Spread Of Strategies Research Articles

Hepatitis D Virus Infection Among Hepatitis B Surface Antigen Carriers and in "Isolated anti-HBc" Antibodies Profile in Central Tunisia.

Background:Hepatitis D Virus (HDV) causes accelerated liver diseases in patients with Hepatitis B Virus (HBV) infection. There is lack of data about its prevalence, related risk factors and interaction with HBV carriers in our country.Objectives:The aim of this study was to estimate the prevalence of hepatitis delta and associated risk factors among Hepatitis B surface antigen (HBsAg) and “isolated anti-HBc” profile carriers in central Tunisia.Patients and Methods:In this cross-sectional study, 540 patients with positive HBsAg and 109 “isolated anti-HBc” profile receiving care in a teaching hospital were tested for the presence of HDV serum-markers using commercially available enzyme immunoassay kit. HBV-DNA was detected by nested PCR in “isolated anti-HBc” profile group.Results:Prevalence of HDV was 8.1% in HBsAg carriers group, but it was significantly higher in active than inactive hepatitis (30.2% and 4.5%, respectively, OR = 9, 95% CI: [4.48-18.58]). There was no significant association between studied risk factors and HDV infection. In the “isolated anti-HBc” profile group, prevalence of HDV was 4.6% and HBV-DNA had negative result in all patients with positive results for HDV.Conclusions:Although HDV had low prevalence in our area, it is vital to plan preventive strategies for HDV spread as well as HBV prevention. It is particularly important to suspect HDV infection in active HBV carriers to manage a particularly severe dual infection. HDV infection should be suspected even in negative HBsAg patients having “isolated anti-HBc” profile.

Abstract B56: Peritoneal tumor spread in high grade serous ovarian cancer: An effect of the competing endogenous RNA network?

Abstract Epithelial ovarian cancer (EOC) is still one of the deadliest malignancies in women frequently involving peritoneal tumor spread and ascites. Despite the heterogeneity of EOC, patients are mostly treated with standard therapy (cytoreductive surgery and platinum based chemotherapy). Understanding molecular mechanisms of EOC and its peritoneal metastasis is essential to develop new targeted therapies. In this study, we extended the transcriptome analysis of large RNA (Auer et al. Oncotarget 2015, 6:17261) to small RNA including micro RNAs (miRNAs) and piwi protein interacting RNAs (piRNAs). The transcriptome was analyzed concerning peritoneal tumor spread as introduced in our previous study: miliary – i.e. numerous small millet-like tumor seedings - versus non-miliary – i.e. big, bulky implants. Small RNA-sequencing (sRNA-seq) was performed with a total of 43 tumor cell enriched samples isolated from ascites and solid tumors from 23 chemo-naïve high grade serous EOC (HGSOC) patients and analyzed together with corresponding RNA-seq data from our previous study. qPCR was applied for validation of sRNA-seq data (n=48). Expression differences were determined (I) between miliary and non-miliary tumor spread in (Ia) ascitic and (Ib) solid tumor cells and (II) between ascitic and solid tumor cells in (IIa) miliary and (IIb) non-miliary on three levels: single miRNAs, gene-miR sets, and general types of RNAs (especially those of the competing endogenous RNA network, ceRNA). sRNA-seq yielded evidence for expression of 649 known and 2,306 newly predicted miRNAs and 22,987 known and 783 newly predicted piRNAs. qPCR validation rate was 90% for 48 selected sRNAs. (Ia) 401 miRNAs, but no gene-miR set and (Ib) one miRNA, but >19,000 gene-miR sets were differentially expressed between miliary and non-miliary in ascitic and solid tumor cells, respectively. 72% of these deregulated gene-miR sets were characterized by down-regulated coding genes and up-regulated miRNAs. (IIa) 109 miRNAs and 49 gene-miR sets and (IIb) 55 miRNAs and no gene-miR set were differentially expressed between ascitic and solid tumor cells in miliary and non-miliary, respectively. These numbers indicate varying strategies for differential expression between miliary and non-miliary, one the one hand, and between e. g. ascitic and solid tumor cells, on the other hand: thousands of small changes in miRNA and gene expression versus few, but greater changes in individual miRNA and gene expression. Global analyses of coding, long non-coding (lncRNAs), circular (circRNAs) RNAs, and miRNAs revealed a down-regulated ceRNA network (i.e. less circRNAs and lncRNAs compared to coding RNAs), but an unchanged total amount of miRNAs. Given the sponge function of the ceRNA network, this indicates more free miRNAs available for regulation in miliary compared to non-miliary. In addition, a 13 sRNA signature was developed to predict the peritoneal tumor spread type from FFPE tissues. It was used for validation of the impact on overall survival (OS) in an independent cohort of 32 HGSOC patients. In accordance with our previous study, miliary tumor spread had a negative impact on OS independent of age and FIGO stage. We are the first to perform an integrative analysis of large and small RNA-seq data of ascitic and solid tumor cells from 23 HGSOC patients. We found evidence for hundreds of known mi- and piRNAs and thousands of newly predicted mi- and piRNAs. We could show a negative prognostic impact of the miliary tumor spread in a validation cohort. Solid tumors of the miliary type seem to be more influenced by miRNA regulation than solid tumors of the non-miliary type which implies different spread strategies. This fundamentally different mechanism of gene regulation and the different prognosis of these two spread types underline the need for alternative treatment regiments. Citation Format: Anna Bachmayr-Heyda, Katharina Auer, Nyamdelger Sukhbaatar, Stefanie Aust, Simon Deycmar, Agnes T. Reiner, Stephan Polterauer, Sabine Dekan, Dietmar Pils. Peritoneal tumor spread in high grade serous ovarian cancer: An effect of the competing endogenous RNA network? [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr B56.

The impact of spatial arrangements on epidemic disease dynamics and intervention strategies

ABSTRACTThe role of spatial arrangements on the spread and management strategies of a cholera epidemic is investigated. We consider the effect of human and pathogen movement on optimal vaccination strategies. A metapopulation model is used, incorporating a susceptible–infected–recovered system of differential equations coupled with an equation modelling the concentration of Vibrio cholerae in an aquatic reservoir. The model compared spatial arrangements and varying scenarios to draw conclusions on how to effectively manage outbreaks. The work is motivated by the 2010 cholera outbreak in Haiti. Results give guidance for vaccination strategies in response to an outbreak.

Identifying main drivers and testing control strategies for CCHFV spread.

Crimean Congo Haemorrhagic Fever (CCHF) is an emerging zoonotic disease. The causative agent is a virus (CCHFV), mainly transmitted by ticks of the species Hyalomma marginatum in Eastern Europe and Turkey. In order to test potential scenarios for the control of pathogen spread, the basic reproduction number (R0) for CCHF was calculated. This calculation was based on a population dynamics model and parameter values from the literature for pathogen transmission. The tick population dynamics model takes into account the major processes involved and gives estimates for tick survival from one stage to the other and number of feeding ticks. It also considers the influence of abiotic (meteorological variables) and biotic factors (host densities) on model outputs, which were compared with data collected in Central Anatolia (Turkey). R0 computation was thereafter used to test control strategies and especially the effect of acaricide treatment. Simulation results indicate that such treatments could have valuable effects provided that the acaricide is applied regularly throughout the spring and summer, and over several years. Furthermore, a sensitivity analysis to abiotic and biotic factors showed that, even though temperature has a strong impact on model outputs, host (mainly hare) densities also play a role. The kind of model we have developed provides insight into the ability of different strategies to prevent and control disease spread and has proved its relevance when associated with field trials.

Infection of an Insect Vector with a Bacterial Plant Pathogen Increases Its Propensity for Dispersal.

The spread of vector-transmitted pathogens relies on complex interactions between host, vector and pathogen. In sessile plant pathosystems, the spread of a pathogen highly depends on the movement and mobility of the vector. However, questions remain as to whether and how pathogen-induced vector manipulations may affect the spread of a plant pathogen. Here we report for the first time that infection with a bacterial plant pathogen increases the probability of vector dispersal, and that such movement of vectors is likely manipulated by a bacterial plant pathogen. We investigated how Candidatus Liberibacter asiaticus (CLas) affects dispersal behavior, flight capacity, and the sexual attraction of its vector, the Asian citrus psyllid (Diaphorina citri Kuwayama). CLas is the putative causal agent of huanglongbing (HLB), which is a disease that threatens the viability of commercial citrus production worldwide. When D. citri developed on CLas-infected plants, short distance dispersal of male D. citri was greater compared to counterparts reared on uninfected plants. Flight by CLas-infected D. citri was initiated earlier and long flight events were more common than by uninfected psyllids, as measured by a flight mill apparatus. Additionally, CLas titers were higher among psyllids that performed long flights than psyllid that performed short flights. Finally, attractiveness of female D. citri that developed on infected plants to male conspecifics increased proportionally with increasing CLas bacterial titers measured within female psyllids. Our study indicates that the phytopathogen, CLas, may manipulate movement and mate selection behavior of their vectors, which is a possible evolved mechanism to promote their own spread. These results have global implications for both current HLB models of disease spread and control strategies.

Effective Strategies to Spread Redesigning Care Processes Among Healthcare Teams.

The purpose of this study was to describe how spread strategies facilitate the successful implementation of the Transforming Care at the Bedside (TCAB) program and their impact on healthcare workers and patients in a major Canadian healthcare organization. This study used a qualitative and descriptive design with focus groups and individual interviews held in May 2014. Participants included managers and healthcare providers from eight TCAB units in a university health center in Quebec, Canada. The sample was composed of 43 individuals. The data were analyzed using NVivo according to the method proposed by Miles and Huberman. The first two themes that emerged from the analysis are related to context (organizational transition requiring many changes) and spread strategies for the TCAB program (senior management support, release time and facilitation, rotation of team members, learning from previous TCAB teams, and engaging patients). The last theme that emerged from the analysis is the impact on healthcare professionals (providing front-line staff and managers with the training they need to make changes, team leadership, and increasing receptivity to hearing patients' and families' needs and requests). This study describes the perspectives of managers and team members to provide a better understanding of how spread strategies can facilitate the successful implementation of the TCAB program in a Canadian healthcare organization. Spread strategies facilitate the implementation of changes to improve the quality and safety of care provided to patients.

Early and late maternal effects on hatching phenology of Heterocypris incongruens (Crustacea: Ostracoda).

In ephemeral ponds, the hatching asynchrony of resting eggs may be adaptive and the result of a maternal bet-hedging strategy. A mother can influence the progeny phenology through conditions experienced during life cycle even in early development stages. We investigated the consequences of a hatching delay for offspring and compared early and late maternal effects in a clonal lineage of Heterocypris incongruens. We used females from genetically identical, 40 months old, resting eggs that hatched, asynchronically, after a first (FI) or a second (SI) inundation event. Maternal origin (FI or SI) was considered an early effect involving the maternal response to hatching stimuli during the embryological dormant stage. Maternal age at deposition and egg size were considered late effects that account for maternal conditions during active stage. We compared size and development time of eggs produced by FI and SI females under laboratory condition (24°C 12:12 L:D photoperiod). Maternal origin affected development time to adulthood which was later in FI than in SI females, and fecundity that was higher in FI than in SI females. SI eggs were smaller than FI eggs: size was affected by maternal age at deposition and was directly related to the egg development time. Development time varied from 1 to 117 days and was shorter in SI eggs than in FI eggs. Our results showed that maternal response during embryological stage affects the performance in successive active stages and suggested that hatching asynchrony may be considered a risk spread strategy.

An ex-ante economic appraisal of Bluetongue virus incursions and control strategies

SUMMARYThe incursion of Bluetongue disease into the UK and elsewhere in Northern Europe in 2008 raised concerns about maintaining an appropriate level of preparedness for the encroachment of exotic diseases as circumstances and risks change. Consequently the Scottish government commissioned the present study to inform policy on the specific threat of Bluetongue virus 8 (BTV8) incursion into Scotland. An interdisciplinary expert panel, including BTV and midge experts, agreed a range of feasible BTV incursion scenarios, patterns of disease spread and specific control strategies. The study was primarily desk-based, applying quantitative methodologies with existing models, where possible, and utilizing data already held by different members of the project team. The most likely distribution of the disease was explored given Scotland's agricultural systems, unique landscape and climate. Epidemiological and economic models are integrated in an ex-ante cost-benefit appraisal of successful prevention of hypothetical BTV8 incursion into Scotland under various feasible incursion scenarios identified by the interdisciplinary panel. The costs of current public and private surveillance efforts are compared to the benefits of the avoided losses of potential disease outbreaks. These avoided losses included the direct costs of alternative vaccination, protection zone (PZ) strategies and their influence on other costs arising from an outbreak as predicted by the epidemiological model. Benefit-cost ratios were ranked within each incursion scenario to evaluate alternative strategies. In all incursion scenarios, the ranking indicated that a strategy, including 100% vaccination within a PZ set at Scottish counties along the England–Scotland border yielded the least benefit in terms of the extent of avoided outbreak losses (per unit cost). The economically optimal vaccination strategy was the scenario that employed 50% vaccination and all Scotland as a PZ. The results provide an indicator of how resources can best be targeted for an efficient ex-ante control strategy.

A Dose- rather than Delivery Profile–Dependent Mechanism Regulates the “Muscle-Full” Effect in Response to Oral Essential Amino Acid Intake in Young Men ,

Background: The anabolic response of skeletal muscle to essential amino acids (EAAs) is dose dependent, maximal at modest doses, and short lived, even with continued EAA availability, a phenomenon termed “muscle-full.” However, the effect of EAA ingestion profile on muscle metabolism remains undefined.Objective: We determined the effect of Bolus vs. Spread EAA feeding in young men and hypothesized that muscle-full is regulated by a dose-, not delivery profile–, dependent mechanism.Methods: We provided 16 young healthy men with 15 g mixed-EAA, either as a single dose (“Bolus”; n = 8) or in 4 fractions at 45-min intervals (“Spread”; n = 8). Plasma insulin and EAA concentrations were assayed by ELISA and ion-exchange chromatography, respectively. Limb blood flow by was determined by Doppler ultrasound, muscle microvascular flow by Sonovue (Bracco) contrast-enhanced ultrasound, and phosphorylation of mammalian target of rapamycin complex 1 substrates by immunoblotting. Intermittent muscle biopsies were taken to quantify myofibrillar-bound 13C6-phenylalanine to determine muscle protein synthesis (MPS).Results: Bolus feeding achieved rapid insulinemia (13.6 μIU · mL−1, 25 min after commencement of feeding), aminoacidemia (∼2500 μM at 45 min), and capillary recruitment (+45% at 45 min), whereas Spread feeding achieved attenuated insulin responses, gradual low-amplitude aminoacidemia (peak: ∼1500 μM at 135 min), and no detectable capillary recruitment (all P < 0.01 vs. Bolus). Despite these differences, identical anabolic responses were observed; fasting fractional synthetic rates of 0.054% · h−1 (Bolus) and 0.066% · h−1 (Spread) increased to 0.095% and 0.104% · h−1 (no difference in increment or final values between regimens). With both Spread and Bolus feeding strategies, a latency of at least 90 min was observed before an upswing in MPS was evident. Similarly with both feeding strategies, MPS returned to fasting rates by 180 min despite elevated circulating EAAs.Conclusion: These data do not support EAA delivery profile as an important determinant of anabolism in young men at rest, nor rapid aminoacidemia/leucinemia as being a key factor in maximizing MPS. This trial was registered at clinicaltrials.gov as NCT01735539.

Electric full flat floor bus's trial production and research of the spread strategy in a public transportation system

We have made an electric full-flat bus as an experiment for the first time in Japan. This is a bus with a combination of eco-design and universal design by the original technology ‘integrated platform’. We have revealed what types of electric buses are better for the companies and users through a social survey. We carried out a fact-finding survey intended for bus companies and sent questionnaires to 216 users in eight prefectures including Tokyo metropolitan area. We have classified the results of the survey into three types of electric full-flat buses as dissemination bus models in Japan. Three dissemination electric full-flat bus models are Model A: an urban type of electric full-flat large size bus (front door and middle door), Model B: a suburban type of electric full-flat large size bus (front door and rear door) and Model C: a small size electric full-flat bus (front door - middle door).

A dynamic replication strategy based on categorization for Data Grid

Data Replication is copying the data from a certain location to another location. Replication is used in Data Grid to have two or more copies of the same data at different locations. In this paper, a Category-based dynamic replication strategy (CDRS) is proposed. The strategy takes into account that the replicas exist on a node belong to different categories. Each of these categories is given a value that determines its importance for the node. When the node's storage is full, the node starts to store only the replicas that belong to the category with the highest value. The results of the simulations show that the new proposed strategy achieved better performance than Plain Caching and Fast Spread strategies in terms of total transit time and total bandwidth consumption.

Quality improvement collaboratives and the wisdom of crowds: spread explained by perceived success at group level.

BackgroundMany studies have been conducted to evaluate the impact of quality improvement collaboratives (QICs) on the quality of healthcare. This article addresses an underexplored topic, namely the use of QICs as ‘intentional spread strategy.’ Its objective is to predict the dissemination of projects within hospitals participating in a change programme based on several QICs. We tested whether the average project success at QIC level (based on opinions of individual project team leaders) explains the dissemination of projects one year later.FindingsAfter one year, 148 project team leaders of 16 hospitals participating in the two-year programme were asked to rate the success of their improvement project on a scale from 1 to 10. At the end of the second year, the programme coordinator of each hospital provided information on the second-year dissemination. Average success scores and dissemination statistics were calculated for each QIC (N = 12). The non-parametric correlation between team leader judgment and dissemination rate at QIC level is 0.73 (P < 0.01).ConclusionsPrevious work, focusing on the team and hospital level, showed which factors contributed to local success stories. It also illustrated how successes play a role in dissemination processes within programme hospitals. The current study suggests that we cannot ignore the extent to which the dissemination potential of individual projects is defined by their QIC. Aggregated team leader judgments at the QIC level might predict the future dissemination in participating organizations. The findings, however, need to be replicated in larger, independent samples.Electronic supplementary materialThe online version of this article (doi:10.1186/s13012-014-0091-2) contains supplementary material, which is available to authorized users.

Prevalence of Hepatitis D Virus Infection Among Patients With Chronic Hepatitis B Attending Birjand Hepatitis Clinic (East of Iran) in 2012

BackgroundHepatitis delta virus (HDV) is a defective RNA virus dependent on Hepatitis B virus (HBV) infection for its replication and expression. All patients with HBV infection should be tested for the presence of HDV infection. It is estimated that approximately 5% of hepatitis B surface antigen (HbsAg) carriers in the world are HDV infected patients. HBV-HDV co-infection may lead to more severe acute disease and higher risks of fulminant hepatitis, cirrhosis, and hepatocellular carcinoma than those having HBV infection alone. Also, HBV infected patients with HDV super-infection have a higher rate of progression to chronic disease and serious complications.ObjectivesOur aim was to determine the prevalence of HDV infection among chronic hepatitis B (CHB) patients attending Birjand Hepatitis Clinic, East of Iran.Materials and MethodsA cross-sectional analytical study was conducted on 413 CHB patients in 2012. Serology test for anti-HDV was measured by ELISA in these patients. CHB patients had positive hepatitis B surface antigen for at least 6 months before the study entrance.ResultsThe mean age of CHB patients was 38.5± 11.9 years and 55.9% of them (231 patients) were male. There were 13 cases (3.1%) with HDV infection. There was no association between positive anti-HDV serology and factors such as age, gender, carrier state, liver enzymes, and positive hepatitis B e antigen (HBeAg) serology.ConclusionsAlthough HDV had a low prevalence in our area, it is important for healthcare providers and policy makers to plan preventive strategies for HDV spread as well as HBV prevention programs among high risk population.

VAR-BASED OPTIMAL PARTIAL HEDGING

AbstractHedging is one of the most important topics in finance. When a financial market is complete, every contingent claim can be hedged perfectly to eliminate any potential future obligations. When the financial market is incomplete, the investor may eliminate his risk exposure by superhedging. In practice, both hedging strategies are not satisfactory due to their high implementation costs, which erode the chance of making any profit. A more practical and desirable strategy is to resort to the partial hedging, which hedges the future obligation only partially. The quantile hedging of Föllmer and Leukert (Finance and Stochastics, vol. 3, 1999, pp. 251–273), which maximizes the probability of a successful hedge for a given budget constraint, is an example of the partial hedging. Inspired by the principle underlying the partial hedging, this paper proposes a general partial hedging model by minimizing any desirable risk measure of the total risk exposure of an investor. By confining to the value-at-risk (VaR) measure, analytic optimal partial hedging strategies are derived. The optimal partial hedging strategy is either a knock-out call strategy or a bull call spread strategy, depending on the admissible classes of hedging strategies. Our proposed VaR-based partial hedging model has the advantage of its simplicity and robustness. The optimal hedging strategy is easy to determine. Furthermore, the structure of the optimal hedging strategy is independent of the assumed market model. This is in contrast to the quantile hedging, which is sensitive to the assumed model as well as the parameter values. Extensive numerical examples are provided to compare and contrast our proposed partial hedging to the quantile hedging.

Costly Advertising and the Evolution of Cooperation

In this paper, I investigate the co-evolution of fast and slow strategy spread and game strategies in populations of spatially distributed agents engaged in a one off evolutionary dilemma game. Agents are characterized by a pair of traits, a game strategy (cooperate or defect) and a binary ‘advertising’ strategy (advertise or don’t advertise). Advertising, which comes at a cost , allows investment into faster propagation of the agents’ traits to adjacent individuals. Importantly, game strategy and advertising strategy are subject to the same evolutionary mechanism. Via analytical reasoning and numerical simulations I demonstrate that a range of advertising costs exists, such that the prevalence of cooperation is significantly enhanced through co-evolution. Linking costly replication to the success of cooperators exposes a novel co-evolutionary mechanism that might contribute towards a better understanding of the origins of cooperation-supporting heterogeneity in agent populations.

Selected FINRA notices and disciplinary actions, September 2012‐April 2013

PurposeThe purpose of this paper is to provide selected Financial Industry Regulatory Authority (FINRA) Regulatory Notices and Disciplinary Actions issued in June, July, and August 2012.Design/methodology/approachThe paper provides FINRA Regulatory Notice 12‐40, SEC Approves New FINRA Rule 5123 Regarding Private Placements of Securities; Regulatory Notice 12‐44, SEC Approves Amendments to FINRA Rule 4210 (Margin Requirements); Regulatory Notice 12‐55, Guidance on FINRA's Suitability Rule; and Regulatory Notice 13‐13, Trading and Quotation Halts in OTC Equity Securities; Trade Reporting Notice of April 17, 2013: Reduction of Reporting Times for Agency Pass‐Through Mortgage‐Backed Securities Traded TBA.FindingsNotice 12‐40: FINRA Rule 5123 is part of a multi‐pronged approach to enhance oversight and investor protection in private placements; the rule will provide FINRA with more timely and complete information about the private placement activities of firms on behalf of other issuers. Notice 12‐44: The SEC approved amendments to FINRA Rule 4210 (Margin Requirements) related to option spread strategies, maintenance margin requirements for non‐margin eligible equity securities, free‐riding, “exempt accounts” and stress testing in portfolio margin accounts. Notice 12‐55: This Notice addresses two issues discussed in Regulatory Notice 12‐25: the scope of the terms “customer” and “investment strategy.” Notice 12‐25 provided guidance in a “frequently asked questions” format in FINRA Rule 2111 (Suitability). Notice 13‐13: The SEC approved amendments to FINRA Rule 6440, which provides authority for FINRA to initiate trading and quotation halts in OTC equity securities in circumstances where it is necessary to protect investors and the public; the rule provides authority to impose foreign regulatory halts, derivative halts and extraordinary event halts. Trade Reporting Notice of April 17, 2013: FINRA reminds firms of the coming reduction in reporting periods for the timely reporting of transactions in agency pass‐through mortgage‐backed securities traded TBA (to be announced) for good delivery and products not traded for good delivery.Originality/valueThese FINRA notices are selected to provide a useful indication of regulatory trends.

Hedging Against a Price Drop Using the Inverse Vertical Ratio Put Spread Strategy Formed by Barrier Options

This paper investigates hedging of a portfolio consisting of a risky underlying asset using the Inverse Vertical Ratio Put Spread (further IVRPS) strategy formed by single barrier options (category exotic options; subcategory path-dependent options) to study the difference between hedging using barrier and vanilla options. This strategy is useful for hedging against a price drop assuming the given underlying asset will be sold in the future. Barrier options were created to provide risk managers with cheaper means to hedge their exposures without paying for the price changes they believed unlikely to occur. They are options with second strike price, called barrier or trigger. Crossing of the barrier (in the form of frontier underlying asset price) during the life of an option implies activation or deactivation of particular barrier option. In general, they are more flexible and cheaper in comparison to plain vanilla options. In our analysis we use an interesting approach based on finding of the income functions from secured position in analytical form, which can simplify hedging process. These theoretical results are robust to different underlying assets and are useful for financial and also non-financial institutions. Many authors use this approach of analyzing for example Amaitiek, Balint and Resovsky (2010), Soltes M. (2010), Soltes V. (2001), Soltes V. and Amaitiek (2010a), Soltes V. and Amaitiek (2010b). A key difference between the previous studies is that in this paper we are concentrated on barrier options. Furthermore, we focus on the application to SPDR Gold Shares (GLD). SPDR Gold Shares offer investors an innovative, relatively cost efficient and secure way to access the gold market without being necessary to take care of delivery and safekeeping. GLD are an appropriate tool for those who want to play in the gold market, not for those who want to buy real gold. It is possible to use them for hedging, forming of option strategies etc. For these reasons they are very popular and SPDR Gold Trust is currently one of the largest holder of the gold in the world. We use vanilla and barrier option on these shares in our analysis. Due to the lack of real-traded barrier option data we calculate the barrier option premiums using an analytical model of Haug, who applied the Black-Scholes-Merton formula for all kinds of barrier options. We realize all calculations in the statistical program R because of simplification. The comparative comparison of proposed variants has shown the best results. We also find the best variants for the investor who speculates, and at the same time hedges against a slight or significant price drop. Our study confirms that this strategy formation using barrier options gives end-users greater flexibility to express a precise view. The results show that IVRPS strategy formation using barrier options is better than this option strategy formation using vanilla option in specific future price situations, but not in every practical situation. DOI: http://dx.doi.org/10.5755/j01.ee.24.1.3505

Impact of Neighborhood Structure on Epidemic Spreading by Means of Cellular Automata Approach

The main goal of this work is to propose a mathematical model, based on two-dimensional cellular automata (CA), to simulate an infectious disease outbreak. Specifically, we revisit the general deterministic SEIR (Susceptible Exposed Infectious Recovered) model by adding terms describing the spatial spreading of disease. The state of each cell is a 4-tuple where each component represents the portion of each compartment in the cell at a given time step. We emphasis the role of the basic reproduction number and its relation with some spatial characteristics of CA models. We study in particular, the impact of the neighborhood structure in relation to the spread of such infectious diseases. The presented model will serve as a basis to simulate real epidemics and will also be concerned with the control problem where efficient strategies for disease spread have to be investigated.

American step-up and step-down default swaps under Lévy models

This paper studies the valuation of a class of default swaps with the embedded option to switch to a different premium and notional principal anytime prior to a credit event. These are early exercisable contracts that give the protection buyer or seller the right to step-up, step-down, or cancel the swap position. The pricing problem is formulated under a structural credit risk model based on Lévy processes. This leads to the analytic and numerical studies of several optimal stopping problems subject to early termination due to default. In a general spectrally negative Lévy model, we rigorously derive the optimal exercise strategy. This allows for instant computation of the credit spread under various specifications. Numerical examples are provided to examine the impacts of default risk and contractual features on the credit spread and exercise strategy.

Assessing the Risks of Trading Strategies Using Acceptability Indices

The paper looks at the quantification of risks of trading strategies in incomplete markets. We realized that the no-arbitrage price intervals are unacceptably large. From a risk management point of view, we are concerned with finding prices that are acceptable to the market. The acceptability of the prices is assessed by risk measures. Plausible risk measures give price bounds that are suitable for use as bid-ask prices. Furthermore, the risk measures should be able to compensate for the unhedgeable risk to an extent. Conic finance provides plausible bid-ask prices that are determined by the probability distribution of the cash flows only. We apply the theory to obtain bid-ask prices in the assessment of the risks of trading strategies. We analyze two popular trading strategies—bull call the spread strategy and bear call spread strategy. Comparison of risk profiles for the strategies is done between the Variance Gamma Scalable Self Decomposable model and the Black-Scholes model. The findings indicate that using bid-ask prices compensates for the unhedgeable risk and reduces the spread between bid-ask prices.