percentage in the countries’ GDP varies from 8 to 80%. Starting from the SWOT analysis of tax evasion in the real and underground economy, the specialists of the liberal trades are called to join the fight against fiscal fraud and share their professionalism in creating a real competitive environment characterized by fair play.

Estimating Border Tax Evasion in Mozambique

DEFF Research Database (Denmark)

Arndt, Channing; Van Dunem, Joao Ernesto

2009-01-01

evasion. Results also strongly confirm the presence of fraudulent classification of merchandise into lower taxed product categories. Finally, analysis of the revenue implications of lower trade taxes finds that the revenue curve is quite flat but remains upward sloping with respect to the tax rate when...

Tax evasion under behavioral structures

Directory of Open Access Journals (Sweden)

Gabriela S. Pantoja

2014-01-01

Full Text Available We study the strategic interactions between the fiscal authority and the taxpayer regarding tax evasion and auditing. We fit this interaction into a Bayesian game and introduce the concept of behavioral consistency, which helps reducing the number of available strategies and models the stylized fact according to which the choice to evade is subject to behavioral patterns.

Avoiding evasion: medical ethics education and emotion theory.

Science.gov (United States)

Leget, C

2004-10-01

Beginning with an exemplary case study, this paper diagnoses and analyses some important strategies of evasion and factors of hindrance that are met in the teaching of medical ethics to undergraduate medical students. Some of these inhibitions are inherent to ethical theories; others are connected with the nature of medicine or cultural trends. It is argued that in order to avoid an attitude of evasion in medical ethics teaching, a philosophical theory of emotions is needed that is able to clarify on a conceptual level the ethical importance of emotions. An approach is proposed with the help of the emotion theory Martha Nussbaum works out in her book Upheavals of thought. The paper ends with some practical recommendations.

Tax Evasion and Swiss Bank Deposits

DEFF Research Database (Denmark)

Johannesen, Niels

Bank deposits in jurisdictions with banking secrecy constitute an effective tool to evade taxes on interest income. A recent EU reform reduces the scope for this type of tax evasion by introducing a source tax on interest income earned by EU residents in Switzerland and several other jurisdictions...

Dynamics of a intraguild predation model with generalist or specialist predator.

Science.gov (United States)

Kang, Yun; Wedekin, Lauren

2013-11-01

Intraguild predation (IGP) is a combination of competition and predation which is the most basic system in food webs that contains three species where two species that are involved in a predator/prey relationship are also competing for a shared resource or prey. We formulate two intraguild predation (IGP: resource, IG prey and IG predator) models: one has generalist predator while the other one has specialist predator. Both models have Holling-Type I functional response between resource-IG prey and resource-IG predator; Holling-Type III functional response between IG prey and IG predator. We provide sufficient conditions of the persistence and extinction of all possible scenarios for these two models, which give us a complete picture on their global dynamics. In addition, we show that both IGP models can have multiple interior equilibria under certain parameters range. These analytical results indicate that IGP model with generalist predator has "top down" regulation by comparing to IGP model with specialist predator. Our analysis and numerical simulations suggest that: (1) Both IGP models can have multiple attractors with complicated dynamical patterns; (2) Only IGP model with specialist predator can have both boundary attractor and interior attractor, i.e., whether the system has the extinction of one species or the coexistence of three species depending on initial conditions; (3) IGP model with generalist predator is prone to have coexistence of three species.

Immune Evasion by Epstein-Barr Virus.

Science.gov (United States)

Ressing, Maaike E; van Gent, Michiel; Gram, Anna M; Hooykaas, Marjolein J G; Piersma, Sytse J; Wiertz, Emmanuel J H J

2015-01-01

Epstein-Bar virus (EBV) is widespread within the human population with over 90% of adults being infected. In response to primary EBV infection, the host mounts an antiviral immune response comprising both innate and adaptive effector functions. Although the immune system can control EBV infection to a large extent, the virus is not cleared. Instead, EBV establishes a latent infection in B lymphocytes characterized by limited viral gene expression. For the production of new viral progeny, EBV reactivates from these latently infected cells. During the productive phase of infection, a repertoire of over 80 EBV gene products is expressed, presenting a vast number of viral antigens to the primed immune system. In particular the EBV-specific CD4+ and CD8+ memory T lymphocytes can respond within hours, potentially destroying the virus-producing cells before viral replication is completed and viral particles have been released. Preceding the adaptive immune response, potent innate immune mechanisms provide a first line of defense during primary and recurrent infections. In spite of this broad range of antiviral immune effector mechanisms, EBV persists for life and continues to replicate. Studies performed over the past decades have revealed a wide array of viral gene products interfering with both innate and adaptive immunity. These include EBV-encoded proteins as well as small noncoding RNAs with immune-evasive properties. The current review presents an overview of the evasion strategies that are employed by EBV to facilitate immune escape during latency and productive infection. These evasion mechanisms may also compromise the elimination of EBV-transformed cells, and thus contribute to malignancies associated with EBV infection.

The Tax Compliance Demand Curve: A Diagrammatical Approach to Income Tax Evasion

Science.gov (United States)

Yaniv, Gideon

2009-01-01

One of the most interesting results in the tax evasion literature is that an increase in the income tax rate would increase tax compliance. Despite its peculiarity, this result has gained acceptance as a cornerstone for further developments of the rational tax evasion model. However, because of the mathematical format by which it is conveyed, this…

A Generalist Protist Predator Enables Coexistence in Multitrophic Predator-Prey Systems Containing a Phage and the Bacterial Predator Bdellovibrio

Directory of Open Access Journals (Sweden)

Julia Johnke

2017-10-01

Full Text Available Complex ecosystems harbor multiple predators and prey species whose direct and indirect interactions are under study. In particular, the combined effects of predator diversity and resource preference on prey removal are not known. To understand the effect of interspecies interactions, combinations of micro-predators—i.e., protists (generalists, predatory bacteria (semi-specialists, and phages (specialists—and bacterial prey were tracked over a 72-h period in miniature membrane bioreactors. While specialist predators alone drove their preferred prey to extinction, the inclusion of a generalist resulted in uniform losses among prey species. Most importantly, presence of a generalist predator enabled coexistence of all predators and prey. As the generalist predator also negatively affected the other predators, we suggest that resource partitioning between predators and the constant availability of resources for bacterial growth due to protist predation stabilizes the system and keeps its diversity high. The appearance of resistant prey strains and subsequent evolution of specialist predators unable to infect the ancestral prey implies that multitrophic communities are able to persist and stabilize themselves. Interestingly, the appearance of BALOs and phages unable to infect their prey was only observed for the BALO or phage in the absence of additional predators or prey species indicating that competition between predators might influence coevolutionary dynamics.

TAX EVASION IN CROSS BORDER TEXTILES OPERATIONS

Directory of Open Access Journals (Sweden)

ANDREESCU Nicoleta Alina

2014-05-01

Full Text Available We appreciated that the work can be divided into four chapters designed to enlighten, as far as possible the negative effects that evasion has, particularly the socio-economic phenomenon, faced by all countries. The negative effects generate an indisputable fraud phenomenon and tax evasion, which are felt directly on the level of tax revenue receipts, causing major distortions in the functioning of the mechanism of the market. Fiscal policy using the taxes generates psychological, financial, economic, social effects on a socio-economic environment. The public power that realizes the reality of the tax consequences of the action taken as solution changes of the tax system structure in order to modulate the effects according with the expected outcome. Therefore, the aimed pursued extent influences the technical characteristics of the taxes, and they influence the micro and macroeconomic effects. In this respect it has been proved that reducing tax evasion it allows the creation of budgetary resources necessary for allotting funds for economic growth. Developing and implementing a modern and predictable tax for a medium and long term, would be indispensable in the context of competition that occurs between the European states for attracting new investment and creating new jobs. The taxes do not have to shape the behavior of taxpayers, they must be the same regardless of the type of income, it should not include distortions. In order to be reasonable, the fiscal tax should be distributed as wide as possible.

Conservation implications when the nest predators are known

Science.gov (United States)

Ribic, Christine; Thompson, Frank

2012-01-01

Conservation and management of passerines has largely focused on habitat manipulation or restoration because the natural communities on which these birds depend have been destroyed and fragmented. However, productivity is another important aspect of avian conservation, and nest predation can be a large source of nesting mortality for passerines. Recent studies using video surveillance to identify nest predators allow researchers to start evaluating what methods could be used to mitigate nest predation to help passerines of conservation concern. From recent studies, we identified latitudinal and habitat-related patterns in the importance of predator groups that depredate passerine nests. We then reviewed how knowledge of specific nest predators can benefit conservation of bird species of concern. Mammals were the dominant predator group in northern grasslands. Snakes were the dominant predator group in southern habitats. Fire ants were only a nest predator in southern latitudes. Differences in the importance of predator species or groups were likely the result of both their geographic patterns of distribution and habitat preferences. Some direct and indirect predator control measures developed for waterfowl management potentially could be used to benefit passerine productivity. We reviewed three examples-cowbirds, snakes in shrublands, and ground squirrels in grasslands-to illustrate how different predator control strategies may be needed in different situations. Mitigation of passerine nest predation will need to be based on knowledge of predator communities to be effective. This requires large samples of predation events with identified predators; video technology is essential for this task.

Linking tumor glycolysis and immune evasion in cancer: Emerging concepts and therapeutic opportunities.

Science.gov (United States)

Ganapathy-Kanniappan, Shanmugasundaram

2017-08-01

Metabolic reprogramming and immune evasion are two hallmarks of cancer. Metabolic reprogramming is exemplified by cancer's propensity to utilize glucose at an exponential rate which in turn is linked with "aerobic glycolysis", popularly known as the "Warburg effect". Tumor glycolysis is pivotal for the efficient management of cellular bioenergetics and uninterrupted cancer growth. Mounting evidence suggests that tumor glycolysis also plays a key role in instigating immunosuppressive networks that are critical for cancer cells to escape immune surveillance ("immune evasion"). Recent data show that induction of cellular stress or metabolic dysregulation sensitize cancer cells to antitumor immune cells implying that metabolic reprogramming and immune evasion harmonize during cancer progression. However, the molecular link between these two hallmarks of cancer remains obscure. In this review the molecular intricacies of tumor glycolysis that facilitate immune evasion has been discussed in the light of recent research to explore immunotherapeutic potential of targeting cancer metabolism. Copyright © 2017 Elsevier B.V. All rights reserved.

Elements of Compared Law concerning Tax Evasion

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Monica Pocora

2015-08-01

Full Text Available The resort to international tax evasion can be explained both through the game, often perverse, of the double taxation, due to the autonomy of the national fiscal regimes, as well as to the fiscal pressures deriving from these. In view of escaping to be subject to two different taxations, the taxpayer wishes actually to avoid them both. And in order to avoid being subject to either of them, he takes cover in the fiscally protected regions. The techniques are numerous and depend on the taxpayer’s imagination. They contain a series of subtle and agile combinations of using the disappearances between the fiscal systems by resorting sometimes to fraudulent mechanisms. This paper aims at analysing the European dimension of the evasion phenomenon, corresponding to some fiscal and social laws that are more favourable.

Top predators induce the evolutionary diversification of intermediate predator species.

Science.gov (United States)

Zu, Jian; Yuan, Bo; Du, Jianqiang

2015-12-21

We analyze the evolutionary branching phenomenon of intermediate predator species in a tritrophic food chain model by using adaptive dynamics theory. Specifically, we consider the adaptive diversification of an intermediate predator species that feeds on a prey species and is fed upon by a top predator species. We assume that the intermediate predator׳s ability to forage on the prey can adaptively improve, but this comes at the cost of decreased defense ability against the top predator. First, we identify the general properties of trade-off relationships that lead to a continuously stable strategy or to evolutionary branching in the intermediate predator species. We find that if there is an accelerating cost near the singular strategy, then that strategy is continuously stable. In contrast, if there is a mildly decelerating cost near the singular strategy, then that strategy may be an evolutionary branching point. Second, we find that after branching has occurred, depending on the specific shape and strength of the trade-off relationship, the intermediate predator species may reach an evolutionarily stable dimorphism or one of the two resultant predator lineages goes extinct. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

The Reform and Design of Commodity Taxes in the Presence of Tax Evasion with Illustrative Evidence from India

OpenAIRE

Ray, R.

1994-01-01

The literature on tax evasion and its implication for optimal tax theory has concentrated on income tax evasion. The issue of commodity tax evasion has received relatively little attention even though it is important in many cases, especially in developing countries. This paper proposes a theory of marginal reform of indirect taxes that recognises the presence of commodity tax evasion. Illustrative evidence from Indian data confirm the sensitivity of the Pareto improving direction of marginal...

THE HARMONISATION OF LEGISLATION ON COMBATTING TAX EVASION IN THE EUROPEAN UNION

Directory of Open Access Journals (Sweden)

DANIELA IANCU

2011-04-01

Full Text Available Combating tax evasion is part of the Lisbon Strategy. Tax fraud created a significant distortion in the functioning of the internal market and prevented fair competition.In its resolution of 2th of September 2008 on a coordinated strategy to improve the fight against fiscal fraud (2008/2033 (INI the European Parliament stressed that the Member States cannot combat cross-border fraud in isolation and called on the Commission to propose mechanisms to promote cooperation between Member States.This paper aims to analyse the main mechanisms to combat the tax evasion at the European level and, also, the changes that our country had to make in the field of legislation in order to achieve the EU standard on the fight against tax evasion.

Immune evasion mechanisms of human papillomavirus: An update.

Science.gov (United States)

Steinbach, Alina; Riemer, Angelika B

2018-01-15

Human papillomavirus (HPV) is the most frequently sexually transmitted agent in the world. It can cause cervical and other anogenital malignancies, and oropharyngeal cancer. HPV has the unique ability to persist in the host's epithelium for a long time-longer than most viruses do-which is necessary to complete its replication cycle. To this end, HPV has developed a variety of immune evasion mechanisms, which unfortunately also favor the progression of the disease from infection to chronic dysplasia and eventually to cancer. This article summarizes the current knowledge about HPV immune evasion strategies. A special emphasis lies in HPV-mediated changes of the antigen processing machinery, which is generating epitopes for T cells and contributes to the detectability of infected cells. © 2017 UICC.

34 CFR 668.207 - Preventing evasion of the consequences of cohort default rates.

Science.gov (United States)

2010-07-01

... 34 Education 3 2010-07-01 2010-07-01 false Preventing evasion of the consequences of cohort default rates. 668.207 Section 668.207 Education Regulations of the Offices of the Department of Education... Cohort Default Rates § 668.207 Preventing evasion of the consequences of cohort default rates. (a...

34 CFR 668.188 - Preventing evasion of the consequences of cohort default rates.

Science.gov (United States)

2010-07-01

... 34 Education 3 2010-07-01 2010-07-01 false Preventing evasion of the consequences of cohort default rates. 668.188 Section 668.188 Education Regulations of the Offices of the Department of Education... Two Year Cohort Default Rates § 668.188 Preventing evasion of the consequences of cohort default rates...

Nest Predation Deviates from Nest Predator Abundance in an Ecologically Trapped Bird.

Science.gov (United States)

Hollander, Franck A; Van Dyck, Hans; San Martin, Gilles; Titeux, Nicolas

2015-01-01

In human-modified environments, ecological traps may result from a preference for low-quality habitat where survival or reproductive success is lower than in high-quality habitat. It has often been shown that low reproductive success for birds in preferred habitat types was due to higher nest predator abundance. However, between-habitat differences in nest predation may only weakly correlate with differences in nest predator abundance. An ecological trap is at work in a farmland bird (Lanius collurio) that recently expanded its breeding habitat into open areas in plantation forests. This passerine bird shows a strong preference for forest habitat, but it has a higher nest success in farmland. We tested whether higher abundance of nest predators in the preferred habitat or, alternatively, a decoupling of nest predator abundance and nest predation explained this observed pattern of maladaptive habitat selection. More than 90% of brood failures were attributed to nest predation. Nest predator abundance was more than 50% higher in farmland, but nest predation was 17% higher in forest. Differences between nest predation on actual shrike nests and on artificial nests suggested that parent shrikes may facilitate nest disclosure for predators in forest more than they do in farmland. The level of caution by parent shrikes when visiting their nest during a simulated nest predator intrusion was the same in the two habitats, but nest concealment was considerably lower in forest, which contributes to explaining the higher nest predation in this habitat. We conclude that a decoupling of nest predator abundance and nest predation may create ecological traps in human-modified environments.

Use of genetically marked minicells as a probe in measurement of predation on bacteria in aquatic environments

International Nuclear Information System (INIS)

Wikner, J.; Andersson, A.; Normark, S.; Hagstroem, A.

1986-01-01

Minicells produced by Escherichia coli M2141 were used as probes to measure predation on pelagic bacteria in situ. The minicells, labeled with [ 35 S]methionine in one specific protein, were shown to disappear in the presence of a microflagellate (Ochromonas sp.), as seen by a decrease in the amount of labeled marker protein with time. Incubation in filtered (pore size, 0.2 μm) and autoclaved seawater did not affect the amount of labeled marker protein in the minicell. The generation time of flagellates feeding on minicells was determined to be similar to that found for flagellates grown on seawater bacteria or living E. coli NC3. Data indicate that minicells are seen as true food particles by the flagellates. The minicell probe was used in recapture experiments, in which predation in situ on pelagic bacteria was demonstrated. The rate of bacterial production showed a clear covariation with the rate of predation, both in different sea areas and in depth profiles. The obtained results (11 field experiments) showed that the rate of predation, on average, accounts for the consumption of 62% of the bacteria produced

Tax avoidance, tax evasion, and tax flight: Do legal differences matter?

OpenAIRE

Schneider, Friedrich; Kirchler, Erich; Maciejovsky, Boris

2001-01-01

Although from an economic point of view, legal considerations apart, tax avoidance, tax evasion and tax flight have similar effects, namely a reduction of revenue yields, and are based on the same desire to reduce the tax burden, it is likely that individuals perceive them as different and as unequally fair. Overall, 252 fiscal officers, business students, business lawyers, and entrepreneurs produced spontaneous associations to a scenario either describing tax avoidance, tax evasion, or tax f...

Attitudes towards Tax Evasion in Turkey and Australia: A Comparative Study

Directory of Open Access Journals (Sweden)

Robert W. McGee

2016-03-01

Full Text Available The authors conducted a survey of 502 Turkish and Australian undergraduate and graduate business and economic students to determine their views regarding the ethics of tax evasion. These two groups were selected on the premise that their views represented the perceptions of two very different cultures, which has not been investigated in previous studies. The survey instrument required students to indicate their level of agreeableness to 18 general statements representing various scenarios in the socio-economic environment. The statements in the survey reflected the three main viewpoints regarding the ethics of tax evasion which have emerged from the literature to date. The results of the study show that although Turkish scores are significantly different from the Australian scores, both Turkish and Australian respondents believe that tax evasion can be ethically justifiable in certain situations, although some arguments are stronger than others.

Staphylococcus aureus innate immune evasion is lineage-specific: a bioinfomatics study.

Science.gov (United States)

McCarthy, Alex J; Lindsay, Jodi A

2013-10-01

Staphylococcus aureus is a major human pathogen, and is targeted by the host innate immune system. In response, S. aureus genomes encode dozens of secreted proteins that inhibit complement, chemotaxis and neutrophil activation resulting in successful evasion of innate immune responses. These proteins include immune evasion cluster proteins (IEC; Chp, Sak, Scn), staphylococcal superantigen-like proteins (SSLs), phenol soluble modulins (PSMs) and several leukocidins. Biochemical studies have indicated that genetic variants of these proteins can have unique functions. To ascertain the scale of genetic variation in secreted immune evasion proteins, whole genome sequences of 88 S. aureus isolates, representing 25 clonal complex (CC) lineages, in the public domain were analysed across 43 genes encoding 38 secreted innate immune evasion protein complexes. Twenty-three genes were variable, with between 2 and 15 variants, and the variants had lineage-specific distributions. They include genes encoding Eap, Ecb, Efb, Flipr/Flipr-like, Hla, Hld, Hlg, Sbi, Scin-B/C and 13 SSLs. Most of these protein complexes inhibit complement, chemotaxis and neutrophil activation suggesting that isolates from each S. aureus lineage respond to the innate immune system differently. In contrast, protein complexes that lyse neutrophils (LukSF-PVL, LukMF, LukED and PSMs) were highly conserved, but can be carried on mobile genetic elements (MGEs). MGEs also encode proteins with narrow host-specificities arguing that their acquisition has important roles in host/environmental adaptation. In conclusion, this data suggests that each lineage of S. aureus evades host immune responses differently, and that isolates can adapt to new host environments by acquiring MGEs and the immune evasion protein complexes that they encode. Cocktail therapeutics that targets multiple variant proteins may be the most appropriate strategy for controlling S. aureus infections. Copyright © 2013 Elsevier B.V. All rights

27 CFR 25.177 - Evasion of or failure to pay tax; failure to file a tax return.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Evasion of or failure to... Pay Tax § 25.177 Evasion of or failure to pay tax; failure to file a tax return. Sections 5671, 5673, 5684, 6651, and 6656 of Title 26 United States Code provide penalties for evasion or failure to pay tax...

Nest Predation Deviates from Nest Predator Abundance in an Ecologically Trapped Bird.

Directory of Open Access Journals (Sweden)

Franck A Hollander

Full Text Available In human-modified environments, ecological traps may result from a preference for low-quality habitat where survival or reproductive success is lower than in high-quality habitat. It has often been shown that low reproductive success for birds in preferred habitat types was due to higher nest predator abundance. However, between-habitat differences in nest predation may only weakly correlate with differences in nest predator abundance. An ecological trap is at work in a farmland bird (Lanius collurio that recently expanded its breeding habitat into open areas in plantation forests. This passerine bird shows a strong preference for forest habitat, but it has a higher nest success in farmland. We tested whether higher abundance of nest predators in the preferred habitat or, alternatively, a decoupling of nest predator abundance and nest predation explained this observed pattern of maladaptive habitat selection. More than 90% of brood failures were attributed to nest predation. Nest predator abundance was more than 50% higher in farmland, but nest predation was 17% higher in forest. Differences between nest predation on actual shrike nests and on artificial nests suggested that parent shrikes may facilitate nest disclosure for predators in forest more than they do in farmland. The level of caution by parent shrikes when visiting their nest during a simulated nest predator intrusion was the same in the two habitats, but nest concealment was considerably lower in forest, which contributes to explaining the higher nest predation in this habitat. We conclude that a decoupling of nest predator abundance and nest predation may create ecological traps in human-modified environments.

The Reform and Design of Commodity Taxes in the Presence of Tax Evasion with Illustrative Evidence from India

NARCIS (Netherlands)

Ray, R.

1994-01-01

The literature on tax evasion and its implication for optimal tax theory has concentrated on income tax evasion. The issue of commodity tax evasion has received relatively little attention even though it is important in many cases, especially in developing countries. This paper proposes a theory of

Immune evasion in cancer: Mechanistic basis and therapeutic strategies.

Science.gov (United States)

Vinay, Dass S; Ryan, Elizabeth P; Pawelec, Graham; Talib, Wamidh H; Stagg, John; Elkord, Eyad; Lichtor, Terry; Decker, William K; Whelan, Richard L; Kumara, H M C Shantha; Signori, Emanuela; Honoki, Kanya; Georgakilas, Alexandros G; Amin, Amr; Helferich, William G; Boosani, Chandra S; Guha, Gunjan; Ciriolo, Maria Rosa; Chen, Sophie; Mohammed, Sulma I; Azmi, Asfar S; Keith, W Nicol; Bilsland, Alan; Bhakta, Dipita; Halicka, Dorota; Fujii, Hiromasa; Aquilano, Katia; Ashraf, S Salman; Nowsheen, Somaira; Yang, Xujuan; Choi, Beom K; Kwon, Byoung S

2015-12-01

Cancer immune evasion is a major stumbling block in designing effective anticancer therapeutic strategies. Although considerable progress has been made in understanding how cancers evade destructive immunity, measures to counteract tumor escape have not kept pace. There are a number of factors that contribute to tumor persistence despite having a normal host immune system. Immune editing is one of the key aspects why tumors evade surveillance causing the tumors to lie dormant in patients for years through "equilibrium" and "senescence" before re-emerging. In addition, tumors exploit several immunological processes such as targeting the regulatory T cell function or their secretions, antigen presentation, modifying the production of immune suppressive mediators, tolerance and immune deviation. Besides these, tumor heterogeneity and metastasis also play a critical role in tumor growth. A number of potential targets like promoting Th1, NK cell, γδ T cell responses, inhibiting Treg functionality, induction of IL-12, use of drugs including phytochemicals have been designed to counter tumor progression with much success. Some natural agents and phytochemicals merit further study. For example, use of certain key polysaccharide components from mushrooms and plants have shown to possess therapeutic impact on tumor-imposed genetic instability, anti-growth signaling, replicative immortality, dysregulated metabolism etc. In this review, we will discuss the advances made toward understanding the basis of cancer immune evasion and summarize the efficacy of various therapeutic measures and targets that have been developed or are being investigated to enhance tumor rejection. Copyright © 2015 Elsevier Ltd. All rights reserved.

Plasticity in early immune evasion strategies of a bacterial pathogen.

Science.gov (United States)

Bernard, Quentin; Smith, Alexis A; Yang, Xiuli; Koci, Juraj; Foor, Shelby D; Cramer, Sarah D; Zhuang, Xuran; Dwyer, Jennifer E; Lin, Yi-Pin; Mongodin, Emmanuel F; Marques, Adriana; Leong, John M; Anguita, Juan; Pal, Utpal

2018-04-17

Borrelia burgdorferi is one of the few extracellular pathogens capable of establishing persistent infection in mammals. The mechanisms that sustain long-term survival of this bacterium are largely unknown. Here we report a unique innate immune evasion strategy of B. burgdorferi , orchestrated by a surface protein annotated as BBA57, through its modulation of multiple spirochete virulent determinants. BBA57 function is critical for early infection but largely redundant for later stages of spirochetal persistence, either in mammals or in ticks. The protein influences host IFN responses as well as suppresses multiple host microbicidal activities involving serum complement, neutrophils, and antimicrobial peptides. We also discovered a remarkable plasticity in BBA57-mediated spirochete immune evasion strategy because its loss, although resulting in near clearance of pathogens at the inoculum site, triggers nonheritable adaptive changes that exclude detectable nucleotide alterations in the genome but incorporate transcriptional reprograming events. Understanding the malleability in spirochetal immune evasion mechanisms that ensures their host persistence is critical for the development of novel therapeutic and preventive approaches to combat long-term infections like Lyme borreliosis.

Tax evasion and growth: a banking approach

Czech Academy of Sciences Publication Activity Database

Gillman, M.; Kejak, Michal

-, 2008/6 (2008), s. 1-32. ISBN 978-963-9796-21-8. ISSN 1785-377X Institutional research plan: CEZ:AV0Z70850503 Keywords : tax evasion * financial intermediation * endogenous growth Subject RIV: AH - Economics http://econ.core.hu/file/download/mtdp/MTDP0806.pdf

Viral evasion of DNA-stimulated innate immune responses.

Science.gov (United States)

Christensen, Maria H; Paludan, Søren R

2017-01-01

Cellular sensing of virus-derived nucleic acids is essential for early defenses against virus infections. In recent years, the discovery of DNA sensing proteins, including cyclic GMP-AMP synthase (cGAS) and gamma-interferon-inducible protein (IFI16), has led to understanding of how cells evoke strong innate immune responses against incoming pathogens carrying DNA genomes. The signaling stimulated by DNA sensors depends on the adaptor protein STING (stimulator of interferon genes), to enable expression of antiviral proteins, including type I interferon. To facilitate efficient infections, viruses have evolved a wide range of evasion strategies, targeting host DNA sensors, adaptor proteins and transcription factors. In this review, the current literature on virus-induced activation of the STING pathway is presented and we discuss recently identified viral evasion mechanisms targeting different steps in this antiviral pathway.

Evasion of Cell Senescence Leads to Medulloblastoma Progression

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Lukas Tamayo-Orrego

2016-03-01

Full Text Available How brain tumors progress from precancerous lesions to advanced cancers is not well understood. Using Ptch1+/− mice to study medulloblastoma progression, we found that Ptch1 loss of heterozygosity (LOH is an early event that is associated with high levels of cell senescence in preneoplasia. In contrast, advanced tumors have evaded senescence. Remarkably, we discovered that the majority of advanced medulloblastomas display either spontaneous, somatic p53 mutations or Cdkn2a locus inactivation. Consistent with senescence evasion, these p53 mutations are always subsequent to Ptch1 LOH. Introduction of a p53 mutation prevents senescence, accelerates tumor formation, and increases medulloblastoma incidence. Altogether, our results show that evasion of senescence associated with Ptch1 LOH allows progression to advanced tumors.

Predation as a landscape effect: the trading off by prey species between predation risks and protection benefits.

Science.gov (United States)

Mönkkönen, M; Husby, M; Tornberg, R; Helle, P; Thomson, R L

2007-05-01

1. Predators impose costs on their prey but may also provide benefits such as protection against other (e.g. nest) predators. The optimal breeding location in relation to the distance from a nesting raptor varies so as to minimize the sum of costs of adult and nest predation. We provide a conceptual model to account for variation in the relative predation risks and derive qualitative predictions for how different prey species should respond to the distance from goshawk Accipiter gentilis nests. 2. We test the model predictions using a comprehensive collection of data from northern Finland and central Norway. First, we carried out a series of experiments with artificial bird nests to test if goshawks may provide protection against nest predation. Second, we conducted standard bird censuses and nest-box experiments to detect how the density or territory occupancy of several prey species varies with distance from the nearest goshawk nest. 3. Nest predation rate increased with distance from goshawk nest indicating that goshawks may provide protection for birds' nests against nest predation. Abundance (or probability of presence) of the main prey species of goshawks peaked at intermediate distances from goshawk nests, reflecting the trade-off. The abundance of small songbird species decreased with distance from goshawk nests. The goshawk poses little risk to small songbirds and they may benefit from goshawk proximity in protection against nest predation. Finally, no pattern with distance in pied flycatcher territory (nest box) occupation rate or the onset of egg-laying was detected. This is expected, as flycatchers neither suffer from marked nest predation risk nor are favoured goshawk prey. 4. Our results suggest that territory location in relation to the nest of a predator is a trade-off situation where adult birds weigh the risk of themselves being predated against the benefits accrued from increased nest survival. Prey species appear able to detect and measure

Rhinoceros beetles suffer male-biased predation by mammalian and avian predators.

Science.gov (United States)

Kojima, Wataru; Sugiura, Shinji; Makihara, Hiroshi; Ishikawa, Yukio; Takanashi, Takuma

2014-03-01

Male sexually-selected traits often impose an increased risk of predation on their bearers, causing male-biased predation. We investigated whether males of the sap-feeding Japanese rhinoceros beetle Trypoxylus dichotomus were more susceptible to predation than females by comparing the morphology of beetles caught in bait traps with the remains of beetles found on the ground. The males of this species are larger than the females and have a horn on the head. We found that predation pressure was greater for males than for females, and that larger individuals of both sexes were more vulnerable to predation. We identified two predators, the raccoon dog Nyctereutes procyonoides and jungle crow Corvus macrorhynchos, by monitoring sap-site trees with infrared video cameras. Raccoon dogs visited sap-site trees at night, while crows came after daybreak. The highest frequency of visits by both predators was observed in the first half of August, which matches the peak season of T. dichotomus. Raccoon dogs often left bite marks on the remains of prey, whereas crows did not. Bite marks were found on most of the remains collected at two distant localities, which suggested that predation by raccoon dogs is common. Size- and sex-dependent differences in the conspicuousness and active period of T. dichotomus probably explain these biased predation patterns. Our results suggest that having a large horn/body is costly in terms of the increased risk of predation. Predation cost may act as a stabilizing selection pressure against the further exaggeration of male sexual traits.

Tax Evasion and the Impact on Economic Growth Acta Universitatis Danubius. OEconomica

Directory of Open Access Journals (Sweden)

Shkendije Demalijaj Ukaj

2014-12-01

Full Text Available The level of taxation is very important for the development of current and future of a country and fiscal policy should always be considered as an important factor in the behavior of participants and their ability to tax evasion and informality. Government fiscal policies can trigger tax increase under pressure, especially in situations such as economic crisis, inflation, unemployment, instability, when the burden of this obligation grows, its effects are considered to take them to tax evasion and informality (Dragomir. et al. 2011. However, these reasons do not relate to all the great presence of this phenomenon in Kosovo, taking into account the recent economic crisis has not reflected in the economy of Kosovo and the Kosovo tax burden is among the lowest in the region, but leading cause of tax evasion and informality can be considered above the corruption of public administration officials including tax and customs officials, insufficient staff for his fighting, weak rule of law, as well as lower fiscal culture for paying taxes. For this reason the scope of this paper will be the theoretical treatment of the informal economy and tax evasion in view of tax avoidance, meaning, characteristics and their effects on the economy and possible recommendations on these viewpoints.

The Underground Economy and Tax Evasion in Pakistan. A Fresh Assessment

OpenAIRE

Zafar Iqbal; Sarfraz Khan Qureshi; Riaz Mahmood

1998-01-01

This paper assesses the size of the underground ~conomy and tax evasion in Pakistan for the period 1973-96. Using monetary approach, the results confirm the existence of large underground economy and higher tax evasion over the period under analysis. The overall underground economy has remarkably increased from 20 percent of GDP in 1973 to 51 percent of GDP in 1996. The evidence also suggests that the rate of growth in th~ underground economy has been higher than the rate of growth of the for...

Lapse of time effects on tax evasion in an agent-based econophysics model

Science.gov (United States)

Seibold, Götz; Pickhardt, Michael

2013-05-01

We investigate an inhomogeneous Ising model in the context of tax evasion dynamics where different types of agents are parameterized via local temperatures and magnetic fields. In particular, we analyze the impact of lapse of time effects (i.e. backauditing) and endogenously determined penalty rates on tax compliance. Both features contribute to a microfoundation of agent-based econophysics models of tax evasion.

International Tax Evasion, State Purchases of Confidential Bank Data and Voluntary Disclosures

OpenAIRE

Bethmann, Dirk; Kvasnicka, Michael

2017-01-01

State purchases of bank data on suspected tax evaders from international tax havens constitute a potential tool to combat international tax evasion. Using self-compiled data for North-Rhine Westphalia on the timing and content of such data acquisitions from whistleblowers and on monthly voluntary disclosures of international tax evasion involving Swiss banks, we show that purchases of data by tax authorities on potential tax evaders have a positive and sizeable effect on voluntary disclosures.

Maternal intraguild predation risk affects offspring anti-predator behavior and learning in mites

Science.gov (United States)

Seiter, Michael; Schausberger, Peter

2015-01-01

Predation risk is a strong selective force shaping prey morphology, life history and behavior. Anti-predator behaviors may be innate, learned or both but little is known about the transgenerational behavioral effects of maternally experienced predation risk. We examined intraguild predation (IGP) risk-induced maternal effects on offspring anti-predator behavior, including learning, in the predatory mite Phytoseiulus persimilis. We exposed predatory mite mothers during egg production to presence or absence of the IG predator Amblyseius andersoni and assessed whether maternal stress affects the anti-predator behavior, including larval learning ability, of their offspring as protonymphs. Protonymphs emerging from stressed or unstressed mothers, and having experienced IGP risk as larvae or not, were subjected to choice situations with and without IG predator traces. Predator-experienced protonymphs from stressed mothers were the least active and acted the boldest in site choice towards predator cues. We argue that the attenuated response of the protonymphs to predator traces alone represents optimized risk management because no immediate risk existed. Such behavioral adjustment could reduce the inherent fitness costs of anti-predator behaviors. Overall, our study suggests that P. persimilis mothers experiencing IGP risk may prime their offspring to behave more optimally in IGP environments. PMID:26449645

Predator effects on reef fish settlement depend on predator origin and recruit density.

Science.gov (United States)

Benkwitt, Cassandra E

2017-04-01

During major life-history transitions, animals often experience high mortality rates due to predation, making predator avoidance particularly advantageous during these times. There is mixed evidence from a limited number of studies, however, regarding how predator presence influences settlement of coral-reef fishes and it is unknown how other potentially mediating factors, including predator origin (native vs. nonnative) or interactions among conspecific recruits, mediate the non-consumptive effects of predators on reef fish settlement. During a field experiment in the Caribbean, approximately 52% fewer mahogany snapper (Lutjanus mahogoni) recruited to reefs with a native predator (graysby grouper, Cephalopholis cruentata) than to predator-free control reefs and reefs with an invasive predator (red lionfish, Pterois volitans) regardless of predator diet. These results suggest that snapper recruits do not recognize nonnative lionfish as a threat. However, these effects depended on the density of conspecific recruits, with evidence that competition may limit the response of snapper to even native predators at the highest recruit densities. In contrast, there was no effect of predator presence or conspecific density on the recruitment of bicolor damselfish (Stegastes partitus). These context-dependent responses of coral-reef fishes to predators during settlement may influence individual survival and shape subsequent population and community dynamics. © 2017 by the Ecological Society of America.

Viral evasion of DNA-stimulated innate immune responses

Science.gov (United States)

Christensen, Maria H; Paludan, Søren R

2017-01-01

Cellular sensing of virus-derived nucleic acids is essential for early defenses against virus infections. In recent years, the discovery of DNA sensing proteins, including cyclic GMP–AMP synthase (cGAS) and gamma-interferon-inducible protein (IFI16), has led to understanding of how cells evoke strong innate immune responses against incoming pathogens carrying DNA genomes. The signaling stimulated by DNA sensors depends on the adaptor protein STING (stimulator of interferon genes), to enable expression of antiviral proteins, including type I interferon. To facilitate efficient infections, viruses have evolved a wide range of evasion strategies, targeting host DNA sensors, adaptor proteins and transcription factors. In this review, the current literature on virus-induced activation of the STING pathway is presented and we discuss recently identified viral evasion mechanisms targeting different steps in this antiviral pathway. PMID:26972769

Multiagent Cooperative Learning Strategies for Pursuit-Evasion Games

Directory of Open Access Journals (Sweden)

Jong Yih Kuo

2015-01-01

Full Text Available This study examines the pursuit-evasion problem for coordinating multiple robotic pursuers to locate and track a nonadversarial mobile evader in a dynamic environment. Two kinds of pursuit strategies are proposed, one for agents that cooperate with each other and the other for agents that operate independently. This work further employs the probabilistic theory to analyze the uncertain state information about the pursuers and the evaders and uses case-based reasoning to equip agents with memories and learning abilities. According to the concepts of assimilation and accommodation, both positive-angle and bevel-angle strategies are developed to assist agents in adapting to their environment effectively. The case study analysis uses the Recursive Porous Agent Simulation Toolkit (REPAST to implement a multiagent system and demonstrates superior performance of the proposed approaches to the pursuit-evasion game.

Functional motifs responsible for human metapneumovirus M2-2-mediated innate immune evasion.

Science.gov (United States)

Chen, Yu; Deng, Xiaoling; Deng, Junfang; Zhou, Jiehua; Ren, Yuping; Liu, Shengxuan; Prusak, Deborah J; Wood, Thomas G; Bao, Xiaoyong

2016-12-01

Human metapneumovirus (hMPV) is a major cause of lower respiratory infection in young children. Repeated infections occur throughout life, but its immune evasion mechanisms are largely unknown. We recently found that hMPV M2-2 protein elicits immune evasion by targeting mitochondrial antiviral-signaling protein (MAVS), an antiviral signaling molecule. However, the molecular mechanisms underlying such inhibition are not known. Our mutagenesis studies revealed that PDZ-binding motifs, 29-DEMI-32 and 39-KEALSDGI-46, located in an immune inhibitory region of M2-2, are responsible for M2-2-mediated immune evasion. We also found both motifs prevent TRAF5 and TRAF6, the MAVS downstream adaptors, to be recruited to MAVS, while the motif 39-KEALSDGI-46 also blocks TRAF3 migrating to MAVS. In parallel, these TRAFs are important in activating transcription factors NF-kB and/or IRF-3 by hMPV. Our findings collectively demonstrate that M2-2 uses its PDZ motifs to launch the hMPV immune evasion through blocking the interaction of MAVS and its downstream TRAFs. Copyright © 2016 Elsevier Inc. All rights reserved.

Stereoscopic filming for investigating evasive side-stepping and anterior cruciate ligament injury risk

Science.gov (United States)

Lee, Marcus J. C.; Bourke, Paul; Alderson, Jacqueline A.; Lloyd, David G.; Lay, Brendan

2010-02-01

Non-contact anterior cruciate ligament (ACL) injuries are serious and debilitating, often resulting from the performance of evasive sides-stepping (Ssg) by team sport athletes. Previous laboratory based investigations of evasive Ssg have used generic visual stimuli to simulate realistic time and space constraints that athletes experience in the preparation and execution of the manoeuvre. However, the use of unrealistic visual stimuli to impose these constraints may not be accurately identifying the relationship between the perceptual demands and ACL loading during Ssg in actual game environments. We propose that stereoscopically filmed footage featuring sport specific opposing defender/s simulating a tackle on the viewer, when used as visual stimuli, could improve the ecological validity of laboratory based investigations of evasive Ssg. Due to the need for precision and not just the experience of viewing depth in these scenarios, a rigorous filming process built on key geometric considerations and equipment development to enable a separation of 6.5 cm between two commodity cameras had to be undertaken. Within safety limits, this could be an invaluable tool in enabling more accurate investigations of the associations between evasive Ssg and ACL injury risk.

Evasion of adaptive and innate immune response mechanisms by γ-herpesviruses

Science.gov (United States)

Feng, Pinghui; Moses, Ashlee; Früh, Klaus

2015-01-01

γ-Herpesviral immune evasion mechanisms are optimized to support the acute, lytic and the longterm, latent phase of infection. During acute infection, specific immune modulatory proteins limit, but also exploit, the antiviral activities of cell intrinsic innate immune responses as well as those of innate and adaptive immune cells. During latent infection, a restricted gene expression program limits immune targeting and cis-acting mechanisms to reduce the antigen presentation as well as antigenicity of latency-associated proteins. Here, we will review recent progress in our understanding of γ-herpesviral immune evasion strategies. PMID:23735334

Drosophila increase exploration after visually detecting predators.

Directory of Open Access Journals (Sweden)

Miguel de la Flor

Full Text Available Novel stimuli elicit behaviors that are collectively known as specific exploration. These behaviors allow the animal to become more familiar with the novel objects within its environment. Specific exploration is frequently suppressed by defensive reactions to predator cues. Herein, we examine if this suppression occurs in Drosophila melanogaster by measuring the response of these flies to wild harvested predators. The flies used in our experiments have been cultured and had not lived under predator threat for multiple decades. In a circular arena with centrally-caged predators, wild type Drosophila actively avoided the pantropical jumping spider, Plexippus paykulli, and the Texas unicorn mantis, Phyllovates chlorophaena, indicating an innate defensive reaction to these predators. Interestingly, wild type Drosophila males also avoided a centrally-caged mock spider, and the avoidance of the mock spider became exaggerated when it was made to move within the cage. Visually impaired Drosophila failed to detect and avoid the Plexippus paykulli and the moving mock spider, while the broadly anosmic orco2 mutants were fully capable of detecting and avoiding Plexippus paykulli, indicating that these flies principally relied upon vison to perceive the predator stimuli. During early exploration of the arena, exploratory activity increased in the presence of Plexippus paykulli and the moving mock spider. The elevated activity induced by Plexippus paykulli disappeared after the fly had finished exploring, suggesting the flies were capable of habituating the predator cues. Taken together, these results indicate that despite being isolated from predators for decades Drosophila will visually detect these predators, retain innate defensive behaviors, respond by increasing exploratory activity in the arena rather than suppressing activity, and may habituate to normal predator cues.

Power lines, roads, and avian nest survival: effects on predator identity and predation intensity.

Science.gov (United States)

DeGregorio, Brett A; Weatherhead, Patrick J; Sperry, Jinelle H

2014-05-01

1 Anthropogenic alteration of landscapes can affect avian nest success by influencing the abundance, distribution, and behavior of predators. Understanding avian nest predation risk necessitates understanding how landscapes affect predator distribution and behavior. 2 From a sample of 463 nests of 17 songbird species, we evaluated how landscape features (distance to forest edge, unpaved roads, and power lines) influenced daily nest survival. We also used video cameras to identify nest predators at 137 nest predation events and evaluated how landscape features influenced predator identity. Finally, we determined the abundance and distribution of several of the principal predators using surveys and radiotelemetry. 3 Distance to power lines was the best predictor of predator identity: predation by brown-headed cowbirds (Molothrus ater), corvids (Corvus sp. and Cyanocitta cristata), racers (Coluber constrictor), and coachwhips (Masticophis flagellum) increased with proximity to power lines, whereas predation by rat snakes (Elaphe obsoleta) and raptors decreased. In some cases, predator density may reliably indicate nest predation risk because racers, corvids, and cowbirds frequently used power line right-of-ways. 4 Of five bird species with enough nests to analyze individually, daily nest survival of only indigo buntings (Passerina cyanea) decreased with proximity to power lines, despite predation by most predators at our site being positively associated with power lines. For all nesting species combined, distance to unpaved road was the model that most influenced daily nest survival. This pattern is likely a consequence of rat snakes, the locally dominant nest predator (28% of predation events), rarely using power lines and associated areas. Instead, rat snakes were frequently associated with road edges, indicating that not all edges are functionally similar. 5 Our results suggest that interactions between predators and landscape features are likely to be specific to

Toward realistic pursuit-evasion using a roadmap-based approach

KAUST Repository

Rodriguez, Samuel

2011-05-01

In this work, we describe an approach for modeling and simulating group behaviors for pursuit-evasion that uses a graph-based representation of the environment and integrates multi-agent simulation with roadmap-based path planning. Our approach can be applied to more realistic scenarios than are typically studied in most previous work, including agents moving in 3D environments such as terrains, multi-story buildings, and dynamic environments. We also support more realistic three-dimensional visibility computations that allow evading agents to hide in crowds or behind hills. We demonstrate the utility of this approach on mobile robots and in simulation for a variety of scenarios including pursuit-evasion and tag on terrains, in multi-level buildings, and in crowds. © 2011 IEEE.

Predation efficiency of Anopheles gambiae larvae by aquatic predators in western Kenya highlands

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Nyindo Mramba

2011-07-01

Full Text Available Abstract Background The current status of insecticide resistance in mosquitoes and the effects of insecticides on non-target insect species have raised the need for alternative control methods for malaria vectors. Predation has been suggested as one of the important regulation mechanisms for malaria vectors in long-lasting aquatic habitats, but the predation efficiency of the potential predators is largely unknown in the highlands of western Kenya. In the current study, we examined the predation efficiency of five predators on Anopheles gambiae s.s larvae in 24 hour and semi- field evaluations. Methods Predators were collected from natural habitats and starved for 12 hours prior to starting experiments. Preliminary experiments were conducted to ascertain the larval stage most predated by each predator species. When each larval instar was subjected to predation, third instar larvae were predated at the highest rate. Third instar larvae of An. gambiae were introduced into artificial habitats with and without refugia at various larval densities. The numbers of surviving larvae were counted after 24 hours in 24. In semi-field experiments, the larvae were counted daily until they were all either consumed or had developed to the pupal stage. Polymerase chain reaction was used to confirm the presence of An. gambiae DNA in predator guts. Results Experiments found that habitat type (P P P P An. gambiae DNA was found in at least three out of ten midguts for all predator species. Gambusia affins was the most efficient, being three times more efficient than tadpoles. Conclusion These experiments provide insight into the efficiency of specific natural predators against mosquito larvae. These naturally occurring predators may be useful in biocontrol strategies for aquatic stage An. gambiae mosquitoes. Further investigations should be done in complex natural habitats for these predators.

Conservation of a unique mechanism of immune evasion across the Lyssavirus genus.

Science.gov (United States)

Wiltzer, L; Larrous, F; Oksayan, S; Ito, N; Marsh, G A; Wang, L F; Blondel, D; Bourhy, H; Jans, D A; Moseley, G W

2012-09-01

The evasion of host innate immunity by Rabies virus, the prototype of the genus Lyssavirus, depends on a unique mechanism of selective targeting of interferon-activated STAT proteins by the viral phosphoprotein (P-protein). However, the immune evasion strategies of other lyssaviruses, including several lethal human pathogens, are unresolved. Here, we show that this mechanism is conserved between the most distantly related members of the genus, providing important insights into the pathogenesis and potential therapeutic targeting of lyssaviruses.

Mercury evasion from a boreal peatland shortens the timeline for recovery from legacy pollution.

Science.gov (United States)

Osterwalder, Stefan; Bishop, Kevin; Alewell, Christine; Fritsche, Johannes; Laudon, Hjalmar; Åkerblom, Staffan; Nilsson, Mats B

2017-11-22

Peatlands are a major source of methylmercury that contaminates downstream aquatic food webs. The large store of mercury (Hg) in peatlands could be a source of Hg for over a century even if deposition is dramatically reduced. However, the reliability of Hg mass balances can be questioned due to missing long-term land-atmosphere flux measurements. We used a novel micrometeorological system for continuous measurement of Hg peatland-atmosphere exchange to derive the first annual Hg budget for a peatland. The evasion of Hg (9.4 µg m -2 yr -1 ) over the course of a year was seven times greater than stream Hg export, and over two times greater than wet bulk deposition to the boreal peatland. Measurements of dissolved gaseous Hg in the peat pore water also indicate Hg evasion. The net efflux may result from recent declines in atmospheric Hg concentrations that have turned the peatland from a net sink into a source of atmospheric Hg. This net Hg loss suggests that open boreal peatlands and downstream ecosystems can recover more rapidly from past atmospheric Hg deposition than previously assumed. This has important implications for future levels of methylmercury in boreal freshwater fish and the estimation of historical Hg accumulation rates from peat profiles.

An update: Epstein-Barr virus and immune evasion via microRNA regulation.

Science.gov (United States)

Zuo, Lielian; Yue, Wenxin; Du, Shujuan; Xin, Shuyu; Zhang, Jing; Liu, Lingzhi; Li, Guiyuan; Lu, Jianhong

2017-06-01

Epstein-Barr virus (EBV) is an oncogenic virus that ubiquitously establishes life-long persistence in humans. To ensure its survival and maintain its B cell transformation function, EBV has developed powerful strategies to evade host immune responses. Emerging evidence has shown that microRNAs (miRNAs) are powerful regulators of the maintenance of cellular homeostasis. In this review, we summarize current progress on how EBV utilizes miRNAs for immune evasion. EBV encodes miRNAs targeting both viral and host genes involved in the immune response. The miRNAs are found in two gene clusters, and recent studies have demonstrated that lack of these clusters increases the CD4 + and CD8 + T cell response of infected cells. These reports strongly indicate that EBV miRNAs are critical for immune evasion. In addition, EBV is able to dysregulate the expression of a variety of host miRNAs, which influence multiple immune-related molecules and signaling pathways. The transport via exosomes of EBV-regulated miRNAs and viral proteins contributes to the construction and modification of the inflammatory tumor microenvironment. During EBV immune evasion, viral proteins, immune cells, chemokines, pro-inflammatory cytokines, and pro-apoptosis molecules are involved. Our increasing knowledge of the role of miRNAs in immune evasion will improve the understanding of EBV persistence and help to develop new treatments for EBV-associated cancers and other diseases.

Simple Motion Pursuit and Evasion Differential Games with Many Pursuers on Manifolds with Euclidean Metric

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Atamurat Kuchkarov

2016-01-01

Full Text Available We consider pursuit and evasion differential games of a group of m pursuers and one evader on manifolds with Euclidean metric. The motions of all players are simple, and maximal speeds of all players are equal. If the state of a pursuer coincides with that of the evader at some time, we say that pursuit is completed. We establish that each of the differential games (pursuit or evasion is equivalent to a differential game of m groups of countably many pursuers and one group of countably many evaders in Euclidean space. All the players in any of these groups are controlled by one controlled parameter. We find a condition under which pursuit can be completed, and if this condition is not satisfied, then evasion is possible. We construct strategies for the pursuers in pursuit game which ensure completion the game for a finite time and give a formula for this time. In the case of evasion game, we construct a strategy for the evader.

Itemised Deductions : A Device to Reduce Tax Evasion

NARCIS (Netherlands)

Piolatto, A.

2010-01-01

Direct incentives and punishments are the most common instruments to fight tax evasion. The theoretical literature disregarded indirect schemes, such as itemised deductions, in which an agent has an interest in that other agents declare their revenue. Itemised deductions provide an incentive for

CAUSES OF TAX EVASION AND HOW TO REDUCE IT

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Marcel ȘUVELEA

2014-12-01

Full Text Available The level of taxation is influenced and determined by several factors such as: the performance of the economy at any given time, the effectiveness of financed from taxes public expenditure, property structure, public needs as determined by Government policy and approved by the Parliament, the degree of contributors’ understanding of budgetary needs and adherence to Government policy, the stage of democracy in one country or another, etc. These make that between tax level and its base, represented by the GDP, not to be a strict correlation On the State budget and public finance, the cases of tax evasion or avoidance may not have manifested but negative effects. In reality, even the potentiality of cases of tax evasion by taxpayers, adversely affect public funds through the necessary expenditure to be earmarked for the prevention and monitoring of the tax payers. The higher is the extent of the phenomenon of tax evasion, the more the public finances of a State will suffer. If this phenomenon is joined by a weak economy and a shaky fiscal system, the negative effects are augmented. It should also be pointed out another important aspect of feeble public finances: chances are that fiscal bodies to act in that tough situation under emergency and pressure status and to deceive this tension on the economy, making it more unfit to uphold degraded public finances.

Conservation of a Unique Mechanism of Immune Evasion across the Lyssavirus Genus

Science.gov (United States)

Wiltzer, L.; Larrous, F.; Oksayan, S.; Ito, N.; Marsh, G. A.; Wang, L. F.; Blondel, D.; Bourhy, H.; Jans, D. A.

2012-01-01

The evasion of host innate immunity by Rabies virus, the prototype of the genus Lyssavirus, depends on a unique mechanism of selective targeting of interferon-activated STAT proteins by the viral phosphoprotein (P-protein). However, the immune evasion strategies of other lyssaviruses, including several lethal human pathogens, are unresolved. Here, we show that this mechanism is conserved between the most distantly related members of the genus, providing important insights into the pathogenesis and potential therapeutic targeting of lyssaviruses. PMID:22740405

Interactions among predators and plant specificity protect herbivores from top predators.

Science.gov (United States)

Bosc, Christopher; Pauw, Anton; Roets, Francois; Hui, Cang

2018-05-04

The worldwide loss of top predators from natural and agricultural systems has heightened the need to understand how important they are in controlling herbivore abundance. The effect of top predators on herbivore species is likely to depend on 1) the importance of the consumption of intermediate predators by top predators (intra-guild predation; IGP), but also on 2) plant specificity by herbivores, because specialists may defend themselves better (enemy-free space; EFS). Insectivorous birds, as top predators, are generally known to effectively control herbivorous insects, despite also consuming intermediate predators such as spiders, but how this effect varies among herbivore species in relation to the cascading effects of IGP and EFS is not known. To explore this, we excluded birds from natural fynbos vegetation in South Africa using large netted cages and recorded changes in abundance relative to control plots for 199 plant-dwelling intermediate predator and 341 herbivore morpho-species that varied in their estimated plant specificity. We found a strong negative effect of birds on the total abundance of all intermediate predators, with especially clear effects on spiders (strong IGP). In contrast with previous studies, which document a negative effect of birds on herbivores, we found an overall neutral effect of birds on herbivore abundance, but the effect varied among species: some species were negatively affected by birds, suggesting that they were mainly consumed by birds, whereas others, likely released from spiders by IGP, were positively affected. Some species were also effectively neutrally affected by birds. These tended to be more specialized to plants compared to the other species, which may imply that some plant specialists benefited from protection provided by EFS from both birds and spiders. These results suggest that the response of herbivore species to top predators may depend on cascading effects of interactions among predators and on their degree

Avoiding evasion: medical ethics education and emotion theory.

NARCIS (Netherlands)

Leget, C.J.W.

2004-01-01

Beginning with an exemplary case study, this paper diagnoses and analyses some important strategies of evasion and factors of hindrance that are met in the teaching of medical ethics to undergraduate medical students. Some of these inhibitions are inherent to ethical theories; others are connected

Predation risk of artificial ground nests in managed floodplain meadows

Science.gov (United States)

Arbeiter, Susanne; Franke, Elisabeth

2018-01-01

Nest predation highly determines the reproductive success in birds. In agricultural grasslands, vegetation characteristics and management practices influences the predation risk of ground breeders. Little is known so far on the predation pressure on non-passerine nests in tall swards. Investigations on the interaction of land use with nesting site conditions and the habitat selection of nest predators are crucial to develop effective conservation measures for grassland birds. In this study, we used artificial nests baited with quail and plasticine eggs to identify potential predators of ground nests in floodplain meadows and related predation risk to vegetation structure and grassland management. Mean daily predation rate was 0.01 (±0.012) after an exposure duration of 21 days. 70% of all observed nest predations were caused by mammals (Red Fox and mustelids) and 17.5% by avian predators (corvids). Nest sites close to the meadow edge and those providing low forb cover were faced with a higher daily predation risk. Predation risk also increased later in the season. Land use in the preceding year had a significant effect on predation risk, showing higher predation rates on unmanaged sites than on mown sites. Unused meadows probably attract mammalian predators, because they provide a high abundance of small rodents and a more favourable vegetation structure for foraging, increasing also the risk of incidental nest predations. Although mowing operation is a major threat to ground-nesting birds, our results suggest that an annual removal of vegetation may reduce predation risk in the subsequent year.

Bribes and Business Tax Evasion

Directory of Open Access Journals (Sweden)

Joulfaian, David

2009-12-01

Full Text Available This paper investigates the role of governance, in particular bribes to tax officials, in shaping business tax compliance behavior in transition economies. The empirical results show that business noncompliance rises with the frequency of tax related bribes. More specifically, the findings from 27 economies suggest that tax evasion thrives when bribes to tax officials are commonplace. These findings are robust to a number of specifications that control for firm and country attributes as well as address the potential endogeneity of bribes.

Ocean acidification alters predator behaviour and reduces predation rate.

Science.gov (United States)

Watson, Sue-Ann; Fields, Jennifer B; Munday, Philip L

2017-02-01

Ocean acidification poses a range of threats to marine invertebrates; however, the emerging and likely widespread effects of rising carbon dioxide (CO 2 ) levels on marine invertebrate behaviour are still little understood. Here, we show that ocean acidification alters and impairs key ecological behaviours of the predatory cone snail Conus marmoreus Projected near-future seawater CO 2 levels (975 µatm) increased activity in this coral reef molluscivore more than threefold (from less than 4 to more than 12 mm min -1 ) and decreased the time spent buried to less than one-third when compared with the present-day control conditions (390 µatm). Despite increasing activity, elevated CO 2 reduced predation rate during predator-prey interactions with control-treated humpbacked conch, Gibberulus gibberulus gibbosus; 60% of control predators successfully captured and consumed their prey, compared with only 10% of elevated CO 2 predators. The alteration of key ecological behaviours of predatory invertebrates by near-future ocean acidification could have potentially far-reaching implications for predator-prey interactions and trophic dynamics in marine ecosystems. Combined evidence that the behaviours of both species in this predator-prey relationship are altered by elevated CO 2 suggests food web interactions and ecosystem structure will become increasingly difficult to predict as ocean acidification advances over coming decades. © 2017 The Author(s).

Does the sole description of a tax authority affect tax evasion?--the impact of described coercive and legitimate power.

Science.gov (United States)

Hartl, Barbara; Hofmann, Eva; Gangl, Katharina; Hartner-Tiefenthaler, Martina; Kirchler, Erich

2015-01-01

Following the classic economic model of tax evasion, taxpayers base their tax decisions on economic determinants, like fine rate and audit probability. Empirical findings on the relationship between economic key determinants and tax evasion are inconsistent and suggest that taxpayers may rather rely on their beliefs about tax authority's power. Descriptions of the tax authority's power may affect taxpayers' beliefs and as such tax evasion. Experiment 1 investigates the impact of fines and beliefs regarding tax authority's power on tax evasion. Experiments 2-4 are conducted to examine the effect of varying descriptions about a tax authority's power on participants' beliefs and respective tax evasion. It is investigated whether tax evasion is influenced by the description of an authority wielding coercive power (Experiment 2), legitimate power (Experiment 3), and coercive and legitimate power combined (Experiment 4). Further, it is examined whether a contrast of the description of power (low to high power; high to low power) impacts tax evasion (Experiments 2-4). Results show that the amount of fine does not impact tax payments, whereas participants' beliefs regarding tax authority's power significantly shape compliance decisions. Descriptions of high coercive power as well as high legitimate power affect beliefs about tax authority's power and positively impact tax honesty. This effect still holds if both qualities of power are applied simultaneously. The contrast of descriptions has little impact on tax evasion. The current study indicates that descriptions of the tax authority, e.g., in information brochures and media reports, have more influence on beliefs and tax payments than information on fine rates. Methodically, these considerations become particularly important when descriptions or vignettes are used besides objective information.

Does the sole description of a tax authority affect tax evasion?--the impact of described coercive and legitimate power.

Directory of Open Access Journals (Sweden)

Barbara Hartl

Full Text Available Following the classic economic model of tax evasion, taxpayers base their tax decisions on economic determinants, like fine rate and audit probability. Empirical findings on the relationship between economic key determinants and tax evasion are inconsistent and suggest that taxpayers may rather rely on their beliefs about tax authority's power. Descriptions of the tax authority's power may affect taxpayers' beliefs and as such tax evasion. Experiment 1 investigates the impact of fines and beliefs regarding tax authority's power on tax evasion. Experiments 2-4 are conducted to examine the effect of varying descriptions about a tax authority's power on participants' beliefs and respective tax evasion. It is investigated whether tax evasion is influenced by the description of an authority wielding coercive power (Experiment 2, legitimate power (Experiment 3, and coercive and legitimate power combined (Experiment 4. Further, it is examined whether a contrast of the description of power (low to high power; high to low power impacts tax evasion (Experiments 2-4. Results show that the amount of fine does not impact tax payments, whereas participants' beliefs regarding tax authority's power significantly shape compliance decisions. Descriptions of high coercive power as well as high legitimate power affect beliefs about tax authority's power and positively impact tax honesty. This effect still holds if both qualities of power are applied simultaneously. The contrast of descriptions has little impact on tax evasion. The current study indicates that descriptions of the tax authority, e.g., in information brochures and media reports, have more influence on beliefs and tax payments than information on fine rates. Methodically, these considerations become particularly important when descriptions or vignettes are used besides objective information.

Tax Evasion Causes and Prevenience or Rebutment Way of Tax Dodger Phenomenon

Directory of Open Access Journals (Sweden)

Corina Nichitcin

2010-12-01

Full Text Available Tax evasion phenomenon, having negative impact on many levels, must be constantly pursued in order to minimize tax circumvention and control section in the issue of tax fraud. From international theory and experience it is known that normal functioning of market economy is conditioned by promotion of certain efficient policies and adequate legislation implementation. So, as Republic of Moldova is no exception among countries where tax evasion is, the study of this subject is up-to-date and it is required for presenting these problems at national and international levels.

Spirochetal Lipoproteins and Immune Evasion

Science.gov (United States)

Christodoulides, Alexei; Boyadjian, Ani; Kelesidis, Theodoros

2017-01-01

Spirochetes are a major threat to public health. However, the exact pathogenesis of spirochetal diseases remains unclear. Spirochetes express lipoproteins that often determine the cross talk between the host and spirochetes. Lipoproteins are pro-inflammatory, modulatory of immune responses, and enable the spirochetes to evade the immune system. In this article, we review the modulatory effects of spirochetal lipoproteins related to immune evasion. Understanding lipoprotein-induced immunomodulation will aid in elucidating innate pathogenesis processes and subsequent adaptive mechanisms potentially relevant to spirochetal disease vaccine development and treatment. PMID:28424696

A comparative analysis of the factors of tax evasion in Ukraine and USA

OpenAIRE

N. Frolova

2014-01-01

The purpose of the article is to reveal effects on the individual's tax compliance, to examine weak points of tax legislation of Ukraine that may induce tax evasion, and to develop recommendations for the improvement of Ukraine's tax system in terms of minimization of tax evasion, in particular, by introducing comprehensive tax reporting. The article presents the findings of various theoretical and empiric investigations by leading domestic and foreign experts on the issues of estimation and ...

Tax havens: Features, operations and solving tax evasion problems

Directory of Open Access Journals (Sweden)

Obradović-Ćuk Jelena

2016-01-01

Full Text Available Tax haven offers minimal or no tax liability to foreign individuals and enterprises in economically and politically stable environment, where little or no financial information is shared with foreign tax authorities. The aim of this research is to create a comprehensive overview of the characteristics and operations of tax havens, as well as to point out to the ways to overcome the problem of tax evasion. The methodology used in the work is characteristic of social science research: analysis, synthesis and discussion, comparative, inductive and historical analysis, together with the usage of relevant national and international sources. This paper describes the basic features of tax havens, as well as specific business models applied in them. A separate chapter deals with overcoming the problem of tax evasion, which is the main adverse effect of doing business through tax havens.

The Effects of Predator Evolution and Genetic Variation on Predator-Prey Population-Level Dynamics.

Science.gov (United States)

Cortez, Michael H; Patel, Swati

2017-07-01

This paper explores how predator evolution and the magnitude of predator genetic variation alter the population-level dynamics of predator-prey systems. We do this by analyzing a general eco-evolutionary predator-prey model using four methods: Method 1 identifies how eco-evolutionary feedbacks alter system stability in the fast and slow evolution limits; Method 2 identifies how the amount of standing predator genetic variation alters system stability; Method 3 identifies how the phase lags in predator-prey cycles depend on the amount of genetic variation; and Method 4 determines conditions for different cycle shapes in the fast and slow evolution limits using geometric singular perturbation theory. With these four methods, we identify the conditions under which predator evolution alters system stability and shapes of predator-prey cycles, and how those effect depend on the amount of genetic variation in the predator population. We discuss the advantages and disadvantages of each method and the relations between the four methods. This work shows how the four methods can be used in tandem to make general predictions about eco-evolutionary dynamics and feedbacks.

ACCOUNTING INFORMATION INDISPENSABLE SOURCE FOR THE DISCOVERY OF TAX EVASION IN THE FIELD OF PRODUCTS SUBJECT TO EXCISE

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Dorel MATEȘ

2015-12-01

Full Text Available The present article aims to highlight the kinds of tax evasion methods in the field of products subject to excise duty and the role of the tax inspection in combating them. The research reveals which are the most common methods of tax evasion, but it tries to discern the probable developments of the process. The article has in view the inexorable reality, namely that the ingenuity method of tax fraud increases with the emergence of the new rules or barriers to the fraud. Following the research carried out we found that the tax evasion phenomenon in the field of products subject to excise duty has currently a significant impact in the economic and social Romanian reality. In order to reduce the tax evasion phenomenon in the field of products subject to excise duty, it must set up a mechanism for monitoring, oversight and fiscal control as well as the amendment of legislation, the tax evasion being mainly a consequence of the inaccuracies or imperfection of laws.

Contributions to Pursuit-Evasion Game Theory

Science.gov (United States)

Oyler, Dave Wilson

This dissertation studies adversarial conflicts among a group of agents moving in the plane, possibly among obstacles, where some agents are pursuers and others are evaders. The goal of the pursuers is to capture the evaders, where capture requires a pursuer to be either co-located with an evader, or in close proximity. The goal of the evaders is to avoid capture. These scenarios, where different groups compete to accomplish conflicting goals, are referred to as pursuit-evasion games, and the agents are called players. Games featuring one pursuer and one evader are analyzed using dominance, where a point in the plane is said to be dominated by a player if that player is able to reach the point before the opposing players, regardless of the opposing players' actions. Two generalizations of the Apollonius circle are provided. One solves games with environments containing obstacles, and the other provides an alternative solution method for the Homicidal Chauffeur game. Optimal pursuit and evasion strategies based on dominance are provided. One benefit of dominance analysis is that it extends to games with many players. Two foundational games are studied; one features multiple pursuers against a single evader, and the other features a single pursuer against multiple evaders. Both are solved using dominance through a reduction to single pursuer, single evader games. Another game featuring competing teams of pursuers is introduced, where an evader cooperates with friendly pursuers to rendezvous before being captured by adversaries. Next, the assumption of complete and perfect information is relaxed, and uncertainties in player speeds, player positions, obstacle locations, and cost functions are studied. The sensitivity of the dominance boundary to perturbations in parameters is provided, and probabilistic dominance is introduced. The effect of information is studied by comparing solutions of games with perfect information to games with uncertainty. Finally, a pursuit law

Does the Sole Description of a Tax Authority Affect Tax Evasion? - The Impact of Described Coercive and Legitimate Power

Science.gov (United States)

Hartl, Barbara; Hofmann, Eva; Gangl, Katharina; Hartner-Tiefenthaler, Martina; Kirchler, Erich

2015-01-01

Following the classic economic model of tax evasion, taxpayers base their tax decisions on economic determinants, like fine rate and audit probability. Empirical findings on the relationship between economic key determinants and tax evasion are inconsistent and suggest that taxpayers may rather rely on their beliefs about tax authority’s power. Descriptions of the tax authority’s power may affect taxpayers’ beliefs and as such tax evasion. Experiment 1 investigates the impact of fines and beliefs regarding tax authority’s power on tax evasion. Experiments 2-4 are conducted to examine the effect of varying descriptions about a tax authority’s power on participants’ beliefs and respective tax evasion. It is investigated whether tax evasion is influenced by the description of an authority wielding coercive power (Experiment 2), legitimate power (Experiment 3), and coercive and legitimate power combined (Experiment 4). Further, it is examined whether a contrast of the description of power (low to high power; high to low power) impacts tax evasion (Experiments 2-4). Results show that the amount of fine does not impact tax payments, whereas participants’ beliefs regarding tax authority’s power significantly shape compliance decisions. Descriptions of high coercive power as well as high legitimate power affect beliefs about tax authority’s power and positively impact tax honesty. This effect still holds if both qualities of power are applied simultaneously. The contrast of descriptions has little impact on tax evasion. The current study indicates that descriptions of the tax authority, e.g., in information brochures and media reports, have more influence on beliefs and tax payments than information on fine rates. Methodically, these considerations become particularly important when descriptions or vignettes are used besides objective information. PMID:25923770

Interactions of bullfrog tadpole predators and an insecticide: Predation release and facilitation

Science.gov (United States)

Boone, M.D.; Semlitsch, R.D.

2003-01-01

The effect of a contaminant on a community may not be easily predicted, given that complex changes in food resources and predator-prey dynamics may result. The objectives of our study were to determine the interactive effects of the insecticide carbaryl and predators on body size, development, survival, and activity of tadpoles of the bullfrog (Rana catesbeiana). We conducted the study in cattle tank mesocosm ponds exposed to 0, 3.5, or 7.0 mg/l carbaryl, and no predators or two red-spotted newts (Notophthalmus viridescens), bluegill sunfish (Lepomis macrochirus), or crayfish (Orconectes sp.). Carbaryl negatively affected predator survival by eliminating crayfish from all ponds, and by eliminating bluegill sunfish from ponds exposed to the highest concentration of carbaryl; carbaryl exposure did not effect survival of red-spotted newts. Because crayfish were eliminated by carbaryl, bullfrogs were released from predation and survival was near that of predator controls at low concentrations of carbaryl exposure. High concentrations of carbaryl reduced tadpole survival regardless of whether predators survived carbaryl exposure or not. Presence of crayfish and newts reduced tadpole survival, while bluegill sunfish appeared to facilitate bullfrog tadpole survival. Presence of carbaryl stimulated bullfrog tadpole mass and development. Our study demonstrates that the presence of a contaminant stress can alter community regulation by releasing prey from predators that are vulnerable to contaminants in some exposure scenarios.

Predator-induced changes in metabolism cannot explain the growth/predation risk tradeoff

DEFF Research Database (Denmark)

Steiner, Uli; Van Buskirk, Josh

2009-01-01

, consistent with the "fight-or-flight" response observed in many organisms. The long term reaction showed the opposite pattern: tadpoles reduced oxygen consumption after three weeks exposure to predators, which would act to reduce the growth cost of predator defence. The results point to an instantaneous...... and reversible stress response to predation risk. This suggests that the tradeoff between avoiding predators and growing rapidly is not caused by changes in metabolic rate, and must be sought in other behavioural or physiological processes....

Predators indirectly control vector-borne disease: linking predator-prey and host-pathogen models.

Science.gov (United States)

Moore, Sean M; Borer, Elizabeth T; Hosseini, Parviez R

2010-01-06

Pathogens transmitted by arthropod vectors are common in human populations, agricultural systems and natural communities. Transmission of these vector-borne pathogens depends on the population dynamics of the vector species as well as its interactions with other species within the community. In particular, predation may be sufficient to control pathogen prevalence indirectly via the vector. To examine the indirect effect of predators on vectored-pathogen dynamics, we developed a theoretical model that integrates predator-prey and host-pathogen theory. We used this model to determine whether predation can prevent pathogen persistence or alter the stability of host-pathogen dynamics. We found that, in the absence of predation, pathogen prevalence in the host increases with vector fecundity, whereas predation on the vector causes pathogen prevalence to decline, or even become extinct, with increasing vector fecundity. We also found that predation on a vector may drastically slow the initial spread of a pathogen. The predator can increase host abundance indirectly by reducing or eliminating infection in the host population. These results highlight the importance of studying interactions that, within the greater community, may alter our predictions when studying disease dynamics. From an applied perspective, these results also suggest situations where an introduced predator or the natural enemies of a vector may slow the rate of spread of an emerging vector-borne pathogen.

Complement and innate immune evasion strategies of the human pathogenic fungus Candida albicans.

Science.gov (United States)

Luo, Shanshan; Skerka, Christine; Kurzai, Oliver; Zipfel, Peter F

2013-12-15

Candida albicans is a medically important fungus that can cause a wide range of diseases ranging from superficial infections to disseminated disease, which manifests primarily in immuno-compromised individuals. Despite the currently applied anti-fungal therapies, both mortality and morbidity caused by this human pathogenic fungus are still unacceptably high. Therefore new prophylactic and therapeutic strategies are urgently needed to prevent fungal infection. In order to define new targets for combating fungal disease, there is a need to understand the immune evasion strategies of C. albicans in detail. In this review, we summarize different sophisticated immune evasion strategies that are utilized by C. albicans. The description of the molecular mechanisms used for immune evasion does on one hand help to understand the infection process, and on the other hand provides valuable information to define new strategies and diagnostic approaches to fight and interfere with Candida infections. Copyright © 2013 Elsevier Ltd. All rights reserved.

Immunological Evasion in Glioblastoma

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Roxana Magaña-Maldonado

2016-01-01

Full Text Available Glioblastoma is the most aggressive tumor in Central Nervous System in adults. Among its features, modulation of immune system stands out. Although immune system is capable of detecting and eliminating tumor cells mainly by cytotoxic T and NK cells, tumor microenvironment suppresses an effective response through recruitment of modulator cells such as regulatory T cells, monocyte-derived suppressor cells, M2 macrophages, and microglia as well as secretion of immunomodulators including IL-6, IL-10, CSF-1, TGF-β, and CCL2. Other mechanisms that induce immunosuppression include enzymes as indolamine 2,3-dioxygenase. For this reason it is important to develop new therapies that avoid this immune evasion to promote an effective response against glioblastoma.

Tax Evasion, Information Reporting, and the Regressive Bias Hypothesis

DEFF Research Database (Denmark)

Boserup, Simon Halphen; Pinje, Jori Veng

A robust prediction from the tax evasion literature is that optimal auditing induces a regressive bias in effective tax rates compared to statutory rates. If correct, this will have important distributional consequences. Nevertheless, the regressive bias hypothesis has never been tested empirically...

Predation and caribou populations

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Dale R. Seip

1991-10-01

Full Text Available Predation, especially wolf (Canis lupus predation, limits many North American caribou (Rangifer tarandus populations below the density that food resources could sustain. The impact of predation depends on the parameters for the functional and numerical response of the wolves, relative to the potential annual increment of the caribou population. Differences in predator-avoidance strategies largely explain the major differences in caribou densities that occur naturally in North America. Caribou migrations that spatially separate caribou from wolves allow relatively high densities of caribou to survive. Non-migratory caribou that live in areas where wolf populations are sustained by alternate prey can be eliminated by wolf predation.

The narrow range of perceived predation: a 19 group study

Directory of Open Access Journals (Sweden)

Olivier Mesly

2013-05-01

Full Text Available This paper rests largely on the works of Mesly (1999 to 2012. It argues that the phenomenon of perceived predation as a functional behavioural phenomenon is subjected to certain limits, a finding based on studies performed on 19 different groups spread over a four-year span. It also finds a constant of k = 1.3 which reflects the invariant nature of perceived predation. These findings add to the theory of financial predation which stipulates that financial predators operate below the limits of detection pertaining to their customers (and market regulators. They are experts at minimizing the perception that clients could have that they are after their money, causing them financial harm, by surprise (perceived predation. Understanding the narrow range in which financial predators operate is setting the grounds to offer better protection to investors and to implementing better control and punitive measures.

Tadpoles balance foraging and predator avoidance: Effects of predation, pond drying, and hunger

Science.gov (United States)

Bridges, C.M.

2002-01-01

Organisms are predicted to make trade-offs when foraging and predator avoidance behaviors present conflicting demands. Balancing conflicting demands is important to larval amphibians because adult fitness can be strongly influenced by size at metamorphosis and duration of the larval period. Larvae in temporary ponds must maximize growth within a short time period to achieve metamorphosis before ponds dry, while simultaneously avoiding predators. To determine whether tadpoles trade off between conflicting demands, I examined tadpole (Pseudacris triseriata) activity and microhabitat use in the presence of red-spotted newts (Notopthalmus viridescens) under varying conditions of pond drying and hunger. Tadpoles significantly decreased activity and increased refuge use when predators were present. The proportion of active time tadpoles spent feeding was significantly greater in predator treatments, suggesting tadpoles adaptively balance the conflicting demands of foraging and predator avoidance without making apparent trade-offs. Tadpoles responded to simulated drying conditions by accelerating development. Pond drying did not modify microhabitat use or activity in the presence of predators, suggesting tadpoles perceived predation and hunger as greater immediate threats than desiccation, and did not take more risks.

TAX EVASION, LEVEL OF INTERNET CORPORATE REPORTING AND FIRM VALUE: EVIDENCE FROM INDONESIAN MANUFACTURING FIRMS

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Asmoro P.S.

2018-03-01

Full Text Available As a developing country that accumulates its source of revenue to taxes, Indonesia is not spared from tax compliance issues. The low level of tax compliance indicates a different point of view between the government and the Taxpayer. The low level of tax compliance indicates a different point of view between the government and the Taxpayer. Taxpayers still consider the obligation to pay taxes as an expense that can reduce their income or profits. Therefore, the rational Taxpayer will try to minimize the tax burden. One of them is by doing Tax Evasion. Taxation management is more often done by the Taxpayer Agency, especially the Manufacturing company. This is because the company has a very high business risk. Tax Evasion can increase organizational complexity which in turn can reduce financial transparency. Therefore, companies are required to disclose more information and provide flexible reporting systems that facilitate stakeholders. This encourages companies in the world to take advantage of the development of information technology and interconnection networking through internet corporate reporting. Utilization of internet corporate reporting is expected to increase the value of the company. This study aims to analyze the relationship between the concept of Tax Evasion, the level of internet corporate reporting disclosure, and the firm value. The results showed that the three hypotheses in this study were accepted. Tax Evasion affects the level of internet corporate reporting disclosure. In addition, Tax Evasion also directly or indirectly influence the firm value through the level disclosure of internet corporate reporting.

TAX EVASION BETWEEN FRAUD AND OPTIMIZATION

OpenAIRE

Emilia Cornelia STOICA

2017-01-01

Tax optimization, often called legal tax evasion is the use of methods and techniques that are within the law, in order to reduce or even cancel the tax liability. To achieve such an approach, the taxpayer or his advisers must know in depth the tax law - and by extension, the financial and administrative law - and, moreover, must be functional tax jurisdictions which allow the use of appropriate assemblies. The recent leasks, as WikiLeaks, LuxLeaks, SwissLeaks, Panama Papers etc. on financial...

Immune Evasion Strategies and Persistence of Helicobacter pylori.

Science.gov (United States)

Mejías-Luque, Raquel; Gerhard, Markus

Helicobacter pylori infection is commonly acquired during childhood, can persist lifelong if not treated, and can cause different gastric pathologies, including chronic gastritis, peptic ulcer disease, and eventually gastric cancer. H. pylori has developed a number of strategies in order to cope with the hostile conditions found in the human stomach as well as successful mechanisms to evade the strong innate and adaptive immune responses elicited upon infection. Thus, by manipulating innate immune receptors and related signaling pathways, inducing tolerogenic dendritic cells and inhibiting effector T cell responses, H. pylori ensures low recognition by the host immune system as well as its persistence in the gastric epithelium. Bacterial virulence factors such as cytotoxin-associated gene A, vacuolating cytotoxin A, or gamma-glutamyltranspeptidase have been extensively studied in the context of bacterial immune escape and persistence. Further, the bacterium possesses other factors that contribute to immune evasion. In this chapter, we discuss in detail the main evasion and persistence strategies evolved by the bacterium as well as the specific bacterial virulence factors involved.

Coexistence for an Almost Periodic Predator-Prey Model with Intermittent Predation Driven by Discontinuous Prey Dispersal

Directory of Open Access Journals (Sweden)

Yantao Luo

2017-01-01

Full Text Available An almost periodic predator-prey model with intermittent predation and prey discontinuous dispersal is studied in this paper, which differs from the classical continuous and impulsive dispersal predator-prey models. The intermittent predation behavior of the predator species only happens in the channels between two patches where the discontinuous migration movement of the prey species occurs. Using analytic approaches and comparison theorems of the impulsive differential equations, sufficient criteria on the boundedness, permanence, and coexistence for this system are established. Finally, numerical simulations demonstrate that, for an intermittent predator-prey model, both the intermittent predation and intrinsic growth rates of the prey and predator species can greatly impact the permanence, extinction, and coexistence of the population.

Immune evasion strategies of ranaviruses and innate immune responses to these emerging pathogens.

Science.gov (United States)

Grayfer, Leon; Andino, Francisco De Jesús; Chen, Guangchun; Chinchar, Gregory V; Robert, Jacques

2012-07-01

Ranaviruses (RV, Iridoviridae) are large double-stranded DNA viruses that infect fish, amphibians and reptiles. For ecological and commercial reasons, considerable attention has been drawn to the increasing prevalence of ranaviral infections of wild populations and in aquacultural settings. Importantly, RVs appear to be capable of crossing species barriers of numerous poikilotherms, suggesting that these pathogens possess a broad host range and potent immune evasion mechanisms. Indeed, while some of the 95-100 predicted ranavirus genes encode putative evasion proteins (e.g., vIFα, vCARD), roughly two-thirds of them do not share significant sequence identity with known viral or eukaryotic genes. Accordingly, the investigation of ranaviral virulence and immune evasion strategies is promising for elucidating potential antiviral targets. In this regard, recombination-based technologies are being employed to knock out gene candidates in the best-characterized RV member, Frog Virus (FV3). Concurrently, by using animal infection models with extensively characterized immune systems, such as the African clawed frog, Xenopus laevis, it is becoming evident that components of innate immunity are at the forefront of virus-host interactions. For example, cells of the macrophage lineage represent important combatants of RV infections while themselves serving as targets for viral infection, maintenance and possibly dissemination. This review focuses on the recent advances in the understanding of the RV immune evasion strategies with emphasis on the roles of the innate immune system in ranaviral infections.

Evasion Mechanisms Used by Pathogens to Escape the Lectin Complement Pathway.

Science.gov (United States)

Rosbjerg, Anne; Genster, Ninette; Pilely, Katrine; Garred, Peter

2017-01-01

The complement system is a crucial defensive network that protects the host against invading pathogens. It is part of the innate immune system and can be initiated via three pathways: the lectin, classical and alternative activation pathway. Overall the network compiles a group of recognition molecules that bind specific patterns on microbial surfaces, a group of associated proteases that initiates the complement cascade, and a group of proteins that interact in proteolytic complexes or the terminal pore-forming complex. In addition, various regulatory proteins are important for controlling the level of activity. The result is a pro-inflammatory response meant to combat foreign microbes. Microbial elimination is, however, not a straight forward procedure; pathogens have adapted to their environment by evolving a collection of evasion mechanisms that circumvent the human complement system. Complement evasion strategies features different ways of exploiting human complement proteins and moreover features different pathogen-derived proteins that interfere with the normal processes. Accumulated, these mechanisms target all three complement activation pathways as well as the final common part of the cascade. This review will cover the currently known lectin pathway evasion mechanisms and give examples of pathogens that operate these to increase their chance of invasion, survival and dissemination.

Was there significant tax evasion after the 1999 50 cent per pack cigarette tax increase in California?

Science.gov (United States)

Emery, S; White, M; Gilpin, E; Pierce, J

2002-01-01

Objectives: Several states, including California, have implemented large cigarette excise tax increases, which may encourage smokers to purchase their cigarettes in other lower taxed states, or from other lower or non-taxed sources. Such tax evasion thwarts tobacco control objectives and may cost the state substantial tax revenues. Thus, this study investigates the extent of tax evasion in the 6–12 months after the implementation of California's $0.50/pack excise tax increase. Design and setting: Retrospective data analysis from the 1999 California Tobacco Surveys (CTS), a random digit dialled telephone survey of California households. Main outcome measures: Sources of cigarettes, average daily cigarette consumption, and reported price paid. Results: Very few (5.1 (0.7)% (±95% confidence limits)) of California smokers avoided the excise tax by usually purchasing cigarettes from non- or lower taxed sources, such as out-of-state outlets, military commissaries, or the internet. The vast majority of smokers purchased their cigarettes from the most convenient and expensive sources: convenience stores/gas (petrol) stations (45.0 (1.9)%), liquor/drug stores (16.4 (1.6)%), and supermarkets (8.8 (1.2)%). Conclusions: Despite the potential savings, tax evasion by individual smokers does not appear to pose a serious threat to California's excise tax revenues or its tobacco control objectives. PMID:12035006

Tax Compliance Inventory: TAX-I Voluntary tax compliance, enforced tax compliance, tax avoidance, and tax evasion

Science.gov (United States)

Kirchler, Erich; Wahl, Ingrid

2010-01-01

Surveys on tax compliance and non-compliance often rely on ad hoc formulated items which lack standardization and empirical validation. We present an inventory to assess tax compliance and distinguish between different forms of compliance and non-compliance: voluntary versus enforced compliance, tax avoidance, and tax evasion. First, items to measure voluntary and enforced compliance, avoidance, and evasion were drawn up (collected from past research and newly developed), and tested empirically with the aim of producing four validated scales with a clear factorial structure. Second, findings from the first analyses were replicated and extended to validation on the basis of motivational postures. A standardized inventory is provided which can be used in surveys in order to collect data which are comparable across research focusing on self-reports. The inventory can be used in either of two ways: either in its entirety, or by applying the single scales independently, allowing an economical and fast assessment of different facets of tax compliance. PMID:20502612

Tax Compliance Inventory: TAX-I Voluntary tax compliance, enforced tax compliance, tax avoidance, and tax evasion.

Science.gov (United States)

Kirchler, Erich; Wahl, Ingrid

2010-06-01

Surveys on tax compliance and non-compliance often rely on ad hoc formulated items which lack standardization and empirical validation. We present an inventory to assess tax compliance and distinguish between different forms of compliance and non-compliance: voluntary versus enforced compliance, tax avoidance, and tax evasion. First, items to measure voluntary and enforced compliance, avoidance, and evasion were drawn up (collected from past research and newly developed), and tested empirically with the aim of producing four validated scales with a clear factorial structure. Second, findings from the first analyses were replicated and extended to validation on the basis of motivational postures. A standardized inventory is provided which can be used in surveys in order to collect data which are comparable across research focusing on self-reports. The inventory can be used in either of two ways: either in its entirety, or by applying the single scales independently, allowing an economical and fast assessment of different facets of tax compliance.

Evasion of T cell immunity by Epstein-Barr virus

NARCIS (Netherlands)

Horst, D.

2011-01-01

Immune evasion strategies are thought to contribute essentially to the life cycle of persistent viruses by delaying the elimination of the infected cell long enough to enable the virus to replicate. Exemplary in this context are the herpesviruses, large DNA viruses that are carried as a persistent

Tax evasion and income source: A comparative experimental study

NARCIS (Netherlands)

Gërxhani, K.; Schram, A.J.H.C.

2006-01-01

We compare tax evasive behavior in a country in transition from communism to that in a developed economy by running an experiment across distinct social groups in Albania and the Netherlands. Aside from the tax compliance decision, subjects choose a source of income, where one type enables

Toward Simulating Realistic Pursuit-Evasion Using a Roadmap-Based Approach

KAUST Repository

Rodriguez, Samuel; Denny, Jory; Zourntos, Takis; Amato, Nancy M.

2010-01-01

In this work, we describe an approach for modeling and simulating group behaviors for pursuit-evasion that uses a graph-based representation of the environment and integrates multi-agent simulation with roadmap-based path planning. We demonstrate

Predator avoidance in extremophile fish.

Science.gov (United States)

Bierbach, David; Schulte, Matthias; Herrmann, Nina; Zimmer, Claudia; Arias-Rodriguez, Lenin; Indy, Jeane Rimber; Riesch, Rüdiger; Plath, Martin

2013-02-06

Extreme habitats are often characterized by reduced predation pressures, thus representing refuges for the inhabiting species. The present study was designed to investigate predator avoidance of extremophile populations of Poecilia mexicana and P. sulphuraria that either live in hydrogen sulfide-rich (sulfidic) springs or cave habitats, both of which are known to have impoverished piscine predator regimes. Focal fishes that inhabited sulfidic springs showed slightly weaker avoidance reactions when presented with several naturally occurring predatory cichlids, but strongest differences to populations from non-sulfidic habitats were found in a decreased shoaling tendency with non-predatory swordtail (Xiphophorus hellerii) females. When comparing avoidance reactions between P. mexicana from a sulfidic cave (Cueva del Azufre) and the adjacent sulfidic surface creek (El Azufre), we found only slight differences in predator avoidance, but surface fish reacted much more strongly to the non-predatory cichlid Vieja bifasciata. Our third experiment was designed to disentangle learned from innate effects of predator recognition. We compared laboratory-reared (i.e., predator-naïve) and wild-caught (i.e., predator-experienced) individuals of P. mexicana from a non-sulfidic river and found no differences in their reaction towards the presented predators. Overall, our results indicate (1) that predator avoidance is still functional in extremophile Poecilia spp. and (2) that predator recognition and avoidance reactions have a strong genetic basis.

Predator Avoidance in Extremophile Fish

Science.gov (United States)

Bierbach, David; Schulte, Matthias; Herrmann, Nina; Zimmer, Claudia; Arias-Rodriguez, Lenin; Indy, Jeane Rimber; Riesch, Rüdiger; Plath, Martin

2013-01-01

Extreme habitats are often characterized by reduced predation pressures, thus representing refuges for the inhabiting species. The present study was designed to investigate predator avoidance of extremophile populations of Poecilia mexicana and P. sulphuraria that either live in hydrogen sulfide-rich (sulfidic) springs or cave habitats, both of which are known to have impoverished piscine predator regimes. Focal fishes that inhabited sulfidic springs showed slightly weaker avoidance reactions when presented with several naturally occurring predatory cichlids, but strongest differences to populations from non-sulfidic habitats were found in a decreased shoaling tendency with non-predatory swordtail (Xiphophorus hellerii) females. When comparing avoidance reactions between P. mexicana from a sulfidic cave (Cueva del Azufre) and the adjacent sulfidic surface creek (El Azufre), we found only slight differences in predator avoidance, but surface fish reacted much more strongly to the non-predatory cichlid Vieja bifasciata. Our third experiment was designed to disentangle learned from innate effects of predator recognition. We compared laboratory-reared (i.e., predator-naïve) and wild-caught (i.e., predator-experienced) individuals of P. mexicana from a non-sulfidic river and found no differences in their reaction towards the presented predators. Overall, our results indicate (1) that predator avoidance is still functional in extremophile Poecilia spp. and (2) that predator recognition and avoidance reactions have a strong genetic basis. PMID:25371337

Predators and the public trust.

Science.gov (United States)

Treves, Adrian; Chapron, Guillaume; López-Bao, Jose V; Shoemaker, Chase; Goeckner, Apollonia R; Bruskotter, Jeremy T

2017-02-01

behavioural ecologies of humans and predators. The scientific community has not reached consensus on sustainable levels of human-caused mortality for many predator populations. This challenge includes both genuine conceptual uncertainty and exploitation of scientific debate for political gain. Second, human intolerance for predators exposes value conflicts about preferences for some wildlife over others and balancing majority rule with the protection of minorities in a democracy. We examine how differences between traditional assumptions and scientific studies of interactions between people and predators impede evidence-based policy. Even if the prior challenges can be overcome, well-reasoned policy on wild animals faces a greater challenge than other environmental assets because animals and humans change behaviour in response to each other in the short term. These coupled, dynamic responses exacerbate clashes between uses that deplete wildlife and uses that enhance or preserve wildlife. Viewed in this way, environmental assets demand sophisticated, careful accounting by disinterested trustees who can both understand the multidisciplinary scientific measurements of relative costs and benefits among competing uses, and justly balance the needs of all beneficiaries including future generations. Without public trust principles, future trustees will seldom prevail against narrow, powerful, and undemocratic interests. Without conservation informed by public trust thinking predator populations will face repeated cycles of eradication and recovery. Our conclusions have implications for the many subfields of the biological sciences that address environmental trust assets from the atmosphere to aquifers. © 2015 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.

Fear of predation drives stable and differentiated social relationships in guppies.

Science.gov (United States)

Heathcote, Robert J P; Darden, Safi K; Franks, Daniel W; Ramnarine, Indar W; Croft, Darren P

2017-02-02

Social relationships can have important consequences for fitness in animals. Whilst numerous studies have shown that individuals often join larger groups in response to perceived predation risk (i.e. fear of predation), the importance of predation risk in driving the formation and stability of social relationships within groups has been relatively ignored. We experimentally tested how predation threat influenced fine-scale social network structure using Trinidadian guppies (Poecilia reticulata). When perceived predation risk was high, individuals developed stable and more differentiated social ties compared to when perceived risk was low. Intriguingly, social differentiation coincided with shoals being somewhat smaller under high-perceived risk, suggesting a possible conflict between forming stable social relationships and larger social groups. Individuals most at risk of predation (large and bold individuals) showed the most exaggerated responses in several social measures. Taken together, we provide the first experimental evidence that proximate risk of predation can increase the intensity of social relationships and fine-scale social structure in animal populations.

Influence of prey body characteristics and performance on predator selection.

Science.gov (United States)

Holmes, Thomas H; McCormick, Mark I

2009-03-01

At the time of settlement to the reef environment, coral reef fishes differ in a number of characteristics that may influence their survival during a predatory encounter. This study investigated the selective nature of predation by both a multi-species predator pool, and a single common predator (Pseudochromis fuscus), on the reef fish, Pomacentrus amboinensis. The study focused on the early post-settlement period of P. amboinensis, when mortality, and hence selection, is known to be highest. Correlations between nine different measures of body condition/performance were examined at the time of settlement, in order to elucidate the relationships between different traits. Single-predator (P. fuscus) choice trials were conducted in 57.4-l aquaria with respect to three different prey characteristics [standard length (SL), body weight and burst swimming speed], whilst multi-species trials were conducted on open patch reefs, manipulating prey body weight only. Relationships between the nine measures of condition/performance were generally poor, with the strongest correlations occurring between the morphological measures and within the performance measures. During aquaria trials, P. fuscus was found to be selective with respect to prey SL only, with larger individuals being selected significantly more often. Multi-species predator communities, however, were selective with respect to prey body weight, with heavier individuals being selected significantly more often than their lighter counterparts. Our results suggest that under controlled conditions, body length may be the most important prey characteristic influencing prey survival during predatory encounters with P. fuscus. In such cases, larger prey size may actually be a distinct disadvantage to survival. However, these relationships appear to be more complex under natural conditions, where the expression of prey characteristics, the selectivity fields of a number of different predators, their relative abundance, and

A test of the predator satiation hypothesis, acorn predator size, and acorn preference

Science.gov (United States)

C.H. Greenberg; S.J. Zarnoch

2018-01-01

Mast seeding is hypothesized to satiate seed predators with heavy production and reduce populations with crop failure, thereby increasing seed survival. Preference for red or white oak acorns could influence recruitment among oak species. We tested the predator satiation hypothesis, acorn preference, and predator size by concurrently...

Cooperation under Predation Risk: Experiments on Costs and Benefits

Science.gov (United States)

Milinski, Manfred; Luthi, Jean H.; Eggler, Rolf; Parker, Geoffrey A.

1997-06-01

Two fish that cooperatively inspect a predator may have negotiated the share of the risk that each takes. A test of both the costs of predator inspection dependent on the distance from which the predator is approached and the potential benefits of cooperation was carried out strictly experimentally. We made either singletons or pairs of dead sticklebacks, Gasterosteus aculeatus, approach hungry pike, Esox lucius, by remote control according to an algorithm that mimicked natural inspection. The predation risk of both single inspectors and parallel inspecting pairs increased with closer inspection distances. A member of an inspecting pair had only about half the risk of that of a single inspector. In pairs, a companion diluted the lead fish's risk of being caught, depending on its distance behind the leader. The absolute risk difference between leader and follower was greatest for close inspection distances and decreased further away from the predator. The leader's relative risk increased with its distance ahead of the laggard. However, for a given distance between leader and laggard, the relative risks to the two fish remained similar with distance from the predator. The cost side of the inequalities that define a 'Prisoner's Dilemma' has thus been measured for this system. In a second experiment the 'attack deterrence hypothesis' of predator inspection (i.e. inspection decreases attack probability) was tested. The pike was offered a choice between two sticklebacks, one of which had carried out a predator inspection visit. There was no indication of attack deterrence through predator inspection.

System-wide significance of predation on juvenile salmonids in Columbia and Snake River reservoirs and evaluation of predation control measures. Annual report 1993

International Nuclear Information System (INIS)

Gadomski, D.M.; Poe, T.P.

1994-01-01

This project had three major goals. The first was to assist the Oregon Department of Fish and Wildlife with predation indexing as part of an effort to estimate the relative magnitude of juvenile salmonid losses to northern squawfish Ptychocheilus oregonensis in reservoirs throughout the Columbia River Basin. The second goal was to evaluate the northern squawfish control program and test critical assumptions about mid-reservoir predation processes. The final goal was to determine mechanisms underlying northern squawfish recruitment and factors affecting year-class strength

Turbidity interferes with foraging success of visual but not chemosensory predators.

Science.gov (United States)

Lunt, Jessica; Smee, Delbert L

2015-01-01

Predation can significantly affect prey populations and communities, but predator effects can be attenuated when abiotic conditions interfere with foraging activities. In estuarine communities, turbidity can affect species richness and abundance and is changing in many areas because of coastal development. Many fish species are less efficient foragers in turbid waters, and previous research revealed that in elevated turbidity, fish are less abundant whereas crabs and shrimp are more abundant. We hypothesized that turbidity altered predatory interactions in estuaries by interfering with visually-foraging predators and prey but not with organisms relying on chemoreception. We measured the effects of turbidity on the predation rates of two model predators: a visual predator (pinfish, Lagodon rhomboides) and a chemosensory predator (blue crabs, Callinectes sapidus) in clear and turbid water (0 and ∼100 nephelometric turbidity units). Feeding assays were conducted with two prey items, mud crabs (Panopeus spp.) that rely heavily on chemoreception to detect predators, and brown shrimp (Farfantepenaus aztecus) that use both chemical and visual cues for predator detection. Because turbidity reduced pinfish foraging on both mud crabs and shrimp, the changes in predation rates are likely driven by turbidity attenuating fish foraging ability and not by affecting prey vulnerability to fish consumers. Blue crab foraging was unaffected by turbidity, and blue crabs were able to successfully consume nearly all mud crab and shrimp prey. Turbidity can influence predator-prey interactions by reducing the feeding efficiency of visual predators, providing a competitive advantage to chemosensory predators, and altering top-down control in food webs.

Tumor immune evasion arises through loss of TNF sensitivity.

Science.gov (United States)

Kearney, Conor J; Vervoort, Stephin J; Hogg, Simon J; Ramsbottom, Kelly M; Freeman, Andrew J; Lalaoui, Najoua; Pijpers, Lizzy; Michie, Jessica; Brown, Kristin K; Knight, Deborah A; Sutton, Vivien; Beavis, Paul A; Voskoboinik, Ilia; Darcy, Phil K; Silke, John; Trapani, Joseph A; Johnstone, Ricky W; Oliaro, Jane

2018-05-18

Immunotherapy has revolutionized outcomes for cancer patients, but the mechanisms of resistance remain poorly defined. We used a series of whole-genome clustered regularly interspaced short palindromic repeat (CRISPR)-based screens performed in vitro and in vivo to identify mechanisms of tumor immune evasion from cytotoxic lymphocytes [CD8 + T cells and natural killer (NK) cells]. Deletion of key genes within the tumor necrosis factor (TNF) signaling, interferon-γ (IFN-γ) signaling, and antigen presentation pathways provided protection of tumor cells from CD8 + T cell-mediated killing and blunted antitumor immune responses in vivo. Deletion of a number of genes in the TNF pathway also emerged as the key mechanism of immune evasion from primary NK cells. Our screens also identified that the metabolic protein 2-aminoethanethiol dioxygenase (Ado) modulates sensitivity to TNF-mediated killing by cytotoxic lymphocytes and is required for optimal control of tumors in vivo. Remarkably, we found that tumors delete the same genes when exposed to perforin-deficient CD8 + T cells, demonstrating that the dominant immune evasion strategy used by tumor cells is acquired resistance to T cell-derived cytokine-mediated antitumor effects. We demonstrate that TNF-mediated bystander killing is a potent T cell effector mechanism capable of killing antigen-negative tumor cells. In addition to highlighting the importance of TNF in CD8 + T cell- and NK cell-mediated killing of tumor cells, our study also provides a comprehensive picture of the roles of the TNF, IFN, and antigen presentation pathways in immune-mediated tumor surveillance. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Predation vulnerability of planktonic copepods: consequences of predator foraging strategies and prey sensory abilities

DEFF Research Database (Denmark)

Viitasalo, M; Kiørboe, T; Flinkman, J.

1998-01-01

We investigated the vulnerability of 2 copepod species (Eurytemora affinis and Temora longicornis) to predation by predators with different foraging modes, three-spined stickleback Gasterosteus aculeatus juveniles and mysid shrimps Neomysis integer. Copepods were videofilmed escaping from predators...

Evasion of CO2 and dissolved carbon in river waters of three small catchments in an area occupied by small family farms in the eastern Amazon

Directory of Open Access Journals (Sweden)

Maria Beatriz Silva da Rosa

2017-08-01

Full Text Available CO2 effluxes from streams and rivers have been hypothesized to be a critical pathway of carbon flow from the biosphere back to the atmosphere. This study was conducted in three small Amazonian catchments to evaluate carbon evasion and dynamics, where land-use change has occurred on small family-farms. Monthly field campaigns were conducted from June 2006 to May 2007 in the Cumaru (CM, Pachibá (PB and São João (SJ streams. Electrical conductivity, pH, temperature, and dissolved oxygen measurements were done in situ, while water samples were collected to determine dissolved organic carbon (DOC and dissolved inorganic carbon (DIC concentrations, as well as carbon dioxide partial pressures (pCO2 and CO2 evasion fluxes. Instantaneous discharge measured by a current meter was used to calculate DOC fluxes. Considering all the sites, DOC, DIC, pCO2, and CO2 flux measurements ranged as follows, respectively: 0.27 - 12.13 mg L-1; 3.5 - 38.9 mg L-1; 2,265 - 26,974 ppm; and 3.39 - 75.35 μmol m-2 s-1. DOC annual flux estimates for CM, SJ and PB were, respectively, 281, 245, and 169 kg C ha-1. CO2 evasion fluxes had an average of 22.70 ± 1.67 μmol m-2 s-1. These CO2 evasion fluxes per unit area were similar to those measured for major Amazonian rivers, thus confirming our hypothesis that small streams can evade substantial quantities of CO2. As secondary vegetation is abundant as a result of family farming management in the region, we conclude that this vegetation can be a major driver of an abundant carbon cycle.

Understanding predation: implications toward forest management

Science.gov (United States)

Harvey R. Smith

1991-01-01

It is generally accepted that when gypsy moths rest in the litter survival is low due to predation by ground-foraging generalist predators and that predation can maintain these populations indefinitely. Forest Service research on predators of gypsy moth continues to focus on population dynamics, the mechanisms of predation and forest management implications.

The Evasion of the Text; Invasion of the Text; Again, Evasion of the Text; "The Eagle and the Mole": The Affective Fallacy Revisited.

Science.gov (United States)

Ducharme, Edward R.; And Others

1970-01-01

Three writers debate whether English teachers should depend on external or internal criteria when analyzing and teaching literature. Each writer discusses the meaning of Elinor Wylie's poem, "The Eagle and the Mole," according to his particular view of literary analysis. Edward Ducharme, in "The Evasion of the Text," submits…

Predation rates, timing, and predator composition for Scoters (Melanitta spp.) in marine habitats

Science.gov (United States)

Anderson, Eric J.; Esler, Daniel N.; Sean, Boyd W.; Evenson, Joseph; Nysewander, David R.; Ward, David H.; Dickson, Rian D.; Uher-Koch, Brian D.; Vanstratt, C.S.; Hupp, Jerry

2012-01-01

Studies of declining populations of sea ducks have focused mainly on bottom-up processes with little emphasis on the role of predation. We identified 11 potential predators of White-winged Scoters (Melanitta fusca (L., 1758)) and Surf Scoters (Melanitta perspicillata (L., 1758)) in North American marine habitats. However, of 596 Scoters marked with VHF transmitters along the Pacific coast, mortalities were recovered in association with just two identifiable categories of predators: in southeast Alaska recoveries occurred mainly near mustelid feeding areas, while those in southern British Columbia and Washington occurred mainly near feeding areas of Bald Eagles (Haliaeetus leucocephalus (L., 1766)). Determining whether marked Scoters had been depredated versus scavenged was often not possible, but mortalities occurred more frequently during winter than during wing molt (13.1% versus 0.7% of both species combined, excluding Scoters that died within a postrelease adjustment period). In two sites heavily used by Scoters, diurnal observations revealed no predation attempts and low rates of predator disturbances that altered Scoter behavior (≤ 0.22/h). These and other results suggest that predation by Bald Eagles occurs mainly at sites and times where densities of Scoters are low, while most predation by mustelids probably occurs when Scoters are energetically compromised.

Tax evasive behavior and gender in a transition count

NARCIS (Netherlands)

Gërxhani, K.; Kuiper, E.

2004-01-01

In this paper, we provide a structural explanation of gender difference with respect to tax evasion. A unique data set, collected from a field survey of households in Albania, allows us to test and explore the established fact, in a transition country. The results show that women tend to evade taxes

A predator-prey system with stage-structure for predator and nonlocal delay

DEFF Research Database (Denmark)

Lin, Z.G.; Pedersen, Michael; Zhang, Lai

2010-01-01

This paper deals with the behavior of solutions to the reaction-diffusion system under homogeneous Neumann boundary condition, which describes a prey-predator model with nonlocal delay. Sufficient conditions for the global stability of each equilibrium are derived by the Lyapunov functional...... and the results show that the introduction of stage-structure into predator positively affects the coexistence of prey and predator. Numerical simulations are performed to illustrate the results....

Significance of Selective Predation and Development of Prey Protection Measures for Juvenile Salmonids in the Columbia and Snake River Reservoirs: Annual Progress Report, February 1991-February 1992.

Energy Technology Data Exchange (ETDEWEB)

Poe, Thomas P.

1992-12-31

This document is the 1991 annual report of progress for the Bonneville Power Administration (BPA) research Project conducted by the US Fish and Wildlife Service (FWS). Our approach was to present the progress achieved during 1991 in a series of separate reports for each major project task. Each report is prepared in the format of a scientific paper and is able to stand alone, whatever the state of progress or completion. This project has two major goals. One is to understand the significance of selective predation and prey vulnerability by determining if substandard juvenile salmonids (dead, injured, stressed, diseased, or naive) are more vulnerable to predation by northern squawfish, than standard or normal juvenile salmonids. The second goal is to develop and test prey protection measures to control predation on juvenile salmonids by reducing predator-smolt encounters or predator capture efficiency.

The effect of turbidity on recognition and generalization of predators and non-predators in aquatic ecosystems.

Science.gov (United States)

Chivers, Douglas P; Al-Batati, Fawaz; Brown, Grant E; Ferrari, Maud C O

2013-02-01

Recent anthropogenic activities have caused a considerable change in the turbidity of freshwater and marine ecosystems. Concomitant with such perturbations are changes in community composition. Understanding the mechanisms through which species interactions are influenced by anthropogenic change has come to the forefront of many ecological disciplines. Here, we examine how a change in the availability of visual information influences the behavior of prey fish exposed to potential predators and non-predators. When fathead minnows, Pimephales promelas, were conditioned to recognize predators and non-predators in clear water, they showed a highly sophisticated ability to distinguish predators from non-predators. However, when learning occurred under conditions of increased turbidity, the ability of the prey to learn and generalize recognition of predators and non-predators was severely impaired. Our work highlights that changes at the community level associated with anthropogenic perturbations may be mediated through altered trophic interactions, and highlights the need to closely examine behavioral interactions to understand how species interactions change.

The effect of turbidity on recognition and generalization of predators and non-predators in aquatic ecosystems

Science.gov (United States)

Chivers, Douglas P; Al-Batati, Fawaz; Brown, Grant E; Ferrari, Maud C O

2013-01-01

Recent anthropogenic activities have caused a considerable change in the turbidity of freshwater and marine ecosystems. Concomitant with such perturbations are changes in community composition. Understanding the mechanisms through which species interactions are influenced by anthropogenic change has come to the forefront of many ecological disciplines. Here, we examine how a change in the availability of visual information influences the behavior of prey fish exposed to potential predators and non-predators. When fathead minnows, Pimephales promelas, were conditioned to recognize predators and non-predators in clear water, they showed a highly sophisticated ability to distinguish predators from non-predators. However, when learning occurred under conditions of increased turbidity, the ability of the prey to learn and generalize recognition of predators and non-predators was severely impaired. Our work highlights that changes at the community level associated with anthropogenic perturbations may be mediated through altered trophic interactions, and highlights the need to closely examine behavioral interactions to understand how species interactions change. PMID:23467451

Reliability of risk assessment measures used in sexually violent predator proceedings.

Science.gov (United States)

Miller, Cailey S; Kimonis, Eva R; Otto, Randy K; Kline, Suzonne M; Wasserman, Adam L

2012-12-01

The field interrater reliability of three assessment tools frequently used by mental health professionals when evaluating sex offenders' risk for reoffending--the Psychopathy Checklist-Revised (PCL-R), the Minnesota Sex Offender Screening Tool-Revised (MnSOST-R) and the Static-99-was examined within the context of sexually violent predator program proceedings. Rater agreement was highest for the Static--99 (intraclass correlation coefficient [ICC₁] = .78) and lowest for the PCL-R (ICC₁ = .60; MnSOST-R ICC₁ = .74), although all instruments demonstrated lower field reliability than that reported in their test manuals. Findings raise concerns about the reliability of risk assessment tools that are used to inform judgments of risk in high-stake sexually violent predator proceedings. Implications for future research and suggestions for improving evaluator training to increase accuracy when informing legal decision making are discussed.

Immune evasion of Plasmodium falciparum by RIFIN via inhibitory receptors

DEFF Research Database (Denmark)

Saito, Fumiji; Hirayasu, Kouyuki; Satoh, Takeshi

2017-01-01

, but the immune regulatory mechanisms used by P. falciparum remain largely unknown. Here we show that P. falciparum uses immune inhibitory receptors to achieve immune evasion. RIFIN proteins are products of a polymorphic multigene family comprising approximately 150-200 genes per parasite genome...

Tax evasion, human capital, and productivity-induced tax rate reduction

Czech Academy of Sciences Publication Activity Database

Gillman, M.; Kejak, Michal

2014-01-01

Roč. 8, č. 1 (2014), s. 42-79 ISSN 1932-8575 Grant - others:UK(CZ) UNCE 204005/2012 Institutional support: PRVOUK-P23 Keywords : tax evasion * human capital * tax rates and tables Subject RIV: AH - Economics Impact factor: 0.600, year: 2014

CMV immune evasion and manipulation of the immune system with aging.

Science.gov (United States)

Jackson, Sarah E; Redeker, Anke; Arens, Ramon; van Baarle, Debbie; van den Berg, Sara P H; Benedict, Chris A; Čičin-Šain, Luka; Hill, Ann B; Wills, Mark R

2017-06-01

Human cytomegalovirus (HCMV) encodes numerous proteins and microRNAs that function to evade the immune response and allow the virus to replicate and disseminate in the face of a competent innate and acquired immune system. The establishment of a latent infection by CMV, which if completely quiescent at the level of viral gene expression would represent an ultimate in immune evasion strategies, is not sufficient for lifelong persistence and dissemination of the virus. CMV needs to reactivate and replicate in a lytic cycle of infection in order to disseminate further, which occurs in the face of a fully primed secondary immune response. Without reactivation, latency itself would be redundant for the virus. It is also becoming clear that latency is not a totally quiescent state, but is characterized by limited viral gene expression. Therefore, the virus also needs immune evasion strategies during latency. An effective immune response to CMV is required or viral replication will cause morbidity and ultimately mortality in the host. There is clearly a complex balance between virus immune evasion and host immune recognition over a lifetime. This poses the important question of whether long-term evasion or manipulation of the immune response driven by CMV is detrimental to health. In this meeting report, three groups used the murine model of CMV (MCMV) to examine if the contribution of the virus to immune senescence is set by the (i) initial viral inoculum, (ii) inflation of T cell responses, (iii) or the balance between functionally distinct effector CD4+ T cells. The work of other groups studying the CMV response in humans is discussed. Their work asks whether the ability to make immune responses to new antigens is compromised by (i) age and HCMV carriage, (ii) long-term exposure to HCMV giving rise to an overall immunosuppressive environment and increased levels of latent virus, or (iii) adapted virus mutants (used as potential vaccines) that have the capacity to

Prey-predator dynamics with prey refuge providing additional food to predator

International Nuclear Information System (INIS)

Ghosh, Joydev; Sahoo, Banshidhar; Poria, Swarup

2017-01-01

Highlights: • The effects of interplay between prey refugia and additional food are reported. • Hopf bifurcation conditions are derived analytically. • Existence of unique limit cycle is shown analytically. • Predator extinction may be possible at very high prey refuge ecological systems. - Abstract: The impacts of additional food for predator on the dynamics of a prey-predator model with prey refuge are investigated. The equilibrium points and their stability behaviours are determined. Hopf bifurcation conditions are derived analytically. Most significantly, existence conditions for unique stable limit cycle in the phase plane are shown analytically. The analytical results are in well agreement with the numerical simulation results. Effects of variation of refuge level as well as the variation of quality and quantity of additional food on the dynamics are reported with the help of bifurcation diagrams. It is found that high quality and high quantity of additional food supports oscillatory coexistence of species. It is observed that predator extinction possibility in high prey refuge ecological systems may be removed by supplying additional food to predator population. The reported theoretical results may be useful to conservation biologist for species conservation in real world ecological systems.

Revealing the role of predator interference in a predator-prey system with disease in prey population

DEFF Research Database (Denmark)

Chakraborty, Subhendu; Kooi, B.W.; Biswas, B.

2015-01-01

Predation on a species subjected to an infectious disease can affect both the infection level and the population dynamics. There is an ongoing debate about the act of managing disease in natural populations through predation. Recent theoretical and empirical evidence shows that predation...... on infected populations can have both positive and negative influences on disease in prey populations. Here, we present a predator-prey system where the prey population is subjected to an infectious disease to explore the impact of predator on disease dynamics. Specifically, we investigate how...... on the strength of interference among predators, predators enhance or control disease outbreaks and population persistence. Moreover, the presence of multistable regimes makes the system very sensitive to perturbations and facilitates a number of regime shifts. Since, the habitat structure and the choice...

The genomic features of parasitism, Polyembryony and immune evasion in the endoparasitic wasp Macrocentrus cingulum.

Science.gov (United States)

Yin, Chuanlin; Li, Meizhen; Hu, Jian; Lang, Kun; Chen, Qiming; Liu, Jinding; Guo, Dianhao; He, Kang; Dong, Yipei; Luo, Jiapeng; Song, Zhenkun; Walters, James R; Zhang, Wenqing; Li, Fei; Chen, Xuexin

2018-05-30

Parasitoid wasps are well-known natural enemies of major agricultural pests and arthropod borne diseases. The parasitoid wasp Macrocentrus cingulum (Hymenoptera: Braconidae) has been widely used to control the notorious insect pests Ostrinia furnacalis (Asian Corn Borer) and O. nubilalis (European corn borer). One striking phenomenon exhibited by M. cingulum is polyembryony, the formation of multiple genetically identical offspring from a single zygote. Moreover, M. cingulum employs a passive parasitic strategy by preventing the host's immune system from recognizing the embryo as a foreign body. Thus, the embryos evade the host's immune system and are not encapsulated by host hemocytes. Unfortunately, the mechanism of both polyembryony and immune evasion remains largely unknown. We report the genome of the parasitoid wasp M. cingulum. Comparative genomics analysis of M. cingulum and other 11 insects were conducted, finding some gene families with apparent expansion or contraction which might be linked to the parasitic behaviors or polyembryony of M. cingulum. Moreover, we present the evidence that the microRNA miR-14b regulates the polyembryonic development of M. cingulum by targeting the c-Myc Promoter-binding Protein 1 (MBP-1), histone-lysine N-methyltransferase 2E (KMT2E) and segmentation protein Runt. In addition, Hemomucin, an O-glycosylated transmembrane protein, protects the endoparasitoid wasp larvae from being encapsulated by host hemocytes. Motif and domain analysis showed that only the hemomucin in two endoparasitoids, M. cingulum and Venturia canescens, possessing the ability of passive immune evasion has intact mucin domain and similar O-glycosylation patterns, indicating that the hemomucin is a key factor modulating the immune evasion. The microRNA miR-14b participates in the regulation of polyembryonic development, and the O-glycosylation of the mucin domain in the hemomucin confers the passive immune evasion in this wasp. These key findings provide

Evasion Mechanisms Used by Pathogens to Escape the Lectin Complement Pathway

DEFF Research Database (Denmark)

Rosbjerg, Anne; Genster, Ninette; Pilely, Katrine

2017-01-01

The complement system is a crucial defensive network that protects the host against invading pathogens. It is part of the innate immune system and can be initiated via three pathways: the lectin, classical and alternative activation pathway. Overall the network compiles a group of recognition...... the level of activity. The result is a pro-inflammatory response meant to combat foreign microbes. Microbial elimination is, however, not a straight forward procedure; pathogens have adapted to their environment by evolving a collection of evasion mechanisms that circumvent the human complement system....... Complement evasion strategies features different ways of exploiting human complement proteins and moreover features different pathogen-derived proteins that interfere with the normal processes. Accumulated, these mechanisms target all three complement activation pathways as well as the final common part...

Analysing and controlling the tax evasion dynamics via majority-vote model

Energy Technology Data Exchange (ETDEWEB)

Lima, F W S, E-mail: fwslima@gmail.co, E-mail: wel@ufpi.edu.b [Departamento de Fisica, Universidade Federal do PiauI, 64049-550, Teresina - PI (Brazil)

2010-09-01

Within the context of agent-based Monte-Carlo simulations, we study the well-known majority-vote model (MVM) with noise applied to tax evasion on simple square lattices, Voronoi-Delaunay random lattices, Barabasi-Albert networks, and Erdoes-Renyi random graphs. In the order to analyse and to control the fluctuations for tax evasion in the economics model proposed by Zaklan, MVM is applied in the neighborhood of the noise critical q{sub c} to evolve the Zaklan model. The Zaklan model had been studied recently using the equilibrium Ising model. Here we show that the Zaklan model is robust because this can be studied using equilibrium dynamics of Ising model also through the nonequilibrium MVM and on various topologies cited above giving the same behavior regardless of dynamic or topology used here.

Analysing and controlling the tax evasion dynamics via majority-vote model

International Nuclear Information System (INIS)

Lima, F W S

2010-01-01

Within the context of agent-based Monte-Carlo simulations, we study the well-known majority-vote model (MVM) with noise applied to tax evasion on simple square lattices, Voronoi-Delaunay random lattices, Barabasi-Albert networks, and Erdoes-Renyi random graphs. In the order to analyse and to control the fluctuations for tax evasion in the economics model proposed by Zaklan, MVM is applied in the neighborhood of the noise critical q c to evolve the Zaklan model. The Zaklan model had been studied recently using the equilibrium Ising model. Here we show that the Zaklan model is robust because this can be studied using equilibrium dynamics of Ising model also through the nonequilibrium MVM and on various topologies cited above giving the same behavior regardless of dynamic or topology used here.

Fishing top predators indirectly affects condition and reproduction in a reef-fish community.

Science.gov (United States)

Walsh, S M; Hamilton, S L; Ruttenberg, B I; Donovan, M K; Sandin, S A

2012-03-01

To examine the indirect effects of fishing on energy allocation in non-target prey species, condition and reproductive potential were measured for five representative species (two-spot red snapper Lutjanus bohar, arc-eye hawkfish Paracirrhites arcatus, blackbar devil Plectroglyphidodon dickii, bicolour chromis Chromis margaritifer and whitecheek surgeonfish Acanthurus nigricans) from three reef-fish communities with different levels of fishing and predator abundance in the northern Line Islands, central Pacific Ocean. Predator abundance differed by five to seven-fold among islands, and despite no clear differences in prey abundance, differences in prey condition and reproductive potential among islands were found. Body condition (mean body mass adjusted for length) was consistently lower at sites with higher predator abundance for three of the four prey species. Mean liver mass (adjusted for total body mass), an indicator of energy reserves, was also lower at sites with higher predator abundance for three of the prey species and the predator. Trends in reproductive potential were less clear. Mean gonad mass (adjusted for total body mass) was high where predator abundance was high for only one of the three species in which it was measured. Evidence of consistently low prey body condition and energy reserves in a diverse suite of species at reefs with high predator abundance suggests that fishing may indirectly affect non-target prey-fish populations through changes in predation and predation risk. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Tax evasion, human capital, and productivity-induced tax rate reduction

Czech Academy of Sciences Publication Activity Database

Gillman, Max; Kejak, Michal

2014-01-01

Roč. 8, č. 1 (2014), s. 42-79 ISSN 1932-8575 R&D Projects: GA ČR GA13-34096S Institutional support: RVO:67985998 Keywords : tax evasion * human capital * tax rates and tables Subject RIV: AH - Economics Impact factor: 0.600, year: 2014

Nest Predation Deviates from Nest Predator Abundance in an Ecologically Trapped Bird

OpenAIRE

Hollander, Franck A.; Van Dyck, Hans; San Martin, Gilles; Titeux, Nicolas

2015-01-01

In human-modified environments, ecological traps may result from a preference for low-quality habitat where survival or reproductive success is lower than in high-quality habitat. It has often been shown that low reproductive success for birds in preferred habitat types was due to higher nest predator abundance. However, between-habitat differences in nest predation may only weakly correlate with differences in nest predator abundance. An ecological trap is at work in a farmland bird (Lanius ...

Complement Evasion by Pathogenic Leptospira.

Science.gov (United States)

Fraga, Tatiana Rodrigues; Isaac, Lourdes; Barbosa, Angela Silva

2016-01-01

Leptospirosis is a neglected infectious disease caused by spirochetes from the genus Leptospira . Pathogenic microorganisms, notably those which reach the blood circulation such as Leptospira , have evolved multiple strategies to escape the host complement system, which is important for innate and acquired immunity. Leptospira avoid complement-mediated killing through: (i) recruitment of host complement regulators; (ii) acquisition of host proteases that cleave complement proteins on the bacterial surface; and, (iii) secretion of proteases that inactivate complement proteins in the Leptospira surroundings. The recruitment of host soluble complement regulatory proteins includes the acquisition of Factor H (FH) and FH-like-1 (alternative pathway), C4b-binding protein (C4BP) (classical and lectin pathways), and vitronectin (Vn) (terminal pathway). Once bound to the leptospiral surface, FH and C4BP retain cofactor activity of Factor I in the cleavage of C3b and C4b, respectively. Vn acquisition by leptospires may result in terminal pathway inhibition by blocking C9 polymerization. The second evasion mechanism lies in plasminogen (PLG) binding to the leptospiral surface. In the presence of host activators, PLG is converted to enzymatically active plasmin, which is able to degrade C3b, C4b, and C5 at the surface of the pathogen. A third strategy used by leptospires to escape from complement system is the active secretion of proteases. Pathogenic, but not saprophytic leptospires, are able to secrete metalloproteases that cleave C3 (central complement molecule), Factor B (alternative pathway), and C4 and C2 (classical and lectin pathways). The purpose of this review is to fully explore these complement evasion mechanisms, which act together to favor Leptospira survival and multiplication in the host.

Predation of Five Generalist Predators on Brown Planthopper (Nilaparvata lugens Stål

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Sri Karindah

2015-09-01

Full Text Available Two generalist predators of brown planthopper,Metioche vittaticollis and Anaxipha longipennis (Gryllidae have not been much studied in Indonesia. This research was conducted to study and compare the predatory ability of M. vittaticollis, A. longipennis (Gryllidae and three coleopterans, Paederus fuscipes (Staphylinidae, Ophionea sp. (Carabidae,and Micraspis sp. (Coccinellidae against brown planthopper (fourth and fifth instars under laboratory condition. In total, 20 nymphs of N. lugens were exposed for 2 hour to each predator for 5 consecutive days. Prey consumptions by the predatory crickets, M. vittaticollis and A. longipennis were greater than the other predators and followed by A. longipennis, Micraspis sp., P. fuscipes, and Ophionea sp. respectively. Consumption rates of M. vittaticolis and A. longipenis were also higher than other predators. Micraspis sp was more active on predation in the morning,while M. vittaticollis, A. longipennis, P. fuscipes, and Ophionea sp. were more active both in the morning and the night but not in the afternoon. However, all five species of predators were not so active in preying during the afternoon. In conclusion, a major effort should be extended to conserve these predatory crickets especially M. vittaticollis and A. longipennis.

Supply Chain-based Solution to Prevent Fuel Tax Evasion

Energy Technology Data Exchange (ETDEWEB)

Franzese, Oscar [ORNL; Capps, Gary J [ORNL; Daugherty, Michael [United States Department of Transportation (USDOT), Federal Highway Administration (FHWA); Siekmann, Adam [ORNL; Lascurain, Mary Beth [ORNL; Barker, Alan M [ORNL

2016-01-01

The primary source of funding for the United States transportation system is derived from motor fuel and other highway use taxes. Loss of revenue attributed to fuel-tax evasion has been assessed to be somewhere between $1 billion per year, or approximately 25% of the total tax collected. Any solution that addresses this problem needs to include not only the tax-collection agencies and auditors, but also the carriers transporting oil products and the carriers customers. This paper presents a system developed by the Oak Ridge National Laboratory for the Federal Highway Administration which has the potential to reduce or eliminate many fuel-tax evasion schemes. The solution balances the needs of tax-auditors and those of the fuel-hauling companies and their customers. The technology was deployed and successfully tested during an eight-month period on a real-world fuel-hauling fleet. Day-to-day operations of the fleet were minimally affected by their interaction with this system. The results of that test are discussed in this paper.

Landscape forest cover and edge effects on songbird nest predation vary by nest predator

Science.gov (United States)

W. Andrew Cox; Frank R. III Thompson; John. Faaborg

2012-01-01

Rates of nest predation for birds vary between and within species across multiple spatial scales, but we have a poor understanding of which predators drive such patterns. We video-monitored nests and identified predators at 120 nests of the Acadian Flycatcher (Empidonax virescens) and the Indigo Bunting (Passerina cyanea) at eight...

Predator Politics

Directory of Open Access Journals (Sweden)

Mary Louisa Cappelli

2017-01-01

Full Text Available Edward Abbey’s Desert Solitaire and Barbara Kingsolver’s Prodigal Summer urges readers to see coyotes as crucial members of the natural community whose predation is essential for the maintenance of biodiversity and ecological stability. Their cultural production provides a human story of ecocritical engagement for understanding the cascading effects of removing top predators from their ecosystems. By envisioning biocentric possibilities within place-based and scientific contexts, Edward Abbey and Barbara Kingsolver share a common theme of political ecology: political processes shape ecological conditions. A close reading of Edward Abbey’s Desert Solitaire and Barbara Kingsolver’s Prodigal Summer provides a literary entryway to connect research, arguments, and discourse across disciplines tasking readers to engage in political discussions of environmental sustainability and to consider viable solutions to preserve the ecological diversity of our predator populations and ecosystems.

Rodent foraging is affected by indirect, but not by direct, cues of predation risk.

Energy Technology Data Exchange (ETDEWEB)

Orrock, John, L.; Danielson, Brent, J.; Brinkerhoff, R., Jory

2004-01-01

Behavioral Ecology Vol. 15 No. 3: 433 - 437 We used foraging trays to determine whether old field mice, Peromyscus polionotus , altered foraging in response to direct cues of predation risk (urine of native and nonnative predators) and indirect cues of predation risk (foraging microhabitat, precipitation, and moon illumination). The proportion of seeds remaining in each tray (a measure of the giving-up density [GUD]) was used to measure risk perceived by mice. Mice did not alter their GUD when presented with cues of native predators (bobcats, Lynx r ufus , and red foxes, Vulpes vulpes), recently introduced predators (coyotes, Canis latrans ), nonnative predators (ocelots, Leopardus pardalis ), a native herbivore (white-tailed deer, Odocoileus virginianus), or a water control. Rather, GUD was related to microhabitat: rodents removed more seeds from foraging trays sheltered beneath vegetative cover compared with exposed trays outside of cover. Rodents also removed more seeds during nights with precipitation and when moon illumination was low. Our results suggest that P. polionotus used indirect cues rather than direct cues to assess risk of vertebrate predation. Indirect cues may be more reliable than are direct scent cues for estimating risk from multiple vertebrate predators that present the most risk in open environments.

Immune-related effects from predation risk in Neotropical blue-black grassquits (Volatinia jacarina).

Science.gov (United States)

Caetano, João V O; Maia, Maya R; Manica, Lilian T; Macedo, Regina H

2014-11-01

Predation is a major force shaping natural history traits of birds because of their vulnerability during nesting and higher visibility during diurnal activities. For most birds in the Neotropics, predation is the major cause of nest failure due to the region's high diversity and abundance of predators. The blue-black grassquit (Volatinia jacarina), similarly to other small passerines in the savanna region of central Brazil, suffers extremely high rates of nest predation. Additionally, males may be particularly vulnerable to predators since they are very conspicuous when executing courtship displays. We assessed some of the non-lethal costs of predation risk on this species by comparing physiological and morphological parameters of birds exposed to predator vocalizations with that of control subjects exposed to non-predator vocalizations. Birds exposed to the predator vocalizations exhibited an immune-related reaction (changes in their H/L ratio), but no changes were observed in other biological parameters measured. This article is part of a Special Issue entitled: Neotropical Behaviour. Copyright © 2014 Elsevier B.V. All rights reserved.

Parental investment decisions in response to ambient nest-predation risk versus actual predation on the prior nest

Science.gov (United States)

Chalfoun, A.D.; Martin, T.E.

2010-01-01

Theory predicts that parents should invest less in dependent offspring with lower reproductive value, such as those with a high risk of predation. Moreover, high predation risk can favor reduced parental activity when such activity attracts nest predators. Yet, the ability of parents to assess ambient nest-predation risk and respond adaptively remains unclear, especially where nest-predator assemblages are diverse and potentially difficult to assess. We tested whether variation in parental investment by a multi-brooded songbird (Brewer's Sparrow, Spizella breweri) in an environment (sagebrush steppe) with diverse predators was predicted by ambient nest-predation risk or direct experience with nest predation. Variation among eight sites in ambient nest-predation risk, assayed by daily probabilities of nest predation, was largely uncorrelated across four years. In this system risk may therefore be unpredictable, and aspects of parental investment (clutch size, egg mass, incubation rhythms, nestling-feeding rates) were not related to ambient risk. Moreover, investment at first nests that were successful did not differ from that at nests that were depredated, suggesting parents could not assess and respond to territorylevel nest-predation risk. However, parents whose nests were depredated reduced clutch sizes and activity at nests attempted later in the season by increasing the length of incubation shifts (on-bouts) and recesses (off-bouts) and decreasing trips to feed nestlings. In this unpredictable environment parent birds may therefore lack sufficient cues of ambient risk on which to base their investment decisions and instead rely on direct experience with nest predation to inform at least some of their decisions. ?? 2010 The Cooper Ornithological Society.

Tax Havens: International Tax Avoidance and Evasion

OpenAIRE

Gravelle, Jane G.

2009-01-01

The federal government loses both individual and corporate income tax revenue from the shifting of profits and income into low-tax countries, often referred to as tax havens. Tax havens are located around the world with concentrations in the Caribbean and Europe. Corporate profit shifting may cost up to $60 billion in revenue and remedies are likely to involve tax law changes. Individual income tax losses more often arise from tax evasion, and are facilitated by the lack of information report...

Signaling pathways and immune evasion mechanisms in classical Hodgkin lymphoma.

Science.gov (United States)

Liu, W Robert; Shipp, Margaret A

2017-11-23

Classical Hodgkin lymphoma (cHL) is an unusual B-cell-derived malignancy in which rare malignant Hodgkin and Reed-Sternberg (HRS) cells are surrounded by an extensive but ineffective inflammatory/immune cell infiltrate. This striking feature suggests that malignant HRS cells escape immunosurveillance and interact with immune cells in the cancer microenvironment for survival and growth. We previously found that cHLs have a genetic basis for immune evasion: near-uniform copy number alterations of chromosome 9p24.1 and the associated PD-1 ligand loci, CD274/PD-L1 and PDCD1LG2/PD-L2, and copy number-dependent increased expression of these ligands. HRS cells expressing PD-1 ligands are thought to engage PD-1 receptor-positive immune effectors in the tumor microenvironment and induce PD-1 signaling and associated immune evasion. The genetic bases of enhanced PD-1 signaling in cHL make these tumors uniquely sensitive to PD-1 blockade. © 2017 by The American Society of Hematology.

A economia da sonegação: teorias e evidências empíricas The economics of tax evasion: theories and emprirical evidences

Directory of Open Access Journals (Sweden)

Marcelo Lettieri Siqueira

2005-12-01

Full Text Available Este artigo fornece uma visão geral da literatura teórica e empírica, nacional e internacional, acerca do estudo econômico da sonegação de impostos. Após apresentar uma definição da sonegação fiscal, em confronto com a elisão fiscal, e analisar a questão da mensuração da sonegação, discutimos o modelo básico de análise da sonegação fiscal de Allingham e Sandmo (1972, apresentamos uma revisão de suas numerosas extensões, avaliamos os efeitos da política de imposição tributária sobre a decisão de sonegar e, por fim, examinamos as evidências empíricas acerca do comportamento do contribuinte e dos níveis de sonegação gerados por ele.This paper provides an overview of the findings of the theoretical and empirical literature on tax evasion. After we define tax evasion, as opposed to tax avoidance, and analyze the question of the tax evasion measurement, we discuss the Allingham and Sandmo's basic model on tax evasion, with a brief review of its numerous extensions, we deal with the effects of tax enforcement policy on the decision to evade taxes, and, finally, we survey the empirical evidence on taxpayer compliance and the tax gap produced for the taxpayer behavior.

Stress triangle: do introduced predators exert indirect costs on native predators and prey?

Directory of Open Access Journals (Sweden)

Jennifer R Anson

Full Text Available Non-consumptive effects of predators on each other and on prey populations often exceed the effects of direct predation. These effects can arise from fear responses elevating glucocorticoid (GC hormone levels (predator stress hypothesis or from increased vigilance that reduces foraging efficiency and body condition (predator sensitive foraging hypothesis; both responses can lead to immunosuppression and increased parasite loads. Non-consumptive effects of invasive predators have been little studied, even though their direct impacts on local species are usually greater than those of their native counterparts. To address this issue, we explored the non-consumptive effects of the invasive red fox Vulpes vulpes on two native species in eastern Australia: a reptilian predator, the lace monitor Varanus varius and a marsupial, the ringtail possum Pseudocheirus peregrinus. In particular, we tested predictions derived from the above two hypotheses by comparing the basal glucocorticoid levels, foraging behaviour, body condition and haemoparasite loads of both native species in areas with and without fox suppression. Lace monitors showed no GC response or differences in haemoparasite loads but were more likely to trade safety for higher food rewards, and had higher body condition, in areas of fox suppression than in areas where foxes remained abundant. In contrast, ringtails showed no physiological or behavioural differences between fox-suppressed and control areas. Predator sensitive foraging is a non-consumptive cost for lace monitors in the presence of the fox and most likely represents a response to competition. The ringtail's lack of response to the fox potentially represents complete naiveté or strong and rapid selection to the invasive predator. We suggest evolutionary responses are often overlooked in interactions between native and introduced species, but must be incorporated if we are to understand the suite of forces that shape community

PREVENTION AND CONTROL OF THE TAX EVASION IMPACT ON ROMANIAN ECONOMY

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Raluca Andreea TRANDAFIR

2015-04-01

Full Text Available Time of occurrence of tax evasion is closely linked even to social developments, this social phenomenon has emerged and evolved at the same time with the company. Since tax evasion is a phenomenon particularly harmful and despicable paradoxically, it has unfortunately been a negative and unintended consequence, with directions of development and different incidents in any country, regardless of size, level of development or form power organization. In Romania, the underground economy is strong because it is determined by the size of the phenomenon of crime in the economic and financial (dirty money, a phenomenon characterized by a very high level of "financial engineering" made in the privatization, investment, financial institutions - banks and the use of public funds. Thus, effective tools are triggered by conversion and diversion of capital flows in order to remove it from licit financial circuit.

Threat-sensitive anti-intraguild predation behaviour: maternal strategies to reduce offspring predation risk in mites.

Science.gov (United States)

Walzer, Andreas; Schausberger, Peter

2011-01-01

Predation is a major selective force for the evolution of behavioural characteristics of prey. Predation among consumers competing for food is termed intraguild predation (IGP). From the perspective of individual prey, IGP differs from classical predation in the likelihood of occurrence because IG prey is usually more rarely encountered and less profitable because it is more difficult to handle than classical prey. It is not known whether IGP is a sufficiently strong force to evolve interspecific threat sensitivity in antipredation behaviours, as is known from classical predation, and if so whether such behaviours are innate or learned. We examined interspecific threat sensitivity in antipredation in a guild of predatory mite species differing in adaptation to the shared spider mite prey (i.e. Phytoseiulus persimilis, Neoseiulus californicus and Amblyseius andersoni). We first ranked the players in this guild according to the IGP risk posed to each other: A. andersoni was the strongest IG predator; P. persimilis was the weakest. Then, we assessed the influence of relative IGP risk and experience on maternal strategies to reduce offspring IGP risk: A. andersoni was insensitive to IGP risk. Threat sensitivity in oviposition site selection was induced by experience in P. persimilis but occurred independently of experience in N. californicus. Irrespective of experience, P. persimilis laid fewer eggs in choice situations with the high- rather than low-risk IG predator. Our study suggests that, similar to classical predation, IGP may select for sophisticated innate and learned interspecific threat-sensitive antipredation responses. We argue that such responses may promote the coexistence of IG predators and prey.

Selective attention in peacocks during predator detection.

Science.gov (United States)

Yorzinski, Jessica L; Platt, Michael L

2014-05-01

Predation can exert strong selective pressure on the evolution of behavioral and morphological traits in birds. Because predator avoidance is key to survival and birds rely heavily on visual perception, predation may have shaped avian visual systems as well. To address this question, we examined the role of visual attention in antipredator behavior in peacocks (Pavo cristatus). Peacocks were exposed to a model predator while their gaze was continuously recorded with a telemetric eye-tracker. We found that peacocks spent more time looking at and made more fixations on the predator compared to the same spatial location before the predator was revealed. The duration of fixations they directed toward conspecifics and environmental features decreased after the predator was revealed, indicating that the peacocks were rapidly scanning their environment with their eyes. Maximum eye movement amplitudes and amplitudes of consecutive saccades were similar before and after the predator was revealed. In cases where conspecifics detected the predator first, peacocks appeared to learn that danger was present by observing conspecifics' antipredator behavior. Peacocks were faster to detect the predator when they were fixating closer to the area where the predator would eventually appear. In addition, pupil size increased after predator exposure, consistent with increased physiological arousal. These findings demonstrate that peacocks selectively direct their attention toward predatory threats and suggest that predation has influenced the evolution of visual orienting systems.

The Effects of Resource Limitation on a Predator-Prey Model with Control Measures as Nonlinear Pulses

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Wenjie Qin

2014-01-01

Full Text Available The dynamical behavior of a Holling II predator-prey model with control measures as nonlinear pulses is proposed and analyzed theoretically and numerically to understand how resource limitation affects pest population outbreaks. The threshold conditions for the stability of the pest-free periodic solution are given. Latin hypercube sampling/partial rank correlation coefficients are used to perform sensitivity analysis for the threshold concerning pest extinction to determine the significance of each parameter. Comparing this threshold value with that without resource limitation, our results indicate that it is essential to increase the pesticide’s efficacy against the pest and reduce its effectiveness against the natural enemy, while enhancing the efficiency of the natural enemies. Once the threshold value exceeds a critical level, both pest and its natural enemies populations can oscillate periodically. Further-more, when the pulse period and constant stocking number as a bifurcation parameter, the predator-prey model reveals complex dynamics. In addition, numerical results are presented to illustrate the feasibility of our main results.

Complement Attack against Aspergillus and Corresponding Evasion Mechanisms

Directory of Open Access Journals (Sweden)

Cornelia Speth

2012-01-01

Full Text Available Invasive aspergillosis shows a high mortality rate particularly in immunocompromised patients. Perpetually increasing numbers of affected patients highlight the importance of a clearer understanding of interactions between innate immunity and fungi. Innate immunity is considered to be the most significant host defence against invasive fungal infections. Complement represents a crucial part of this first line defence and comprises direct effects against invading pathogens as well as bridging functions to other parts of the immune network. However, despite the potency of complement to attack foreign pathogens, the prevalence of invasive fungal infections is increasing. Two possible reasons may explain that phenomenon: First, complement activation might be insufficient for an effective antifungal defence in risk patients (due to, e.g., low complement levels, poor recognition of fungal surface, or missing interplay with other immune elements in immunocompromised patients. On the other hand, fungi may have developed evasion strategies to avoid recognition and/or eradication by complement. In this review, we summarize the most important interactions between Aspergillus and the complement system. We describe the various ways of complement activation by Aspergillus and the antifungal effects of the system, and also show proven and probable mechanisms of Aspergillus for complement evasion.

Inflammation promotes oral squamous carcinoma immune evasion via induced programmed death ligand-1 surface expression.

Science.gov (United States)

Lu, Wanlu; Lu, Libing; Feng, Yun; Chen, Jiao; Li, Yan; Kong, Xiangli; Chen, Sixiu; Li, Xiaoyu; Chen, Qianming; Zhang, Ping

2013-05-01

The association between inflammation and cancer provides a new target for tumor biotherapy. The inflammatory cells and molecules within the tumor microenvironment have decisive dual roles in antitumor immunity and immune evasion. In the present study, phytohemagglutinin (PHA) was used to stimulate peripheral blood mononuclear cells (PBMCs) to simulate the tumor inflammatory microenvironment. The effect of immune cells and inflammatory cytokines on the surface expression of programmed cell death-1 ligand 1 (PD-L1) and tumor immune evasion was investigated using flow cytometry (FCM) and an in vivo xenotransplantation model. Based on the data, PHA-activated, but not resting, immune cells were able to promote the surface expression of PD-L1 in Tca8113 oral squamous carcinoma cells via the secretion of inflammatory cytokines, but not by cell-cell contact. The majority of the inflammatory cytokines had no significant effect on the proliferation, cell cycle progression and apoptosis of the Tca8113 cells, although they each induced the expression of PD-L1 in a dose-dependent manner. In total, 99% of the Tca8113 cells expressed PD-L1 following treatment with the supernatant of PHA-stimulated PBMCs. The PHA-supernatant pretreated Tca8113 cells unusually induced Tca8113 antigen-specific CD8 + T cell apoptosis in vitro and the evasion of antigen-specific T cell attraction in a nude mouse tumor-bearing model. These results indicate a new mechanism for the promotion of tumor immune evasion by the tumor inflammatory microenvironment.

Predator-induced physiological responses in tadpoles challenged with herbicide pollution

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Pablo BURRACO, Lidia Jiménez DUARTE, Ivan GOMEZ-MESTRE

2013-08-01

Full Text Available Predators induce plastic responses in multiple prey taxa, ranging from morphological to behavioral or physiological changes. In amphibians, tadpoles activate plastic responses to reduce predation risk by reducing their activity rate and altering their morphology, specifically tail depth and pigmentation. Furthermore, there is now evidence that tadpoles’ defenses are modified when predators combine with other stressful factors such as pollutants or competitors, but our knowledge on the physiological responses underlying these responses is still scarce. Here we study physiological responses in Pelobates cultripes tadpoles exposed to a natural predator (larvae of the aquatic beetle Dytiscus circumflexus, non-lethal concentrations of herbicide (glyphosate, 0.5 mg/L and 1.0 mg/L or both factors combined. We measured corticosterone levels, standard metabolic rate, oxidative damage (TBARS and activity of antioxidant enzymes, and immune response (via leukocyte count. Tadpoles reduced their corticosterone concentration by ca. 24% in the presence of predator cues, whereas corticosterone did not change in the presence of glyphosate. Two enzymes involved in antioxidant response also decreased in the presence of predators (14.7% and 13.2% respectively but not to glyphosate. Herbicide, however, increased the number of neutrophils and reduced that of lymphocytes, and had an interaction effect with predator presence. Standard metabolic rate did not vary across treatments in our experiment. Thus we show a marked physiological response to the presence of predators but little evidence for interaction between predators and low levels of herbicide. Multiple assessment of the physiological state of animals is important to understand the basis and consequences of phenotypic plasticity [Current Zoology 59 (4: 475–484, 2013].

Pemangsaan Propagul Mangrove Rhizophora sp. Sebagai Bukti Teori Dominance-Predation (Predation of Mangrove Propagule, Rhizophora sp. as Evidence of Dominance-Predation Theory

Directory of Open Access Journals (Sweden)

Rudhi Pribadi

2014-06-01

Propagule predation on mangrove in some extent reduced its viability to grow into seedling. The predation could happened before (pre-dispersal or after (post-dispersal the propagule drop from the tree.The reasearch was conducted in Pasar Banggi, Rembang District, Central Java. The aim was to investigate the predation rate of Rhizophora mucronata Lamk., R. stylosa Griff. and R. apiculata Blume propagules pre-dispersal and post-dispersal. Firstly, preface experiment for find domination spesies in the location, Second, with applied descriptive-based survey sampling and field experiment methods. Than all propagules of five replication trees were harvested and checked for its condition on pre-dispersal step. The third, with post-dispersal study there were twenty propagules from each spesies and tied them with used nylon string and placed on the forest floor for 2 until 18 days and checked its condition every 2 days after placement. This study is also set for tested the Smith’s theory on propagule predation related to tree domination. Rhizophora stylosa propagule was  most predated before they fall (mean 61,06%, range 45,40-76,05%, followed by R. apiculata (mean 58,18%, range 47,41-68% and the lowest isR. mucronata with mean 11,88% (range 7,06-15,71%. After 18 days of experiment in the field R. stylosa propagule in R. stylosa–dominated area was the lowest predated (mean 46,67% compared to propagule in the area dominated by R. apiculata (63,33% and also in R. mucronata area (83,33 Predated R. mucronata propagule is the highest in the R. mucronata dominated area (mean 95% compared with R. apiculata dominated area (mean 55% and also in R. stylosa dominated area (45%. Pradated of R. apiculata propagule is the lowest in the domination area of R. apiculata (50% compared with R. stylosa area domination with (mean 70% also R. mucronata (73,33%. The result showed that the theory of dominance-predation can be proved only for R. stylosa and R. apiculata spesies, but not for R

Tax Evasion and Auditing in a Federal Economy

OpenAIRE

Traxler, Christian (Prof. Dr.); Stöwhase, Sven

2017-01-01

This paper analyzes the relation between tax auditing and fiscal equalization in the context of fiscal competition. We incorporate a model of tax evasion by firms into a standard tax competition framework where regional governments use their audit rates as a strategic instrument to engage in fiscal competition. We compare the region's choice of audit policies for three different cases: A scenario of unconfined competition without interregional transfers, a scenario with a gross revenue equali...

Does Tax Evasion Affect Unemployment and Educational Choice ?

DEFF Research Database (Denmark)

Kolm, Ann-Sofie; Larsen, Birthe

2003-01-01

While examining the macroeconomic effects of government taxand punishment policies, this paper develops a three-sector generalequilibrium model featuring matching frictions and worker-firm wagebargaining. Workers are assumed to differ in ability, and the choiceof education is determined endogenou...... to choose punishment rates so to more than fully counteractthe distortion created by the government's inability to tax theinformal sector.JEL-codes: H26, I21, J64Keywords: Tax evasion, underground economy, education, matching,unemployment....

A minimal model of predator-swarm interactions.

Science.gov (United States)

Chen, Yuxin; Kolokolnikov, Theodore

2014-05-06

We propose a minimal model of predator-swarm interactions which captures many of the essential dynamics observed in nature. Different outcomes are observed depending on the predator strength. For a 'weak' predator, the swarm is able to escape the predator completely. As the strength is increased, the predator is able to catch up with the swarm as a whole, but the individual prey is able to escape by 'confusing' the predator: the prey forms a ring with the predator at the centre. For higher predator strength, complex chasing dynamics are observed which can become chaotic. For even higher strength, the predator is able to successfully capture the prey. Our model is simple enough to be amenable to a full mathematical analysis, which is used to predict the shape of the swarm as well as the resulting predator-prey dynamics as a function of model parameters. We show that, as the predator strength is increased, there is a transition (owing to a Hopf bifurcation) from confusion state to chasing dynamics, and we compute the threshold analytically. Our analysis indicates that the swarming behaviour is not helpful in avoiding the predator, suggesting that there are other reasons why the species may swarm. The complex shape of the swarm in our model during the chasing dynamics is similar to the shape of a flock of sheep avoiding a shepherd.

Seasonal shift in the effects of predators on juvenile Atlantic salmon (Salmo salar) energetics

Science.gov (United States)

Darren M. Ward; Keith H. Nislow; Carol L. Folt; James Grant

2011-01-01

Predator effects on prey populations are determined by the number of prey consumed and effects on the traits of surviving prey. Yet the effects of predators on prey traits are rarely evaluated in field studies. We measured the effects of predators on energetic traits (consumption and growth rates) of juvenile Atlantic salmon (Salmo salar) in a...

Multiagent pursuit-evasion games: Algorithms and experiments

Science.gov (United States)

Kim, Hyounjin

Deployment of intelligent agents has been made possible through advances in control software, microprocessors, sensor/actuator technology, communication technology, and artificial intelligence. Intelligent agents now play important roles in many applications where human operation is too dangerous or inefficient. There is little doubt that the world of the future will be filled with intelligent robotic agents employed to autonomously perform tasks, or embedded in systems all around us, extending our capabilities to perceive, reason and act, and replacing human efforts. There are numerous real-world applications in which a single autonomous agent is not suitable and multiple agents are required. However, after years of active research in multi-agent systems, current technology is still far from achieving many of these real-world applications. Here, we consider the problem of deploying a team of unmanned ground vehicles (UGV) and unmanned aerial vehicles (UAV) to pursue a second team of UGV evaders while concurrently building a map in an unknown environment. This pursuit-evasion game encompasses many of the challenging issues that arise in operations using intelligent multi-agent systems. We cast the problem in a probabilistic game theoretic framework and consider two computationally feasible pursuit policies: greedy and global-max. We also formulate this probabilistic pursuit-evasion game as a partially observable Markov decision process and employ a policy search algorithm to obtain a good pursuit policy from a restricted class of policies. The estimated value of this policy is guaranteed to be uniformly close to the optimal value in the given policy class under mild conditions. To implement this scenario on real UAVs and UGVs, we propose a distributed hierarchical hybrid system architecture which emphasizes the autonomy of each agent yet allows for coordinated team efforts. We then describe our implementation on a fleet of UGVs and UAVs, detailing components such

Invasive predators and global biodiversity loss.

Science.gov (United States)

Doherty, Tim S; Glen, Alistair S; Nimmo, Dale G; Ritchie, Euan G; Dickman, Chris R

2016-10-04

Invasive species threaten biodiversity globally, and invasive mammalian predators are particularly damaging, having contributed to considerable species decline and extinction. We provide a global metaanalysis of these impacts and reveal their full extent. Invasive predators are implicated in 87 bird, 45 mammal, and 10 reptile species extinctions-58% of these groups' contemporary extinctions worldwide. These figures are likely underestimated because 23 critically endangered species that we assessed are classed as "possibly extinct." Invasive mammalian predators endanger a further 596 species at risk of extinction, with cats, rodents, dogs, and pigs threatening the most species overall. Species most at risk from predators have high evolutionary distinctiveness and inhabit insular environments. Invasive mammalian predators are therefore important drivers of irreversible loss of phylogenetic diversity worldwide. That most impacted species are insular indicates that management of invasive predators on islands should be a global conservation priority. Understanding and mitigating the impact of invasive mammalian predators is essential for reducing the rate of global biodiversity loss.

Immune Evasion Strategies of Pathogens in Macrophages: the Potential for Limiting Pathogen Transmission.

Science.gov (United States)

Ren, Yuwei; Khan, Faheem Ahmed; Pandupuspitasari, Nuruliarizki Shinta; Zhang, Shujun

2017-01-01

Preventing pathogen transmission to a new host is of major interest to the immunologist and could benefit from a detailed investigation of pathogen immune evasion strategies. The first line of defense against pathogen invasion is provided by macrophages. When they sense pathogens, macrophages initiate signals to inflammatory and pro-inflammatory cytokines through pattern recognition receptors (PRRs) subsequently mediating phagocytosis and inflammation. The macrophage immune machinery classically includes two subsets: the activated M1 and the activated M2 that respond accordingly in diverse immune challenges. The lipid and glycogen metabolic pathways work together with the lysosome to help the mature phagosome to degrade and eliminate intracellular pathogens in macrophages. The viral evasion strategies are even more complex due to the interplay between autophagy and apoptosis. However, pathogens evolve several strategies to camouflage themselves against immune responses in order to ensure their survival, replication and transmission. These strategies include the muting of PRRs initiated inflammatory responses, attenuation of M1 and/or induction of M2 macrophages, suppression of autophago-lysosomal formation, interference with lipid and glycogen metabolism, and viral mediation of autophagy and apoptosis cross-talk to enhance viral replication. This review focuses on pathogen immune evasion methods and on the strategies used by the host against camouflaged pathogens.

Neuroendocrine changes upon exposure to predator odors.

Science.gov (United States)

Hegab, Ibrahim M; Wei, Wanhong

2014-05-28

Predator odors are non-intrusive and naturalistic stressors of high ethological relevance in animals. Upon exposure to a predator or its associated cues, robust physiological and molecular anti-predator defensive strategies are elicited thereby allowing prey species to recognize, avoid and defend against a possible predation threat. In this review, we will discuss the nature of neuroendocrine stress responses upon exposure to predator odors. Predator odors can have a profound effect on the endocrine system, including activation of the hypothalamic-pituitary-adrenal axis, and induction of stress hormones such as corticosterone and adrenocorticotropic hormone. On a neural level, short-term exposure to predator odors leads to induction of the c-fos gene, while induction of ΔFosB in a different brain region is detected under chronic predation stress. Future research should aim to elucidate the relationships between neuroendocrine and behavioral outputs to gage the different levels of anti-predator responses in prey species. Copyright © 2014 Elsevier Inc. All rights reserved.

Immune evasion mechanisms and immune checkpoint inhibition in advanced merkel cell carcinoma.

Science.gov (United States)

Schadendorf, Dirk; Nghiem, Paul; Bhatia, Shailender; Hauschild, Axel; Saiag, Philippe; Mahnke, Lisa; Hariharan, Subramanian; Kaufman, Howard L

2017-01-01

Merkel cell carcinoma (MCC) is a rare skin cancer caused by Merkel cell polyomavirus (MCPyV) infection and/or ultraviolet radiation-induced somatic mutations. The presence of tumor-infiltrating lymphocytes is evidence that an active immune response to MCPyV and tumor-associated neoantigens occurs in some patients. However, inhibitory immune molecules, including programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1), within the MCC tumor microenvironment aid in tumor evasion of T-cell-mediated clearance. Unlike chemotherapy, treatment with anti-PD-L1 (avelumab) or anti-PD-1 (pembrolizumab) antibodies leads to durable responses in MCC, in both virus-positive and virus-negative tumors. As many tumors are established through the evasion of infiltrating immune-cell clearance, the lessons learned in MCC may be broadly relevant to many cancers.

Social Dimensions of Tax Evasion: Trust and Tax Morale in Contemporary Spain

Directory of Open Access Journals (Sweden)

Sandro Giachi

2014-01-01

Full Text Available This article tackles the problem of tax evasion from a sociological view. The rational action approach is integrated here with the concepts of trust and tax morale. The aim is to discover why people justify fi scal fraud or have lax tax morale. The main hypothesis maintained here is that tax system social factors ?such as trust? have an effect on the justifi cation of fraud. Using two survey datasets referred to the past ten years, we observe that tax morale seems to be mainly composed by trust in tax system, trust in other taxpayers as well as diverse contextual factors. Finally, I present an interpretive framework that takes into consideration individual factors as well as social and geographic dimensions of tax evasion in Spain.

Morphology of seahorse head hydrodynamically aids in capture of evasive prey.

Science.gov (United States)

Gemmell, Brad J; Sheng, Jian; Buskey, Edward J

2013-01-01

Syngnathid fish (seahorses, pipefish and sea dragons) are slow swimmers yet capture evasive prey (copepods) using a technique known as the 'pivot' feeding, which involves rapid movement to overcome prey escape capabilities. However, this feeding mode functions only at short range and requires approaching very closely to hydrodynamically sensitive prey without triggering an escape. Here we investigate the role of head morphology on prey capture using holographic and particle image velocimetry (PIV). We show that head morphology functions to create a reduced fluid deformation zone, minimizing hydrodynamic disturbance where feeding strikes occur (above the end of the snout), and permits syngnathid fish to approach highly sensitive copepod prey (Acartia tonsa) undetected. The results explain how these animals can successfully employ short range 'pivot' feeding effectively on evasive prey. The need to approach prey with stealth may have selected for a head shape that produces lower deformation rates than other fish.

Beyond Predation: The Zoophytophagous Predator Macrolophus pygmaeus Induces Tomato Resistance against Spider Mites.

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Maria L Pappas

Full Text Available Many predatory insects that prey on herbivores also feed on the plant, but it is unknown whether plants affect the performance of herbivores by responding to this phytophagy with defence induction. We investigate whether the prior presence of the omnivorous predator Macrolophus pygmaeus (Rambur on tomato plants affects plant resistance against two different herbivore species. Besides plant-mediated effects of M. pygmaeus on herbivore performance, we examined whether a plant defence trait that is known to be inducible by herbivory, proteinase inhibitors (PI, may also be activated in response to the interactions of this predator with the tomato plant. We show that exposing tomato plants to the omnivorous predator M. pygmaeus reduced performance of a subsequently infesting herbivore, the two-spotted spider mite Tetranychus urticae Koch, but not of the greenhouse whitefly Trialeurodes vaporariorum (Westwood. The spider-mite infested tomato plants experience a lower herbivore load, i.e., number of eggs deposited and individuals present, when previously exposed to the zoophytophagous predator. This effect is not restricted to the exposed leaf and persists on exposed plants for at least two weeks after the removal of the predators. The decreased performance of spider mites as a result of prior exposure of the plant to M. pygmaeus is accompanied by a locally and systemically increased accumulation of transcripts and activity of proteinase inhibitors that are known to be involved in plant defence. Our results demonstrate that zoophytophagous predators can induce plant defence responses and reduce herbivore performance. Hence, the suppression of populations of certain herbivores via consumption may be strengthened by the induction of plant defences by zoophytophagous predators.

Predator control promotes invasive dominated ecological states.

Science.gov (United States)

Wallach, Arian D; Johnson, Christopher N; Ritchie, Euan G; O'Neill, Adam J

2010-08-01

Invasive species are regarded as one of the top five drivers of the global extinction crisis. In response, extreme measures have been applied in an attempt to control or eradicate invasives, with little success overall. We tested the idea that state shifts to invasive dominance are symptomatic of losses in ecosystem resilience, due to the suppression of apex predators. This concept was investigated in Australia where the high rate of mammalian extinctions is largely attributed to the destructive influence of invasive species. Intensive pest control is widely applied across the continent, simultaneously eliminating Australia's apex predator, the dingo (Canis lupus dingo). We show that predator management accounts for shifts between two main ecosystem states. Lethal control fractures dingo social structure and leads to bottom-up driven increases in invasive mesopredators and herbivores. Where control is relaxed, dingoes re-establish top-down regulation of ecosystems, allowing for the recovery of biodiversity and productivity.

General Considerations on fiscal evasion

Directory of Open Access Journals (Sweden)

Pripoaie Silviu

2009-10-01

Full Text Available Analysis of performance of any economy involves the measurement and correlation of three basic elements: the rate of economic growth,the rate of inflation and unemployment rate. When the rate of growth (rate of real GDP is high, the production of goods and services is growing andtherefore increasing the number of jobs, decrease unemployment and raise living standards. If the economy is in recession phase, increasing fiscalpressure to ensure the necessary budgetary funds triggers complex economic mechanisms. Rules more strictly is that those who are not able tooperate in the normal economy to slide towards the underground economy, and this not because he wants to tax evasion, but because they simplycannot cope with new regulations. It is widely accepted in economic theory and practice the idea that reliability scale macroeconomic indicators of acountry is affected by size of underground economy and the various tests made so far on this subject, focusing either on the social aspect or theeconomic or moral, or emphasizes the illegal or the edge of legality. This has led to various studies in this area do not provide comparable data orprovide data to the contrary. Worldwide were put in place, however, some calculation methods provided that applied the same country and sameperiod, the results are rarely consistent, sometimes even in fundamentally different.

Xenopus-FV3 host-pathogen interactions and immune evasion.

Science.gov (United States)

Jacques, Robert; Edholm, Eva-Stina; Jazz, Sanchez; Odalys, Torres-Luquis; Francisco, De Jesús Andino

2017-11-01

We first review fundamental insights into anti-ranavirus immunity learned with the Xenopus laevis/ranavirus FV3 model that are generally applicable to ectothermic vertebrates. We then further investigate FV3 genes involved in immune evasion. Focusing on FV3 knockout (KO) mutants defective for a putative viral caspase activation and recruitment domain-containing (CARD)-like protein (Δ64R-FV3), a β-hydroxysteroid dehydrogenase homolog (Δ52L-FV3), and an immediate-early18kDa protein (FV3-Δ18K), we assessed the involvement of these viral genes in replication, dissemination and interaction with peritoneal macrophages in tadpole and adult frogs. Our results substantiate the role of 64R and 52L as critical immune evasion genes, promoting persistence and dissemination in the host by counteracting type III IFN in tadpoles and type I IFN in adult frogs. Comparably, the substantial accumulation of genome copy numbers and exacerbation of type I and III IFN gene expression responses but deficient release of infectious virus suggests that 18K is a viral regulatory gene. Copyright © 2017 Elsevier Inc. All rights reserved.

Inferring predator behavior from attack rates on prey-replicas that differ in conspicuousness.

Directory of Open Access Journals (Sweden)

Yoel E Stuart

Full Text Available Behavioral ecologists and evolutionary biologists have long studied how predators respond to prey items novel in color and pattern. Because a predatory response is influenced by both the predator's ability to detect the prey and a post-detection behavioral response, variation among prey types in conspicuousness may confound inference about post-prey-detection predator behavior. That is, a relatively high attack rate on a given prey type may result primarily from enhanced conspicuousness and not predators' direct preference for that prey. Few studies, however, account for such variation in conspicuousness. In a field experiment, we measured predation rates on clay replicas of two aposematic forms of the poison dart frog Dendrobates pumilio, one novel and one familiar, and two cryptic controls. To ask whether predators prefer or avoid a novel aposematic prey form independently of conspicuousness differences among replicas, we first modeled the visual system of a typical avian predator. Then, we used this model to estimate replica contrast against a leaf litter background to test whether variation in contrast alone could explain variation in predator attack rate. We found that absolute predation rates did not differ among color forms. Predation rates relative to conspicuousness did, however, deviate significantly from expectation, suggesting that predators do make post-detection decisions to avoid or attack a given prey type. The direction of this deviation from expectation, though, depended on assumptions we made about how avian predators discriminate objects from the visual background. Our results show that it is important to account for prey conspicuousness when investigating predator behavior and also that existing models of predator visual systems need to be refined.

A robust and scalable TCR-based reporter cell assay to measure HIV-1 Nef-mediated T cell immune evasion.

Science.gov (United States)

Anmole, Gursev; Kuang, Xiaomei T; Toyoda, Mako; Martin, Eric; Shahid, Aniqa; Le, Anh Q; Markle, Tristan; Baraki, Bemuluyigza; Jones, R Brad; Ostrowski, Mario A; Ueno, Takamasa; Brumme, Zabrina L; Brockman, Mark A

2015-11-01

HIV-1 evades cytotoxic T cell responses through Nef-mediated downregulation of HLA class I molecules from the infected cell surface. Methods to quantify the impact of Nef on T cell recognition typically employ patient-derived T cell clones; however, these assays are limited by the cost and effort required to isolate and maintain primary cell lines. The variable activity of different T cell clones and the limited number of cells generated by re-stimulation can also hinder assay reproducibility and scalability. Here, we describe a heterologous T cell receptor reporter assay and use it to study immune evasion by Nef. Induction of NFAT-driven luciferase following co-culture with peptide-pulsed or virus-infected target cells serves as a rapid, quantitative and antigen-specific measure of T cell recognition of its cognate peptide/HLA complex. We demonstrate that Nef-mediated downregulation of HLA on target cells correlates inversely with T cell receptor-dependent luminescent signal generated by effector cells. This method provides a robust, flexible and scalable platform that is suitable for studies to measure Nef function in the context of different viral peptide/HLA antigens, to assess the function of patient-derived Nef alleles, or to screen small molecule libraries to identify novel Nef inhibitors. Copyright © 2015 Elsevier B.V. All rights reserved.

Learned predation risk management by spider mites

Directory of Open Access Journals (Sweden)

Thomas eHackl

2014-09-01

Full Text Available Predation is a prime selective force shaping prey behavior. Investment in anti-predator behavior is traded-off against time and energy for other fitness-enhancing activities such as foraging or reproduction. To optimize this benefit/cost trade-off, prey should be able to innately and/or by experience modulate their behavior to the level of predation risk. Here, we assessed learned predation risk management in the herbivorous two-spotted spider mite Tetranychus urticae. We exposed spider mites coming from benign (naïve or high immediate predation risk (experienced environments to latent and/or no risk and assessed their site choice, activity and oviposition. Benign environments were characterized by the absence of any predator cues, high immediate risk environments by killed spider mites, physical presence of the predatory mite Phytoseiulus persimilis and associated chemosensory traces left on the surface, and latent risk environments by only predator traces. In the no-choice experiment both naïve and experienced spider mites laid their first egg later on leaves with than without predator traces. Irrespective of predator traces presence/absence, experienced mites laid their first egg earlier than naïve ones did. Naïve spider mites were more active, indicating higher restlessness, and laid fewer eggs on leaves with predator traces, whereas experienced mites were less active and laid similar numbers of eggs on leaves with and without predator traces. In the choice experiment both naïve and experienced spider mites preferentially resided and oviposited on leaves without predator traces but experienced mites were less active than naïve ones. Overall, our study suggests that spider mites experienced with high predation risk behave bolder under latent risk than naïve spider mites. Since predator traces alone do not indicate immediate risk, we argue that the attenuated anti-predator response of experienced spider mites represents adaptive learned

A predator-2 prey fast-slow dynamical system for rapid predator evolution

DEFF Research Database (Denmark)

Piltz, Sofia Helena; Veerman, Frits; Maini, Philip K.

2017-01-01

We consider adaptive change of diet of a predator population that switches its feeding between two prey populations. We develop a novel 1 fast-3 slow dynamical system to describe the dynamics of the three populations amidst continuous but rapid evolution of the predator's diet choice. The two ext...

On multi-team predator-prey models

International Nuclear Information System (INIS)

Elettreby, M.F.; Saker, S.H.; Ahmed, E.

2005-05-01

Many creatures form teams. This has, at least, two main advantages: the first is the improvement in foraging, since looking for food in a team is more efficient than doing it alone. The second is that living in a team reduces predation risk due to early spotting of predators and that existing in a team gives a higher probability that the predator will attack another member of the team. In this paper models are given where two teams of predators interact with two teams of preys. The teams of each group (predators or preys) help each other. In this paper we propose three different versions of the multi-team predator prey model. We study the equilibrium solutions, the conditions of their local asymptotic stability, persistence and the global stability of the solution of one of the models. Some numerical simulations are done. (author)

Weed seed predation in organic and conventional fields

DEFF Research Database (Denmark)

Navntoft, Søren; Wratten, S.D.; Kristensen, Kristian

2009-01-01

Enhanced biological control of weed seeds may improve sustainability of agricultural production. Biological control due to seed predation may be higher in organic fields because organic production generally supports more seed predators. To investigate such a difference, weed seed predation...... University and in two of the fields used for estimating seed predation. Recording of predators had therefore limited overlap with seed predation assays but was expected to give important information on key seed predators in the region. The mean seed removal rate was 17% in organic fields compared with 10...... edges. Overall, there was no consistent effect of distance from the field edge. Vegetation had a significant influence on the predation rates, with maximum rates at a medium-dense plant cover. Based on the video images, birds were the most important seed predators. The higher weed seed predation rate...

Stabilization and complex dynamics in a predator-prey model with predator suffering from an infectious disease.

NARCIS (Netherlands)

Kooi, B.W.; van Voorn, G.A.K.; Pada Das, K.

2011-01-01

We study the effects of a non-specified infectious disease of the predator on the dynamics a predator-prey system, by evaluating the dynamics of a three-dimensional model. The predator population in this (PSI) model is split into a susceptible and an unrecoverable infected population, while all

Selective Predation of a Stalking Predator on Ungulate Prey.

Directory of Open Access Journals (Sweden)

Marco Heurich

Full Text Available Prey selection is a key factor shaping animal populations and evolutionary dynamics. An optimal forager should target prey that offers the highest benefits in terms of energy content at the lowest costs. Predators are therefore expected to select for prey of optimal size. Stalking predators do not pursue their prey long, which may lead to a more random choice of prey individuals. Due to difficulties in assessing the composition of available prey populations, data on prey selection of stalking carnivores are still scarce. We show how the stalking predator Eurasian lynx (Lynx lynx selects prey individuals based on species identity, age, sex and individual behaviour. To address the difficulties in assessing prey population structure, we confirm inferred selection patterns by using two independent data sets: (1 data of 387 documented kills of radio-collared lynx were compared to the prey population structure retrieved from systematic camera trapping using Manly's standardized selection ratio alpha and (2 data on 120 radio-collared roe deer were analysed using a Cox proportional hazards model. Among the larger red deer prey, lynx selected against adult males-the largest and potentially most dangerous prey individuals. In roe deer lynx preyed selectively on males and did not select for a specific age class. Activity during high risk periods reduced the risk of falling victim to a lynx attack. Our results suggest that the stalking predator lynx actively selects for size, while prey behaviour induces selection by encounter and stalking success rates.

Species invasion shifts the importance of predator dependence.

Science.gov (United States)

Griffen, Blaine D; Delaney, David G

2007-12-01

The strength of interference between foraging individuals can influence per capita consumption rates, with important consequences for predator and prey populations and system stability. Here we demonstrate how the replacement of a previously established invader, the predatory crab Carcinus maenas, by the recently invading predatory crab Hemigrapsus sanguineus shifts predation from a species that experiences strong predator interference (strong predator dependence) to one that experiences weak predator interference (weak predator dependence). We demonstrate using field experiments that differences in the strength of predator dependence persist for these species both when they forage on a single focal prey species only (the mussel Mytilus edulis) and when they forage more broadly across the entire prey community. This shift in predator dependence with species replacement may be altering the biomass across trophic levels, consistent with theoretical predictions, as we show that H. sanguineus populations are much larger than C. maenas populations throughout their invaded ranges. Our study highlights that predator dependence may differ among predator species and demonstrates that different predatory impacts of two conspicuous invasive predators may be explained at least in part by different strengths of predator dependence.

Predation pressure in Ugandan cotton fields measured by a sentinel prey method

DEFF Research Database (Denmark)

Howe, Andy G.; Nachman, Gösta; Lövei, Gabor L

2015-01-01

Pest suppression by natural enemies is an important ecosystem service, which is a valuable resource to poor smallholders in developing countries. Diverse natural enemy assemblages of arthropod predators and parasitoids are documented in various regions in Africa, but our knowledge of their impact...

Lewis Lung Cancer Cells Promote SIGNR1(CD209b)-Mediated Macrophages Polarization Induced by IL-4 to Facilitate Immune Evasion.

Science.gov (United States)

Yan, Xiaolong; Li, Wenhai; Pan, Lei; Fu, Enqing; Xie, Yonghong; Chen, Min; Mu, Deguang

2016-05-01

Tumor-associated macrophages are a prominent component of lung cancer and contribute to tumor progression by facilitating the immune evasion of cancer cells. DC-SIGN (CD209) assists in the immune evasion of a broad spectrum of pathogens and neoplasms by inhibiting the maturation of DCs and subsequent cytokines production. However, the expression of DC-SIGN in macrophages and its role in mediating immune evasion in lung cancer and the underlying mechanism remain unclear. Our study aimed to identify the immunosuppressive role of SIGNR1 in murine macrophage differentiation and lung cancer progression. We found that SIGNR1-positive RAW264.7 macrophages were enriched in mixed cultures with Lewis lung cancer cells (LLC) (ratio of RAW 264.7 to LLC being 1:1) after stimulation with IL-4. Moreover, LLC-educated macrophages exhibited significantly higher levels of IL-10 but lower IL-12 in response to IL-4 treatment as determined by RT-PCR and ELISA. However, inhibition of SIGNR1 markedly hampered the production of IL-10, indicating that SIGNR1 was indispensable for IL-4+LLC induced macrophage polarization towards the M2 subtype. Furthermore, polarized M2 cells immersed in a tumor microenvironment promoted the migration of LLCs, as measured by transwell assays, but migration was suppressed after blockade of SIGNR1 using CD209b antibody. In addition, IL-4+LLC-educated macrophages reduced the proliferation of the activated T cells and reduced IFN-γ-mediated Th1 response in T cells, while SIGNR1 inhibition rescued Th1 cell functions. In conclusion, murine SIGNR1 expressed in LLC-educated macrophages appears to mediate IL-4-induced RAW264.7 macrophage polarization and thus facilitate lung cancer evasion. © 2015 Wiley Periodicals, Inc.

Humans as predators: an overview of predation strategies of hunters with contrasting motivational drivers

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Fredrik Dalerum

2018-01-01

Full Text Available Predator-prey theory suggests that generalist predators are linked to demographic stability of prey whereas specialists are destabilizing. We overview the demographic consequences of different predation strategies and hypothesize that subsistence hunting occurs opportunistically, persecution hunters behave like specialist predators, and recreational hunters behave like generalist predators. Under this hypothesis, persecution hunting would have destabilizing effects, whereas the effects of subsistence and recreational hunting would be neutral or stabilizing. We found poor empirical support for this hypothesis, but there was scarce empirical data. Recreational hunters mainly hunted opportunistically and hunting as managed persecution followed a type III functional response, i.e. with low hunting intensity at low game abundances and a switch to an increased intensity at some level of abundance. We suggest that recreational hunters have limited destabilizing effects on game populations and that hunting may be an ineffective way of complete the removal of invasive species. We urge for further studies quantifying the responses of hunters to game abundances, in particular studies evaluating the responses of subsistence hunters and illegal persecution.

Generalization of predator recognition: Velvet geckos display anti-predator behaviours in response to chemicals from non-dangerous elapid snakes

Directory of Open Access Journals (Sweden)

Jonathan K. WEBB, Weiguo DU, David PIKE, Richard SHINE

2010-06-01

Full Text Available Many prey species detect chemical cues from predators and modify their behaviours in ways that reduce their risk of predation. Theory predicts that prey should modify their anti-predator responses according to the degree of threat posed by the predator. That is, prey should show the strongest responses to chemicals of highly dangerous prey, but should ignore or respond weakly to chemicals from non-dangerous predators. However, if anti-predator behaviours are not costly, and predators are rarely encountered, prey may exhibit generalised antipredator behaviours to dangerous and non-dangerous predators. In Australia, most elapid snakes eat lizards, and are therefore potentially dangerous to lizard prey. Recently, we found that the nocturnal velvet gecko Oedura lesueurii responds to chemicals from dangerous and non-dangerous elapid snakes, suggesting that it displays generalised anti-predator behaviours to chemicals from elapid snakes. To explore the generality of this result, we videotaped the behaviour of velvet geckos in the presence of chemical cues from two small elapid snakes that rarely consume geckos: the nocturnal golden-crowned snake Cacophis squamulosus and the diurnal marsh snake Hemiaspis signata. We also videotaped geckos in trials involving unscented cards (controls and cologne-scented cards (pungency controls. In trials involving Cacophis and Hemiaspis chemicals, 50% and 63% of geckos spent long time periods (> 3 min freezing whilst pressed flat against the substrate, respectively. Over half the geckos tested exhibited anti-predator behaviours (tail waving, tail vibration, running in response to Cacophis (67% or Hemiaspis (63% chemicals. These behaviours were not observed in control or pungency control trials. Our results support the idea that the velvet gecko displays generalised anti-predator responses to chemical cues from elapid snakes. Generalised responses to predator chemicals may be common in prey species that co-occur with

A predator-prey model with a holling type I functional response including a predator mutual interference

Science.gov (United States)

Seo, G.; DeAngelis, D.L.

2011-01-01

The most widely used functional response in describing predator-prey relationships is the Holling type II functional response, where per capita predation is a smooth, increasing, and saturating function of prey density. Beddington and DeAngelis modified the Holling type II response to include interference of predators that increases with predator density. Here we introduce a predator-interference term into a Holling type I functional response. We explain the ecological rationale for the response and note that the phase plane configuration of the predator and prey isoclines differs greatly from that of the Beddington-DeAngelis response; for example, in having three possible interior equilibria rather than one. In fact, this new functional response seems to be quite unique. We used analytical and numerical methods to show that the resulting system shows a much richer dynamical behavior than the Beddington-DeAngelis response, or other typically used functional responses. For example, cyclic-fold, saddle-fold, homoclinic saddle connection, and multiple crossing bifurcations can all occur. We then use a smooth approximation to the Holling type I functional response with predator mutual interference to show that these dynamical properties do not result from the lack of smoothness, but rather from subtle differences in the functional responses. ?? 2011 Springer Science+Business Media, LLC.

TAX EVASION AND MONEY LAUNDERING – WAYS OF EVADING THE PAYMENT OF THE STATE BUDGET LIABILITIES

Directory of Open Access Journals (Sweden)

Constantin AFANASE

2005-01-01

Full Text Available Tax evasion is an antisocial phenomenon to be fight against with all forces. By reducing collection oftaxes, this phenomenon abridges society of significant public resources which could be used forachieving some social and economic goals used by the whole society. It is known that since the oldtimes tax payers were looking for means of reducing tax liabilities through various and ingeniousmethods. Basis of tax evasion phenomenon are in the deep structures of human cerebration, in theselfish spirit of human being, which always tend to bring specific interest before overall interest.

The informal sector in transition: Tax evasion in an institutional vacuum

NARCIS (Netherlands)

Gërxhani, K.

2002-01-01

This thesis discusses the informal sector mainly focusing on the study of tax evasion. Individuals' decision whether or not to evade taxes is the core of the studies presented here. The role of institutions in this individual decision is considered to be of crucial importance. As a natural

Legal Considerations of Tax Evasion and Tax Avoidance

OpenAIRE

Dániel Deák

2004-01-01

The study of fiscal non-compliance - in particular, that of tax evasion - is quite extensive in the literature of economics. Lawyers do not show much interest in fiscal anomalies. An exception for this is perhaps tax avoidance which is usually interpreted as the problem of the form and substance. Apart from the modest interest in irregularities in fiscal law, the legal theories of obedience, or disobedience, and coherence have grown significantly, thanks to the precept of William Ross on prim...

Malaria parasite evasion of classical complement pathway attack

DEFF Research Database (Denmark)

Larsen, Mads Delbo; Ditlev, Sisse; Olmos, Rafael Bayarri

2017-01-01

of the protective antibodies that are gradually acquired in response to P. falciparum-IEs. Although this response is dominated by IgG1 and IgG3, complement-mediated attack following activation of the classical pathway does not appear to be a major effector mechanism. We hypothesized that this is related to the knob...... is that the knob-restricted expression of PfEMP1 on the IE surface may serve as a hitherto unappreciated immune evasion mechanism employed by P. falciparum parasites....

Evasion of CO2 from streams - the dominant component of the carbon export through the aquatic conduit in a boreal landscape.

Science.gov (United States)

Wallin, Marcus B; Grabs, Thomas; Buffam, Ishi; Laudon, Hjalmar; Agren, Ånneli; Öquist, Mats G; Bishop, Kevin

2013-03-01

Evasion of gaseous carbon (C) from streams is often poorly quantified in landscape C budgets. Even though the potential importance of the capillary network of streams as C conduits across the land-water-atmosphere interfaces is sometimes mentioned, low-order streams are often left out of budget estimates due to being poorly characterized in terms of gas exchange and even areal surface coverage. We show that evasion of C is greater than all the total dissolved C (both organic and inorganic) exported downstream in the waters of a boreal landscape. In this study evasion of carbon dioxide (CO2 ) from running waters within a 67 km(2) boreal catchment was studied. During a 4 year period (2006-2009) 13 streams were sampled on 104 different occasions for dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). From a locally determined model of gas exchange properties, we estimated the daily CO2 evasion with a high-resolution (5 × 5 m) grid-based stream evasion model comprising the entire ~100 km stream network. Despite the low areal coverage of stream surface, the evasion of CO2 from the stream network constituted 53% (5.0 (±1.8) g C m(-2)  yr(-1) ) of the entire stream C flux (9.6 (±2.4) g C m(-2)  yr(-1) ) (lateral as DIC, DOC, and vertical as CO2 ). In addition, 72% of the total CO2 loss took place already in the first- and second-order streams. This study demonstrates the importance of including CO2 evasion from low-order boreal streams into landscape C budgets as it more than doubled the magnitude of the aquatic conduit for C from this landscape. Neglecting this term will consequently result in an overestimation of the terrestrial C sink strength in the boreal landscape. © 2012 Blackwell Publishing Ltd.

Effect of woodland patch size on rodent seed predation in a fragmented landscape

Directory of Open Access Journals (Sweden)

J. Loman

2007-05-01

Full Text Available Predation on large woody plant seeds; chestnuts, acorns and sloe kernels, was studied in deciduous forests of two size classes: small woodlots (<1 ha and large woods (at least 25 ha in southern Sweden. Seeds used for the study were artificially distributed on the forest ground and seed predation measured as seed removal. Predation rate was similar in both types of woods. However, rodent density was higher in small woodlots and a correction for differences in rodent density showed that predation rate per individual rodent was higher in the large woods. This suggests that the small woodlots (including the border zone and their adjacent fields have more rodent food per area unit. A small woodlot cannot be considered a representative sample of a large continuous forest, even if the habitats appear similar. There was a strong effect of rodent density on seed predation rate. This suggests that rodents are major seed predators in this habitat.

Predator confusion is sufficient to evolve swarming behaviour.

Science.gov (United States)

Olson, Randal S; Hintze, Arend; Dyer, Fred C; Knoester, David B; Adami, Christoph

2013-08-06

Swarming behaviours in animals have been extensively studied owing to their implications for the evolution of cooperation, social cognition and predator-prey dynamics. An important goal of these studies is discerning which evolutionary pressures favour the formation of swarms. One hypothesis is that swarms arise because the presence of multiple moving prey in swarms causes confusion for attacking predators, but it remains unclear how important this selective force is. Using an evolutionary model of a predator-prey system, we show that predator confusion provides a sufficient selection pressure to evolve swarming behaviour in prey. Furthermore, we demonstrate that the evolutionary effect of predator confusion on prey could in turn exert pressure on the structure of the predator's visual field, favouring the frontally oriented, high-resolution visual systems commonly observed in predators that feed on swarming animals. Finally, we provide evidence that when prey evolve swarming in response to predator confusion, there is a change in the shape of the functional response curve describing the predator's consumption rate as prey density increases. Thus, we show that a relatively simple perceptual constraint--predator confusion--could have pervasive evolutionary effects on prey behaviour, predator sensory mechanisms and the ecological interactions between predators and prey.

On Some Pursuit and Evasion Differential Game Problems for an Infinite Number of First-Order Differential Equations

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Abbas Badakaya Ja'afaru

2012-01-01

Full Text Available We study pursuit and evasion differential game problems described by infinite number of first-order differential equations with function coefficients in Hilbert space l2. Problems involving integral, geometric, and mix constraints to the control functions of the players are considered. In each case, we give sufficient conditions for completion of pursuit and for which evasion is possible. Consequently, strategy of the pursuer and control function of the evader are constructed in an explicit form for every problem considered.

Introduced mammalian predators induce behavioural changes in parental care in an endemic New Zealand bird.

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Melanie Massaro

Full Text Available The introduction of predatory mammals to oceanic islands has led to the extinction of many endemic birds. Although introduced predators should favour changes that reduce predation risk in surviving bird species, the ability of island birds to respond to such novel changes remains unstudied. We tested whether novel predation risk imposed by introduced mammalian predators has altered the parental behaviour of the endemic New Zealand bellbird (Anthornis melanura. We examined parental behaviour of bellbirds at three woodland sites in New Zealand that differed in predation risk: 1 a mainland site with exotic predators present (high predation risk, 2 a mainland site with exotic predators experimentally removed (low risk recently and, 3 an off-shore island where exotic predators were never introduced (low risk always. We also compared parental behaviour of bellbirds with two closely related Tasmanian honeyeaters (Phylidonyris spp. that evolved with native nest predators (high risk always. Increased nest predation risk has been postulated to favour reduced parental activity, and we tested whether island bellbirds responded to variation in predation risk. We found that females spent more time on the nest per incubating bout with increased risk of predation, a strategy that minimised activity at the nest during incubation. Parental activity during the nestling period, measured as number of feeding visits/hr, also decreased with increasing nest predation risk across sites, and was lowest among the honeyeaters in Tasmania that evolved with native predators. These results demonstrate that some island birds are able to respond to increased risk of predation by novel predators in ways that appear adaptive. We suggest that conservation efforts may be more effective if they take advantage of the ability of island birds to respond to novel predators, especially when the elimination of exotic predators is not possible.

Introduced mammalian predators induce behavioural changes in parental care in an endemic New Zealand bird

Science.gov (United States)

Massaro, M.; Starling-Windhof, A.; Briskie, J.V.; Martin, T.E.

2008-01-01

The introduction of predatory mammals to oceanic islands has led to the extension of many birds. Although introduced predators should favour changes that reduce predation risk in surviving bird species, the ability of island birds to respond to such novel changes remains unstudied. We tested whether novel predation risk imposed by introduced mammalian predators has altered the parental behaviour of the endemic New Zealand bellbird (Anthomis melanura). We examined parental behaviour of billbnirds at three woodlands sites in New Zealand that differed in predation risk: 1) a mainland site with exotic predators present (high predation risk), 2) a mainland site with exotic predators experimentally removed (low risk recently) and, 3) an off-shore island where exotic predators were never introduced (low risk always). We also compared parental behavior of bellbirds with two closely related Tasmanian honeyeaters (Phylidonyris spp) that evolved with native nest predators (high risk always). Increased nest predation risk has been postulated to favour reduced parental activity, and we tested whether island bellbirds responded to variation in predation risk. We found that females spent more time on the nest per incubating bout with increased risk of predation, a strategy that minimised activity at the nest during incubation. Parental activity during the nestling period, measured as number of feeding visits/hr, also decreased with increasing nest predation risk across sites, and was lowest among the honeyeaters in Tasmania that evolved with native predators. These results demonstrates that some island birds are able to respond to increased risk of predation by novel predators in ways that appear adaptive. We suggest that conservation efforts may be more effective if they take advantage of the ability of island birds to respond to novel predators, especially when the elimination of exotic predators is not possible.

Tax evasion between fiscal and penalty

Directory of Open Access Journals (Sweden)

Andreea Mihaela Corîci

2017-12-01

Full Text Available Although in present times a big importance is given to combating and preventing tax evasion, as well as to all tax frauds, there are, however, people who are tax evaders from the point of view of the criminal body, who manage to ease of payment of tax liabilities to the state. By imposing more drastic or lighter penalties, it is attempted to determine the taxpayer in order not to escape the payment of taxes and to commit the crime.If for the financial controlling authority a fiscal crime has a direct impact on the budget of a certain area, the fiscal action is a criminal one for the criminal authority.

Species diversity modulates predation

NARCIS (Netherlands)

Kratina, P.; Vos, M.; Anholt, B.R.

2007-01-01

Predation occurs in a context defined by both prey and non-prey species. At present it is largely unknown how species diversity in general, and species that are not included in a predator's diet in particular, modify predator–prey interactions.Therefore we studied how both the density and diversity

Bioinsecticide-predator interactions: azadirachtin behavioral and reproductive impairment of the coconut mite predator Neoseiulus baraki.

Directory of Open Access Journals (Sweden)

Debora B Lima

Full Text Available Synthetic pesticide use has been the dominant form of pest control since the 1940s. However, biopesticides are emerging as sustainable pest control alternatives, with prevailing use in organic agricultural production systems. Foremost among botanical biopesticides is the limonoid azadirachtin, whose perceived environmental safety has come under debate and scrutiny in recent years. Coconut production, particularly organic coconut production, is one of the agricultural systems in which azadirachtin is used as a primary method of pest control for the management of the invasive coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae. The management of this mite species also greatly benefits from predation by Neoseiulus baraki (Athias-Henriot (Acari: Phytoseiidae. Here, we assessed the potential behavioral impacts of azadirachtin on the coconut mite predator, N. baraki. We explored the effects of this biopesticide on overall predator activity, female searching time, and mating behavior and fecundity. Azadirachtin impairs the overall activity of the predator, reducing it to nearly half; however, female searching was not affected. In contrast, mating behavior was compromised by azadirachtin exposure particularly when male predators were exposed to the biopesticide. Consequently, predator fecundity was also compromised by azadirachtin, furthering doubts about its environmental safety and selectivity towards biological control agents.

Bioinsecticide-predator interactions: azadirachtin behavioral and reproductive impairment of the coconut mite predator Neoseiulus baraki.

Science.gov (United States)

Lima, Debora B; Melo, José Wagner S; Guedes, Nelsa Maria P; Gontijo, Lessando M; Guedes, Raul Narciso C; Gondim, Manoel Guedes C

2015-01-01

Synthetic pesticide use has been the dominant form of pest control since the 1940s. However, biopesticides are emerging as sustainable pest control alternatives, with prevailing use in organic agricultural production systems. Foremost among botanical biopesticides is the limonoid azadirachtin, whose perceived environmental safety has come under debate and scrutiny in recent years. Coconut production, particularly organic coconut production, is one of the agricultural systems in which azadirachtin is used as a primary method of pest control for the management of the invasive coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae). The management of this mite species also greatly benefits from predation by Neoseiulus baraki (Athias-Henriot) (Acari: Phytoseiidae). Here, we assessed the potential behavioral impacts of azadirachtin on the coconut mite predator, N. baraki. We explored the effects of this biopesticide on overall predator activity, female searching time, and mating behavior and fecundity. Azadirachtin impairs the overall activity of the predator, reducing it to nearly half; however, female searching was not affected. In contrast, mating behavior was compromised by azadirachtin exposure particularly when male predators were exposed to the biopesticide. Consequently, predator fecundity was also compromised by azadirachtin, furthering doubts about its environmental safety and selectivity towards biological control agents.

Transfer Pricing - between Optimization and International Tax Evasion

Directory of Open Access Journals (Sweden)

Valentin SAVA

2017-06-01

Full Text Available Each enterprise in the private sector aims to increase financial return, which is achieved by obtaining a the higher net profit by increasing revenue and reducing expenditure. In this endeavor, compliance with tax obligations occupy a very important role because handling taxes may lead to an increase in revenue and / or a reduction of spending, and this action is called tax optimization. In the case of multinational companies, the main tool that can be used to lower the tax burden and increasing, sometimes in sizeable benefits in net, is the transfer prices or the prices they registered entities in the group transactions between them, along with another instrument with great impact, ie tax havens. Tax evasion, designating evading payment obligations of a company according to the national tax system, may be legal in the sense that tax optimization does not violate the rules, but exploiting loopholes that are in them. But when legal tax rules are violated, we deal with tax fraud, which will be subject to punitive measures by public authorities as it affects the whole population.

Vertebrate predator-prey interactions in a seasonal environment

DEFF Research Database (Denmark)

Schmidt, Niels Martin; Berg, Thomas B; Forchhammer, Mads

2008-01-01

erminea predation and stabilising predation from the generalist predators, in Zackenbergdalen mainly the arctic fox Alopex lagopus. In Zackenbergdalen, however, the coupling between the specialist stoat and the lemming population is relatively weak. During summer, the predation pressure is high......The High Arctic, with its low number of species, is characterised by a relatively simple ecosystem, and the vertebrate predator-prey interactions in the valley Zackenbergdalen in Northeast Greenland are centred around the collared lemming Dicrostonyx groenlandicus and its multiple predators...

Interclonal proteomic responses to predator exposure in Daphnia magna may depend on predator composition of habitats.

Science.gov (United States)

Otte, Kathrin A; Schrank, Isabella; Fröhlich, Thomas; Arnold, Georg J; Laforsch, Christian

2015-08-01

Phenotypic plasticity, the ability of one genotype to express different phenotypes in response to changing environmental conditions, is one of the most common phenomena characterizing the living world and is not only relevant for the ecology but also for the evolution of species. Daphnia, the water flea, is a textbook example for predator-induced phenotypic plastic defences; however, the analysis of molecular mechanisms underlying these inducible defences is still in its early stages. We exposed Daphnia magna to chemical cues of the predator Triops cancriformis to identify key processes underlying plastic defensive trait formation. To get a more comprehensive idea of this phenomenon, we studied four genotypes with five biological replicates each, originating from habitats characterized by different predator composition, ranging from predator-free habitats to habitats containing T. cancriformis. We analysed the morphologies as well as proteomes of predator-exposed and control animals. Three genotypes showed morphological changes when the predator was present. Using a high-throughput proteomics approach, we found 294 proteins which were significantly altered in their abundance after predator exposure in a general or genotype-dependent manner. Proteins connected to genotype-dependent responses were related to the cuticle, protein synthesis and calcium binding, whereas the yolk protein vitellogenin increased in abundance in all genotypes, indicating their involvement in a more general response. Furthermore, genotype-dependent responses at the proteome level were most distinct for the only genotype that shares its habitat with Triops. Altogether, our study provides new insights concerning genotype-dependent and general molecular processes involved in predator-induced phenotypic plasticity in D. magna. © 2015 John Wiley & Sons Ltd.

Body size, swimming speed, or thermal sensitivity? Predator-imposed selection on amphibian larvae.

Science.gov (United States)

Gvoždík, Lumír; Smolinský, Radovan

2015-11-02

Many animals rely on their escape performance during predator encounters. Because of its dependence on body size and temperature, escape velocity is fully characterized by three measures, absolute value, size-corrected value, and its response to temperature (thermal sensitivity). The primary target of the selection imposed by predators is poorly understood. We examined predator (dragonfly larva)-imposed selection on prey (newt larvae) body size and characteristics of escape velocity using replicated and controlled predation experiments under seminatural conditions. Specifically, because these species experience a wide range of temperatures throughout their larval phases, we predict that larvae achieving high swimming velocities across temperatures will have a selective advantage over more thermally sensitive individuals. Nonzero selection differentials indicated that predators selected for prey body size and both absolute and size-corrected maximum swimming velocity. Comparison of selection differentials with control confirmed selection only on body size, i.e., dragonfly larvae preferably preyed on small newt larvae. Maximum swimming velocity and its thermal sensitivity showed low group repeatability, which contributed to non-detectable selection on both characteristics of escape performance. In the newt-dragonfly larvae interaction, body size plays a more important role than maximum values and thermal sensitivity of swimming velocity during predator escape. This corroborates the general importance of body size in predator-prey interactions. The absence of an appropriate control in predation experiments may lead to potentially misleading conclusions about the primary target of predator-imposed selection. Insights from predation experiments contribute to our understanding of the link between performance and fitness, and further improve mechanistic models of predator-prey interactions and food web dynamics.

Differences in predators of artificial and real songbirds nests: Evidence of bias in artificial nest studies

Science.gov (United States)

Frank R. Thompson; Dirk E. Burhans

2004-01-01

In the past two decades, many researchers have used artificial nest to measure relative rates of nest predation. Recent comparisons show that real and artificial nests may not be depredated at the same rate, but no one has examined the mechanisms underlying these patterns. We determined differences in predator-specific predation rates of real and artificial nests. we...

Predator diversity effects in an exotic freshwater food web.

Science.gov (United States)

Naddafi, Rahmat; Rudstam, Lars G

2013-01-01

Cascading trophic interactions are often defined as the indirect effects of a predator on primary producers through the effect of the predator on herbivores. These effects can be both direct through removal of herbivores [density-mediated indirect interactions (DMIIs)] or indirect through changes in the behavior of the herbivores [trait-mediated indirect interactions (TMIIs)]. How the relative importance of these two indirect interactions varies with predator diversity remains poorly understood. We tested the effect of predator diversity on both TMIIs and DMIIs on phytoplankton using two competitive invasive dreissenid mussel species (zebra mussel and quagga mussel) as the herbivores and combinations of one, two or all three species of the predators pumpkinseed sunfish, round goby, and rusty crayfish. Predators had either direct access to mussels and induced both TMII and DMII, or no direct access and induced only TMII through the presence of risk cues. In both sets of treatments, the predators induced a trophic cascade which resulted in more phytoplankton remaining with predators present than with only mussels present. The trophic cascade was weaker in three-predator and two-predator treatments than in one-predator treatments when predators had direct access to dreissenids (DMIIs and TMIIs). Crayfish had higher cascading effects on phytoplankton than both pumpkinseed and round goby. Increased predator diversity decreased the strength of DMIIs but had no effect on the strength of TMIIs. The strength of TMIIs was higher with zebra than quagga mussels. Our study suggests that inter-specific interference among predators in multi-species treatments weakens the consumptive cascading effects of predation on lower trophic levels whereas the importance of predator diversity on trait mediated effects depends on predator identity.

Predator diversity effects in an exotic freshwater food web.

Directory of Open Access Journals (Sweden)

Rahmat Naddafi

Full Text Available Cascading trophic interactions are often defined as the indirect effects of a predator on primary producers through the effect of the predator on herbivores. These effects can be both direct through removal of herbivores [density-mediated indirect interactions (DMIIs] or indirect through changes in the behavior of the herbivores [trait-mediated indirect interactions (TMIIs]. How the relative importance of these two indirect interactions varies with predator diversity remains poorly understood. We tested the effect of predator diversity on both TMIIs and DMIIs on phytoplankton using two competitive invasive dreissenid mussel species (zebra mussel and quagga mussel as the herbivores and combinations of one, two or all three species of the predators pumpkinseed sunfish, round goby, and rusty crayfish. Predators had either direct access to mussels and induced both TMII and DMII, or no direct access and induced only TMII through the presence of risk cues. In both sets of treatments, the predators induced a trophic cascade which resulted in more phytoplankton remaining with predators present than with only mussels present. The trophic cascade was weaker in three-predator and two-predator treatments than in one-predator treatments when predators had direct access to dreissenids (DMIIs and TMIIs. Crayfish had higher cascading effects on phytoplankton than both pumpkinseed and round goby. Increased predator diversity decreased the strength of DMIIs but had no effect on the strength of TMIIs. The strength of TMIIs was higher with zebra than quagga mussels. Our study suggests that inter-specific interference among predators in multi-species treatments weakens the consumptive cascading effects of predation on lower trophic levels whereas the importance of predator diversity on trait mediated effects depends on predator identity.

Hijacking Complement Regulatory Proteins for Bacterial Immune Evasion.

Science.gov (United States)

Hovingh, Elise S; van den Broek, Bryan; Jongerius, Ilse

2016-01-01

The human complement system plays an important role in the defense against invading pathogens, inflammation and homeostasis. Invading microbes, such as bacteria, directly activate the complement system resulting in the formation of chemoattractants and in effective labeling of the bacteria for phagocytosis. In addition, formation of the membrane attack complex is responsible for direct killing of Gram-negative bacteria. In turn, bacteria have evolved several ways to evade complement activation on their surface in order to be able to colonize and invade the human host. One important mechanism of bacterial escape is attraction of complement regulatory proteins to the microbial surface. These molecules are present in the human body for tight regulation of the complement system to prevent damage to host self-surfaces. Therefore, recruitment of complement regulatory proteins to the bacterial surface results in decreased complement activation on the microbial surface which favors bacterial survival. This review will discuss recent advances in understanding the binding of complement regulatory proteins to the bacterial surface at the molecular level. This includes, new insights that have become available concerning specific conserved motives on complement regulatory proteins that are favorable for microbial binding. Finally, complement evasion molecules are of high importance for vaccine development due to their dominant role in bacterial survival, high immunogenicity and homology as well as their presence on the bacterial surface. Here, the use of complement evasion molecules for vaccine development will be discussed.

Species Diversity Enhances Predator Growth Rates

International Nuclear Information System (INIS)

Olson, M.H.; Jacobs, R.P.; O'Donnell, E.B.

2007-01-01

Predators can be important top-down regulators of community structure and are known to have both positive and negative effects on species diversity. However, little is known about the reciprocal effects of species diversity on predators. Across a set of 80 lakes in Connecticut, USA, we found a strong positive correlation between prey species diversity (using the Shannon-Weiner Diversity Index) and growth rates of largemouth bass (Micropterus salmoides). This correlation was strongest for small predators and decreased with body size. Although the underlying mechanisms are not known, the correlation is not driven by total fish abundance, predator abundance, or productivity.

Predators on private land: broad-scale socioeconomic interactions influence large predator management

Directory of Open Access Journals (Sweden)

Hayley S. Clements

2016-06-01

Full Text Available The proliferation of private land conservation areas (PLCAs is placing increasing pressure on conservation authorities to effectively regulate their ecological management. Many PLCAs depend on tourism for income, and charismatic large mammal species are considered important for attracting international visitors. Broad-scale socioeconomic factors therefore have the potential to drive fine-scale ecological management, creating a systemic scale mismatch that can reduce long-term sustainability in cases where economic and conservation objectives are not perfectly aligned. We assessed the socioeconomic drivers and outcomes of large predator management on 71 PLCAs in South Africa. Owners of PLCAs that are stocking free-roaming large predators identified revenue generation as influencing most or all of their management decisions, and rated profit generation as a more important objective than did the owners of PLCAs that did not stock large predators. Ecotourism revenue increased with increasing lion (Panthera leo density, which created a potential economic incentive for stocking lion at high densities. Despite this potential mismatch between economic and ecological objectives, lion densities were sustainable relative to available prey. Regional-scale policy guidelines for free-roaming lion management were ecologically sound. By contrast, policy guidelines underestimated the area required to sustain cheetah (Acinonyx jubatus, which occurred at unsustainable densities relative to available prey. Evidence of predator overstocking included predator diet supplementation and frequent reintroduction of game. We conclude that effective facilitation of conservation on private land requires consideration of the strong and not necessarily beneficial multiscale socioeconomic factors that influence private land management.

High trees increase sunflower seed predation by birds in an agricultural landscape of Israel

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Jessica eSchäckermann

2014-07-01

Full Text Available Natural habitats in agricultural landscapes promote agro-ecosystem services but little is known about negative effects (dis-services derived by natural habitats such as crop seed predation. Birds are important seed predators and use high landscape structures to perch and hide. High trees in agricultural landscapes may therefore drive seed predation. We examined if the presence, the distance and the percentages of high trees (tree height >5 m and the percentages of natural habitat surrounding sunflower fields, increased seed predation by birds in Israel. At the field scale, we assessed seed predation across a sample grid of an entire field. At the landscape scale, we assessed seed predation at the field margins and interiors of 20 sunflower fields. Seed predation was estimated as the percentage of removed seeds from sunflower heads. Distances of sample points to the closest high tree and percentage of natural habitat and of high trees in a 1km radius surrounding the fields were measured.We found that seed predation increased with decreasing distance to the closest high tree at the field and landscape scale. At the landscape scale, the percentage of high trees and natural habitat did not increase seed predation. Seed predation in the fields increased by 37 %, with a maximum seed predation of 92 %, when a high tree was available within zero to 50 m to the sunflower fields. If the closest high tree was further away, seed predation was less than 5 %. Sunflower seed predation by birds can be reduced, when avoiding sowing sunflowers within a radius of 50 m to high trees. Farmers should plan to grow crops, not sensitive to bird seed predation, closer to trees to eventually benefit from ecosystem services provided by birds, such as predation of pest insects, while avoiding these locations for growing crops sensitive to bird seed predation. Such management recommendations are directing towards sustainable agricultural landscapes.

Cuckoos vs. top predators as prime bioindicators of biodiversity in disturbed environments.

Science.gov (United States)

Morelli, Federico; Mousseau, Timothy A; Møller, Anders Pape

2017-10-01

We studied the abundance of the common cuckoo Cuculus canorus L. little cuckoo Cuculus poliocephalus L. and Asian cuckoo Cuculus saturatus L. and avian top predators as indicators of bird species richness (surrogate of biodiversity) in disturbed environments caused by radioactive contamination in Chernobyl, Ukraine and Fukushima, Japan, comparing their efficiency as indicators of local biodiversity hotspots. Bird species richness and birds abundance were quantified in each sample site during the breeding seasons between 2006 and 2015 and the level of background radiation was measured at every site. The correlation between number of cuckoos, top predators, land use composition and level of background radiation with bird species richness as response variable were examined using Generalized Linear Mixed Models. The strength of correlation between species richness and abundance and the covariates obtained from the model outputs were used as measure of the efficiency of each predictor, as well as the AIC of each model. Background radiation was negatively correlated with bird species richness and bird abundance in both countries, while number of top predators and cuckoos were both positively correlated with bird species richness and abundance. However, model with number of cuckoos was more performant than model with number of avian top predators. These differences in performance supports the hypothesis that cuckoos are a largely superior bioindicator than top predators. Copyright © 2017 Elsevier Ltd. All rights reserved.

Regional-scale lateral carbon transport and CO2 evasion in temperate stream catchments

Science.gov (United States)

Magin, Katrin; Somlai-Haase, Celia; Schäfer, Ralf B.; Lorke, Andreas

2017-11-01

Inland waters play an important role in regional to global-scale carbon cycling by transporting, processing and emitting substantial amounts of carbon, which originate mainly from their catchments. In this study, we analyzed the relationship between terrestrial net primary production (NPP) and the rate at which carbon is exported from the catchments in a temperate stream network. The analysis included more than 200 catchment areas in southwest Germany, ranging in size from 0.8 to 889 km2 for which CO2 evasion from stream surfaces and downstream transport with stream discharge were estimated from water quality monitoring data, while NPP in the catchments was obtained from a global data set based on remote sensing. We found that on average 13.9 g C m-2 yr-1 (corresponding to 2.7 % of terrestrial NPP) are exported from the catchments by streams and rivers, in which both CO2 evasion and downstream transport contributed about equally to this flux. The average carbon fluxes in the catchments of the study area resembled global and large-scale zonal mean values in many respects, including NPP, stream evasion and the carbon export per catchment area in the fluvial network. A review of existing studies on aquatic-terrestrial coupling in the carbon cycle suggests that the carbon export per catchment area varies in a relatively narrow range, despite a broad range of different spatial scales and hydrological characteristics of the study regions.

Aquatic insect predators and mosquito control.

Science.gov (United States)

Shaalan, Essam Abdel-Salam; Canyon, Deon V

2009-12-01

Mosquitoes are serious biting pests and obligate vectors of many vertebrate pathogens. Their immature larval and pupal life stages are a common feature in most tropical and many temperate water bodies and often form a significant proportion of the biomass. Control strategies rely primarily on the use of larvicides and environmental modification to reduce recruitment and adulticides during periods of disease transmission. Larvicides are usually chemical but can involve biological toxins, agents or organisms. The use of insect predators in mosquito control has been exploited in a limited fashion and there is much room for further investigation and implementation. Insects that are recognized as having predatorial capacity with regard to mosquito prey have been identified in the Orders Odonata, Coleoptera, Diptera (primarily aquatic predators), and Hemiptera (primarily surface predators). Although their capacity is affected by certain biological and physical factors, they could play a major role in mosquito control. Furthermore, better understanding for the mosquitoes-predators relationship(s) could probably lead to satisfactory reduction of mosquito-borne diseases by utilizing either these predators in control programs, for instance biological and/or integrated control, or their kairomones as mosquitoes' ovipoisting repellents. This review covers the predation of different insect species on mosquito larvae, predator-prey-habitat relationships, co-habitation developmental issues, survival and abundance, oviposition avoidance, predatorial capacity and integrated vector control.

An MHC class I immune evasion gene of Marek׳s disease virus.

Science.gov (United States)

Hearn, Cari; Preeyanon, Likit; Hunt, Henry D; York, Ian A

2015-01-15

Marek׳s disease virus (MDV) is a widespread α-herpesvirus of chickens that causes T cell tumors. Acute, but not latent, MDV infection has previously been shown to lead to downregulation of cell-surface MHC class I (Virology 282:198-205 (2001)), but the gene(s) involved have not been identified. Here we demonstrate that an MDV gene, MDV012, is capable of reducing surface expression of MHC class I on chicken cells. Co-expression of an MHC class I-binding peptide targeted to the endoplasmic reticulum (bypassing the requirement for the TAP peptide transporter) partially rescued MHC class I expression in the presence of MDV012, suggesting that MDV012 is a TAP-blocking MHC class I immune evasion protein. This is the first unique non-mammalian MHC class I immune evasion gene identified, and suggests that α-herpesviruses have conserved this function for at least 100 million years. Copyright © 2014 Elsevier Inc. All rights reserved.

Fatal attraction? Intraguild facilitation and suppression among predators

Science.gov (United States)

Sivy, Kelly J.; Pozzanghera, Casey B.; Grace, James B.; Prugh, Laura R.

2017-01-01

Competition and suppression are recognized as dominant forces that structure predator communities. Facilitation via carrion provisioning, however, is a ubiquitous interaction among predators that could offset the strength of suppression. Understanding the relative importance of these positive and negative interactions is necessary to anticipate community-wide responses to apex predator declines and recoveries worldwide. Using state-sponsored wolf (Canis lupus) control in Alaska as a quasi experiment, we conducted snow track surveys of apex, meso-, and small predators to test for evidence of carnivore cascades (e.g., mesopredator release). We analyzed survey data using an integrative occupancy and structural equation modeling framework to quantify the strengths of hypothesized interaction pathways, and we evaluated fine-scale spatiotemporal responses of nonapex predators to wolf activity clusters identified from radio-collar data. Contrary to the carnivore cascade hypothesis, both meso- and small predator occupancy patterns indicated guild-wide, negative responses of nonapex predators to wolf abundance variations at the landscape scale. At the local scale, however, we observed a near guild-wide, positive response of nonapex predators to localized wolf activity. Local-scale association with apex predators due to scavenging could lead to landscape patterns of mesopredator suppression, suggesting a key link between occupancy patterns and the structure of predator communities at different spatial scales.

Fatal Attraction? Intraguild Facilitation and Suppression among Predators.

Science.gov (United States)

Sivy, Kelly J; Pozzanghera, Casey B; Grace, James B; Prugh, Laura R

2017-11-01

Competition and suppression are recognized as dominant forces that structure predator communities. Facilitation via carrion provisioning, however, is a ubiquitous interaction among predators that could offset the strength of suppression. Understanding the relative importance of these positive and negative interactions is necessary to anticipate community-wide responses to apex predator declines and recoveries worldwide. Using state-sponsored wolf (Canis lupus) control in Alaska as a quasi experiment, we conducted snow track surveys of apex, meso-, and small predators to test for evidence of carnivore cascades (e.g., mesopredator release). We analyzed survey data using an integrative occupancy and structural equation modeling framework to quantify the strengths of hypothesized interaction pathways, and we evaluated fine-scale spatiotemporal responses of nonapex predators to wolf activity clusters identified from radio-collar data. Contrary to the carnivore cascade hypothesis, both meso- and small predator occupancy patterns indicated guild-wide, negative responses of nonapex predators to wolf abundance variations at the landscape scale. At the local scale, however, we observed a near guild-wide, positive response of nonapex predators to localized wolf activity. Local-scale association with apex predators due to scavenging could lead to landscape patterns of mesopredator suppression, suggesting a key link between occupancy patterns and the structure of predator communities at different spatial scales.

Predator recognition in rainbowfish, Melanotaenia duboulayi, embryos.

Directory of Open Access Journals (Sweden)

Lois Jane Oulton

Full Text Available Exposure to olfactory cues during embryonic development can have long term impacts on birds and amphibians behaviour. Despite the vast literature on predator recognition and responses in fishes, few researchers have determined how fish embryos respond to predator cues. Here we exposed four-day-old rainbowfish (Melanotaenia duboulayi embryos to cues emanating from a novel predator, a native predator and injured conspecifics. Their response was assessed by monitoring heart rate and hatch time. Results showed that embryos have an innate capacity to differentiate between cues as illustrated by faster heart rates relative to controls. The greatest increase in heart rate occurred in response to native predator odour. While we found no significant change in the time taken for eggs to hatch, all treatments experienced slight delays as expected if embryos are attempting to reduce exposure to larval predators.

COMPARATIVE ANALYSIS OF TAX EVASION BETWEEN MOLDOVA AND ROMANIA

Directory of Open Access Journals (Sweden)

OANA-CARMEN RĂVAŞ

2015-12-01

Full Text Available Tax evasion is actually failure by the taxpayer, tax liabilities. And the negative effects of this are felt directly on the level of tax revenue receipts, causing major distortions in the functioning of the market mechanism. It is believed that the first cause of fraud is itself impossible, fairer tax system in which develops based on the principle of declaring taxpayer benefiting from a presumption of honesty and that is a temptation to hide.

Tax havens: Features, operations and solving tax evasion problems

OpenAIRE

Obradović-Ćuk, Jelena; Mitić, Petar; Dinić, Vladimir

2016-01-01

Tax haven offers minimal or no tax liability to foreign individuals and enterprises in economically and politically stable environment, where little or no financial information is shared with foreign tax authorities. The aim of this research is to create a comprehensive overview of the characteristics and operations of tax havens, as well as to point out to the ways to overcome the problem of tax evasion. The methodology used in the work is characteristic of social science research: analysis,...

Tax evasion – Notion and means to commit it

Directory of Open Access Journals (Sweden)

Diana G. IONAŞ

2012-01-01

Full Text Available Tax evasion is the circumvention, by any means, from the enforcement or payment of taxes, contributions or any amounts owed to the state budget, the local budget, the state social insurance budget and the budgets for special funds by Romanian or foreign natural persons or companies, commonly referred to as tax payers in the text of the law. It is currently present under various methods and represents a direct and dangerous threat for society’s stability.

Are lemmings prey or predators?

Science.gov (United States)

Turchin, P.; Oksanen, L.; Ekerholm, P.; Oksanen, T.; Henttonen, H.

2000-06-01

Large oscillations in the populations of Norwegian lemmings have mystified both professional ecologists and lay public. Ecologists suspect that these oscillations are driven by a trophic mechanism: either an interaction between lemmings and their food supply, or an interaction between lemmings and their predators. If lemming cycles are indeed driven by a trophic interaction, can we tell whether lemmings act as the resource (`prey') or the consumer (`predator')? In trophic interaction models, peaks of resource density generally have a blunt, rounded shape, whereas peaks of consumer density are sharp and angular. Here we have applied several statistical tests to three lemming datasets and contrasted them with comparable data for cyclic voles. We find that vole peaks are blunt, consistent with their cycles being driven by the interaction with predators. In contrast, the shape of lemming peaks is consistent with the hypothesis that lemmings are functional predators, that is, their cycles are driven by their interaction with food plants. Our findings suggest that a single mechanism, such as interaction between rodents and predators, is unlikely to provide the `universal' explanation of all cyclic rodent dynamics.

Viral Evasion of Natural Killer Cell Activation

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Yi Ma

2016-04-01

Full Text Available Natural killer (NK cells play a key role in antiviral innate defenses because of their abilities to kill infected cells and secrete regulatory cytokines. Additionally, NK cells exhibit adaptive memory-like antigen-specific responses, which represent a novel antiviral NK cell defense mechanism. Viruses have evolved various strategies to evade the recognition and destruction by NK cells through the downregulation of the NK cell activating receptors. Here, we review the recent findings on viral evasion of NK cells via the impairment of NK cell-activating receptors and ligands, which provide new insights on the relationship between NK cells and viral actions during persistent viral infections.

Mechanism of immune evasion in breast cancer

Science.gov (United States)

Wang, Mozhi; Zhang, Changwang; Song, Yongxi; Wang, Zhenning; Wang, Yaojia; Luo, Fang; Xu, Yujie; Zhao, Yi; Wu, Zhonghua; Xu, Yingying

2017-01-01

Breast cancer (BC) is the most common malignant tumor among women, with high morbidity and mortality. Its onset, development, metastasis, and prognosis vary among individuals due to the interactions between tumors and host immunity. Many diverse mechanisms have been associated with BC, with immune evasion being the most widely studied to date. Tumor cells can escape from the body’s immune response, which targets abnormal components and foreign bodies, using different approaches including modification of surface antigens and modulation of the surrounding environment. In this review, we summarize the mechanisms and factors that impact the immunoediting process and analyze their functions in detail. PMID:28352189

Viral Evasion of Natural Killer Cell Activation.

Science.gov (United States)

Ma, Yi; Li, Xiaojuan; Kuang, Ersheng

2016-04-12

Natural killer (NK) cells play a key role in antiviral innate defenses because of their abilities to kill infected cells and secrete regulatory cytokines. Additionally, NK cells exhibit adaptive memory-like antigen-specific responses, which represent a novel antiviral NK cell defense mechanism. Viruses have evolved various strategies to evade the recognition and destruction by NK cells through the downregulation of the NK cell activating receptors. Here, we review the recent findings on viral evasion of NK cells via the impairment of NK cell-activating receptors and ligands, which provide new insights on the relationship between NK cells and viral actions during persistent viral infections.

Role of intraguild predation in aphidophagous guilds

Czech Academy of Sciences Publication Activity Database

Hemptinne, J. L.; Magro, A.; Saladin, C.; Dixon, Anthony F. G.

2012-01-01

Roč. 136, č. 3 (2012), s. 161-170 ISSN 0931-2048 Institutional support: RVO:67179843 Keywords : aphidophagous guilds * cost of intraguild predation * interspecific predation * intraguild predation * ladybird beetles * omnivory Subject RIV: EH - Ecology, Behaviour Impact factor: 1.560, year: 2012

Predators and predation rates of skylark Alauda arvensis and woodlark Lullula arborea nests in a semi-natural area in the Netherlands

NARCIS (Netherlands)

Praus, Libor; Hegemann, Arne; Tieleman, B. Irene; Weidinger, Karel

2014-01-01

Predation is a major cause of breeding failure in bird species with open nests. Although many studies have investigated nest predation rates, direct identification of nest predators is sporadic, especially in (semi-)natural habitats. We quantified nest success and identified nest predators in a

Fortune favours the bold: a higher predator reduces the impact of a native but not an invasive intermediate predator.

Science.gov (United States)

Barrios-O'Neill, Daniel; Dick, Jaimie T A; Emmerson, Mark C; Ricciardi, Anthony; MacIsaac, Hugh J; Alexander, Mhairi E; Bovy, Helene C

2014-05-01

Emergent multiple predator effects (MPEs) might radically alter predictions of predatory impact that are based solely on the impact of individuals. In the context of biological invasions, determining if and how the individual-level impacts of invasive predators relates to their impacts in multiple-individual situations will inform understanding of how such impacts might propagate through recipient communities. Here, we use functional responses (the relationship between prey consumption rate and prey density) to compare the impacts of the invasive freshwater mysid crustacean Hemimysis anomala with a native counterpart Mysis salemaai when feeding on basal cladoceran prey (i) as individuals, (ii) in conspecific groups and (iii) in conspecific groups in the presence of a higher fish predator, Gasterosteus aculeatus. In the absence of the higher predator, the invader consumed significantly more basal prey than the native, and consumption was additive for both mysid species - that is, group consumption was predictable from individual-level consumption. Invaders and natives were themselves equally susceptible to predation when feeding with the higher fish predator, but an MPE occurred only between the natives and higher predator, where consumption of basal prey was significantly reduced. In contrast, consumption by the invaders and higher predator remained additive. The presence of a higher predator serves to exacerbate the existing difference in individual-level consumption between invasive and native mysids. We attribute the mechanism responsible for the MPE associated with the native to a trait-mediated indirect interaction, and further suggest that the relative indifference to predator threat on the part of the invader contributes to its success and impacts within invaded communities. © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.

Dynamics of a Diffusive Predator-Prey Model with Allee Effect on Predator

Directory of Open Access Journals (Sweden)

Xiaoqin Wang

2013-01-01

Full Text Available The reaction-diffusion Holling-Tanner prey-predator model considering the Allee effect on predator, under zero-flux boundary conditions, is discussed. Some properties of the solutions, such as dissipation and persistence, are obtained. Local and global stability of the positive equilibrium and Turing instability are studied. With the help of the numerical simulations, the rich Turing patterns, including holes, stripes, and spots patterns, are obtained.

Tax evasion in transition: Outcome of an institutional clash? - Testing Feige's conjecture

NARCIS (Netherlands)

Gërxhani, K.

2003-01-01

A field survey of households was conducted in Tirana, Albania in 2000. A response rate of 89.3% yielded 1.340 valid questionnaires, allowing us to test Feige’s (1997) conjecture that more tax evasion will be observed, when formal and informal institutions clash. Respondents’ attitudes towards formal

Evasion of CO2 injected into the ocean in the context of CO2 stabilization

International Nuclear Information System (INIS)

Kheshgi, Haroon S.

2004-01-01

The eventual evasion of injected CO 2 to the atmosphere is one consideration when assessing deep-sea disposal of CO 2 as a potential response option to climate change concerns. Evasion estimated using an ocean carbon cycle model is compared to long-term trajectories for future CO 2 emissions, including illustrative cases leading to stabilization of CO 2 concentration at various levels. Modeled residence time for CO 2 injected into the deep ocean exceeds the 100-year time-scale usually considered in scenarios for future emissions, and the potential impacts of climate change. Illustrative cases leading monotonically to constant CO 2 concentration have been highlighted by the Intergovernmental Panel on Climate Change to give guidance on possible timing of emission reductions that may be required to stabilize greenhouse gas concentrations at various levels. For stabilization cases considered, significant modeled evasion does not occur until long after CO 2 emissions have reached a maximum and begun to decline. Illustrative cases can also lead to a maximum in CO 2 concentration followed by a decline to slowly decreasing concentrations. In such cases, future injection of emissions into the deep ocean leads to lower maximum CO 2 concentration, with less effect on concentration later on in time

Interleukin-36 cytokines may overcome microbial immune evasion strategies that inhibit interleukin-1 family signaling.

Science.gov (United States)

Jensen, Liselotte E

2017-08-15

Pathogens deploy immune evasion strategies to successfully establish infections within their hosts. Naturally, the host responds by acquiring mechanisms to counter these strategies. There is increasing evidence that the three interleukin-36 (IL-36) cytokines, IL-36α, IL-36β and IL-36γ, play important roles in host immunity. With a focus on the skin as a target for microbial and viral invasion, the current knowledge of IL-36 functions is reviewed. Furthermore, the hypothesis that the IL-36s have evolved to counteract virulence factors is presented using viruses as an example. The IL-36s are related to IL-1α, IL-1β, IL-18, and IL-33. Numerous viruses affecting the skin have developed immune evasion strategies that neutralize IL-1α, IL-1β, or IL-18 signaling or combinations of these pathways. Through small differences in activation mechanisms and receptor utilization, it is possible that IL-36 signaling may proceed unhindered in the presence of these viral inhibitors. Thus, one physiological function of the IL-36s may be to counteract microbial immune evasion. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Competition and Dispersal in Predator-Prey Waves

NARCIS (Netherlands)

Savill, N.J.; Hogeweg, P.

1998-01-01

Dispersing predators and prey can exhibit complex spatio-temporal wave-like patterns if the interactions between them cause oscillatory dynamics. We study the effect of these predator- prey density waves on the competition between prey populations and between predator popu- lations with different

Diversity of protists and bacteria determines predation performance and stability.

Science.gov (United States)

Saleem, Muhammad; Fetzer, Ingo; Harms, Hauke; Chatzinotas, Antonis

2013-10-01

Predation influences prey diversity and productivity while it effectuates the flux and reallocation of organic nutrients into biomass at higher trophic levels. However, it is unknown how bacterivorous protists are influenced by the diversity of their bacterial prey. Using 456 microcosms, in which different bacterial mixtures with equal initial cell numbers were exposed to single or multiple predators (Tetrahymena sp., Poterioochromonas sp. and Acanthamoeba sp.), we showed that increasing prey richness enhanced production of single predators. The extent of the response depended, however, on predator identity. Bacterial prey richness had a stabilizing effect on predator performance in that it reduced variability in predator production. Further, prey richness tended to enhance predator evenness in the predation experiment including all three protists predators (multiple predation experiment). However, we also observed a negative relationship between prey richness and predator production in multiple predation experiments. Mathematical analysis of potential ecological mechanisms of positive predator diversity-functioning relationships revealed predator complementarity as a factor responsible for both enhanced predator production and prey reduction. We suggest that the diversity at both trophic levels interactively determines protistan performance and might have implications in microbial ecosystem processes and services.

Evidence of leopard predation on bonobos (Pan paniscus).

Science.gov (United States)

D'Amour, Danielle E; Hohmann, Gottfried; Fruth, Barbara

2006-01-01

Current models of social organization assume that predation is one of the major forces that promotes group living in diurnal primates. As large body size renders some protection against predators, gregariousness of great apes and other large primate species is usually related to other parameters. The low frequency of observed cases of nonhuman predation on great apes seems to support this assumption. However, recent efforts to study potential predator species have increasingly accumulated direct and indirect evidence of predation by leopards (Panthera pardus) on chimpanzees and gorillas. The following report provides the first evidence of predation by a leopard on bonobos (Pan paniscus). Copyright 2006 S. Karger AG, Basel.

Fear on the move: predator hunting mode predicts variation in prey mortality and plasticity in prey spatial response.

Science.gov (United States)

Miller, Jennifer R B; Ament, Judith M; Schmitz, Oswald J

2014-01-01

Ecologists have long searched for a framework of a priori species traits to help predict predator-prey interactions in food webs. Empirical evidence has shown that predator hunting mode and predator and prey habitat domain are useful traits for explaining predator-prey interactions. Yet, individual experiments have yet to replicate predator hunting mode, calling into question whether predator impacts can be attributed to hunting mode or merely species identity. We tested the effects of spider predators with sit-and-wait, sit-and-pursue and active hunting modes on grasshopper habitat domain, activity and mortality in a grassland system. We replicated hunting mode by testing two spider predator species of each hunting mode on the same grasshopper prey species. We observed grasshoppers with and without each spider species in behavioural cages and measured their mortality rates, movements and habitat domains. We likewise measured the movements and habitat domains of spiders to characterize hunting modes. We found that predator hunting mode explained grasshopper mortality and spider and grasshopper movement activity and habitat domain size. Sit-and-wait spider predators covered small distances over a narrow domain space and killed fewer grasshoppers than sit-and-pursue and active predators, which ranged farther distances across broader domains and killed more grasshoppers, respectively. Prey adjusted their activity levels and horizontal habitat domains in response to predator presence and hunting mode: sedentary sit-and-wait predators with narrow domains caused grasshoppers to reduce activity in the same-sized domain space; more mobile sit-and-pursue predators with broader domains caused prey to reduce their activity within a contracted horizontal (but not vertical) domain space; and highly mobile active spiders led grasshoppers to increase their activity across the same domain area. All predators impacted prey activity, and sit-and-pursue predators generated strong

Diet quality in a wild grazer declines under the threat of an ambush predator.

Science.gov (United States)

Barnier, Florian; Valeix, Marion; Duncan, Patrick; Chamaillé-Jammes, Simon; Barre, Philippe; Loveridge, Andrew J; Macdonald, David W; Fritz, Hervé

2014-06-22

Predators influence prey populations not only through predation itself, but also indirectly through prompting changes in prey behaviour. The behavioural adjustments of prey to predation risk may carry nutritional costs, but this has seldom been studied in the wild in large mammals. Here, we studied the effects of an ambush predator, the African lion (Panthera leo), on the diet quality of plains zebras (Equus quagga) in Hwange National Park, Zimbabwe. We combined information on movements of both prey and predators, using GPS data, and measurements of faecal crude protein, an index of diet quality in the prey. Zebras which had been in close proximity to lions had a lower quality diet, showing that adjustments in behaviour when lions are within short distance carry nutritional costs. The ultimate fitness cost will depend on the frequency of predator-prey encounters and on whether bottom-up or top-down forces are more important in the prey population. Our finding is the first attempt to our knowledge to assess nutritionally mediated risk effects in a large mammalian prey species under the threat of an ambush predator, and brings support to the hypothesis that the behavioural effects of predation induce important risk effects on prey populations.

Predicting prey population dynamics from kill rate, predation rate and predator-prey ratios in three wolf-ungulate systems.

Science.gov (United States)

Vucetich, John A; Hebblewhite, Mark; Smith, Douglas W; Peterson, Rolf O

2011-11-01

1. Predation rate (PR) and kill rate are both fundamental statistics for understanding predation. However, relatively little is known about how these statistics relate to one another and how they relate to prey population dynamics. We assess these relationships across three systems where wolf-prey dynamics have been observed for 41 years (Isle Royale), 19 years (Banff) and 12 years (Yellowstone). 2. To provide context for this empirical assessment, we developed theoretical predictions of the relationship between kill rate and PR under a broad range of predator-prey models including predator-dependent, ratio-dependent and Lotka-Volterra dynamics. 3. The theoretical predictions indicate that kill rate can be related to PR in a variety of diverse ways (e.g. positive, negative, unrelated) that depend on the nature of predator-prey dynamics (e.g. structure of the functional response). These simulations also suggested that the ratio of predator-to-prey is a good predictor of prey growth rate. That result motivated us to assess the empirical relationship between the ratio and prey growth rate for each of the three study sites. 4. The empirical relationships indicate that PR is not well predicted by kill rate, but is better predicted by the ratio of predator-to-prey. Kill rate is also a poor predictor of prey growth rate. However, PR and ratio of predator-to-prey each explained significant portions of variation in prey growth rate for two of the three study sites. 5. Our analyses offer two general insights. First, Isle Royale, Banff and Yellowstone are similar insomuch as they all include wolves preying on large ungulates. However, they also differ in species diversity of predator and prey communities, exploitation by humans and the role of dispersal. Even with the benefit of our analysis, it remains difficult to judge whether to be more impressed by the similarities or differences. This difficulty nicely illustrates a fundamental property of ecological

Immune Evasion Mechanisms of Entamoeba histolytica: Progression to Disease.

Science.gov (United States)

Begum, Sharmin; Quach, Jeanie; Chadee, Kris

2015-01-01

Entamoeba histolytica (Eh) is a protozoan parasite that infects 10% of the world's population and results in 100,000 deaths/year from amebic dysentery and/or liver abscess. In most cases, this extracellular parasite colonizes the colon by high affinity binding to MUC2 mucin without disease symptoms, whereas in some cases, Eh triggers an aggressive inflammatory response upon invasion of the colonic mucosa. The specific host-parasite factors critical for disease pathogenesis are still not well characterized. From the parasite, the signature events that lead to disease progression are cysteine protease cleavage of the C-terminus of MUC2 that dissolves the mucus layer followed by Eh binding and cytotoxicity of the mucosal epithelium. The host mounts an ineffective excessive host pro-inflammatory response following contact with host cells that causes tissue damage and participates in disease pathogenesis as Eh escapes host immune clearance by mechanisms that are not completely understood. Ameba can modulate or destroy effector immune cells by inducing neutrophil apoptosis and suppressing respiratory burst or nitric oxide (NO) production from macrophages. Eh adherence to the host cells also induce multiple cytotoxic effects that can promote cell death through phagocytosis, apoptosis or by trogocytosis (ingestion of living cells) that might play critical roles in immune evasion. This review focuses on the immune evasion mechanisms that Eh uses to survive and induce disease manifestation in the host.

The functional response of a generalist predator.

Directory of Open Access Journals (Sweden)

Sophie Smout

Full Text Available BACKGROUND: Predators can have profound impacts on the dynamics of their prey that depend on how predator consumption is affected by prey density (the predator's functional response. Consumption by a generalist predator is expected to depend on the densities of all its major prey species (its multispecies functional response, or MSFR, but most studies of generalists have focussed on their functional response to only one prey species. METHODOLOGY AND PRINCIPAL FINDINGS: Using Bayesian methods, we fit an MSFR to field data from an avian predator (the hen harrier Circus cyaneus feeding on three different prey species. We use a simple graphical approach to show that ignoring the effects of alternative prey can give a misleading impression of the predator's effect on the prey of interest. For example, in our system, a "predator pit" for one prey species only occurs when the availability of other prey species is low. CONCLUSIONS AND SIGNIFICANCE: The Bayesian approach is effective in fitting the MSFR model to field data. It allows flexibility in modelling over-dispersion, incorporates additional biological information into the parameter priors, and generates estimates of uncertainty in the model's predictions. These features of robustness and data efficiency make our approach ideal for the study of long-lived predators, for which data may be sparse and management/conservation priorities pressing.

Biological control of toxic cyanobacteria by mixotrophic predators: an experimental test of intraguild predation theory

NARCIS (Netherlands)

Wilken, S.; Verspagen, J.M.H.; Naus-Wiezer, S.M.H.; Van Donk, E.; Huisman, Jef

2014-01-01

Intraguild predators both feed on and compete with their intraguild prey. In theory, intraguild predators can therefore be very effective as biological control agents of intraguild prey species, especially in productive environments. We investigated this hypothesis using the mixotrophic chrysophyte

The increased risk of predation enhances cooperation

Science.gov (United States)

Krams, Indrikis; Bērziņš, Arnis; Krama, Tatjana; Wheatcroft, David; Igaune, Kristīne; Rantala, Markus J.

2010-01-01

Theory predicts that animals in adverse conditions can decrease individual risks and increase long-term benefits by cooperating with neighbours. However, some empirical studies suggest that animals often focus on short-term benefits, which can reduce the likelihood that they will cooperate with others. In this experimental study, we tested between these two alternatives by evaluating whether increased predation risk (as a correlate of environmental adversity) enhances or diminishes the occurrence of cooperation in mobbing, a common anti-predator behaviour, among breeding pied flycatchers Ficedula hypoleuca. We tested whether birds would join their mobbing neighbours more often and harass a stuffed predator placed near their neighbours' nests more intensely in areas with a higher perceived risk of predation. Our results show that birds attended mobs initiated by their neighbours more often, approached the stuffed predator significantly more closely, and mobbed it at a higher intensity in areas where the perceived risk of predation was experimentally increased. In such high-risk areas, birds also were more often involved in between-pair cooperation. This study demonstrates the positive impact of predation risk on cooperation in breeding songbirds, which might help in explaining the emergence and evolution of cooperation. PMID:19846454

THE VALUE ADDED TAX AND THE EVASION CHAIN OF INTRA-COMMUNITARIAN VAT

Directory of Open Access Journals (Sweden)

Deliman Eugen

2011-12-01

Full Text Available The relationship IRS taxpayer runs the risk of turning into a psychological war in which, however, given the positions held, the IRS is by far on a favorable footing. Between the apparently excessively formal position held by the IRS, which seems to conceal behind the laws, and the sometimes forced interpretation of the laws, by the taxpayer, there are the courts of law, also disturbed by the legislative changes which appear to have entered a perpetual motion. The objective of the fiscal administration regarding the value added tax is to combat tax evasion and fraud. It is very important to combat evasion in the VAT field because it represents the indirect tax of the largest share in the consolidated general budget. VAT evasion represents the intention of not paying the tax, withholding or not declaring it, or requesting its refund which would not be fit, due to the exaggeration of the deductible amount of the VAT. The essential aim of the IRS inspector is to verify the correctness of the declared amount of the value added tax. It should also be observed whether the incorrectness is deliberate or whether it was due to misunderstanding, carelessness or the ignorance of the payer. In all cases judgment is necessary, as for the cases of negligence the amount to be paid must be corrected and accompanied by applying fines and / or penalties, and in the cases of intended fraud legal actions are to be applied in order to obtain a conviction. Deceitful deductions represent other methods for tax evasion and are undertaken based on fake invoices, invoices often used several times for deduction, or invoices related to purchases that have never been made. Thus there are examples of economic agents who have practiced the right to deduct the VAT due to the acquisition of goods which consisted in the property of other economic agents. In other cases noticed was the deduction of VAT on goods or services that were not included in the activities of the economic

Effects of Microphallus turgidus (Trematoda: Microphallidae) on the predation, behavior, and swimming stamina of the grass shrimp Palaemonetes pugio.

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Kunz, Alyssa K; Pung, Oscar J

2004-06-01

The effect of the trematode Microphallus turgidus on its second intermediate host, the grass shrimp, Palaemonetes pugio, was tested. To do so, we measured the susceptibility of infected and uninfected shrimp to predation by the mummichog, Fundulus heteroclitus. Shrimp behavior was compared in the presence and absence of a fish predator, and the swimming stamina and backthrust escape responses of infected and uninfected shrimp were measured. Infected shrimp were more likely to be eaten by a predator than uninfected shrimp, had lower swimming stamina, and spent more time swimming and less time motionless in the presence of a predator. There was no difference between backthrust distances traveled in response to a stimulus by either infected or uninfected shrimp. Thus, M. turgidus may increase the predation of P. pugio in the wild, possibly by affecting the swimming stamina and predator avoidance responses of the shrimp.

Predator-induced reduction of freshwater carbon dioxide emissions

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Atwood, Trisha B.; Hammill, Edd; Greig, Hamish S.; Kratina, Pavel; Shurin, Jonathan B.; Srivastava, Diane S.; Richardson, John S.

2013-03-01

Predators can influence the exchange of carbon dioxide between ecosystems and the atmosphere by altering ecosystem processes such as decomposition and primary production, according to food web theory. Empirical knowledge of such an effect in freshwater systems is limited, but it has been suggested that predators in odd-numbered food chains suppress freshwater carbon dioxide emissions, and predators in even-numbered food chains enhance emissions. Here, we report experiments in three-tier food chains in experimental ponds, streams and bromeliads in Canada and Costa Rica in the presence or absence of fish (Gasterosteus aculeatus) and invertebrate (Hesperoperla pacifica and Mecistogaster modesta) predators. We monitored carbon dioxide fluxes along with prey and primary producer biomass. We found substantially reduced carbon dioxide emissions in the presence of predators in all systems, despite differences in predator type, hydrology, climatic region, ecological zone and level of in situ primary production. We also observed lower amounts of prey biomass and higher amounts of algal and detrital biomass in the presence of predators. We conclude that predators have the potential to markedly influence carbon dioxide dynamics in freshwater systems.

Smelling out predators is innate in birds

NARCIS (Netherlands)

Amo, L.; Visser, M.E.; Van Oers, K.

2011-01-01

The role of olfaction for predation risk assessment remains barely explored in birds, although predator chemical cues could be useful in predator detection under low visibility conditions for many bird species. We examine whether Great Tits Parus major are able to use the odour of mustelids to

Colonial waterbird predation on Lost River and Shortnose suckers in the Upper Klamath Basin

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Evans, Allen F.; Hewitt, David A.; Payton, Quinn; Cramer, Bradley M.; Collis, Ken; Roby, Daniel D.

2016-01-01

We evaluated predation on Lost River Suckers Deltistes luxatus and Shortnose Suckers Chasmistes brevirostris by American white pelicans Pelecanus erythrorhynchos and double-crested cormorants Phalacrocorax auritus nesting at mixed-species colonies in the Upper Klamath Basin of Oregon and California during 2009–2014. Predation was evaluated by recovering (detecting) PIT tags from tagged fish on bird colonies and calculating minimum predation rates, as the percentage of available suckers consumed, adjusted for PIT tag detection probabilities but not deposition probabilities (i.e., probability an egested tag was deposited on- or off-colony). Results indicate that impacts of avian predation varied by sucker species, age-class (adult, juvenile), bird colony location, and year, demonstrating dynamic predator–prey interactions. Tagged suckers ranging in size from 72 to 730 mm were susceptible to cormorant or pelican predation; all but the largest Lost River Suckers were susceptible to bird predation. Minimum predation rate estimates ranged annually from <0.1% to 4.6% of the available PIT-tagged Lost River Suckers and from <0.1% to 4.2% of the available Shortnose Suckers, and predation rates were consistently higher on suckers in Clear Lake Reservoir, California, than on suckers in Upper Klamath Lake, Oregon. There was evidence that bird predation on juvenile suckers (species unknown) in Upper Klamath Lake was higher than on adult suckers in Upper Klamath Lake, where minimum predation rates ranged annually from 5.7% to 8.4% of available juveniles. Results suggest that avian predation is a factor limiting the recovery of populations of Lost River and Shortnose suckers, particularly juvenile suckers in Upper Klamath Lake and adult suckers in Clear Lake Reservoir. Additional research is needed to measure predator-specific PIT tag deposition probabilities (which, based on other published studies, could increase predation rates presented herein by a factor of roughly 2

The scale-dependent impact of wolf predation risk on resource selection by three sympatric ungulates.

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Kittle, Andrew M; Fryxell, John M; Desy, Glenn E; Hamr, Joe

2008-08-01

Resource selection is a fundamental ecological process impacting population dynamics and ecosystem structure. Understanding which factors drive selection is vital for effective species- and landscape-level management. We used resource selection probability functions (RSPFs) to study the influence of two forms of wolf (Canis lupus) predation risk, snow conditions and habitat variables on white-tailed deer (Odocoileus virginianus), elk (Cervus elaphus) and moose (Alces alces) resource selection in central Ontario's mixed forest French River-Burwash ecosystem. Direct predation risk was defined as the frequency of a predator's occurrence across the landscape and indirect predation risk as landscape features associated with a higher risk of predation. Models were developed for two winters, each at two spatial scales, using a combination of GIS-derived and ground-measured data. Ungulate presence was determined from snow track transects in 64 16- and 128 1-km(2) resource units, and direct predation risk from GPS radio collar locations of four adjacent wolf packs. Ungulates did not select resources based on the avoidance of areas of direct predation risk at any scale, and instead exhibited selection patterns that tradeoff predation risk minimization with forage and/or mobility requirements. Elk did not avoid indirect predation risk, while both deer and moose exhibited inconsistent responses to this risk. Direct predation risk was more important to models than indirect predation risk but overall, abiotic topographical factors were most influential. These results indicate that wolf predation risk does not limit ungulate habitat use at the scales investigated and that responses to spatial sources of predation risk are complex, incorporating a variety of anti-predator behaviours. Moose resource selection was influenced less by snow conditions than cover type, particularly selection for dense forest, whereas deer showed the opposite pattern. Temporal and spatial scale

Information Dynamics in the Interaction between a Prey and a Predator Fish

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Feng Hu

2015-10-01

Full Text Available Accessing information efficiently is vital for animals to make the optimal decisions, and it is particularly important when they are facing predators. Yet until now, very few quantitative conclusions have been drawn about the information dynamics in the interaction between animals due to the lack of appropriate theoretic measures. Here, we employ transfer entropy (TE, a new information-theoretic and model-free measure, to explore the information dynamics in the interaction between a predator and a prey fish. We conduct experiments in which a predator and a prey fish are confined in separate parts of an arena, but can communicate with each other visually and tactilely. TE is calculated on the pair’s coarse-grained state of the trajectories. We find that the prey’s TE is generally significantly bigger than the predator’s during trials, which indicates that the dominant information is transmitted from predator to prey. We then demonstrate that the direction of information flow is irrelevant to the parameters used in the coarse-grained procedures. We further calculate the prey’s TE at different distances between it and the predator. The resulted figure shows that there is a high plateau in the mid-range of the distance and that drops quickly at both the near and the far ends. This result reflects that there is a sensitive space zone where the prey is highly vigilant of the predator’s position.

Effects of habitat features on size-biased predation on salmon by bears.

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Andersson, Luke C; Reynolds, John D

2017-05-01

Predators can drive trait divergence among populations of prey by imposing differential selection on prey traits. Habitat characteristics can mediate predator selectivity by providing refuge for prey. We quantified the effects of stream characteristics on biases in the sizes of spawning salmon caught by bears (Ursus arctos and U. americanus) on the central coast of British Columbia, Canada by measuring size-biased predation on spawning chum (Oncorhynchus keta) and pink (O. gorbuscha) salmon in 12 streams with varying habitat characteristics. We tested the hypotheses that bears would catch larger than average salmon (size-biased predation) and that this bias toward larger fish would be higher in streams that provide less protection to spawning salmon from predation (e.g., less pools, wood, undercut banks). We then we tested for how such size biases in turn translate into differences among populations in the sizes of the fish. Bears caught larger-than-average salmon as the spawning season progressed and as predicted, this was most pronounced in streams with fewer refugia for the fish (i.e., wood and undercut banks). Salmon were marginally smaller in streams with more pronounced size-biased predation but this predictor was less reliable than physical characteristics of streams, with larger fish in wider, deeper streams. These results support the hypothesis that selective forces imposed by predators can be mediated by habitat characteristics, with potential consequences for physical traits of prey.

Multivariate Analysis for the Choice and Evasion of the Student in a Higher Educational Institution from Southern of Santa Catarina, in Brazil

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Queiroz, Fernanda Cristina Barbosa Pereira; Samohyl, Robert Wayne; Queiroz, Jamerson Viegas; Lima, Nilton Cesar; de Souza, Gustavo Henrique Silva

2014-01-01

This paper aims to develop and implement a method to identify the causes of the choice of a course and the reasons for evasion in higher education. This way, we sought to identify the factors that influence student choice to opt for Higher Education Institution parsed, as well as the factors influencing its evasion. The methodology employed was…

More than just immune evasion: Hijacking complement by Plasmodium falciparum.

Science.gov (United States)

Schmidt, Christoph Q; Kennedy, Alexander T; Tham, Wai-Hong

2015-09-01

Malaria remains one of the world's deadliest diseases. Plasmodium falciparum is responsible for the most severe and lethal form of human malaria. P. falciparum's life cycle involves two obligate hosts: human and mosquito. From initial entry into these hosts, malaria parasites face the onslaught of the first line of host defence, the complement system. In this review, we discuss the complex interaction between complement and malaria infection in terms of hosts immune responses, parasite survival and pathogenesis of severe forms of malaria. We will focus on the role of complement receptor 1 and its associated polymorphisms in malaria immune complex clearance, as a mediator of parasite rosetting and as an entry receptor for P. falciparum invasion. Complement evasion strategies of P. falciparum parasites will also be highlighted. The sexual forms of the malaria parasites recruit the soluble human complement regulator Factor H to evade complement-mediated killing within the mosquito host. A novel evasion strategy is the deployment of parasite organelles to divert complement attack from infective blood stage parasites. Finally we outline the future challenge to understand the implications of these exploitation mechanisms in the interplay between successful infection of the host and pathogenesis observed in severe malaria. Copyright © 2015 Elsevier Ltd. All rights reserved.

Predation on exotic zebra mussels by native fishes: Effects on predator and prey

Science.gov (United States)

Magoulick, D.D.; Lewis, L.C.

2002-01-01

1. Exotic zebra mussels, Dreissena polymorpha, occur in southern U.S. waterways in high densities, but little is known about the interaction between native fish predators and zebra mussels. Previous studies have suggested that exotic zebra mussels are low profitability prey items and native vertebrate predators are unlikely to reduce zebra mussel densities. We tested these hypotheses by observing prey use of fishes, determining energy content of primary prey species of fishes, and conducting predator exclusion experiments in Lake Dardanelle, Arkansas. 2. Zebra mussels were the primary prey eaten by 52.9% of blue catfish, Ictalurus furcatus; 48.2% of freshwater drum, Aplodinotus grunniens; and 100% of adult redear sunfish, Lepomis microlophus. Blue catfish showed distinct seasonal prey shifts, feeding on zebra mussels in summer and shad, Dorosoma spp., during winter. Energy content (joules g-1) of blue catfish prey (threadfin shad, Dorosoma petenense; gizzard shad, D. cepedianum; zebra mussels; and asiatic clams, Corbicula fluminea) showed a significant species by season interaction, but shad were always significantly greater in energy content than bivalves examined as either ash-free dry mass or whole organism dry mass. Fish predators significantly reduced densities of large zebra mussels (>5 mm length) colonising clay tiles in the summers of 1997 and 1998, but predation effects on small zebra mussels (???5 mm length) were less clear. 3. Freshwater drum and redear sunfish process bivalve prey by crushing shells and obtain low amounts of higher-energy food (only the flesh), whereas blue catfish lack a shell-crushing apparatus and ingest large amounts of low-energy food per unit time (bivalves with their shells). Blue catfish appeared to select the abundant zebra mussel over the more energetically rich shad during summer, then shifted to shad during winter when shad experienced temperature-dependent stress and mortality. Native fish predators can suppress adult zebra

Susceptibility of Select Agents to Predation by Predatory Bacteria

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Riccardo Russo

2015-12-01

Full Text Available Select Agents are microorganisms and toxins considered to be exploitable as biological weapons. Although infections by many Select Agents can be treated by conventional antibiotics, the risk of an emerging or engineered drug resistant strain is of great concern. One group of microorganisms that is showing potential to control drug resistant Gram-negative bacteria are the predatory bacteria from the genera Bdellovibrio spp. and Micavibrio spp. In this study, we have examined the ability of Bdellovibrio bacteriovorus (B. bacteriovorus strain 109J, HD100 and Micavibrio aeruginosavorus (M. aeruginosavorus ARL-13 to prey on a variety of Select Agents. Our findings demonstrate that B. bacteriovorus and M. aeruginosavorus are able to prey efficiently on Yersinia pestis and Burkholderia mallei. Modest predation was also measured in co-cultures of B. bacteriovorus and Francisella tularensis. However, neither of the predators showed predation when Burkholderia pseudomallei and Brucella melitensis were used as prey.

Transfer Pricing – Between Optimization and International Tax Evasion

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Valentin SAVA

2017-04-01

Full Text Available Each enterprise in the private sector aims to increase financial return, which is achieved by obtaining the higher net profit by increasing revenue and reducing expenditure. In this endeavor, compliance with tax obligations occupy a very important role because handling taxes may lead to an increase in revenue and / or a reduction of spending, and this action is called tax optimization. In the case of multinational companies, the main tool that can be used to lower the tax burden and increasing, sometimes in sizeable benefits in net, is the transfer prices or the prices they registered entities in the group transactions between them, along with another instrument with great impact, ie tax havens. Tax evasion, designating evading payment obligations of a company according to the national tax system, may be legal in the sense that tax optimization does not violate the rules, but exploiting loopholes that are in them. But when legal tax rules are violated, we deal with tax fraud, which will be subject to punitive measures by public authorities as it affects the whole population.

Biodiversity effects of the predation gauntlet

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Stier, Adrian C.; Stallings, Christopher D.; Samhouri, Jameal F.; Albins, Mark A.; Almany, Glenn R.

2017-06-01

The ubiquity of trophic downgrading has led to interest in the consequences of mesopredator release on prey communities and ecosystems. This issue is of particular concern for reef-fish communities, where predation is a key process driving ecological and evolutionary dynamics. Here, we synthesize existing experiments that have isolated the effects of mesopredators to quantify the role of predation in driving changes in the abundance and biodiversity of recently settled reef fishes. On average, predators reduced prey abundance through generalist foraging behavior, which, through a statistical sampling artifact, caused a reduction in alpha diversity and an increase in beta diversity. Thus, the synthesized experiments provide evidence that predation reduces overall abundance within prey communities, but—after accounting for sampling effects—does not cause disproportionate effects on biodiversity.

Do Predation Rates on Artificial Nests Accurately Reflect Predation Rates on Natural Bird Nests?

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David I. King; Richard M. DeGraaf; Curtice R. Griffin; Thomas J. Maier

1999-01-01

Artificial nests are widely used in avian field studies. However, it is unclear how well predation rates on artificial nests reflect predation rates on natural nests. Therefore, we compared survival rates of artificial nests (unused natural nests baited with House Sparrow eggs) with survival rates of active bird nests in the same habitat at the same sites. Survival...

The Surface-Exposed Protein SntA Contributes to Complement Evasion in Zoonotic Streptococcus suis.

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Deng, Simin; Xu, Tong; Fang, Qiong; Yu, Lei; Zhu, Jiaqi; Chen, Long; Liu, Jiahui; Zhou, Rui

2018-01-01

Streptococcus suis is an emerging zoonotic pathogen causing streptococcal toxic shock like syndrome (STSLS), meningitis, septicemia, and even sudden death in human and pigs. Serious septicemia indicates this bacterium can evade the host complement surveillance. In our previous study, a functionally unknown protein SntA of S. suis has been identified as a heme-binding protein, and contributes to virulence in pigs. SntA can interact with the host antioxidant protein AOP2 and consequently inhibit its antioxidant activity. In the present study, SntA is identified as a cell wall anchored protein that functions as an important player in S. suis complement evasion. The C3 deposition and membrane attack complex (MAC) formation on the surface of sntA -deleted mutant strain Δ sntA are demonstrated to be significantly higher than the parental strain SC-19 and the complementary strain CΔ sntA . The abilities of anti-phagocytosis, survival in blood, and in vivo colonization of Δ sntA are obviously reduced. SntA can interact with C1q and inhibit hemolytic activity via the classical pathway. Complement activation assays reveal that SntA can also directly activate classical and lectin pathways, resulting in complement consumption. These two complement evasion strategies may be crucial for the pathogenesis of this zoonotic pathogen. Concerning that SntA is a bifunctional 2',3'-cyclic nucleotide 2'-phosphodiesterase/3'-nucleotidase in many species of Gram-positive bacteria, these complement evasion strategies may have common biological significance.

A test of maternal programming of offspring stress response to predation risk in threespine sticklebacks.

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Mommer, Brett C; Bell, Alison M

2013-10-02

Non-genetic maternal effects are widespread across taxa and challenge our traditional understanding of inheritance. Maternal experience with predators, for example, can have lifelong consequences for offspring traits, including fitness. Previous work in threespine sticklebacks showed that females exposed to simulated predation risk produced eggs with higher cortisol content and offspring with altered anti-predator behavior. However, it is unknown whether this maternal effect is mediated via the offspring glucocorticoid stress response and if it is retained over the entire lifetime of offspring. Therefore, we tested the hypothesis that maternal exposure to simulated predation risk has long-lasting effects on the cortisol response to simulated predation risk in stickleback offspring. We measured circulating concentrations of cortisol before (baseline), 15 min after, and 60 min after exposure to a simulated predation risk. We compared adult offspring of predator-exposed mothers and control mothers in two different social environments (alone or in a group). Relative to baseline, offspring plasma cortisol was highest 15 min after exposure to simulated predation risk and decreased after 60 min. Offspring of predator-exposed mothers differed in the cortisol response to simulated predation risk compared to offspring of control mothers. In general, females had higher cortisol than males, and fish in a group had lower cortisol than fish that were by themselves. The buffering effect of the social environment did not differ between maternal treatments or between males and females. Altogether the results show that while a mother's experience with simulated predation risk might affect the physiological response of her adult offspring to a predator, sex and social isolation have much larger effects on the stress response to predation risk in sticklebacks. Copyright © 2013 Elsevier Inc. All rights reserved.

Rotorcraft pursuit-evasion in nap-of-the-earth flight

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Menon, P. K. A.; Cheng, V. H. L.; Kim, E.

1990-01-01

Two approaches for studying the pursuit-evasion problem between rotorcraft executing nap-of-the-earth flight are presented. The first of these employs a constant speed kinematic helicopter model, while the second approach uses a three degree of freedom point-mass model. The candidate solutions to the first differential game are generated by integrating the state-costate equations backward in time. The second problem employs feedback linearization to obtain guidance laws in nonlinear feedback form. Both approaches explicitly use the terrain profile data. Sample extremals are presented.

The sea-air exchange of mercury (Hg) in the marine boundary layer of the Augusta basin (southern Italy): concentrations and evasion flux.

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Bagnato, E; Sproveri, M; Barra, M; Bitetto, M; Bonsignore, M; Calabrese, S; Di Stefano, V; Oliveri, E; Parello, F; Mazzola, S

2013-11-01

The first attempt to systematically investigate the atmospheric mercury (Hg) in the MBL of the Augusta basin (SE Sicily, Italy) has been undertaken. In the past the basin was the receptor for Hg from an intense industrial activity which contaminated the bottom sediments of the Bay, making this area a potential source of pollution for the surrounding Mediterranean. Three oceanographic cruises have been thus performed in the basin during the winter and summer 2011/2012, where we estimated averaged Hgatm concentrations of about 1.5±0.4 (range 0.9-3.1) and 2.1±0.98 (range 1.1-3.1) ng m(-3) for the two seasons, respectively. These data are somewhat higher than the background Hg atm value measured over the land (range 1.1±0.3 ng m(-3)) at downtown Augusta, while are similar to those detected in other polluted regions elsewhere. Hg evasion fluxes estimated at the sea/air interface over the Bay range from 3.6±0.3 (unpolluted site) to 72±0.1 (polluted site of the basin) ng m(-2) h(-1). By extending these measurements to the entire area of the Augusta basin (~23.5 km(2)), we calculated a total sea-air Hg evasion flux of about 9.7±0.1 g d(-1) (~0.004 tyr(-1)), accounting for ~0.0002% of the global Hg oceanic evasion (2000 tyr(-1)). The new proposed data set offers a unique and original study on the potential outflow of Hg from the sea-air interface at the basin, and it represents an important step for a better comprehension of the processes occurring in the marine biogeochemical cycle of this element. Copyright © 2013 Elsevier Ltd. All rights reserved.

Birds as predators in tropical agroforestry systems.

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Van Bael, Sunshine A; Philpott, Stacy M; Greenberg, Russell; Bichier, Peter; Barber, Nicholas A; Mooney, Kailen A; Gruner, Daniel S

2008-04-01

Insectivorous birds reduce arthropod abundances and their damage to plants in some, but not all, studies where predation by birds has been assessed. The variation in bird effects may be due to characteristics such as plant productivity or quality, habitat complexity, and/or species diversity of predator and prey assemblages. Since agroforestry systems vary in such characteristics, these systems provide a good starting point for understanding when and where we can expect predation by birds to be important. We analyze data from bird exclosure studies in forests and agroforestry systems to ask whether birds consistently reduce their arthropod prey base and whether bird predation differs between forests and agroforestry systems. Further, we focus on agroforestry systems to ask whether the magnitude of bird predation (1) differs between canopy trees and understory plants, (2) differs when migratory birds are present or absent, and (3) correlates with bird abundance and diversity. We found that, across all studies, birds reduce all arthropods, herbivores, carnivores, and plant damage. We observed no difference in the magnitude of bird effects between agroforestry systems and forests despite simplified habitat structure and plant diversity in agroforests. Within agroforestry systems, bird reduction of arthropods was greater in the canopy than the crop layer. Top-down effects of bird predation were especially strong during censuses when migratory birds were present in agroforestry systems. Importantly, the diversity of the predator assemblage correlated with the magnitude of predator effects; where the diversity of birds, especially migratory birds, was greater, birds reduced arthropod densities to a greater extent. We outline potential mechanisms for relationships between bird predator, insect prey, and habitat characteristics, and we suggest future studies using tropical agroforests as a model system to further test these areas of ecological theory.

Two-prey one-predator model

International Nuclear Information System (INIS)

Elettreby, M.F.

2009-01-01

In this paper we propose a new multi-team prey-predator model, in which the prey teams help each other. We study its local stability. In the absence of predator, there is no help between the prey teams. So, we study the global stability and persistence of the model without help.

Invasive Egg Predators and Food Availability Interactively Affect Maternal Investment in Egg Chemical Defense

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Sarah C. Paul

2018-01-01

Full Text Available Invasive species commonly predate the offspring of native species and eggs are the life stage most vulnerable to this predation. In many species with no maternal care, females can alter the phenotype of eggs to protect them, for instance through chemical defense. In ladybirds egg alkaloids deter predators, including invasive predatory species of ladybirds, but conversely may attract cannibals who benefit from the consumption of eggs with higher alkaloid levels. Invasive predators tend to be more abundant where resources are also abundant, but in high resource environments the maternal fitness benefits of sibling cannibalism are low. Consequently this presents a conflict for female ladybirds between the different factors that influence egg alkaloid level, as protecting her eggs from predators might come with the cost of inadvertently encouraging within-clutch cannibalism under circumstances where it is not beneficial. We investigated how the ladybird Adalia bipunctata addresses this trade-off experimentally, by measuring the quantity of alkaloids in eggs laid by ladybirds in environments that differed in levels of resource availability and perceived predation risk from an invasive predator Harmonia axyridis. Females did lay eggs with higher egg alkaloid levels under poor resource conditions, but only when predator cues were absent. The resulting negative correlation between egg number and egg alkaloid level under poor resource conditions indicates a trade-off between these two attributes of maternal investment, mediated by female response to offspring predation risk. This implies that selection pressures on mothers to adaptively adjust the risk of siblicide may outweigh the need to protect offspring from interspecific predation. Our results demonstrate that maternal effects are an important aspect of species' responses to invasive predators, and highlight the value of studying maternal effects in the context of the multifaceted environments in

Plant species composition alters the sign and strength of an emergent multi-predator effect by modifying predator foraging behaviour.

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Andrew Wilby

Full Text Available The prediction of pest-control functioning by multi-predator communities is hindered by the non-additive nature of species functioning. Such non-additivity, commonly termed an emergent multi-predator effect, is known to be affected by elements of the ecological context, such as the structure and composition of vegetation, in addition to the traits of the predators themselves. Here we report mesocosm experiments designed to test the influence of plant density and species composition (wheat monoculture or wheat and faba bean polyculture on the emergence of multi-predator effects between Adalia bipunctata and Chrysoperla carnea, in their suppression of populations of the aphid Metopolophium dirhodum. The mesocosm experiments were followed by a series of behavioural observations designed to identify how interactions among predators are modified by plant species composition and whether these effects are consistent with the observed influence of plant species composition on aphid population suppression. Although plant density was shown to have no influence on the multi-predator effect on aphid population growth, plant composition had a marked effect. In wheat monoculture, Adalia and Chrysoperla mixed treatments caused greater suppression of M. dirhodum populations than expected. However this positive emergent effect was reversed to a negative multi-predator effect in wheat and faba bean polyculture. The behavioural observations revealed that although dominant individuals did not respond to the presence of faba bean plants, the behaviour of sub-dominants was affected markedly, consistent with their foraging for extra-floral nectar produced by the faba bean. This interaction between plant composition and predator community composition on the foraging behaviour of sub-dominants is thought to underlie the observed effect of plant composition on the multi-predator effect. Thus, the emergence of multi-predator effects is shown to be strongly influenced by

High refuge availability on coral reefs increases the vulnerability of reef-associated predators to overexploitation.

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Rogers, Alice; Blanchard, Julia L; Newman, Steven P; Dryden, Charlie S; Mumby, Peter J

2018-02-01

Refuge availability and fishing alter predator-prey interactions on coral reefs, but our understanding of how they interact to drive food web dynamics, community structure and vulnerability of different trophic groups is unclear. Here, we apply a size-based ecosystem model of coral reefs, parameterized with empirical measures of structural complexity, to predict fish biomass, productivity and community structure in reef ecosystems under a broad range of refuge availability and fishing regimes. In unfished ecosystems, the expected positive correlation between reef structural complexity and biomass emerges, but a non-linear effect of predation refuges is observed for the productivity of predatory fish. Reefs with intermediate complexity have the highest predator productivity, but when refuge availability is high and prey are less available, predator growth rates decrease, with significant implications for fisheries. Specifically, as fishing intensity increases, predators in habitats with high refuge availability exhibit vulnerability to over-exploitation, resulting in communities dominated by herbivores. Our study reveals mechanisms for threshold dynamics in predators living in complex habitats and elucidates how predators can be food-limited when most of their prey are able to hide. We also highlight the importance of nutrient recycling via the detrital pathway, to support high predator biomasses on coral reefs. © 2018 by the Ecological Society of America.

[Regulatory Mechanisms of PD-L1 Expression and Its Role in Immune Evasion].

Science.gov (United States)

Kataoka, Keisuke

2017-11-01

Immune checkpoint blockade therapy using anti-PD-1 or anti-PD-L1 antibodies can unleash anti-tumor immunity and induce durable remission in a variety ofhuman cancers. However, the regulatory mechanisms of PD-L1 expression mediating immune evasion ofcancer cells have not been fully elucidated, including the genetic alterations causing PD-L1 overexpression. Recently, we have reported a novel genetic mechanism ofimmune evasion associated with structural variations(SVs)disrupting the 3'-untranslated region(UTR)ofthe PD-L1 gene in various malignancies, such as aggressive lymphomas and gastrointestinal cancers. Despite a heterogenous nature ofthese SVs, they are closely associated with a marked upregulation of PD-L1 expression, which augments tumor growth and escape from anti-tumor immunity. Here we present an overview of the regulatory mechanisms of PD-L1 expression in cancer cells, highlighting the genetic mechanisms of PD-L1 constitutive activation, with specific focus on PD-L1 3'-UTR disruption.

An Analysis of Predator Selection to Affect Aposematic Coloration in a Poison Frog Species.

Science.gov (United States)

Dreher, Corinna E; Cummings, Molly E; Pröhl, Heike

2015-01-01

Natural selection is widely noted to drive divergence of phenotypic traits. Predation pressure can facilitate morphological divergence, for example the evolution of both cryptic and conspicuous coloration in animals. In this context Dendrobatid frogs have been used to study evolutionary forces inducing diversity in protective coloration. The polytypic strawberry poison frog (Oophaga pumilio) shows strong divergence in aposematic coloration among populations. To investigate whether predation pressure is important for color divergence among populations of O. pumilio we selected four mainland populations and two island populations from Costa Rica and Panama. Spectrometric measurements of body coloration were used to calculate color and brightness contrasts of frogs as an indicator of conspicuousness for the visual systems of several potential predators (avian, crab and snake) and a conspecific observer. Additionally, we conducted experiments using clay model frogs of different coloration to investigate whether the local coloration of frogs is better protected than non-local color morphs, and if predator communities vary among populations. Overall predation risk differed strongly among populations and interestingly was higher on the two island populations. Imprints on clay models indicated that birds are the main predators while attacks of other predators were rare. Furthermore, clay models of local coloration were equally likely to be attacked as those of non-local coloration. Overall conspicuousness (and brightness contrast) of local frogs was positively correlated with attack rates by birds across populations. Together with results from earlier studies we conclude that conspicuousness honestly indicates toxicity to avian predators. The different coloration patterns among populations of strawberry poison frogs in combination with behavior and toxicity might integrate into equally efficient anti-predator strategies depending on local predation and other ecological

The modeling of predator-prey interactions

OpenAIRE

Muhammad Shakil; H. A. Wahab; Muhammad Naeem, et al.

2015-01-01

In this paper, we aim to study the interactions between the territorial animals like foxes and the rabbits. The territories for the foxes are considered to be the simple cells. The interactions between predator and its prey are represented by the chemical reactions which obey the mass action law. In this sense, we apply the mass action law for predator prey models and the quasi chemical approach is applied for the interactions between the predator and its prey to develop the modeled equations...

Which Is More Efficient in Fighting Tax Evasion: The Carrot or the Stick? A Cross-Country Comparison around the World

OpenAIRE

Bãtrâncea Larissa-Magareta; Bãtrâncea Ioan; Nichita Ramona-Anca

2012-01-01

Regardless of the economic development status, type of government or citizens’ trust level in tax authorities, tax evasion is a ubiquitous phenomenon across societies and a proof that people tend to display the same behavior all around the world. As tax evasion hinders economic growth and affects the provision of high quality public goods, tax authorities try to mitigate taxpayers’ tendency of dodging taxes by implementing either deterrence-based or reward-based strategies. The present paper ...

Immune evasion mechanisms of Entamoeba histolytica: progression to disease

Directory of Open Access Journals (Sweden)

Sharmin eBegum

2015-12-01

Full Text Available Entamoeba histolytica (Eh is a protozoan parasite that infects 10% of the world’s population and results in 100,000 deaths/year from amebic dysentery and/or liver abscess. In most cases, this extracellular parasite colonizes the colon by high affinity binding to MUC2 mucin without disease symptoms, whereas in some cases, Eh triggers an aggressive inflammatory response upon invasion of the colonic mucosa. The specific host-parasite factors critical for disease pathogenesis are still not well characterized. From the parasite, the signature events that lead to disease progression are cysteine protease cleavage of the C-terminus of MUC2 that dissolves the mucus layer followed by Eh binding and cytotoxicity of the mucosal epithelium. The host mounts an ineffective excessive host pro-inflammatory response following contact with host cells that causes tissue damage and participates in disease pathogenesis as Eh escapes host immune clearance by mechanisms that are not completely understood. Ameba can modulate or destroy effector immune cells by inducing neutrophil apoptosis and suppressing respiratory burst or nitric oxide (NO production from macrophages. Eh adherence to the host cells also induce multiple cytotoxic effects that can promote cell death through phagocytosis, apoptosis or by trogocytosis (ingestion of living cells that might play critical roles in immune evasion. This review focuses on the immune evasion mechanisms that Eh uses to survive and induce disease manifestation in the host.

Conserved hypothetical protein Rv1977 in Mycobacterium tuberculosis strains contains sequence polymorphisms and might be involved in ongoing immune evasion.

Science.gov (United States)

Jiang, Yi; Liu, Haican; Wang, Xuezhi; Li, Guilian; Qiu, Yan; Dou, Xiangfeng; Wan, Kanglin

2015-01-01

Host immune pressure and associated parasite immune evasion are key features of host-pathogen co-evolution. A previous study showed that human T cell epitopes of Mycobacterium tuberculosis are evolutionarily hyperconserved and thus it was deduced that M. tuberculosis lacks antigenic variation and immune evasion. Here, we selected 151 clinical Mycobacterium tuberculosis isolates from China, amplified gene encoding Rv1977 and compared the sequences. The results showed that Rv1977, a conserved hypothetical protein, is not conserved in M. tuberculosis strains and there are polymorphisms existed in the protein. Some mutations, especially one frameshift mutation, occurred in the antigen Rv1977, which is uncommon in M.tb strains and may lead to the protein function altering. Mutations and deletion in the gene all affect one of three T cell epitopes and the changed T cell epitope contained more than one variable position, which may suggest ongoing immune evasion.

Lymphoma: Immune Evasion Strategies

International Nuclear Information System (INIS)

Upadhyay, Ranjan; Hammerich, Linda; Peng, Paul; Brown, Brian; Merad, Miriam; Brody, Joshua D.

2015-01-01

While the cellular origin of lymphoma is often characterized by chromosomal translocations and other genetic aberrations, its growth and development into a malignant neoplasm is highly dependent upon its ability to escape natural host defenses. Neoplastic cells interact with a variety of non-malignant cells in the tumor milieu to create an immunosuppressive microenvironment. The resulting functional impairment and dysregulation of tumor-associated immune cells not only allows for passive growth of the malignancy but may even provide active growth signals upon which the tumor subsequently becomes dependent. In the past decade, the success of immune checkpoint blockade and adoptive cell transfer for relapsed or refractory lymphomas has validated immunotherapy as a possible treatment cornerstone. Here, we review the mechanisms by which lymphomas have been found to evade and even reprogram the immune system, including alterations in surface molecules, recruitment of immunosuppressive subpopulations, and secretion of anti-inflammatory factors. A fundamental understanding of the immune evasion strategies utilized by lymphomas may lead to better prognostic markers and guide the development of targeted interventions that are both safer and more effective than current standards of care

Lymphoma: Immune Evasion Strategies

Energy Technology Data Exchange (ETDEWEB)

Upadhyay, Ranjan; Hammerich, Linda; Peng, Paul [Division of Hematology and Medical Oncology, Icahn School of Medicine at Mount Sinai, New York, NY 10029 (United States); Brown, Brian [Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029 (United States); Merad, Miriam [Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029 (United States); Brody, Joshua D., E-mail: joshua.brody@mssm.edu [Division of Hematology and Medical Oncology, Icahn School of Medicine at Mount Sinai, New York, NY 10029 (United States)

2015-04-30

While the cellular origin of lymphoma is often characterized by chromosomal translocations and other genetic aberrations, its growth and development into a malignant neoplasm is highly dependent upon its ability to escape natural host defenses. Neoplastic cells interact with a variety of non-malignant cells in the tumor milieu to create an immunosuppressive microenvironment. The resulting functional impairment and dysregulation of tumor-associated immune cells not only allows for passive growth of the malignancy but may even provide active growth signals upon which the tumor subsequently becomes dependent. In the past decade, the success of immune checkpoint blockade and adoptive cell transfer for relapsed or refractory lymphomas has validated immunotherapy as a possible treatment cornerstone. Here, we review the mechanisms by which lymphomas have been found to evade and even reprogram the immune system, including alterations in surface molecules, recruitment of immunosuppressive subpopulations, and secretion of anti-inflammatory factors. A fundamental understanding of the immune evasion strategies utilized by lymphomas may lead to better prognostic markers and guide the development of targeted interventions that are both safer and more effective than current standards of care.

Interactive effects of prey refuge and additional food for predator in a diffusive predator-prey system

DEFF Research Database (Denmark)

Chakraborty, Subhendu; Tiwari, P. K.; Sasmal, S.K.

2017-01-01

a predator-prey system with prey refuge and additional food for predator apart from the focal prey in the presence of diffusion. Our main aim is to study the interactive effects of prey refuge and additional food on the system dynamics and especially on the controllability of prey (pest). Different types......Additional food for predators has been considered as one of the best established techniques in integrated pest management and biological conservation programs. In natural systems, there are several other factors, e.g., prey refuge, affect the success of pest control. In this paper, we analyze...... of Turing patterns such as stripes, spots, holes, and mixtures of them are obtained. It is found that the supply of additional food to the predator is unable to control the prey (pest) population when prey refuge is high. Moreover, when both prey refuge and additional food are low, spatial distribution...

COMPARATIVE ASPECTS OF TAX EVASION IN CONCEPTS AND PRACTICES

Directory of Open Access Journals (Sweden)

Georgeta Dragomir

2008-05-01

Full Text Available The paper analyze the forms of the tax evasion, în construct representation and comparativelaw, with exemplification on several European states and manifestations identified în international plain. Thereare elucidate the aspects of „tax evasion” and „tax avoidance”, through realities of contemporary world înprogress more and more the eludation actions are transferred from the interior of the national fiscal systems,beyond the state frontiers, being defined by the economic, politic and social globalization tendencies - and thesolutions have there changes în view.

ERAP1 overexpression in HPV-induced malignancies: A possible novel immune evasion mechanism.

Science.gov (United States)

Steinbach, Alina; Winter, Jan; Reuschenbach, Miriam; Blatnik, Renata; Klevenz, Alexandra; Bertrand, Miriam; Hoppe, Stephanie; von Knebel Doeberitz, Magnus; Grabowska, Agnieszka K; Riemer, Angelika B

2017-01-01

Immune evasion of tumors poses a major challenge for immunotherapy. For human papillomavirus (HPV)-induced malignancies, multiple immune evasion mechanisms have been described, including altered expression of antigen processing machinery (APM) components. These changes can directly influence epitope presentation and thus T-cell responses against tumor cells. To date, the APM had not been studied systematically in a large array of HPV + tumor samples. Therefore in this study, systematic expression analysis of the APM was performed on the mRNA and protein level in a comprehensive collection of HPV16 + cell lines. Subsequently, HPV + cervical tissue samples were examined by immunohistochemistry. ERAP1 (endoplasmic reticulum aminopeptidase 1) was the only APM component consistently altered - namely overexpressed - in HPV16 + tumor cell lines. ERAP1 was also found to be overexpressed in cervical intraepithelial neoplasia and cervical cancer samples; expression levels were increasing with disease stage. On the functional level, the influence of ERAP1 expression levels on HPV16 E7-derived epitope presentation was investigated by mass spectrometry and in cytotoxicity assays with HPV16-specific T-cell lines. ERAP1 overexpression did not cause a complete destruction of any of the HPV epitopes analyzed, however, an influence of ERAP1 overexpression on the presentation levels of certain HPV epitopes could be demonstrated by HPV16-specific CD8 + T-cells. These showed enhanced killing toward HPV16 + CaSki cells whose ERAP1 expression had been attenuated to normal levels. ERAP1 overexpression may thus represent a novel immune evasion mechanism in HPV-induced malignancies, in cases when presentation of clinically relevant epitopes is reduced by overactivity of this peptidase.

Relation of criminal offence of tax evasion and criminal offence of non-payment of withholding tax in Serbian criminal law

OpenAIRE

Kulić, Mirko; Milošević, Goran

2011-01-01

Countries often resort to tightening of criminal sanctions against those who do not fulfill their tax obligations on time. Instead of more organized undertaking of measures to eliminate the causes of tax crime, Serbia seeks to solve the problem by upgrading the criminal legislation. There are six criminal offences which provide for criminal law protection of public revenues. Among these criminal offences, the central place belongs to the criminal offence of tax evasion and criminal offence of...

Methane evasion and oxidation in the Big Cypress National Preserve—a low relief carbonate wetland

Science.gov (United States)

Ward, N. D.; Bianchi, T. S.; Cohen, M. J.; Martin, J. B.; Quintero, C.; Brown, A.; Osborne, T.; Sawakuchi, H. O.

2016-12-01

The Big Cypress National Preserve is a low relief carbonate wetland characterized by unique basin patterning known as "cypress domes." Here we examine the concentration and stable isotopic composition of methane in pore waters, surface waters, and bubbles from the sediment across horizontal gradients in four domes during three sampling campaigns. The proportion of methane oxidized in surface waters was estimated based on isotopic differences between surface water and pore waters/bubbles. Rates of methane evasion from surface waters, soils, and cypress knees to the atmosphere were also measured. Surface water CH4 concentrations ranged from 170 to 4,533 ppm with the highest levels generally being observed during wet periods. Pore water CH4 concentrations ranged from 748 to 75,213 ppm. The concentration of methane in bubbles ranged from 6.5 to 71%. The stable isotopic composition of CH4 ranged from -69.2 to -43.8‰ for all samples and was generally more enriched in surface waters compared to bubbles and porewaters, particularly in the two domes that were persistently inundated throughout the year. Based on these isotopic values, the average percentage of surface water CH4 that was oxidized was 37 ± 16% (maximum of 67%) and 19 ± 4% (maximum of 47%) in the two domes that are persistently inundated versus the two domes that are not inundated during the dry season, respectively. The average rate of CH4 evasion was 3.6 ± 1.6 mmol m-2 d-1 via diffusion, 7.6 ± 4.7 mmol m-2 d-1 via ebullition, 10.9 ± 11.4 mmol m-2 d-1­ from soil surfaces, and 34.3 ± 27.4 mmol m-2 d-1 from cypress knees. These results indicate that CH4 is produced in great quantities in inundated sediments, particularly in the center of the cypress domes. Diffusive fluxes from surface waters are suppressed by microbial oxidation in the water column, whereas ebullition from sediments and evasion through cypress knees, and likely other vascular vegetation, are the primary pathways for CH4 outgassing.

Inhibition between invasives: a newly introduced predator moderates the impacts of a previously established invasive predator.

Science.gov (United States)

Griffen, Blaine D; Guy, Travis; Buck, Julia C

2008-01-01

1. With continued globalization, species are being transported and introduced into novel habitats at an accelerating rate. Interactions between invasive species may provide important mechanisms that moderate their impacts on native species. 2. The European green crab Carcinus maenas is an aggressive predator that was introduced to the east coast of North America in the mid-1800 s and is capable of rapid consumption of bivalve prey. A newer invasive predator, the Asian shore crab Hemigrapsus sanguineus, was first discovered on the Atlantic coast in the 1980s, and now inhabits many of the same regions as C. maenas within the Gulf of Maine. Using a series of field and laboratory investigations, we examined the consequences of interactions between these predators. 3. Density patterns of these two species at different spatial scales are consistent with negative interactions. As a result of these interactions, C. maenas alters its diet to consume fewer mussels, its preferred prey, in the presence of H. sanguineus. Decreased mussel consumption in turn leads to lower growth rates for C. maenas, with potential detrimental effects on C. maenas populations. 4. Rather than an invasional meltdown, this study demonstrates that, within the Gulf of Maine, this new invasive predator can moderate the impacts of the older invasive predator.

Invasion and predation in aquatic ecosystems

Directory of Open Access Journals (Sweden)

Judith S. WEIS

2011-10-01

Full Text Available This article reviews biological invasions in which predation (or its absence plays a major role in the success of the invader. Examples are described in which the invader out-competes native species for the same food, and cases in which the invader consumes valued native species. In many instances, better predator avoidance by the invasive species or the absence of predators in the new habitat contributes to the success of the invaders; in other cases native or introduced predators appear to be able to keep the invasive species in check. A relatively new management approach in the US is the idea of adding another trophic level – to have humans act as the predators and consume the invasive species. This approach is being utilized in Florida and throughout the Caribbean against the lionfish, but could be extended to other fishes, as well as to various invasive crustaceans and mollusks. This idea is controversial, and current regulations prohibiting the possession of individuals of the invasive species (e.g., mitten crabs or snakefish would preclude the development of a fishery for them [Current Zoology 57 (5: 613–624, 2011].

Nest predation research: Recent findings and future perspectives

Science.gov (United States)

Chalfoun, Anna D.; Ibanez-Alamo, J. D.; Magrath, R. D.; Schmidt, Kenneth A.; Thomson, R. L.; Oteyza, Juan C.; Haff, T. M.; Martin, T.E.

2016-01-01

Nest predation is a key source of selection for birds that has attracted increasing attention from ornithologists. The inclusion of new concepts applicable to nest predation that stem from social information, eavesdropping or physiology has expanded our knowledge considerably. Recent methodological advancements now allow focus on all three players within nest predation interactions: adults, offspring and predators. Indeed, the study of nest predation now forms a vital part of avian research in several fields, including animal behaviour, population ecology, evolution and conservation biology. However, within nest predation research there are important aspects that require further development, such as the comparison between ecological and evolutionary antipredator responses, and the role of anthropogenic change. We hope this review of recent findings and the presentation of new research avenues will encourage researchers to study this important and interesting selective pressure, and ultimately will help us to better understand the biology of birds.

The effects of recruitment to direct predator cues on predator responses in meerkats

OpenAIRE

Zottl, M.; Lienert, R.; Clutton-Brock, T.; Millesi, E.; Manser, M B.

2017-01-01

Behavioral responses of animals to direct predator cues (DPCs; e.g., urine) are common and may improve their survival. We investigated wild meerkat (Suricata suricatta) responses to DPCs by taking an experimental approach. When meerkats encounter a DPC they often recruit group members by emitting a call type, which causes the group members to interrupt foraging and approach the caller. The aim of this study was to identify the qualities of olfactory predator cues, which affect the strength of...

New technique for quantification of elemental hg in mine wastes and its implications for mercury evasion into the atmosphere

Science.gov (United States)

Jew, A.D.; Kim, C.S.; Rytuba, J.J.; Gustin, M.S.; Brown, Gordon E.

2011-01-01

Mercury in the environment is of prime concern to both ecosystem and human health. Determination of the molecular-level speciation of Hg in soils and mine wastes is important for understanding its sequestration, mobility, and availability for methylation. Extended X-ray absorption fine structure (EXAFS) spectroscopy carried out under ambient P-T conditions has been used in a number of past studies to determine Hg speciation in complex mine wastes and associated soils. However, this approach cannot detect elemental (liquid) mercury in Hg-polluted soils and sediments due to the significant structural disorder of liquid Hg at ambient-temperature. A new sample preparation protocol involving slow cooling through the crystallization temperature of Hg(0) (234 K) results in its transformation to crystalline ??-Hg(0). The presence and proportion of Hg(0), relative to other crystalline Hg-bearing phases, in samples prepared in this way can be quantified by low-temperature (77 K) EXAFS spectroscopy. Using this approach, we have determined the relative concentrations of liquid Hg(0) in Hg mine wastes from several sites in the California Coast Range and have found that they correlate well with measured fluxes of gaseous Hg released during light and dark exposure of the same samples, with higher evasion ratios from samples containing higher concentrations of liquid Hg(0). Two different linear relationships are observed in plots of the ratio of Hg emission under light and dark conditions vs % Hg(0), corresponding to silica-carbonate- and hot springs-type Hg deposits, with the hot springs-type samples exhibiting higher evasion fluxes than silica-carbonate type samples at similar Hg(0) concentrations. Our findings help explain significant differences in Hg evasion data for different mine sites in the California Coast Range. ?? 2011 American Chemical Society.

Biomarkers of evasive resistance predict disease progression in cancer patients treated with antiangiogenic therapies

Science.gov (United States)

Pircher, Andreas; Jöhrer, Karin; Kocher, Florian; Steiner, Normann; Graziadei, Ivo; Heidegger, Isabel; Pichler, Renate; Leonhartsberger, Nicolai; Kremser, Christian; Kern, Johann; Untergasser, Gerold; Gunsilius, Eberhard; Hilbe, Wolfgang

2016-01-01

Numerous antiangiogenic agents are approved for the treatment of oncological diseases. However, almost all patients develop evasive resistance mechanisms against antiangiogenic therapies. Currently no predictive biomarker for therapy resistance or response has been established. Therefore, the aim of our study was to identify biomarkers predicting the development of therapy resistance in patients with hepatocellular cancer (n = 11), renal cell cancer (n = 7) and non-small cell lung cancer (n = 2). Thereby we measured levels of angiogenic growth factors, tumor perfusion, circulating endothelial cells (CEC), circulating endothelial progenitor cells (CEP) and tumor endothelial markers (TEM) in patients during the course of therapy with antiangiogenic agents, and correlated them with the time to antiangiogenic progression (aTTP). Importantly, at disease progression, we observed an increase of proangiogenic factors, upregulation of CEC/CEP levels and downregulation of TEMs, such as Robo4 and endothelial cell-specific chemotaxis regulator (ECSCR), reflecting the formation of torturous tumor vessels. Increased TEM expression levels tended to correlate with prolonged aTTP (ECSCR high = 275 days vs. ECSCR low = 92.5 days; p = 0.07 and for Robo4 high = 387 days vs. Robo4 low = 90.0 days; p = 0.08). This indicates that loss of vascular stabilization factors aggravates the development of antiangiogenic resistance. Thus, our observations confirm that CEP/CEC populations, proangiogenic cytokines and TEMs contribute to evasive resistance in antiangiogenic treated patients. Higher TEM expression during disease progression may have clinical and pathophysiological implications, however, validation of our results is warranted for further biomarker development. PMID:26956051

Colisional Cloud Debris and Propelled Evasive Maneuvers

Science.gov (United States)

Ferreira, L. S.; Jesus, A. D. C.; Carvalho, T. C. F.; Sousa, R. R.

2017-10-01

Space debris clouds exist at various altitudes in the environment outside the Earth. Fragmentation of debris and/or collision between the debris of a cloud increases the amount of debris, producing smaller debris. This event also increases significantly the chances of collision with operational vehicles in orbit. In this work we study clouds of debris that are close to a spacecraft in relation to its distance from the center of the Earth. The results show several layers of colliding debris depending on their size over time of evasive maneuvers of the vehicle. In addition, we have tested such maneuvers for propulsion systems with a linear and exponential mass variation model. The results show that the linear propulsion system is more efficient.

An Analysis of Predator Selection to Affect Aposematic Coloration in a Poison Frog Species.

Directory of Open Access Journals (Sweden)

Corinna E Dreher

Full Text Available Natural selection is widely noted to drive divergence of phenotypic traits. Predation pressure can facilitate morphological divergence, for example the evolution of both cryptic and conspicuous coloration in animals. In this context Dendrobatid frogs have been used to study evolutionary forces inducing diversity in protective coloration. The polytypic strawberry poison frog (Oophaga pumilio shows strong divergence in aposematic coloration among populations. To investigate whether predation pressure is important for color divergence among populations of O. pumilio we selected four mainland populations and two island populations from Costa Rica and Panama. Spectrometric measurements of body coloration were used to calculate color and brightness contrasts of frogs as an indicator of conspicuousness for the visual systems of several potential predators (avian, crab and snake and a conspecific observer. Additionally, we conducted experiments using clay model frogs of different coloration to investigate whether the local coloration of frogs is better protected than non-local color morphs, and if predator communities vary among populations. Overall predation risk differed strongly among populations and interestingly was higher on the two island populations. Imprints on clay models indicated that birds are the main predators while attacks of other predators were rare. Furthermore, clay models of local coloration were equally likely to be attacked as those of non-local coloration. Overall conspicuousness (and brightness contrast of local frogs was positively correlated with attack rates by birds across populations. Together with results from earlier studies we conclude that conspicuousness honestly indicates toxicity to avian predators. The different coloration patterns among populations of strawberry poison frogs in combination with behavior and toxicity might integrate into equally efficient anti-predator strategies depending on local predation and

Measurable Strategies in Differential Games

Science.gov (United States)

Ivanov, R. P.

1990-02-01

Nonlinear approach-evasion differential games are considered in which the initial data depend on the time. These games are investigated in the class of strategies that are functions of three variables, namely, the time, the phase variable, and the current value of the other player's control, and are measurable jointly with respect to the time and the phase variable. The ideas of the Pontryagin methods in differential games and Krasovskiĭ's ideas on extremal aiming are developed, and it is shown that measurable strategies have broad applicability. It is proved that measurable strategies are compatible with differential equations with discontinuous right-hand side, and general theorems on the existence of solving measurable strategies in approach-evasion problems are proved, along with some auxiliary assertions. It is shown that the saddle point condition in the small game ensures the existence of solving measurable strategies. An example is given. Bibliography: 14 titles.

Relative effects of exophytic predation, endophytic predation, and intraspecific competition on a subcortical herbivore: consequences to the reproduction of Ips pini and Thanasimus dubius.

Science.gov (United States)

Aukema, Brian H; Raffa, Kenneth F

2002-12-01

We used a laboratory assay to partition the effects of predation and intraspecific competition on the establishment, mating success, and brood development of an endophytic herbivore. We selected a system in which the same predator feeds both exophytically and endophytically on the same prey, to evaluate the role of herbivore feeding guild on predator numerical and functional responses. The bark beetle, Ips pini (Coleoptera: Scolytidae) reproduces within the stems of conifers. Males establish mating chambers under the bark, produce aggregation pheromones, and are subsequently joined by females that construct ovipositional galleries. Thanasimus dubius (Coleoptera: Cleridae) adults prey on adults alighting on the bark surface. T. dubius females then oviposit at the bark beetles' entrance sites, and their larvae prey on developing bark beetle larvae within the tree. We imposed a controlled 3×3 factorial design of prey and predator adult densities on red pine logs. Both predation and competition decreased I. pini reproduction. However, the per capita effect of predation was greater than competition, with one adult T. dubius reducing herbivore reproduction by an equivalent amount as four to five competing males and their harems. Increased densities of adult T. dubius on the plant surface reduced the number of prey captured per predator. Total predation on adults and larvae was similar. However, adult T. dubius on the plant surface ate approximately 18-35 times more I. pini per day than did their endophytic larvae. Within the plant, cannibalism among T. dubius, low herbivore densities, limited feeding times, and presumably the complex gallery architecture of I. pini reduced the number of predator progeny. The progeny of I. pini showed even sex ratios in the absence of predators, but were female biased when predators were present. We quantified a relatively narrow set of predator and prey densities that can generate replacement rates greater than one for this predator

Predator cannibalism can intensify negative impacts on heterospecific prey.

Science.gov (United States)

Takatsu, Kunio; Kishida, Osamu

2015-07-01

Although natural populations consist of individuals with different traits, and the degree of phenotypic variation varies among populations, the impact of phenotypic variation on ecological interactions has received little attention, because traditional approaches to community ecology assume homogeneity of individuals within a population. Stage structure, which is a common way of generating size and developmental variation within predator populations, can drive cannibalistic interactions, which can affect the strength of predatory effects on the predator's heterospecific prey. Studies have shown that predator cannibalism weakens predatory effects on heterospecific prey by reducing the size of the predator population and by inducing less feeding activity of noncannibal predators. We predict, however, that predator cannibalism, by promoting rapid growth of the cannibals, can also intensify predation pressure on heterospecific prey, because large predators have large resource requirements and may utilize a wider variety of prey species. To test this hypothesis, we conducted an experiment in which we created carnivorous salamander (Hynobius retardatus) populations with different stage structures by manipulating the salamander's hatch timing (i.e., populations with large or small variation in the timing of hatching), and explored the resultant impacts on the abundance, behavior, morphology, and life history of the salamander's large heterospecific prey, Rana pirica frog tadpoles. Cannibalism was rare in salamander populations having small hatch-timing variation, but was frequent in those having large hatch-timing variation. Thus, giant salamander cannibals occurred only in the latter. We clearly showed that salamander giants exerted strong predation pressure on frog tadpoles, which induced large behavioral and morphological defenses in the tadpoles and caused them to metamorphose late at large size. Hence, predator cannibalism arising from large variation in the timing

Predators are attracted to the olfactory signals of prey.

Directory of Open Access Journals (Sweden)

Nelika K Hughes

2010-09-01

Full Text Available Predator attraction to prey social signals can force prey to trade-off the social imperatives to communicate against the profound effect of predation on their future fitness. These tradeoffs underlie theories on the design and evolution of conspecific signalling systems and have received much attention in visual and acoustic signalling modes. Yet while most territorial mammals communicate using olfactory signals and olfactory hunting is widespread in predators, evidence for the attraction of predators to prey olfactory signals under field conditions is lacking.To redress this fundamental issue, we examined the attraction of free-roaming predators to discrete patches of scents collected from groups of two and six adult, male house mice, Mus domesticus, which primarily communicate through olfaction. Olfactorily-hunting predators were rapidly attracted to mouse scent signals, visiting mouse scented locations sooner, and in greater number, than control locations. There were no effects of signal concentration on predator attraction to their prey's signals.This implies that communication will be costly if conspecific receivers and eavesdropping predators are simultaneously attracted to a signal. Significantly, our results also suggest that receivers may be at greater risk of predation when communicating than signallers, as receivers must visit risky patches of scent to perform their half of the communication equation, while signallers need not.

Selective predation and prey class behaviour as possible ...

African Journals Online (AJOL)

To test these mechanisms, a study was conducted on Samara Private Game Reserve to investigate the potential impact cheetah (Acinonyx jubatus) predation has had on the kudu (Tragelaphus strepciseros) population. Kudu age and sex data were collected across both predator-present and predator-absent sections using ...

Responses of urban crows to con- and hetero-specic alarm calls in predator and non-predator zoo enclosures.

OpenAIRE

BÍLÁ, Kateřina

2017-01-01

I investigated if urban crows respond to con- and heterospecific alarm signals in predator and non-predator contexts in enclosures in the ZOO of Vienna. Crows responded strongly to the crow and also jackdaw alarms in both types of contexts, but also responded to the singing of great tit (control) in the predator context. This suggests that crows are aware of the danger the wolf and bear represent but are generally very cautious at the exotic Zoo animals.

Stabilization and complex dynamics in a predator-prey model with predator suffering from an infectious disease

NARCIS (Netherlands)

Kooi, B.W.; Voorn, van G.A.K.; Das, pada Krishna

2011-01-01

We study the effects of a non-specified infectious disease of the predator on the dynamics a predator–prey system, by evaluating the dynamics of a three-dimensional model. The predator population in this (PSI) model is split into a susceptible and an unrecoverable infected population, while all

Escaping peril: perceived predation risk affects migratory propensity

DEFF Research Database (Denmark)

Hulthén, Kaj; Chapman, Ben B.; Nilsson, P. Anders

2015-01-01

Although migratory plasticity is increasingly documented, the ecological drivers of plasticity are not well understood. Predation risk can influence migratory dynamics, but whether seasonal migrants can adjust their migratory behaviour according to perceived risk is unknown. We used electronic ta......) affected timing but not propensity showing that elevated risk carried over to alter migratory behaviour in the wild. Our key finding demonstrates predator-driven migratory plasticity, highlighting the powerful role of predation risk for migratory decision-making and dynamics.......Although migratory plasticity is increasingly documented, the ecological drivers of plasticity are not well understood. Predation risk can influence migratory dynamics, but whether seasonal migrants can adjust their migratory behaviour according to perceived risk is unknown. We used electronic tags...... in their lake summer habitat and monitored individual migration to connected streams over an entire season. Individuals exposed to increased perceived direct predation risk (i.e. a live predator) showed a higher migratory propensity but no change in migratory timing, while indirect risk (i.e. roach density...

Dynamics of riverine CO2 in the Yangtze River fluvial network and their implications for carbon evasion

Science.gov (United States)

Ran, Lishan; Lu, Xi Xi; Liu, Shaoda

2017-04-01

Understanding riverine carbon dynamics is critical for not only better estimates of various carbon fluxes but also evaluating their significance in the global carbon budget. As an important pathway of global land-ocean carbon exchange, the Yangtze River has received less attention regarding its vertical carbon evasion compared with lateral transport. Using long-term water chemistry data, we calculated CO2 partial pressure (pCO2) from pH and alkalinity and examined its spatial and temporal dynamics and the impacts of environmental settings. With alkalinity ranging from 415 to > 3400 µeq L-1, the river waters were supersaturated with dissolved CO2, generally 2-20-fold the atmospheric equilibrium (i.e., 390 µatm). Changes in pCO2 were collectively controlled by carbon inputs from terrestrial ecosystems, hydrological regime, and rock weathering. High pCO2 values were observed spatially in catchments with abundant carbonate presence and seasonally in the wet season when recently fixed organic matter was exported into the river network. In-stream processing of organic matter facilitated CO2 production and sustained the high pCO2, although the alkalinity presented an apparent dilution effect with water discharge. The decreasing pCO2 from the smallest headwater streams through tributaries to the mainstem channel illustrates the significance of direct terrestrial carbon inputs in controlling riverine CO2. With a basin-wide mean pCO2 of 2662 ± 1240 µatm, substantial CO2 evasion from the Yangtze River fluvial network is expected. Future research efforts are needed to quantify the amount of CO2 evasion and assess its biogeochemical implications for watershed-scale carbon cycle. In view of the Yangtze River's relative importance in global carbon export, its CO2 evasion would be significant for global carbon budget.

A meta-analysis of predation risk effects on pollinator behaviour.

Directory of Open Access Journals (Sweden)

Gustavo Q Romero

Full Text Available Flower-visiting animals are constantly under predation risk when foraging and hence might be expected to evolve behavioural adaptations to avoid predators. We reviewed the available published and unpublished data to assess the overall effects of predators on pollinator behaviour and to examine sources of variation in these effects. The results of our meta-analysis showed that predation risk significantly decreased flower visitation rates (by 36% and time spent on flowers (by 51% by pollinators. The strength of the predator effects depended neither on predator taxa and foraging mode (sit-and-wait or active hunters nor on pollinator lifestyle (social vs. solitary. However, predator effects differed among pollinator taxa: predator presence reduced flower visitation rates and time spent on flowers by Squamata, Lepidoptera and Hymenoptera, but not by Diptera. Furthermore, larger pollinators showed weaker responses to predation risk, probably because they are more difficult to capture. Presence of live crab spiders on flowers had weaker effects on pollinator behaviour than presence of dead or artificial crab spiders or other objects (e.g. dead bees, spheres, suggesting that predator crypsis may be effective to some extent. These results add to a growing consensus on the importance of considering both predator and pollinator characteristics from a community perspective.

A meta-analysis of predation risk effects on pollinator behaviour.

Science.gov (United States)

Romero, Gustavo Q; Antiqueira, Pablo A P; Koricheva, Julia

2011-01-01

Flower-visiting animals are constantly under predation risk when foraging and hence might be expected to evolve behavioural adaptations to avoid predators. We reviewed the available published and unpublished data to assess the overall effects of predators on pollinator behaviour and to examine sources of variation in these effects. The results of our meta-analysis showed that predation risk significantly decreased flower visitation rates (by 36%) and time spent on flowers (by 51%) by pollinators. The strength of the predator effects depended neither on predator taxa and foraging mode (sit-and-wait or active hunters) nor on pollinator lifestyle (social vs. solitary). However, predator effects differed among pollinator taxa: predator presence reduced flower visitation rates and time spent on flowers by Squamata, Lepidoptera and Hymenoptera, but not by Diptera. Furthermore, larger pollinators showed weaker responses to predation risk, probably because they are more difficult to capture. Presence of live crab spiders on flowers had weaker effects on pollinator behaviour than presence of dead or artificial crab spiders or other objects (e.g. dead bees, spheres), suggesting that predator crypsis may be effective to some extent. These results add to a growing consensus on the importance of considering both predator and pollinator characteristics from a community perspective.

Square and bow-tie configurations in the cyclic evasion problem

Science.gov (United States)

Arnold, M. D.; Golich, M.; Grim, A.; Vargas, L.; Zharnitsky, V.

2017-05-01

Cyclic evasion of four agents on the plane is considered. There are two stationary shapes of configurations: square and degenerate bow-tie. The bow-tie is asymptotically attracting while the square is of focus-center type. Normal form analysis shows that square is nonlinearly unstable. The stable manifold consists of parallelograms that all converge to the square configuration. Based on these observations and numerical simulations, it is conjectured that any non-parallelogram non-degenerate configuration converges to the bow-tie.

The impact of rural-urban gradient and spatial distribution on predation rates on sentinel prey in a riparian forest in Hungary

DEFF Research Database (Denmark)

Eötvös, Csaba Béla; Magura, Tibor; Lövei, Gabor L.

2015-01-01

is the predation pressure in this kind of habitat? (2) What are the differences in predation between rural, suburban and urban habitats? (3) What inter-prey distances are necessary for different predator groups that the dummy caterpillars would be independent? We found 17.76% overall predation rate, decreasing...... from rural to urban habitats (33.5%, 18.29% and 3.91%, respectively). Most of the ground level arthropod predation was related to carabids. We applied variogram analysis to acquire optimal placement distances. According to our results, in case all of the predators (except mammals), 5-10 m distances......Measuring predation rates under field conditions is rife with ecological and logistical difficulties. The use of artificial sentinel prey offers a simple and cheap possibility to comparable predation activity in various habitats by various predator groups. This method can replace the classical...

Predator removal and nesting waterbird success at San Francisco Bay, California

Science.gov (United States)

Meckstroth, A.M.; Miles, A.K.

2005-01-01

The efficacy of long-term predator removal in urbanized areas is poorly understood. The impact of predation on ground-nesting waterbirds, as well as predator abundance and composition in predator removal versus non-removal or reference sites were examined at South San Francisco Bay. The success of natural nests and predator activity was monitored using track plates, trip cameras, wire haircatchers and simulated nests. Removal sites had higher nest densities, but lower hatching success than reference sites. Predator composition and abundance were not different at the removal and reference sites for any predator other than feral Cat (Felis domesticus). Striped Skunk (Mephitis mephitis) comprised the majority (84%) of predators removed, yet remained the most abundant predators in removal and reference sites. Urban environments provide supplemental food that may influence skunks and other nest predators to immigrate into vacancies created by predator removal. Based on the findings from this study, predator removal should be applied intensively over a larger geographic area in order to be a viable management strategy for some mammalian species in urbanized areas.

Predator-induced phenotypic plasticity within- and across-generations: a challenge for theory?

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Walsh, Matthew R; Cooley, Frank; Biles, Kelsey; Munch, Stephan B

2015-01-07

Much work has shown that the environment can induce non-genetic changes in phenotype that span multiple generations. Theory predicts that predictable environmental variation selects for both increased within- and across-generation responses. Yet, to the best of our knowledge, there are no empirical tests of this prediction. We explored the relationship between within- versus across-generation plasticity by evaluating the influence of predator cues on the life-history traits of Daphnia ambigua. We measured the duration of predator-induced transgenerational effects, determined when transgenerational responses are induced, and quantified the cues that activate transgenerational plasticity. We show that predator exposure during embryonic development causes earlier maturation and increased reproductive output. Such effects are detectable two generations removed from predator exposure and are similar in magnitude in response to exposure to cues emitted by injured conspecifics. Moreover, all experimental contexts and traits yielded a negative correlation between within- versus across-generation responses. That is, responses to predator cues within- and across-generations were opposite in sign and magnitude. Although many models address transgenerational plasticity, none of them explain this apparent negative relationship between within- and across-generation plasticities. Our results highlight the need to refine the theory of transgenerational plasticity. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Developing a predation index and evaluating ways to reduce salmonid losses to predation in the Columbia River basin

International Nuclear Information System (INIS)

Nigro, A.A.

1990-12-01

We report our results of studies to develop a predation index and evaluate ways to reduce juvenile salmonid losses to predation in the Columbia River Basin. Study objectives of each were: develop an index to estimate predation losses of juvenile salmonids (Oncorhynchus spp) in reservoirs throughout the Columbia River Basin, describe the relationships among predator-caused mortality of juvenile salmonids and physical and biological variables, examine the feasibility of developing bounty, commercial or recreational fisheries on northern squawfish (Ptychocheilus oregonensis) and develop a plan to evaluate the efficacy of predator control fisheries; determine the economic feasibility of developing bounty and commercial fisheries for northern squawfish, assist ODFW with evaluating the economic feasibility of recreational fisheries for northern squawfish and assess the economic feasibility of utilizing northern squawfish, carp (Cyprinus carpio) and suckers (Castostomus spp) in multispecies fisheries; evaluate commercial technology of various fishing methods for harvesting northern squawfish in Columbia River reservoirs and field test the effectiveness of selected harvesting systems, holding facilities and transportation systems; and modify the existing Columbia River Ecosystem Model (CREM) to include processes necessary to evaluate effects of removing northern squawfish on their population size structure and abundance, document the ecological processes, mathematical equations and computer (FORTRAN) programming of the revised version of CREM and conduct systematic analyses of various predator removal scenarios, using revised CREM to generate the simulations. Individual reports are indexed separately

Landscape-moderated bird nest predation in hedges and forest edges

Science.gov (United States)

Ludwig, Martin; Schlinkert, Hella; Holzschuh, Andrea; Fischer, Christina; Scherber, Christoph; Trnka, Alfréd; Tscharntke, Teja; Batáry, Péter

2012-11-01

Landscape-scale agricultural intensification has caused severe declines in biodiversity. Hedges and forest remnants may mitigate biodiversity loss by enhancing landscape heterogeneity and providing habitat to a wide range of species, including birds. However, nest predation, the major cause of reproductive failure of birds, has been shown to be higher in forest edges than in forest interiors. Little is known about how spatial arrangement (configuration) of hedges affects the avian nest predation. We performed an experiment with artificial ground and elevated nests (resembling yellowhammer and whitethroat nests) baited with quail and plasticine eggs. Nests were placed in three habitat types with different degrees of isolation from forests: forest edges, hedges connected to forests and hedges isolated from forests. Nest predation was highest in forest edges, lowest in hedges connected to forests and intermediate in isolated hedges. In the early breeding season, we found similar nest predation on ground and elevated nests, but in the late breeding season nest predation was higher on ground nests than on elevated nests. Small mammals were the main predators of ground nests and appeared to be responsible for the increase in predation from early to late breeding season, whereas the elevated nests were mainly depredated by small birds and small mammals. High predation pressure at forest edges was probably caused by both forest and open-landscape predators. The influence of forest predators may be lower at hedges, leading to lower predation pressure than in forest edges. Higher predation pressure in isolated than connected hedges might be an effect of concentration of predators in these isolated habitats. We conclude that landscape configuration of hedges is important in nest predation, with connected hedges allowing higher survival than isolated hedges and forest edges.

Behavioural responses of two-spotted spider mites induced by predator-borne and prey-borne cues.

Science.gov (United States)

Gyuris, Enikő; Szép, Erna; Kontschán, Jenő; Hettyey, Attila; Tóth, Zoltán

2017-11-01

Applying predatory mites as biological control agents is a well established method against spider mites which are major pests worldwide. Although antipredator responses can influence the outcome of predator-prey interactions, we have limited information about what cues spider mites use to adjust their behavioural antipredator responses. We experimentally exposed two-spotted spider mites (Tetranychus urticae) to different predator-borne cues (using a specialist predator, Phytoseiulus persimilis, or a generalist predator, Amblyseius swirskii), conspecific prey-borne cues, or both, and measured locomotion and egg-laying activity. The reactions to predator species compared to each other manifested in reversed tendencies: spider mites increased their locomotion activity in the presence of P. persimilis, whereas they decreased it when exposed to A. swirskii. The strongest response was triggered by the presence of a killed conspecific: focal spider mites decreased their locomotion activity compared to the control group. Oviposition activity was not affected by either treatment. Our results point out that spider mites may change their behaviour in response to predators, and also to the presence of killed conspecifics, but these effects were not enhanced when both types of cues were present. The effect of social contacts among prey conspecifics on predator-induced behavioural defences is discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Herpesvirus microRNAs for use in gene therapy immune-evasion strategies.

Science.gov (United States)

Bots, S T F; Hoeben, R C

2017-07-01

Transplantation of allogeneic cells as well as of genetically corrected autologous cells are potent approaches to restore cellular functions in patients suffering from genetic diseases. The recipient's immune responses against non-self-antigens may compromise the survival of the grafted cells. Recipients of the graft may therefore require lifelong treatment with immunosuppressive drugs. An alternative approach to reduce graft rejection could involve the use of immune-evasion molecules. Expression of such molecules in cells of the graft may subvert recognition by the host's immune system. Viruses in particular are masters of exploitation and modulation of their hosts immune response. The Herpesviridae family provides a proof of concept for this as these viruses are capable to establish latency and a lifelong persistence in the infected hosts. While several viral proteins involved in immune evasion have been characterized, the Herpesviridae also encode a multitude of viral microRNA (miRNAs). Several of these miRNAs have been demonstrated to reduce the sensitivity of the infected cells to the destructive action of the host's immune cells. In this review, the miRNAs of some common herpesviruses that are associated with immune modulation will be discussed with a focus on their potential use in strategies aiming at generating non-immunogenic cells for transplantation.

Sublethal effects of catch-and-release fishing: measuring capture stress, fish impairment, and predation risk using a condition index

Science.gov (United States)

Campbell, Matthew D.; Patino, Reynaldo; Tolan, J.M.; Strauss, R.E.; Diamond, S.

2009-01-01

The sublethal effects of simulated capture of red snapper (Lutjanus campechanus) were analysed using physiological responses, condition indexing, and performance variables. Simulated catch-and-release fishing included combinations of depth of capture and thermocline exposure reflective of environmental conditions experienced in the Gulf of Mexico. Frequency of occurrence of barotrauma and lack of reflex response exhibited considerable individual variation. When combined into a single condition or impairment index, individual variation was reduced, and impairment showed significant increases as depth increased and with the addition of thermocline exposure. Performance variables, such as burst swimming speed (BSS) and simulated predator approach distance (AD), were also significantly different by depth. BSSs and predator ADs decreased with increasing depth, were lowest immediately after release, and were affected for up to 15 min, with longer recovery times required as depth increased. The impairment score developed was positively correlated with cortisol concentration and negatively correlated with both BSS and simulated predator AD. The impairment index proved to be an efficient method to estimate the overall impairment of red snapper in the laboratory simulations of capture and shows promise for use in field conditions, to estimate release mortality and vulnerability to predation.

Streptococcus pneumoniae PspC Subgroup Prevalence in Invasive Disease and Differences in Contribution to Complement Evasion.

Science.gov (United States)

van der Maten, Erika; van den Broek, Bryan; de Jonge, Marien I; Rensen, Kim J W; Eleveld, Marc J; Zomer, Aldert L; Cremers, Amelieke J H; Ferwerda, Gerben; de Groot, Ronald; Langereis, Jeroen D; van der Flier, Michiel

2018-04-01

The pneumococcal capsular serotype is an important determinant of complement resistance and invasive disease potential, but other virulence factors have also been found to contribute. Pneumococcal surface protein C (PspC), a highly variable virulence protein that binds complement factor H to evade C3 opsonization, is divided into two subgroups: choline-bound subgroup I and LPxTG-anchored subgroup II. The prevalence of different PspC subgroups in invasive pneumococcal disease (IPD) and functional differences in complement evasion are unknown. The prevalence of PspC subgroups in IPD isolates was determined in a collection of 349 sequenced strains of Streptococcus pneumoniae isolated from adult patients. pspC deletion mutants and isogenic pspC switch mutants were constructed to study differences in factor H binding and complement evasion in relation to capsule thickness. Subgroup I pspC was far more prevalent in IPD isolates than subgroup II pspC The presence of capsule was associated with a greater ability of bound factor H to reduce complement opsonization. Pneumococcal subgroup I PspC bound significantly more factor H and showed more effective complement evasion than subgroup II PspC in isogenic encapsulated pneumococci. We conclude that variation in the PspC subgroups, independent of capsule serotypes, affects pneumococcal factor H binding and its ability to evade complement deposition. Copyright © 2018 American Society for Microbiology.

Size-selective predation and predator-induced life-history shifts alter the outcome of competition between planktonic grazers

NARCIS (Netherlands)

Hülsmann, S.; Rinke, K.; Mooij, W.M.

2011-01-01

1.We studied the effect of size-selective predation on the outcome of competition between two differently sized prey species in a homogenous environment. 2. Using a physiologically structured population model, we calculated equilibrium food concentrations for a range of predation scenarios defined

Alcohol impairs predation risk response and communication in zebrafish.

Directory of Open Access Journals (Sweden)

Thiago Acosta Oliveira

Full Text Available The effects of ethanol exposure on Danio rerio have been studied from the perspectives of developmental biology and behavior. However, little is known about the effects of ethanol on the prey-predator relationship and chemical communication of predation risk. Here, we showed that visual contact with a predator triggers stress axis activation in zebrafish. We also observed a typical stress response in zebrafish receiving water from these conspecifics, indicating that these fish chemically communicate predation risk. Our work is the first to demonstrate how alcohol effects this prey-predator interaction. We showed for the first time that alcohol exposure completely blocks stress axis activation in both fish seeing the predator and in fish that come in indirect contact with a predator by receiving water from these conspecifics. Together with other research results and with the translational relevance of this fish species, our data points to zebrafish as a promising animal model to study human alcoholism.

Host evasion by Burkholderia cenocepacia

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Shyamala eGanesan

2012-01-01

Full Text Available Burkholderia cenocepacia is an opportunistic respiratory pathogen of individuals with cystic fibrosis (CF. It is one of the highly transmissible species of Burkholderia cepacia complex and very resistant to almost all the antibiotics. Approximately 1/3rd of B. cenocepacia infected CF patients go on to develop fatal ‘cepacia syndrome’. During the last two decades, substantial progress has been made with regards to evasion of host innate defense mechanisms by B. cenocepacia. Almost all strains of B. cenocepacia has capacity to survive and replicate intracellularly in both airway epithelial cells and macrophages, which are primary centennials of the lung and play a pivotal role in clearance of infecting bacteria. Some strains of B. cenocepaica, which express cable pili and the associated 22kDa adhesin are also capable of transmigrating across airway epithelium and persist in mouse models of infection. In this review, we will discuss how this type of interaction between B. cenocepacia and host may lead to persistence of bacteria and contribute to lung inflammation in CF patients.

Let's Tie the Knot: Marriage of Complement and Adaptive Immunity in Pathogen Evasion, for Better or Worse.

Science.gov (United States)

Bennett, Kaila M; Rooijakkers, Suzan H M; Gorham, Ronald D

2017-01-01

The complement system is typically regarded as an effector arm of innate immunity, leading to recognition and killing of microbial invaders in body fluids. Consequently, pathogens have engaged in an arms race, evolving molecules that can interfere with proper complement responses. However, complement is no longer viewed as an isolated system, and links with other immune mechanisms are continually being discovered. Complement forms an important bridge between innate and adaptive immunity. While its roles in innate immunity are well-documented, its function in adaptive immunity is less characterized. Therefore, it is no surprise that the field of pathogenic complement evasion has focused on blockade of innate effector functions, while potential inhibition of adaptive immune responses (via complement) has been overlooked to a certain extent. In this review, we highlight past and recent developments on the involvement of complement in the adaptive immune response. We discuss the mechanisms by which complement aids in lymphocyte stimulation and regulation, as well as in antigen presentation. In addition, we discuss microbial complement evasion strategies, and highlight specific examples in the context of adaptive immune responses. These emerging ties between complement and adaptive immunity provide a catalyst for future discovery in not only the field of adaptive immune evasion but in elucidating new roles of complement.

Evasion of CO{sub 2} injected into the ocean in the content of CO{sub 2} stabilization

Energy Technology Data Exchange (ETDEWEB)

Kheshgi, H.S. [ExxonMobil Research and Engineering Co., Annandale, NJ (United States)

2004-08-01

The eventual evasion of injected CO{sub 2} to the atmosphere is one consideration when assessing deep-sea disposal of CO{sub 2} as a potential response option to climate change concerns. Evasion estimated using an ocean carbon cycle model is compared to long-term trajectories for future CO{sub 2} emissions, including illustrative cases leading to stabilization of CO{sub 2} concentration at various levels. Modeled residence time for CO{sub 2} injected into the deep ocean exceeds the 100-year time-scale usually considered in scenarios for future emissions, and the potential impacts of climate change. Illustrative cases leading monotonically to constant CO{sub 2} concentration have been highlighted by the Intergovernmental Panel on Climate Change to give guidance on possible timing of emission reductions that may be required to stabilize greenhouse gas concentrations at various levels. For stabilization cases considered, significant modeled evasion does not occur until long after CO{sub 2} emissions have reached a maximum and begun to decline. Illustrative cases can also lead to a maximum in CO{sub 2} concentration followed by a decline to slowly decreasing concentrations. In such cases, future injection of emissions into the deep ocean leads to lower maximum CO{sub 2} concentration, with less effect on concentration later on in time. (author)

Evasion of CO{sub 2} injected into the ocean in the context of CO{sub 2} stabilization

Energy Technology Data Exchange (ETDEWEB)

Kheshgi, Haroon S

2004-08-01

The eventual evasion of injected CO{sub 2} to the atmosphere is one consideration when assessing deep-sea disposal of CO{sub 2} as a potential response option to climate change concerns. Evasion estimated using an ocean carbon cycle model is compared to long-term trajectories for future CO{sub 2} emissions, including illustrative cases leading to stabilization of CO{sub 2} concentration at various levels. Modeled residence time for CO{sub 2} injected into the deep ocean exceeds the 100-year time-scale usually considered in scenarios for future emissions, and the potential impacts of climate change. Illustrative cases leading monotonically to constant CO{sub 2} concentration have been highlighted by the Intergovernmental Panel on Climate Change to give guidance on possible timing of emission reductions that may be required to stabilize greenhouse gas concentrations at various levels. For stabilization cases considered, significant modeled evasion does not occur until long after CO{sub 2} emissions have reached a maximum and begun to decline. Illustrative cases can also lead to a maximum in CO{sub 2} concentration followed by a decline to slowly decreasing concentrations. In such cases, future injection of emissions into the deep ocean leads to lower maximum CO{sub 2} concentration, with less effect on concentration later on in time.

Space-time clusters for early detection of grizzly bear predation.

Science.gov (United States)

Kermish-Wells, Joseph; Massolo, Alessandro; Stenhouse, Gordon B; Larsen, Terrence A; Musiani, Marco

2018-01-01

Accurate detection and classification of predation events is important to determine predation and consumption rates by predators. However, obtaining this information for large predators is constrained by the speed at which carcasses disappear and the cost of field data collection. To accurately detect predation events, researchers have used GPS collar technology combined with targeted site visits. However, kill sites are often investigated well after the predation event due to limited data retrieval options on GPS collars (VHF or UHF downloading) and to ensure crew safety when working with large predators. This can lead to missing information from small-prey (including young ungulates) kill sites due to scavenging and general site deterioration (e.g., vegetation growth). We used a space-time permutation scan statistic (STPSS) clustering method (SaTScan) to detect predation events of grizzly bears ( Ursus arctos ) fitted with satellite transmitting GPS collars. We used generalized linear mixed models to verify predation events and the size of carcasses using spatiotemporal characteristics as predictors. STPSS uses a probability model to compare expected cluster size (space and time) with the observed size. We applied this method retrospectively to data from 2006 to 2007 to compare our method to random GPS site selection. In 2013-2014, we applied our detection method to visit sites one week after their occupation. Both datasets were collected in the same study area. Our approach detected 23 of 27 predation sites verified by visiting 464 random grizzly bear locations in 2006-2007, 187 of which were within space-time clusters and 277 outside. Predation site detection increased by 2.75 times (54 predation events of 335 visited clusters) using 2013-2014 data. Our GLMMs showed that cluster size and duration predicted predation events and carcass size with high sensitivity (0.72 and 0.94, respectively). Coupling GPS satellite technology with clusters using a program based

Cross-border reproductive care for law evasion: should physicians be allowed to help infertility patients evade the law of their own country?

Science.gov (United States)

Van Hoof, Wannes; Pennings, Guido; De Sutter, Petra

2016-07-01

There are fundamental differences between countries with regard to legislation on assisted reproduction. Many infertility patients are looking to evade the law of their own country and make use of reproductive services abroad. The role of the local physician in cross-border reproductive care for law evasion has been characterized as "channeling local patients to foreign medical establishments" and "against the spirit and essence of the law". The logical view is that by supporting CBRC for law evasion, physicians are essentially supporting immoral behavior. We will tackle this position on two levels. First, we will argue that governments should generally be tolerant toward people with different positions on assisted reproduction. Second, we will show that contributing to cross-border reproductive care for law evasion is not necessarily immoral, because the prima facie wrongness of complicity in law evasion can be outweighed by the fact that physicians should act in the best interest of the patient. Several countries have tried to prevent local physicians from helping patients to make use of reproductive services abroad, but they should rather leave it up to the individual physicians to decide whether or not to support a particular patient. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Mechanisms of virus immune evasion lead to development from chronic inflammation to cancer formation associated with human papillomavirus infection.

Science.gov (United States)

Senba, Masachika; Mori, Naoki

2012-10-02

Human papillomavirus (HPV) has developed strategies to escape eradication by innate and adaptive immunity. Immune response evasion has been considered an important aspect of HPV persistence, which is the main contributing factor leading to HPV-related cancers. HPV-induced cancers expressing viral oncogenes E6 and E7 are potentially recognized by the immune system. The major histocompatibility complex (MHC) class I molecules are patrolled by natural killer cells and CD8+ cytotoxic T lymphocytes, respectively. This system of recognition is a main target for the strategies of immune evasion deployed by viruses. The viral immune evasion proteins constitute useful tools to block defined stages of the MHC class I presentation pathway, and in this way HPV avoids the host immune response. The long latency period from initial infection to persistence signifies that HPV evolves mechanisms to escape the immune response. It has now been established that there are oncogenic mechanisms by which E7 binds to and degrades tumor suppressor Rb, while E6 binds to and inactivates tumor suppressor p53. Therefore, interaction of p53 and pRb proteins can give rise to an increased immortalization and genomic instability. Overexpression of NF-κB in cervical and penile cancers suggests that NF-κB activation is a key modulator in driving chronic inflammation to cancer. HPV oncogene-mediated suppression of NF-κB activity contributes to HPV escape from the immune system. This review focuses on the diverse mechanisms of the virus immune evasion with HPV that leads to chronic inflammation and cancer.

Edge, height and visibility effects on nest predation by birds and mammals in the Brazilian cerrado

Science.gov (United States)

Dodonov, Pavel; Paneczko, Ingrid Toledo; Telles, Marina

2017-08-01

Edge influence is one of the main impacts in fragmented landscapes; yet, most of studies on edge influence have focused on high-contrast edges, and the impacts of low-contrast edges and narrow linear openings are less understood. Edge influence often affects bird nest predation, but these effects are not ubiquitous and may depend on characteristics such as nest height and visibility. We performed an experiment on nest predation in a migratory passerine, Elaenia chiriquensis (Lesser Elaenia; Passeriformes: Tyrannidae), in a savanna vegetation of the Brazilian Cerrado biome in South-Eastern Brazil. We used 89 real E. chiriquensis nests, collected during previous reproductive seasons, with two plasticine eggs in each, and randomly distributed them at two locations (edge - up to 20 m from a firebreak edge and interior - approx. 150-350 m from the edge) and two heights (low - 60-175 cm and high - 190-315 cm above ground). We also measured leaf and branch density around each nest. We performed this study on two 15-days campaigns, checking the nests every 2-3 days and removing those with predation marks. We sorted the predation marks into those made by birds, mammals, or unidentified predators, and used generalized linear models to assess the effects of location, height and leaf density on survival time and predator type. Only four nests had not been predated during the experiment; 55 nests were predated by birds, 7 by mammals, and 23 by unidentified predators. Low nests in the interior tended to have larger survival times whereas high nests at the edge tended to be more predated by birds and less predated by mammals. Thus, even a low-contrast (firebreak) edge may significantly increase nest predation, which is also affected by the nest's height, mainly due to predation by birds. These effects may be due to predator movement along the edge as well as to edge-related changes in vegetation structure. We suggest that higher-contrast edges which may also be used as movement

A three-state kinetic agent-based model to analyze tax evasion dynamics

Science.gov (United States)

Crokidakis, Nuno

2014-11-01

In this work we study the problem of tax evasion on a fully-connected population. For this purpose, we consider that the agents may be in three different states, namely honest tax payers, tax evaders and undecided, that are individuals in an intermediate class among honests and evaders. Every individual can change his/her state following a kinetic exchange opinion dynamics, where the agents interact by pairs with competitive negative (with probability q) and positive (with probability 1-q) couplings, representing agreement/disagreement between pairs of agents. In addition, we consider the punishment rules of the Zaklan econophysics model, for which there is a probability pa of an audit each agent is subject to in every period and a length of time k detected tax evaders remain honest. Our results suggest that below the critical point qc=1/4 of the opinion dynamics the compliance is high, and the punishment rules have a small effect in the population. On the other hand, for q>qc the tax evasion can be considerably reduced by the enforcement mechanism. We also discuss the impact of the presence of the undecided agents in the evolution of the system.

Pursit-evasion game analysis in a line of sight coordinate system

Science.gov (United States)

Shinar, J.; Davidovitz, A.

1985-01-01

The paper proposes to use line of sight coordinates for the analysis of pursuit-evasion games. The advantage of this method for two-target games is shown to be evident. As a demonstrative example the game of two identical cars is formulated and solved in such coordinate systems. A new type of singular surface, overlooked in a previous study of the same problem, is discovered as a consequence of the simplicity of the solution.

Fish ladders: safe fish passage or hotspot for predation?

Directory of Open Access Journals (Sweden)

Angelo Antonio Agostinho

Full Text Available Fish ladders are a strategy for conserving biodiversity, as they can provide connectivity between fragmented habitats and reduce predation on shoals that accumulate immediately below dams. Although the impact of predation downstream of reservoirs has been investigated, especially in juvenile salmonids during their downstream movements, nothing is known about predation on Neotropical fish in the attraction and containment areas commonly found in translocation facilities. This study analysed predation in a fish passage system at the Lajeado Dam on the Tocantins River in Brazil. The abundance, distribution, and the permanence (time spent of large predatory fish along the ladder, the injuries imposed by piranhas during passage and the presence of other vertebrate predators were investigated. From December 2002 to October 2003, sampling was conducted in four regions (downstream, along the ladder, in the forebay, and upstream of the reservoir using gillnets, cast nets and counts or visual observations. The captured fish were tagged with thread and beads, and any mutilations were registered. Fish, birds and dolphins were the main predator groups observed, with a predominance of the first two groups. The entrance to the ladder, in the downstream region, was the area with the highest number of large predators and was the only region with relevant non-fish vertebrates. The main predatory fish species were Rhaphiodon vulpinus, Hydrolycus armatus, and Serrasalmus rhombeus. Tagged individuals were detected predating along the ladder for up to 90 days. Mutilations caused by Serrasalmus attacks were noted in 36% of species and 4% of individuals at the top of the ladder. Our results suggested that the high density of fish in the restricted ladder environment, which is associated with injuries suffered along the ladder course and the presence of multiple predator groups with different predation strategies, transformed the fish corridor into a hotspot for

Squidpops: A Simple Tool to Crowdsource a Global Map of Marine Predation Intensity.

Directory of Open Access Journals (Sweden)

J Emmett Duffy

Full Text Available We present a simple, standardized assay, the squidpop, for measuring the relative feeding intensity of generalist predators in aquatic systems. The assay consists of a 1.3-cm diameter disk of dried squid mantle tethered to a rod, which is either inserted in the sediment in soft-bottom habitats or secured to existing structure. Each replicate squidpop is scored as present or absent after 1 and 24 hours, and the data for analysis are proportions of replicate units consumed at each time. Tests in several habitats of the temperate southeastern USA (Virginia and North Carolina and tropical Central America (Belize confirmed the assay's utility for measuring variation in predation intensity among habitats, among seasons, and along environmental gradients. In Belize, predation intensity varied strongly among habitats, with reef > seagrass = mangrove > unvegetated bare sand. Quantitative visual surveys confirmed that assayed feeding intensity increased with abundance and species richness of fishes across sites, with fish abundance and richness explaining up to 45% and 70% of the variation in bait loss respectively. In the southeastern USA, predation intensity varied seasonally, being highest during summer and declining in late autumn. Deployments in marsh habitats generally revealed a decline in mean predation intensity from fully marine to tidal freshwater sites. The simplicity, economy, and standardization of the squidpop assay should facilitate engagement of scientists and citizens alike, with the goal of constructing high-resolution maps of how top-down control varies through space and time in aquatic ecosystems, and addressing a broad array of long-standing hypotheses in macro- and community ecology.

Local and landscape drivers of predation services in urban gardens.

Science.gov (United States)

Philpott, Stacy M; Bichier, Peter

2017-04-01

In agroecosystems, local and landscape features, as well as natural enemy abundance and richness, are significant predictors of predation services that may result in biological control of pests. Despite the increasing importance of urban gardening for provisioning of food to urban populations, most urban gardeners suffer from high pest problems, and have little knowledge about how to manage their plots to increase biological control services. We examined the influence of local, garden scale (i.e., herbaceous and arboreal vegetation abundance and diversity, ground cover) and landscape (i.e., landscape diversity and surrounding land use types) characteristics on predation services provided by naturally occurring predators in 19 urban gardens in the California central coast. We introduced sentinel pests (moth eggs and larvae and pea aphids) onto greenhouse-raised plants taken to gardens and assigned to open or bagged (predator exclosure) treatments. We found high predation rates with between 40% and 90% of prey items removed in open treatments. Predation services varied with local and landscape factors, but significant predictors differed by prey species. Predation of eggs and aphids increased with vegetation complexity in gardens, but larvae predation declined with vegetation complexity. Smaller gardens experienced higher predation services, likely due to increases in predator abundance in smaller gardens. Several ground cover features influenced predation services. In contrast to patterns in rural agricultural landscapes, predation on aphids declined with increases in landscape diversity. In sum, we report the relationships between several local management factors, as well as landscape surroundings, and implications for garden management. © 2017 by the Ecological Society of America.

Simulating effectiveness of helicopter evasive manoeuvres to RPG attack

Science.gov (United States)

Anderson, D.; Thomson, D. G.

2010-04-01

The survivability of helicopters under attack by ground troops using rocket propelled grenades has been amply illustrated over the past decade. Given that an RPG is unguided and it is infeasible to cover helicopters in thick armour, existing optical countermeasures are ineffective - the solution is to compute an evasive manoeuvre. In this paper, an RPG/helicopter engagement model is presented. Manoeuvre profiles are defined in the missile approach warning sensor camera image plane using a local maximum acceleration vector. Required control inputs are then computed using inverse simulation techniques. Assessments of platform survivability to several engagement scenarios are presented.

Fixed Duration Pursuit-Evasion Differential Game with Integral Constraints

International Nuclear Information System (INIS)

Ibragimov G I; Kuchkarov A Sh

2013-01-01

We investigate a pursuit-evasion differential game of countably many pursuers and one evader. Integral constraints are imposed on control functions of the players. Duration of the game is fixed and the payoff of the game is infimum of the distances between the evader and pursuers when the game is completed. Purpose of the pursuers is to minimize the payoff and that of the evader is to maximize it. Optimal strategies of the players are constructed, and the value of the game is found. It should be noted that energy resource of any pursuer may be less than that of the evader.

Pasta Predation.

Science.gov (United States)

Waugh, Michael L.

1986-01-01

Presents a predator-prey simulation which involves students in collecting data, solving problems, and making predictions on the evolution of prey populations. Provides directives on how to perform the chi-square test and also includes an Applesoft BASK program that performs the calculations. (ML)

Alien vs. predator: bacterial challenge alters coral microbiomes unless controlled by Halobacteriovorax predators

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Rory M. Welsh

2017-05-01

Full Text Available Coral microbiomes are known to play important roles in organismal health, response to environmental stress, and resistance to disease. The coral microbiome contains diverse assemblages of resident bacteria, ranging from defensive and metabolic symbionts to opportunistic bacteria that may turn harmful in compromised hosts. However, little is known about how these bacterial interactions influence the mechanism and controls of overall structure, stability, and function of the microbiome. We sought to test how coral microbiome dynamics were affected by interactions between two bacteria: Vibrio coralliilyticus, a known temperature-dependent pathogen of some corals, and Halobacteriovorax, a unique bacterial predator of Vibrio and other gram-negative bacteria. We challenged reef-building coral with V. coralliilyticus in the presence or absence of Halobacteriovorax predators, and monitored microbial community dynamics with 16S rRNA gene profiling time-series. Vibrio coralliilyticus inoculation increased the mean relative abundance of Vibrios by greater than 35% from the 4 to 8 hour time point, but not in the 24 & 32 hour time points. However, strong secondary effects of the Vibrio challenge were also observed for the rest of the microbiome such as increased richness (observed species, and reduced stability (increased beta-diversity. Moreover, after the transient increase in Vibrios, two lineages of bacteria (Rhodobacterales and Cytophagales increased in coral tissues, suggesting that V. coralliilyticus challenge opens niche space for these known opportunists. Rhodobacterales increased from 6.99% (±0.05 SEM to a maximum mean relative abundance of 48.75% (±0.14 SEM in the final time point and Cytophagales from <0.001% to 3.656%. Halobacteriovorax predators are commonly present at low-abundance on coral surfaces. Based on the keystone role of predators in many ecosystems, we hypothesized that Halobacteriovorax predators might help protect corals by

Response of predators to Western Sandpiper nest exclosures

Science.gov (United States)

Niehaus, Amanda C.; Ruthrauff, Daniel R.; McCaffery, Brian J.

2004-01-01

In 2001, predator exclosures were used to protect nests of the Western Sandpiper (Calidris mauri) in western Alaska. During the exclosure experiment, nest contents in exclosures had significantly higher daily survival rates than control nests, however, late in the study predators began to cue in on exclosures and predate the nest contents. An Arctic Fox (Alopex lagopus) dug under one exclosure and took the newly hatched chicks, and Long-tailed Jaegers (Stercorarius longicaudus) learned to associate exclosures with active nests and repeatedly visited them. The jaegers attempted to gain access to exclosed nests and pursued adult sandpipers as they emerged from the exclosures. The exclosures were removed to reduce potential mortality to adult and young sandpipers, but subsequently, post-exclosure nests had lower daily survival rates than controls during the same time period. Predation of post-exclosure eggs and chicks highlighted the lasting influence of the exclosure treatment on offspring survival because predators probably remembered nest locations. Researchers are urged to use caution when considering use of predator exclosures in areas where jaegers occur.

Pupation Behavior and Predation on Drosophila suzukii (Diptera: Drosophilidae) Pupae in Maine Wild Blueberry Fields.

Science.gov (United States)

Ballman, Elissa S; Collins, Judith A; Drummond, Francis A

2017-12-05

Drosophila suzukii (Matsumura; Diptera: Drosophilidae) is an invasive vinegar fly and pest of soft fruits in North America, including wild blueberries (Vaccinium angustifolium Aiton) in Maine. Despite its presence in the continental United States for 9 yr, little is known about its natural enemy complex. Here we report the results of a 3-yr study designed to identify naturally-occurring predators in Maine's wild blueberry fields. Experiments were conducted to determine pupation site and pupation depth to understand D. suzukii's predation vulnerability. Predation rates in the field of fully-exposed, caged, and buried pupae were measured. Pitfall traps were deployed to identify the potential predator assemblage, and laboratory experiments were conducted to determine how many pupae were consumed by commonly occurring ground beetle species (Carabidae) and field crickets (Gryllus pennsylvanicus Burmeister). The most commonly collected predators were ants, ground beetles, harvestmen, and field crickets. Significantly more pupae were found to occur in the soil compared to blueberry fruit, with most pupae in the top 0.5 cm layer of soil. Pupal predation rates in the field were high, with higher rates of predation on exposed pupae compared to buried pupae. Laboratory studies revealed that ground beetles and field crickets are likely predators of D. suzukii pupae. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Impact of conservation areas on trophic interactions between apex predators and herbivores on coral reefs.

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Rizzari, Justin R; Bergseth, Brock J; Frisch, Ashley J

2015-04-01

Apex predators are declining at alarming rates due to exploitation by humans, but we have yet to fully discern the impacts of apex predator loss on ecosystem function. In a management context, it is critically important to clarify the role apex predators play in structuring populations of lower trophic levels. Thus, we examined the top-down influence of reef sharks (an apex predator on coral reefs) and mesopredators on large-bodied herbivores. We measured the abundance, size structure, and biomass of apex predators, mesopredators, and herbivores across fished, no-take, and no-entry management zones in the Great Barrier Reef Marine Park, Australia. Shark abundance and mesopredator size and biomass were higher in no-entry zones than in fished and no-take zones, which indicates the viability of strictly enforced human exclusion areas as tools for the conservation of predator communities. Changes in predator populations due to protection in no-entry zones did not have a discernible influence on the density, size, or biomass of different functional groups of herbivorous fishes. The lack of a relationship between predators and herbivores suggests that top-down forces may not play a strong role in regulating large-bodied herbivorous coral reef fish populations. Given this inconsistency with traditional ecological theories of trophic cascades, trophic structures on coral reefs may need to be reassessed to enable the establishment of appropriate and effective management regimes. © 2014 Society for Conservation Biology.

Fasting or fear: disentangling the roles of predation risk and food deprivation in the nitrogen metabolism of consumers.

Science.gov (United States)

Dalton, Christopher M; Tracy, Karen E; Hairston, Nelson G; Flecker, Alexander S

2018-03-01

Predators can alter nutrient cycles simply by inducing stress in prey. This stress accelerates prey's protein catabolism, nitrogen waste production, and nitrogen cycling. Yet predators also reduce the feeding rates of their prey, inducing food deprivation that is expected to slow protein catabolism and nitrogen cycling. The physiology of prey under predation risk thus balances the influences of predation risk and food deprivation, and this balance is central to understanding the role of predators in nutrient cycles. We explored the separate and combined effects of predation risk and food deprivation on prey physiology and nutrient cycling by exposing guppies (Poecilia reticulata) to predation risk and food deprivation in a 2 × 2 design. We simulated predation risk using chemical cues from a natural predator of guppies, and we created food deprivation by rationing food availability. We measured guppy response as food consumption, growth, tissue energy density, tissue carbon:nitrogen, and nitrogen (N) excretion and assimilation. We found that N-linked physiological processes (N consumption, assimilation, excretion) were strongly affected by predation risk, independent of food consumption. Guppies excreted substantially less under predation risk than they did under food deprivation or control conditions. These results suggest that predation risk, per se, triggers physiological changes in guppies that increase N retention and decrease N excretion. We suggest that slower N metabolism under predation risk is an adaptive response that minimizes protein loss in the face of predictable, predator-induced food restriction. Notably, N metabolism shares common hormonal control with food seeking behavior, and we speculate that increased N retention is a direct and immediate result of reduced food seeking under predation risk. Contrary to predation-stress-based hypotheses for how predators affect nutrient cycling by prey, our result indicates that even short-term exposure to predators

Olfactory systems and neural circuits that modulate predator odor fear

Directory of Open Access Journals (Sweden)

Lorey K. Takahashi

2014-03-01

Full Text Available When prey animals detect the odor of a predator a constellation of fear-related autonomic, endocrine, and behavioral responses rapidly occur to facilitate survival. How olfactory sensory systems process predator odor and channel that information to specific brain circuits is a fundamental issue that is not clearly understood. However, research in the last 15 years has begun to identify some of the essential features of the sensory detection systems and brain structures that underlie predator odor fear. For instance, the main (MOS and accessory olfactory systems (AOS detect predator odors and different types of predator odors are sensed by specific receptors located in either the MOS or AOS. However, complex predator chemosignals may be processed by both the MOS and AOS, which complicate our understanding of the specific neural circuits connected directly and indirectly from the MOS and AOS to activate the physiological and behavioral components of unconditioned and conditioned fear. Studies indicate that brain structures including the dorsal periaqueductal gray, paraventricular nucleus of the hypothalamus, and the medial amygdala appear to be broadly involved in predator odor induced autonomic activity and hypothalamic-pituitary-adrenal stress hormone secretion. The medial amygdala also plays a key role in predator odor unconditioned fear behavior and retrieval of contextual fear memory associated with prior predator odor experiences. Other neural structures including the bed nucleus of the stria terminalis and the ventral hippocampus appear prominently involve in predator odor fear behavior. The basolateral amygdala, medial hypothalamic nuclei, and medial prefrontal cortex are also activated by some but not all predator odors. Future research that characterizes how distinct predator odors are uniquely processed in olfactory systems and neural circuits will provide significant insights into the differences of how diverse predator odors activate

Olfactory systems and neural circuits that modulate predator odor fear

Science.gov (United States)

Takahashi, Lorey K.

2014-01-01

When prey animals detect the odor of a predator a constellation of fear-related autonomic, endocrine, and behavioral responses rapidly occur to facilitate survival. How olfactory sensory systems process predator odor and channel that information to specific brain circuits is a fundamental issue that is not clearly understood. However, research in the last 15 years has begun to identify some of the essential features of the sensory detection systems and brain structures that underlie predator odor fear. For instance, the main (MOS) and accessory olfactory systems (AOS) detect predator odors and different types of predator odors are sensed by specific receptors located in either the MOS or AOS. However, complex predator chemosignals may be processed by both the MOS and AOS, which complicate our understanding of the specific neural circuits connected directly and indirectly from the MOS and AOS to activate the physiological and behavioral components of unconditioned and conditioned fear. Studies indicate that brain structures including the dorsal periaqueductal gray (DPAG), paraventricular nucleus (PVN) of the hypothalamus, and the medial amygdala (MeA) appear to be broadly involved in predator odor induced autonomic activity and hypothalamic-pituitary-adrenal (HPA) stress hormone secretion. The MeA also plays a key role in predator odor unconditioned fear behavior and retrieval of contextual fear memory associated with prior predator odor experiences. Other neural structures including the bed nucleus of the stria terminalis and the ventral hippocampus (VHC) appear prominently involved in predator odor fear behavior. The basolateral amygdala (BLA), medial hypothalamic nuclei, and medial prefrontal cortex (mPFC) are also activated by some but not all predator odors. Future research that characterizes how distinct predator odors are uniquely processed in olfactory systems and neural circuits will provide significant insights into the differences of how diverse predator

Development of a System wide Predator Control Program: Stepwise Implementation of a Predation Index, Predator Control Fisheries, and Evaluation Plan in the Columbia River Basin; Section II: Evaluation; 1996 Annual Report

International Nuclear Information System (INIS)

Young, Franklin R.

1997-01-01

Predator control fisheries aimed at reducing predation on juvenile salmonids by northern squawfish (Ptychocheilus oregonensis) were implemented for the seventh consecutive year in the mainstream Columbia and Snake rivers

Would Tax Evasion and Tax Avoidance Undermine a National Retail Sales Tax?

OpenAIRE

Murray, Matthew N.

1997-01-01

Argues that shifting to an indirect tax system (a national sales tax) will not necessarily reduce tax avoidance and tax evasion behavior by businesses and individuals, particularly if the tax rate is set high to maintain revenue neutrality. Lack of experience in administering a high-rate, indirect tax system precludes definitive statements regarding the likely extent of tax base erosion under a national sales tax.

Disentangling mite predator-prey relationships by multiplex PCR.

Science.gov (United States)

Pérez-Sayas, Consuelo; Pina, Tatiana; Gómez-Martínez, María A; Camañes, Gemma; Ibáñez-Gual, María V; Jaques, Josep A; Hurtado, Mónica A

2015-11-01

Gut content analysis using molecular techniques can help elucidate predator-prey relationships in situations in which other methodologies are not feasible, such as in the case of trophic interactions between minute species such as mites. We designed species-specific primers for a mite community occurring in Spanish citrus orchards comprising two herbivores, the Tetranychidae Tetranychus urticae and Panonychus citri, and six predatory mites belonging to the Phytoseiidae family; these predatory mites are considered to be these herbivores' main biological control agents. These primers were successfully multiplexed in a single PCR to test the range of predators feeding on each of the two prey species. We estimated prey DNA detectability success over time (DS50), which depended on the predator-prey combination and ranged from 0.2 to 18 h. These values were further used to weight prey detection in field samples to disentangle the predatory role played by the most abundant predators (i.e. Euseius stipulatus and Phytoseiulus persimilis). The corrected predation value for E. stipulatus was significantly higher than for P. persimilis. However, because this 1.5-fold difference was less than that observed regarding their sevenfold difference in abundance, we conclude that P. persimilis is the most effective predator in the system; it preyed on tetranychids almost five times more frequently than E. stipulatus did. The present results demonstrate that molecular tools are appropriate to unravel predator-prey interactions in tiny species such as mites, which include important agricultural pests and their predators. © 2015 John Wiley & Sons Ltd.

Assessing predation risk: optimal behaviour and rules of thumb.

Science.gov (United States)

Welton, Nicky J; McNamara, John M; Houston, Alasdair I

2003-12-01

We look at a simple model in which an animal makes behavioural decisions over time in an environment in which all parameters are known to the animal except predation risk. In the model there is a trade-off between gaining information about predation risk and anti-predator behaviour. All predator attacks lead to death for the prey, so that the prey learns about predation risk by virtue of the fact that it is still alive. We show that it is not usually optimal to behave as if the current unbiased estimate of the predation risk is its true value. We consider two different ways to model reproduction; in the first scenario the animal reproduces throughout its life until it dies, and in the second scenario expected reproductive success depends on the level of energy reserves the animal has gained by some point in time. For both of these scenarios we find results on the form of the optimal strategy and give numerical examples which compare optimal behaviour with behaviour under simple rules of thumb. The numerical examples suggest that the value of the optimal strategy over the rules of thumb is greatest when there is little current information about predation risk, learning is not too costly in terms of predation, and it is energetically advantageous to learn about predation. We find that for the model and parameters investigated, a very simple rule of thumb such as 'use the best constant control' performs well.

Trichinella spiralis Calreticulin Binds Human Complement C1q As an Immune Evasion Strategy.

Science.gov (United States)

Zhao, Limei; Shao, Shuai; Chen, Yi; Sun, Ximeng; Sun, Ran; Huang, Jingjing; Zhan, Bin; Zhu, Xinping

2017-01-01

As a multicellular parasitic nematode, Trichinella spiralis regulates host immune responses by producing a variety of immunomodulatory molecules to escape from host immune attack, but the mechanisms underlying the immune evasion are not well understood. Here, we identified that T. spiralis calreticulin ( Ts -CRT), a Ca 2+ -binding protein, facilitated T. spiralis immune evasion by interacting with the first component of human classical complement pathway, C1q. In the present study, Ts -CRT was found to be expressed on the surface of different developmental stages of T. spiralis as well as in the secreted products of adult and muscle larval worms. Functional analysis identified that Ts -CRT was able to bind to human C1q, resulting in the inhibition of C1q-initiated complement classical activation pathway reflected by reduced C4/C3 generation and C1q-dependent lysis of antibody-sensitized sheep erythrocytes. Moreover, recombinant Ts -CRT (r Ts -CRT) binding to C1q suppressed C1q-induced THP-1-derived macrophages chemotaxis and reduced monocyte-macrophages release of reactive oxygen intermediates (ROIs). Blocking Ts -CRT on the surface of newborn larvae (NBL) of T. spiralis with anti- Ts -CRT antibody increased the C1q-mediated adherence of monocyte-macrophages to larvae and impaired larval infectivity. All of these results suggest that T. spiralis -expressed Ts -CRT plays crucial roles in T. spiralis immune evasion and survival in host mostly by directly binding to host complement C1q, which not only reduces C1q-mediated activation of classical complement pathway but also inhibits the C1q-induced non-complement activation of macrophages.

‘Do You Want a Receipt?’ Combating VAT and RST Evasion with Lottery Tickets

NARCIS (Netherlands)

S.J.C. Hemels (Sigrid); M. Fabbri (Marco)

2013-01-01

textabstractGovernments both in developed and developing countries are facing the problem of value added tax (VAT) and retail sales tax (RST) evasion. This explains a growing interest in policies alternative to the traditional methods of deterrence. This paper describes the achievements resulting

Air-water CO2 evasion from US East Coast estuaries

Science.gov (United States)

Gildas Laruelle, Goulven; Goossens, Nicolas; Arndt, Sandra; Cai, Wei-Jun; Regnier, Pierre

2017-05-01

This study presents the first regional-scale assessment of estuarine CO2 evasion along the US East Coast (25-45° N). The focus is on 42 tidal estuaries, which together drain a catchment of 697 000 km2 or 76 % of the total area within this latitudinal band. The approach is based on the Carbon-Generic Estuary Model (C-GEM) that allows the simulation of hydrodynamics, transport, and biogeochemistry for a wide range of estuarine systems using readily available geometric parameters and global databases of seasonal climatic, hydraulic, and riverine biogeochemical information. Our simulations, performed using conditions representative of the year 2000, suggest that, together, US East Coast estuaries emit 1.9 Tg C yr-1 in the form of CO2, which corresponds to about 40 % of the carbon inputs from rivers, marshes, and mangroves. Carbon removal within estuaries results from a combination of physical (outgassing of supersaturated riverine waters) and biogeochemical processes (net heterotrophy and nitrification). The CO2 evasion and its underlying drivers show important variations across individual systems, but reveal a clear latitudinal pattern characterized by a decrease in the relative importance of physical over biogeochemical processes along a north-south gradient. Finally, the results reveal that the ratio of estuarine surface area to the river discharge, S/Q (which has a scale of per meter discharged water per year), could be used as a predictor of the estuarine carbon processing in future regional- and global-scale assessments.

Putting prey and predator into the CO2 equation--qualitative and quantitative effects of ocean acidification on predator-prey interactions.

Science.gov (United States)

Ferrari, Maud C O; McCormick, Mark I; Munday, Philip L; Meekan, Mark G; Dixson, Danielle L; Lonnstedt, Öona; Chivers, Douglas P

2011-11-01

Little is known about the impact of ocean acidification on predator-prey dynamics. Herein, we examined the effect of carbon dioxide (CO(2)) on both prey and predator by letting one predatory reef fish interact for 24 h with eight small or large juvenile damselfishes from four congeneric species. Both prey and predator were exposed to control or elevated levels of CO(2). Mortality rate and predator selectivity were compared across CO(2) treatments, prey size and species. Small juveniles of all species sustained greater mortality at high CO(2) levels, while large recruits were not affected. For large prey, the pattern of prey selectivity by predators was reversed under elevated CO(2). Our results demonstrate both quantitative and qualitative consumptive effects of CO(2) on small and larger damselfish recruits respectively, resulting from CO(2)-induced behavioural changes likely mediated by impaired neurological function. This study highlights the complexity of predicting the effects of climate change on coral reef ecosystems. © 2011 Blackwell Publishing Ltd/CNRS.

Tax Evasion in Switzerland: The Roles of Deterrence and Tax Morale

OpenAIRE

Feld, Lars P; Frey, Bruno S

2006-01-01

The traditional economic approach to tax evasion does not appear to be particularly successful in explaining the extent of tax compliance. We argue instead that a psychological tax contract which establishes a fiscal exchange between the state and the citizens shapes tax compliance to a large extent. In that respect, a case study of Switzerland is useful because the small size of the cantons and their direct democratic political systems procedurally establish a close exchange relationship bet...

Prey change behaviour with predation threat, but demographic effects vary with prey density: experiments with grasshoppers and birds.

Science.gov (United States)

Belovsky, Gary E; Laws, Angela Nardoni; Slade, Jennifer B

2011-04-01

Increasingly, ecologists emphasize that prey frequently change behaviour in the presence of predators and these behavioural changes can reduce prey survival and reproduction as much or more than predation itself. However, the effects of behavioural changes on survival and reproduction may vary with prey density due to intraspecific competition. In field experiments, we varied grasshopper density and threat of avian predation and measured grasshopper behaviour, survival and reproduction. Grasshopper behaviour changed with the threat of predation and these behavioural changes were invariant with grasshopper density. Behavioural changes with the threat of predation decreased per capita reproduction over all grasshopper densities; whereas the behavioural changes increased survival at low grasshopper densities and then decreased survival at high densities. At low grasshopper densities, the total reproductive output of the grasshopper population remained unchanged with predation threat, but declined at higher densities. The effects of behavioural changes with predation threat varied with grasshopper density because of a trade-off between survival and reproduction as intraspecific competition increased with density. Therefore, resource availability may need to be considered when assessing how prey behavioural changes with predation threat affect population and food web dynamics. © 2011 Blackwell Publishing Ltd/CNRS.

Tax evasion and Swiss bank deposits