Null Cost Research Articles

Lead generation of UPPS inhibitors targeting MRSA: Using 3D-QSAR pharmacophore modeling, virtual screening, molecular docking, and molecular dynamic simulations

Undecaprenyl Pyrophosphate Synthase (UPPS) is a vital target enzyme in the early stages of bacterial cell wall biosynthesis. UPPS inhibitors have antibacterial activity against resistant strains such as MRSA and VRE. In this study, we used several consecutive computer-based protocols to identify novel UPPS inhibitors. The 3D QSAR pharmacophore model generation (HypoGen algorithm) protocol was used to generate a valid predictive pharmacophore model using a set of UPPS inhibitors with known reported activity. The developed model consists of four pharmacophoric features: one hydrogen bond acceptor, two hydrophobic, and one aromatic ring. It had a correlation coefficient of 0.86 and a null cost difference of 191.39, reflecting its high predictive power. Hypo1 was proven to be statistically significant using Fischer’s randomization at a 95% confidence level. The validated pharmacophore model was used for the virtual screening of several databases. The resulting hits were filtered using SMART and Lipinski filters. The hits were docked into the binding site of the UPPS protein, affording 70 hits with higher docking affinities than the reference compound (6TC, − 21.17 kcal/mol). The top five hits were selected through extensive docking analysis and visual inspection based on docking affinities, fit values, and key residue interactions with the UPPS receptor. Moreover, molecular dynamic simulations of the top hits were performed to confirm the stability of the protein–ligand complexes, yielding five promising novel UPPS inhibitors.Graphical

Asymptotic behavior of null controllability cost for parabolic equations with vanishing diffusivity under Robin and Neumann boundary conditions

In this paper we study the null controllability cost of a transport-diffusion system under Robin boundary conditions with distributed control and in which the transport coefficient is a gradient field. First, we provide some conditions on transport coefficient and boundary potential to show that the control cost decays exponentially when the viscosity vanishes and the control time is sufficiently large. On the other hand, if the range of the control region by the transport flow does not cover that of Ω, we prove that the control cost explodes exponentially for the Neumann boundary conditions case with vanishing viscosity and all control time.

Development of the mirror-image sensitivity for different object categories-Evidence from the mirror costs of object images in children and adults.

Object recognition relies on a multitude of factors, including size, orientation, and so on. Mirrored orientation, particularly due to children's mirror confusion in reading, holds special significance among various object orientations. Brain imaging studies suggest that the visual ventral and dorsal streams exhibit distinct orientation sensitivity across diverse object categories. Yet, it remains unclear whether mirror orientation sensitivity also varies among these categories during development at the behavioral level. Here, we explored the mirror sensitivity of children and adults across five distinct categories, which encompass tools that activate both the visual ventral stream for function information and the dorsal stream for manipulation information, and animals and faces that mainly activate the ventral stream. Two types of symbols, letters and Chinese characters, were also included. Mirror sensitivity was assessed through mirror costs-that is, the additional reaction time or error rate in the mirrored versus the same orientation condition when judging the identity of object pairs. The mirror costs in reaction times and error rates consistently revealed that children exhibited null mirror costs for tools, and the mirror costs for tools in adults were minimal, if any, and were smaller than those for letters and characters. The mirror costs reflected in absolute reaction time and error rate were similar across adults and children, but when the overall difference in reaction times was considered, adults showed a larger mirror cost than children. Overall, our investigation unveils categorical distinctions and development in mirror sensitivity of object recognition across the ventral and dorsal streams.

A care substitution service in the Netherlands: impact on referral, cost, and patient satisfaction

BackgroundIn care substitution services, medical specialists offer brief consultations to provide general practitioners (GPs) with advice on diagnosis, treatment, or hospital referral. When GPs serve as gatekeepers to secondary care, these regional services could reduce pressures on healthcare systems. The aim is to determine the impact of implementing a care substitution service for dermatology, orthopaedics, and cardiology on the hospital referral rate, health care costs, and patient satisfaction.MethodsA before-after study was used to evaluate hospital referral rates and health care costs during a follow-up period of 1 year. The study population comprised patients with eligible International Classification of Primary Care codes for referral to the care substitution service (only dermatology, orthopaedic, cardiology indications), as pre-defined by GPs and medical specialists. We compared referral rates before and after implementation by χ2 tests and evaluated patient preference by qualitative analysis.ResultsIn total, 4,930 patients were included, 2,408 before and 2,522 after implementation. The care substitution service decreased hospital referrals during the follow-up period from 15 to 11%. The referral rate decreased most for dermatology (from 15 to 9%), resulting in a cost reduction of €10.59 per patient, while the other two specialisms experienced smaller reductions in referral rates. Patients reported being satisfied, mainly because of the null cost, improved organisation, improved care, and positive experience of the consultation.ConclusionsThe care substitution service showed promise for specialisms that require fewer hospital facilities, as exemplified by dermatology.

Optimal Sizing of a Photovoltaic/Battery Energy Storage System to Supply Electric Substation Auxiliary Systems under Contingency

Electric substations (ESS) are important facilities that must operate even under contingency to guarantee the electrical system’s performance. To achieve this goal, the Brazilian national electricity system operator establishes that alternating current (AC) auxiliary systems of ESS must have, at least, two power supplies, and in the case of failure of these sources, an emergency generator (EG) must at least supply energy to the essential loads. In order to improve the availability of auxiliary systems, a microgrid with other sources, such as photovoltaic (PV) systems and Battery Energy Storage Systems (BESS), can be an alternative. In this case, an economical optimization of the PV/BESS system must be addressed considering the costs associated with the installation and maintenance of equipment, and the gains from the credits generated by the photovoltaic system in the net metering scheme. In this paper, the size of the BESS system was determined to supply energy to the load of auxiliary systems of an ESS, as well as a PV system to achieve a null total cost. Furthermore, multi-objective optimization using the genetic algorithm technique was employed to optimize the size of the hybrid PV/BESS to minimize the investment cost and time when the demand was not met. Simulations under different scenarios of contingency were allowed to obtain the Pareto frontier for the optimal sizing of a PV/BESS system to supply energy to AC auxiliary systems in an ESS under contingency.

Pacific white shrimp and tomato production using water effluents and salinity-tolerant grafted plants in an integrated aquaponic production system

A vital goal of cleaner production involves developing agricultural production systems capable of ensuring sufficient yields of highly necessary foods to meet the increasing needs of the global population while minimizing the associated economic and ecological costs. Integrated agri-aquaculture systems (IAAS) offer a number of advantages for sustainable agriculture, including water reutilization, discharge mitigation, and increased profitability by leveraging the symbiotic relationship between organic waste, bacterial mineralization, and plant filtration. The aim of this study was to assess the production of two food items of global socio-economic importance cultivated at different salinities: Pacific white shrimp (Penaeus vannamei) and tomatoes (Solanum lycopersicum L.) grafted to salinity tolerant wild tomatoes. Pacific white shrimp were cultured at a density of 125 organisms/m3 and tomatoes at a density of 3 plants/m. The shrimp growth test consisted of three salinity levels: 2, 4, and 6 g/L. The corresponding tomato salinity treatments were conducted using shrimp water effluents; Steiner’s universal nutrient solution (SNS) was used for the control treatment. The experimental period lasted 175 days. The highest tomato production (77.46 t/ha) was attained with SNS, with no significant difference from the salinity of 2 g/L. Shrimp final mean weight, survival, and production were higher at the 6 g/L salinity; and all the other zootechnical parameters decreased with lower salinity. When compared with the hydroponic system using a cost-benefit analysis (CBA), the production costs associated with the IAAS were lower primarily because of the reduced (or null) costs of fertilizer, and irrigation water. When grafted plants were used, the salinity tolerance of the commercial hybrid increased and shrimp could be cultured at appropriate salinity to facilitate osmoregulation. Chemical fertilization requirements were reduced and acceptable yields were obtained for the tomato crop by grafting to salinity-tolerant rootstocks.

Sex Differences in Demand for Highly Palatable Foods: Role of the Orexin System.

BackgroundThe prevalence of eating disorders, including binge eating disorder, is significantly higher in women. These findings are mirrored by preclinical studies, which indicate that female rats have a higher preference for palatable food and show greater binge-like eating compared with male rats.MethodsHere, we describe a novel within-session behavioral-economic paradigm that allows for the simultaneous measurement of the intake at null cost (Q0) and normalized demand elasticity (α) of 3 types of palatable food (low fat, high fat, and chocolate sucrose pellets) via demand curve analysis. In light of evidence that the orexin (hypocretin) system is critically involved in reward and feeding behaviors, we also examined the role of orexin function in sex differences of economic demand for palatable foods.ResultsThe novel within-session behavioral-economic approach revealed that female rats have higher intake (demand) than males for all palatable foods at low cost (normalized to body weight) but no difference in intake at higher prices, indicating sex-dependent differences in the hedonic, but not motivational, aspects of palatable food. Immediately following behavioral-economic testing, we observed more orexin-expressing neurons and Fos expression (measure of recent neural activation) in these neurons in female rats compared with male rats. Moreover, the orexin-1 receptor antagonist SB334867 reduced both low- and high-cost intake for palatable food in both male and female rats.ConclusionsThese findings provide evidence of higher demand at low prices for palatable food in females and indicate that these behavioral differences may be associated with sexual dimorphism in orexin system function.

ESTIMATION OF THE GEOECOLOGICAL STATE OF THE LEFT INFLOWS OF THE DNISTER RIVER (MOHYLIV-PODILSKY SITE)

The results of hydrochemical, lithogeochemical tests of surface waters, bottom sediments and soils of the coastal zone of the left inflows of Podolsk part of the Dnister river within the limits of Mogilev-Podolsky site are given. Among the investigated elements common to bottom sediments, water and soils from the banks of watercourses are Mn, Ni, Ti, V, Cr, Mo, Zr, Nb, Cu, Ba, Pb. The main attention is paid to the concentration of lead, chrome, manganese and copper in surface waters, bottom sediments and soils of the coastal zone of rivers Dnister, Zhvan, Karaets, Lyadova, Serebrya, Nemiia, Derlo. The content of the indicated elements there are less maximum permissible concentrations (MPC) of sanitary toxicological requirements and MPC of standard in water of the investigated reservoirs. In the soils and bottom sediments of the Dnister river, insignificant concentrations of most metals (at the average concentrations for river waters) were detected. The results of researches on the distribution of concentrations of chrome, lead, copper and manganesein water, bottom sediments of rivers and soils selected from their shores for better visibility are represent in the form of diagrams for each chemical element. Complex research of water, bottom sediments and soils of the coastal zone made it possible to obtain a coherent picture of the geoecological state of the rivers within their ancestral part. Taking into account that the content of the majority of investigated elements in watercourses does not exceed the MPC and answers to the average concentrations of metals in river waters of Ukraine, then it is possible to draw conclusion about the satisfactory state of reservoirs and the catchment area. It has been found that such complex and systematic studies have not been carried out in the past, so it is not possible to compare the results with the results of research in previous years. Also sharply the problem of null information costs about the geoecological state of right inflows of Dnister (the territory of the Republic of Moldova) common to both countries of the transboundary water.

The role of orexin-1 receptor signaling in demand for the opioid fentanyl.

The orexin system is a potential treatment target for drug addiction. Orexin-1 receptor (OxR1) antagonism reduces demand for cocaine and remifentanil, indicating that orexin-based therapies may reduce demand for many classes of abused drugs. However, pharmacokinetics vary greatly among opioids and it is unclear if OxR1 antagonism would reduce demand for all opioids, particularly ones with high abuse liability. Here, we established a behavioral economics (BE) procedure to assess the effects of OxR1 antagonism on demand for the highly abused opioid fentanyl. We also investigated the utility of our procedure to predict OxR1 antagonism efficacy and relapse propensity. Demand parameters α (demand elasticity or price sensitivity of consumption, an inverse measure of drug motivation) and Qo (drug consumption at null cost) were assessed. The OxR1 antagonist SB-334867 (SB) decreased motivation (increased α) for fentanyl without affecting Qo. Baseline α values predicted SB efficacy, such that SB was most effective at reducing motivation (increasing α) in highly motivated rats. Baseline α values predicted the amount of cued reinstatement of fentanyl seeking; this reinstatement behavior was attenuated by SB administration. These results highlight the promise of the orexin system as a treatment target for opioid addiction and emphasize the usefulness of BE procedures in the study of opioid abuse.

Energy-aware lot sizing problem: Complexity analysis and exact algorithms

The single-item lot sizing problem under a periodic energy limitation is considered in this paper. Identical and parallel capacitated machines constitute the production system, each one consuming a certain amount of energy when being switched on, when reserved, and when producing. We consider a cost for starting-up the machines, a reservation cost to keep the machines ready for production, in addition to classical lot sizing costs, such as, joint setup cost, unit production cost and unit holding cost, all being time-dependent. Besides the classical lot sizing decisions of how much and in which periods to produce, we have to decide the number of machines to switch on and to switch off in each period. We show that this problem is NP-hard even under restricted conditions. In contrast, assuming stationary energy parameters, we propose two polynomial time dynamic programming algorithms to solve the problem to optimality. The first algorithm is proposed for the case with null setup cost, null reservation cost and null reservation energy consumption, and runs in O(M5T4) time, with M being the number of machines and T the number of periods. We show that we can extend this algorithm to solve the generalized version of the problem in time complexity O(M6T6).

Spin-imbalanced pairing and Fermi surface deformation in flat bands

We study the attractive Hubbard model with spin imbalance on two lattices featuring a flat band: the Lieb and kagome lattices. We present mean-field phase diagrams featuring exotic superfluid phases, similar to the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, whose stability is confirmed by dynamical mean-field theory. The nature of the pairing is found to be richer than just the Fermi surface shift responsible for the usual FFLO state. The presence of a flat band allows for changes in the particle momentum distributions at null energy cost. This facilitates formation of nontrivial superfluid phases via multiband Cooper pair formation: the momentum distribution of the spin component in the flat band deforms to mimic the Fermi surface of the other spin component residing in a dispersive band. The Fermi surface of the unpaired particles that are typical for gapless superfluids becomes deformed as well. The results highlight the profound effect of flat dispersions on Fermi surface instabilities, and provide a potential route for observing spin-imbalanced superfluidity and superconductivity.

Characterization and benchmarking of seven managed aquifer recharge systems in south-western Europe

The European MARSOL project includes different examples of managed aquifer recharge (MAR) facilities in the Mediterranean area. A methodical characterization of the whole recharge process has been carried out to ensure that all functions and facilities are clearly comparable independent of size, budget or location. The seven selected MAR demo sites are located in two countries. Four are in Portugal—Rio Seco and Noras (Campina de Faro Aquifer), S. Bartolomeu de Messines and Cerro do Bardo (Querenca-Silves) in Algarve, and three are in Spain—Llobregat (Catalonia), Santiuste and El Carracillo (Castilla y Leon). The systems have been defined using a form divided into four sections, including alpha-numerical data, orthophotographs, sketches and schedules. A first draft using a bibliography was reviewed by the authors, who recorded a detailed analysis and further reports to complete the characterization, as shown in several tables. The article covers MAR benchmarking serial steps for infrastructure measurements (surfaces, lengths, facilities, costs), functions categorization (transport, infiltration, treatment, restoration) and evolution in time and space (maps, sketches and calendars). MAR measuring displays contrasting interpretations depending on scale. The benchmarking process was found to be difficult to apply to seven sites with different sizes, aims, operational procedures and time scales. However, some parameters, such as mean infiltration rate, have shown their potential as management decision tools in the long term. Mediterranean areas, characterized by water supply irregularity, which is likely to be exacerbated by climate change models, can benefit from the use of MAR as a water management technique and from its diverse functions, although these objectives have not generally been attached to recharge. Null energy cost and low initial investment can also play important roles in boosting MAR development as a feasible alternative in short-term water planning.

PCB in the environment: bio-based processes for soil decontamination and management of waste from the industrial production of Pleurotus ostreatus

Polychlorinated biphenyls (PCBs) are hazardous soil contaminants for which a bio-based technology for their recovery is essential. The objective of this study was to validate the exploitation of spent mushroom substrate (SMS), a low or null cost organic waste derived from the industrial production of P. ostreatus, as bulking agent in a dynamic biopile pilot plant. The SMS shows potential oxidative capacity towards recalcitrant compounds. The aim was consistent with the design of a process of oxidation of highly chlorinated PCBs, which is independent from their reductive dehalogenation. Feasibility was verified at a mesocosm scale and validated at pilot scale in a dynamic biopile pilot plant treating ten tons of a historically contaminated soil (9.28±0.08mg PCB/kg soil dry weight). Mixing of the SMS with the soil was required for the depletion of the contaminants. At the pilot scale, after eight months of incubation, 94.1% depletion was recorded. A positive correlation between Actinobacteria and Firmicutes active metabolism, soil laccase activity and PCB removal was observed. The SMS was found to be exploitable as a versatile low cost organic substrate capable of activating processes for the oxidation of highly chlorinated PCBs. Moreover, its exploitation as bulking agent in biopiles is a valuable management strategy for the re-utilisation of an organic waste deriving from the industrial cultivation of edible mushrooms.

The cost of controlling weakly degenerate parabolic equations by boundary controls

We consider the one-dimensional degenerate parabolic equation \begin{document}$u_t - (x^α u_x)_x =0 \;\;x∈(0,1), t ∈ (0,T) ,$ \end{document} controlled by a boundary force acting at the degeneracy point \begin{document}$ x=0$\end{document} . We study the reachable targets at some given time \begin{document}$T$\end{document} using \begin{document}$ H^1$\end{document} controls, studying the influence of the degeneracy parameter \begin{document}$ α ∈ [0,1)$\end{document} . First we obtain precise upper and lower bounds for the null controllability cost, proving that the cost blows up rationnally as \begin{document}$ \mathit{\alpha } \to {{\rm{1}}^{\rm{ - }}}$\end{document} and exponentially fast when \begin{document}$ \mathit{T} \to {{\rm{0}}^{\rm{ + }}}$\end{document} . Next, thanks to the special structure of the eigenfunctions of the problem, we investigate and obtain (partial) results concerning the structure of the reachable states. Our approach is based on the moment method developed by Fattorini and Russell [ 19 , 20 ]. To achieve our goals, we extend some of their general results concerning biorthogonal families, using complex analysis techniques developped by Seidman [ 48 ], Guichal [ 26 ], Tenenbaum-Tucsnak [ 49 ] and Lissy [ 35 , 36 ].

Prospects for crowdsourced information on the geomorphic ‘engineering’ by the invasive Coypu (Myocastor coypus)

AbstractAmong the most invasive species, the Coypu (Myocastor coypus) best exemplifies the widespread effect of alien species on ecosystems. Among the impacts, the induced erosion in riverbanks has an increasing economic and social importance. Despite its significance, this type of erosion is rarely quantified, and the available information is limited to local knowledge, grey literature, and maintenance reports. This research shows the potential of freely and instantly available Structure‐from‐Motion (SfM) photogrammetry to obtain crowdsourced information based on smartphone images. The results highlight how it is possible to provide a rough estimate of the damages with relatively low or null cost of application, and limited expert knowledge and expenditure of time, depending on the scale of analysis. The proposed technique provides a fresh approach to a known long‐standing issue, offering a new source of information for farmers, researchers, wildlife managers, as well as for land managers and planners. The potential applications of such a technique and its unprecedented ease of use and very low cost offer effective tools for management plans and scientific research, providing a basis to relate eroded volumes to the functioning of the drainage system and the connected agroecosystem. The method would also enable the opportunity of participatory and opportunistic crowdsourced sensing. Further scientific research on the crowd‐based data on erosion should encourage standardisation of data gathering and accessibility, together with a public involvement in information exchange, to generate a better understanding and awareness of erosion problems also for other fields of research. Copyright © 2016 John Wiley & Sons, Ltd.

Alternating between pro- and antisaccades: switch-costs manifest via decoupling the spatial relations between stimulus and response.

Antisaccades are a nonstandard task requiring a response mirror-symmetrical to the location of a target. The completion of an antisaccade has been shown to delay the reaction time (RT) of a subsequent prosaccade, whereas the converse switch elicits a null RT cost (i.e., the unidirectional prosaccade switch-cost). The present study sought to determine whether the prosaccade switch-cost arises from low-level interference specific to the sensory features of a target (i.e., modality-dependent) or manifests via the high-level demands of dissociating the spatial relations between stimulus and response (i.e., modality-independent). Participants alternated between pro- and antisaccades wherein the target associated with the response alternated between visual and auditory modalities. Thus, the present design involved task-switch (i.e., switching from a pro- to antisaccade and vice versa) and modality-switch (i.e., switching from a visual to auditory target and vice versa) trials as well as their task- and modality-repetition counterparts. RTs were longer for modality-switch than modality-repetition trials. Notably, however, modality-switch trials did not nullify or lessen the unidirectional prosaccade switch-cost; that is, the magnitude of the RT cost for task-switch prosaccades was equivalent across modality-switch and modality-repetition trials. Thus, competitive interference within a sensory modality does not contribute to the unidirectional prosaccade switch-cost. Instead, the modality-independent findings evince that dissociating the spatial relations between stimulus and response instantiates a high-level and inertially persistent nonstandard task-set that impedes the planning of a subsequent prosaccade.

Pharmacophore Modeling, Docking and Molecular Dynamics Studies on Caspase-3 Activators Binding at β-Tubulin Site.

Induction of apoptosis by the activation of caspase 3 makes it a promising target for designing anticancer drugs hence an investigation for the essential structural features mandatory for caspase 3 activation has been carried out using a dataset comprising of caspase 3 activator candidate drug Azixa in phase II clinical trial and its analogs using DS2.0. A training set of 40 compounds was selected for the purpose of model generation from 76 molecules with an activity range spanning from 0.002μM to 6.9μM. Among the generated pharmacophore models, the best model Hypo1 constituted by two hydrophobic aliphatic (Hal), two hydrophobic aromatic (Har), and one hydrogen bond acceptor (HBA) features with a correlation coefficient of 0.85, and a cost difference (null cost - total cost) of 46 bits well predicted the test set of 36 compounds (Rpred = 0.8). The key mechanism conferring caspase 3 activation is due to binding of Azixa at β-tubulin site that is located close to or at same site as colchicine. In the absence of co-crystal structure we have proposed a binding mode of Azixa at the tubulin site by performing docking studies and performed molecular dynamics simulation to ascertain the temporal changes of the protein-ligand complex.

The influence of doctor-patient and midwife-patient relationship in quality care perception of italian pregnant women: an exploratory study.

BackgroundThe study focuses on the perceived nature / technique opposition in pregnancy and delivery emerging from gynaecologist/ midwife/ pregnant woman relationships. We developed a cross-sectional survey to identify, by means of a multidimensional data-driven approach, the main latent concepts structuring the between items correlation correspondent to the different general opinions present in the data set. The obtained results can set the basis to improve patient satisfaction while decreasing healthcare costs.MethodsThe sample is made of 90 pregnant women within 24-48 hours after natural or operative birth, from three maternity units in Italy. Women filled in a questionnaire about their relationship with gynaecologist and midwife during pregnancy and hospital stay for delivery.ResultsParticipation rate approached 100%. The emerging factorial structure gave a proof-of-concept of the hypothesis of ‘nature vs. technique’ as the main dimension shaping women opinions. The results highlighted the role of midwife as the ‘link’ between the natural and technical dimension of birth. The quality of welcome and the establishing of an empathic relation between mother and healthcare professional was shown to decrease further request of care in the post-partum period.ConclusionsThe “fault plane” between nature and technique is a very critical zone for litigation. Women are particularly sensitive to the consideration and attention they receive at their admission in the hospital, as well as to the quality of human relationship with midwife. The perceived quality of welcome scaled with a decreased need of additional care and, more in general, with a more faithful attitude towards health professionals. We hypothesize that increasing the quality of welcome can exert an effect on both welfare costs and litigation. This opens the way (through an extension of this pilot study to wider populations) to relevant ameliorative actions on quality of care at practically null cost.

Cost-free feed-in tariffs for renewable energy deployment in Spain

Feed-in-tariff (FIT) schemes have been widely employed to promote renewable energy deployment. While FITs may be perceived by consumers as an extra cost, renewable energies cause a noticeable price reduction in wholesale electricity markets. We analyse both effects for the case of the Spanish electricity market during 2010. In particular, we examine the level of FITs that makes savings and extra costs to be similar on an hourly basis. Results are obtained for a wide range of renewable generation scenarios. It is found that FITs with null extra costs for consumers are in the range of 50–80 €/MWh. Some of the side-effects of a high penetration of renewable energy in the market are analysed in detail and discussed.

PRM237 - Bayesian Models for Cost-Effectiveness Analysis in the Presence of Structural Zero Costs

Bayesian modelling for cost-effectiveness data has received much attention in both the health economics and the statistical literature in recent years. Cost-effectiveness data are characterised by a relatively complex structure of relationships linking the suitable measure of clinical benefit (\eg QALYs) and the associated costs. Simplifying assumptions, such as (bivariate) normality of the underlying distributions are usually not granted, particularly for the cost variable, which is characterised by markedly skewed distributions. In addition, individual-level datasets are often characterised by the presence of structural zeros in the cost variable. Hurdle models can be used to account for the presence of excess zeros in a distribution and have been applied in the context of cost data. We extend their application to cost-effectiveness data, defining a full Bayesian model which consists of a selection model for the subjects with null costs, a marginal model for the costs and a conditional model for the measure of effectiveness (conditionally on the observed costs). The model is presented using a working example to describe its main features.