Client-contractor bargaining on net present value in project scheduling with limited resources

The client-contractor bargaining problem addressed here is in the context of a multi-mode resource constrained project scheduling problem with discounted cash flows, which is formulated as a progress payments model. In this model, the contractor receives payments from the client at predetermined regular time intervals. The last payment is paid at the first predetermined payment point right after project completion. The second payment model considered in this paper is the one with payments at activity completions. The project is represented on an Activity-on-Node (AON) project network. Activity durations are assumed to be deterministic. The project duration is bounded from above by a deadline imposed by the client, which constitutes a hard constraint. The bargaining objective is to maximize the bargaining objective function comprised of the objectives of both the client and the contractor. The bargaining objective function is expected to reflect the two-party nature of the problem environment and seeks a compromise between the client and the contractor. The bargaining power concept is introduced into the problem by the bargaining power weights used in the bargaining objective function. Simulated annealing algorithm and genetic algorithm approaches are proposed as solution procedures. The proposed solution methods are tested with respect to solution quality and solution times. Sensitivity analyses are conducted among different parameters used in the model, namely the profit margin, the discount rate, and the bargaining power weights

Modelling the effects of net pens to the marine ecosystems

Fen Bilimleri Enstitüsü, Su Ürünleri Ana Bilim DalıAkuakültür sektörü geçen yirmi yıl boyunca oldukça gelişmiştir ve günümüzde dünya deniz ürünleri üretiminin %50'sine ulaşmıştır. Bu üretimin önemli kısmı kıyısal alanlarda yapılan ağ-kafes yetiştiriciliğinden gelmektedir. Bununla birlikte, denizel akuakültürdeki bu gelişim kıyısal bölgedeki çevresel sürdürülebilirlik hakkındaki endişeleri artırmaktadır. Akuakültür uygulamalarının zararlı etkilere sahip olabilmesi aşırı yemleme ve katı atık yönetiminin zayıf olmasına bağlıdır. Türkiye'deki çevresel potansiyel endişelerin büyük çoğunluğu spekülatif ve bilimsel dayanağı bulunmayan nedenlerdir.Bu projenin amacı, Türkiye'nin batısında, kıyısal bölgede konuşlanmış bulunan denizel ağ-kafes çiftliklerinin çevresel etkilerinin belirlenmesi ve daha iyi bir yönetim prosedürü ortaya koyarak gelecek projelere destek oluşturmaktır. Bu çalışmanın önemli bir parçası organik materyal birikiminin bir bilgisayar programı (MERAMOD) ile 2 yıl boyunca elde edilen gerçek veriler kullanılarak simüle edilmesidir. Ayrıca çalışmada, sediment tuzaklarından elde edilen gerçek veriler, simülasyon çıktıları ile karşılaştırılmıştır.Arazi verileri, sedimentasyon oranlarının 0,05-58,85 g/m2/gün değer aralığında olduğunu göstermiştir. Bununla birlikte, bilgisayar simülasyonları ile elde edilen organik materyal sedimentasyon oranları, arazi verilerine göre önemli derecede düşük çıkmıştır. Bu yüzden sediment tuzaklarından elde edilen verilerin simülasyonlarla doğrulanması gerekmektedir. Toplam organik karbon birikimi oranları 0,55-648,9 g/m2/yıl değer aralığında çıkmıştır. Öne çıkan en önemli sonuç, deniz tabanında yem ve fekal atıkların oluşturduğu partiküle sedimentasyona bağlı organik zenginliğin en çok kafes altlarında oluşmasıdır.Devlet birimleri ile birçok bilimsel disiplinlerin bir araya getirilerek ağ-kafes işletmelerinin kurulabileceği sağlıklı alanların belirlenmesi ve sürdürülebilir yönetim stratejilerinin geliştirilmesi ile ilgili yaklaşımların oluşturulması gerekmektedir.Advances in the field of aquaculture has resulted in increased production during the last two decades and today aquaculture produces 50% of the world?s seafood. A considerable portion of this production comes from cage (net pen) aquaculture in coastal areas. However, the development of marine aquaculture along the coastal areas raises concerns about the sustainability of natural environment. The effects of aquaculture can be deleterious by increasing turbidity through over-feeding and poor waste management. In Turkey, the majority of potential environmental concerns is of a speculative nature and in many cases is not supported by scientific evidence.The current project aims to determine the effects of marine cage farms located in coastal regions in western Turkey with a view to suggesting procedures for better management in the planning and impact assessments and to assisting in the evaluation of future projects. An important part of this study concerns simulating the accumulation of organic material by a modeling software (MERAMOD) using field data collected during 2 years. We have also compared simulation results with data collected from sediment traps.Field data indicated that sedimentation rates ranged between 0,05-58,85 g/m2/day. However, computer simulations on sedimentation rate of organic material were significantly less than those of field data. Therefore, there is a need to validate simulations against data collected from sediment traps. Total organic carbon accumulation rates ranged between 0,55-648,9 g/m2/year. The organic enrichment of the seabed directly beneath the cages was the most prominent result of the sedimentation of particulate waste due to feeding and fecal wastes. It is in the interest of governmental agencies to integrate a multi-disciplinary approach in order to determine potential cage farm sites to develop sustainable management strategies

Plasmodium Infections in Natural Populations of Anolis sagrei Reflect Tolerance Rather Than Susceptibility

This is the author accepted manuscript. The final version is available from OUP via the DOI in this record.Parasites can represent formidable selection pressures for hosts, but the cost of infection is sometimes difficult to demonstrate in natural populations. While parasite exploitation strategies may, in some instances, actually inflict low costs on their hosts, the response of hosts to infection is also likely to determine whether or not these costs can be detected. Indeed, costs of infection may be obscured if infected individuals in the wild are those that are the most tolerant, rather than the most susceptible, to infection. Here we test this hypothesis in two natural populations of Anolis sagrei, one of the most common anole lizard of the Bahamas. Plasmodium parasites were detected in > 7% of individuals and belonged to two distinct clades: P. mexicanum and P. floriensis. Infected individuals displayed greater body condition than non-infected ones and we found no association between infection status, stamina, and survival to the end of the breeding season. Furthermore, we found no significant difference in the immuno-competence (measured as a response to phytohemagglutinin challenge) of infected versus non-infected individuals. Taken together, our results suggest that the infected individuals that are caught in the wild are those most able to withstand the cost of the infection and that susceptible, infected individuals have been removed from the population (i.e., through disease-induced mortality). This study highlights the need for caution when interpreting estimates of infection costs in natural populations, as costs may appear low either when parasites exploitation strategies truly inflict low costs on their hosts or when those costs are so high that susceptible hosts are removed from the population.This work was supported by a National Geographic Society [grant #8002-06 to R.C.]; a Natural Environment Research Council [research grant NE/M00256X to C.B.]; The symposium was supported by National Science Foundation [grant # IOS-1637160]; Company of Biologists [grant EA1233] both Simon Lailvaux and Jerry Husak; and bySociety for Integrative and Comparative Biology divisions DAB, DCB, DEC, DEDE, DEE, DNB, and DVM

Comparison of predicted and measured levels of organic material input from a commercial cage farm in Western Turkey

In this study, two different sediment trap trials were carried out to determine the deposition rate (flux) of particulate organic materials (POM) from marine cage farms. Flux predicted using a commercial software (Meramod), measured almost two-fold higher (1,355.5 g m-2 yr- 1) in 2009 compared to that in 2008 (765.0 g m-2yr-1). Predicted levels of flux were higher than measured values in all trials and ranged between 1,251.6 g m-2 yr-1 in 2008 and 1,811.9 g m-2 yr-1 in 2009. There were also considerable differences in measured and predicted rates of flux at each station. High variations of flux in repeated measures indicated the need for strict control of farm maintenance routines during long-term trap studies. Near bottom current speeds, periodic resuspension events and the presence of wild fish assemblages were considered as major factors that may have effects in predicting the accumulation rates of POM.TUBITAK [105G038]This study was funded by TUBITAK grant no. #105G038. We would like to thank the owners and staff of the fish farms for their assistance in carrying out this study. And we also thank the editorial team and referees for their valuable help and suggestions in editing the article

Fear of mating out (FOMO): voyeurism does not increase mating propensity in fruit flies

Mate availability and social information can influence mating behaviour in both males and females. Social information obtained from conspecifics can influence mate choice, particularly shown by studies on mate choice copying. However, the role of directly observing conspecific mating on mating behaviour has been less explored. As such, whether conspecifics are copulating or not could inform ‘observers’ about the availability of mates, or even stimulate observers to mate themselves. Using Drosophila melanogaster, we tested whether exposure to the visual cue of a mating pair would increase the mating propensity of an observer pair (i.e., voyeur). We followed a factorial design where a male-female pair (voyeur flies) were placed together with or without visual access to another pair of flies (who were either mating or not mating). We found no evidence that mating latency or duration of mating were affected by whether voyeurs had visual access to a mating or non-mating pair. These results could be due to biological factors (e.g., use of other non-visual cues by flies to acquire information related to sex), or methodological limitations of our study (e.g., flies unable to watch other pairs). Generally, our results suggest that fruit flies do not use visual cues from conspecifics mating to adjust their own mating latency or mating duration

Evolutionary genetics of immunological supertypes reveals two faces of the Red Queen

Red Queen host-parasite co-evolution can drive adaptations of immune-genes by positive selection that erodes genetic variation (Red Queen Arms Race), or result in a balanced polymorphism (Red Queen Dynamics) and the long-term preservation of genetic variation (trans-species polymorphism). These two Red Queen processes are opposite extremes of the co-evolutionary spectrum. Here we show that both Red Queen processes can operate simultaneously, analyzing the Major Histocompatibility Complex (MHC) in guppies (Poecilia reticulata and P. obscura), and swamp guppies (Micropoecilia picta). Sub-functionalization of MHC alleles into “supertypes” explains how polymorphisms persist during rapid host-parasite co-evolution. Simulations show the maintenance of supertypes as balanced polymorphisms, consistent with Red Queen Dynamics, whereas alleles within supertypes are subject to positive selection in a Red Queen Arms Race. Building on the Divergent Allele Advantage hypothesis, we show that functional aspects of allelic diversity help to elucidate the evolution of polymorphic genes involved in Red Queen co-evolution

No evidence for paternal age effects on sons or daughters, when accounting for paternal sperm storage

A father’s age at conception is predicted to affect not only his own fertility but also his offspring’s fitness. Offspring born to old fathers are assumed to be less fit than those of young fathers. However, under low mating rates, paternal age might be confounded with the duration for which mature sperm are stored in fathers prior to ejaculation. Studies that disentangle the confounding paternal effects of sperm storage duration from those of age on offspring are lacking. We use Drosophila melanogaster to test the separate and interactive effects of paternal age and sexual rest on offspring fitness. As expected, old fathers produce fewer offspring than young fathers; however, paternal age does not influence the survival or age-dependent reproductive success of sons or daughters. Instead, a long duration of paternal sexual rest negatively impacts the reproductive success of the conceived sons. Furthermore, daughters of low reproductive quality selectively disappear with age, but sons do not, highlighting that demographic processes can further modulate paternal age effects. Overall, we highlight that paternal age effects might not be as pervasive as previously assumed and suggest that paternal sexual rest might be more important in influencing offspring phenotypes

The Developmental Environment Mediates Adult Seminal Proteome Allocation in Male Drosophila melanogaster

Early life conditions can have long‐lasting effects on fitness. In insects, larval crowding increases intraspecific competition, shaping adult phenotypes and influencing male reproductive success in pre‐ and post‐mating competition. Although some larval crowding effects on seminal fluid protein (Sfp) allocation are known, studies often focus on a small subset of Sfps and overlook male–female interactions. A comprehensive understanding of how male and female larval environments interact to influence seminal proteome composition and transfer is still lacking. Here, we manipulated Drosophila melanogaster larval crowding (low vs. high) to generate large and small adults and mated individuals in a fully factorial design. We then measured Sfp production, composition and transfer. Large males produced relatively higher quantities of Sfps. However, small males transferred greater quantities of a subset of Sfps. When examining proteins individually, 10 Sfps were transferred at significantly higher abundances by small males than large males. Our findings suggest that small males invest more per mating, potentially due to fewer mating opportunities or cues of high larval density influencing reproductive strategies. This study provides new insights into early life effects on ejaculate allocation in D. melanogaster , highlighting physiological and behavioural responses to developmental conditions. Understanding these mechanisms offers valuable perspectives on reproductive strategies and fitness trade‐offs in insects

Quantitative proteomics identification of seminal fluid proteins in male Drosophila melanogaster

Seminal fluid contains some of the fastest evolving proteins currently known. These seminal fluid proteins (Sfps) play crucial roles in reproduction, such as supporting sperm function, and particularly in insects, modifying female physiology and behaviour. Identification of Sfps in small animals is challenging, and often relies on samples taken from the female reproductive tract after mating. A key pitfall of this method is that it might miss Sfps that are of low abundance due to dilution in the female-derived sample or rapid processing in females. Here we present a new and complementary method, which provides added sensitivity to Sfp identification. We applied label-free quantitative proteomics to Drosophila melanogaster male reproductive tissue – where Sfps are unprocessed, and highly abundant – and quantified Sfps before and immediately after mating, to infer those transferred during copulation. We also analysed female reproductive tracts immediately before and after copulation to confirm the presence and abundance of known and candidate Sfps, where possible. Results were cross-referenced with transcriptomic and sequence databases to improve confidence in Sfp detection. Our data were consistent with 125 previously reported Sfps. We found nine high-confidence novel candidate Sfps, which were both depleted in mated versus unmated males and identified within the reproductive tract of mated but not virgin females. We also identified 42 more candidates that are likely Sfps based on their abundance, known expression and predicted characteristics, and revealed that four proteins previously identified as Sfps are at best minor contributors to the ejaculate. The estimated copy numbers for our candidate Sfps were lower than for previously identified Sfps, supporting the idea that our technique provides a deeper analysis of the Sfp proteome than previous studies. Our results demonstrate a novel, high-sensitivity approach to the analysis of seminal fluid proteomes, whose application will further our understanding of reproductive biology

Reproductive output of old males is limited by seminal fluid, not sperm number

Male reproductive senescence is typically characterized by a decline in the number of sperm produced and transferred by old males, a phenomenon that may be exacerbated in polygynous species where males mate multiply. However, males also transfer seminal fluid to females, and little is known about its role in modulating male reproductive senescence. Here, we explore the contributions of sperm and seminal fluid towards male reproductive senescence in a series of sequential matings, using Drosophila melanogaster. As expected, old males produce fewer offspring than young males. However, this pattern is not driven by sperm limitation: old males have more sperm and transfer similar numbers to females, compared to young males. Instead, females storing fewer sperm of old males compared to that of young males, over a long term, drives male reproductive senescence. We are able to mitigate the age-related decline in male reproductive output by supplementing females with the seminal fluid of a young male, before she mates with an old male. Similarly, we alleviate the reduction in reproductive output across sequential matings by supplementing females with seminal fluid. Our findings highlight that seminal fluid, rather than sperm number, limits reproductive success in old or multiply mating males, highlighting its underappreciated role in reproductive aging