Net Preference Research Articles

Role of the long non-coding RNA PVT1 in the dysregulation of the ceRNA-ceRNA network in human breast cancer.

Recent findings have identified competing endogenous RNAs (ceRNAs) as the drivers in many disease conditions, including cancers. The ceRNAs indirectly regulate each other by reducing the amount of microRNAs (miRNAs) available to target messenger RNAs (mRNAs). The ceRNA interactions mediated by miRNAs are modulated by a titration mechanism, i.e. large changes in the ceRNA expression levels either overcome, or relieve, the miRNA repression on competing RNAs; similarly, a very large miRNA overexpression may abolish competition. The ceRNAs are also called miRNA “decoys” or miRNA “sponges” and encompass different RNAs competing with each other to attract miRNAs for interactions: mRNA, long non-coding RNAs (lncRNAs), pseudogenes, or circular RNAs. Recently, we developed a computational method for identifying ceRNA-ceRNA interactions in breast invasive carcinoma. We were interested in unveiling which lncRNAs could exert the ceRNA activity. We found a drastic rewiring in the cross-talks between ceRNAs from the physiological to the pathological condition. The main actor of this dysregulated lncRNA-associated ceRNA network was the lncRNA PVT1, which revealed a net biding preference towards the miR-200 family members in normal breast tissues. Despite its up-regulation in breast cancer tissues, mimicked by the miR-200 family members, PVT1 stops working as ceRNA in the cancerous state. The specific conditions required for a ceRNA landscape to occur are still far from being determined. Here, we emphasized the importance of the relative concentration of the ceRNAs, and their related miRNAs. In particular, we focused on the withdrawal in breast cancer tissues of the PVT1 ceRNA activity and performed a gene expression and sequence analysis of its multiple isoforms. We found that the PVT1 isoform harbouring the binding site for a representative miRNA of the miR-200 family shows a drastic decrease in its relative concentration with respect to the miRNA abundance in breast cancer tissues, providing a plausibility argument to the breakdown of the sponge program orchestrated by the oncogene PVT1.

Controlled and Chemoselective Hydrogenation of Nitrobenzene over Ru@C60 Catalysts

Electron-deficient ruthenium nanoparticles supported on Ru fulleride nanospheres allow the successive and chemoselective hydrogenation of nitrobenzene to aniline and then to cyclohexylamine. The catalysts were prepared in a straightforward manner by decomposition under dihydrogen of [Ru(COD)(COT)] in the presence of C60. The nitrobenzene hydrogenation reaction is solvent sensitive and proceeds more quickly in methanol than in other alcohols. The same behavior, i.e. a two-step successive hydrogenation, has been observed for several substituted nitroarenes. Density functional theory calculations suggest that the observed chemoselectivity is mainly governed by the presence of surface hydrides on the electron-deficient Ru nanoparticles. At the threshold value of 1.5 H per Ru surface atom, the formation of aniline is favored due to the net preference of the NO2 coordination.

An algorithmic approach to group decision making problems under fuzzy and dynamic environment

Our paper introduces a new methodology to solve group decision-making problems under fuzzy and dynamic environment. The methodology takes group members’ linguistically defined pair wise preferences of alternatives in different time intervals and aggregates them across the intervals to obtain each member's net preference levels. Each member's net preference levels are again aggregated across the members to obtain the group's preference. Our paper attaches higher importance to the members whose involvement in the decision process is more recent than the members who opined their views in the past. The fuzzy aggregation operator, IOWA (Induced Ordered Weighted Average) is used to aggregate their views in accordance to their importance in the group. The Ranked_List algorithm, introduced in our paper, inputs the aggregated views of the members in pair wise form and produces the set of sequences of ranked list of alternatives representing the group's consensus view as output. The Ranked_List algorithm is validated and analyzed through a series of synthetic data sets and its results are compared with a movie selection case study. The methodology is illustrated with a numerical example.

Bidirectional helical motility of cytoplasmic dynein around microtubules.

Cytoplasmic dynein is a molecular motor responsible for minus-end-directed cargo transport along microtubules (MTs). Dynein motility has previously been studied on surface-immobilized MTs in vitro, which constrains the motors to move in two dimensions. In this study, we explored dynein motility in three dimensions using an MT bridge assay. We found that dynein moves in a helical trajectory around the MT, demonstrating that it generates torque during cargo transport. Unlike other cytoskeletal motors that produce torque in a specific direction, dynein generates torque in either direction, resulting in bidirectional helical motility. Dynein has a net preference to move along a right-handed helical path, suggesting that the heads tend to bind to the closest tubulin binding site in the forward direction when taking sideways steps. This bidirectional helical motility may allow dynein to avoid roadblocks in dense cytoplasmic environments during cargo transport.

Frequency shifts in the myelin water compartment

Frequency shifts in the myelin water compartment

Cross-helicity in Rotating Homogeneous Shear-Stratified Turbulence

We consider homogeneous shear-stratified turbulence in a rotating frame, that exhibits complex nonlinear dynamics. Since the analysis of relative orientation between coupled fluctuating fields helps us to understand turbulence dynamics, we focus on the alignment properties of both the velocity and gravity fields with the potential vorticity gradient. With the help of statistical mechanics, we define a vector field which plays a role in the analogous so-called cross-helicity in magnetohydrodynamics. High-resolution direct numerical simulations of developed homogeneous baroclinic turbulence are performed, and a detailed analysis of probability density functions for cross-helicity is provided. A net preference for positive cross-helicity is shown to be related to a new alignment mechanism. We argue that the analysis of cross-helicity is crucial for understanding the dynamics of buoyancy driven flows.

Computational analysis identifies a sponge interaction network between long non-coding RNAs and messenger RNAs in human breast cancer

BackgroundNon-coding RNAs (ncRNAs) are emerging as key regulators of many cellular processes in both physiological and pathological states. Moreover, the constant discovery of new non-coding RNA species suggests that the study of their complex functions is still in its very early stages. This variegated class of RNA species encompasses the well-known microRNAs (miRNAs) and the most recently acknowledged long non-coding RNAs (lncRNAs). Interestingly, in the last couple of years, a few studies have shown that some lncRNAs can act as miRNA sponges, i.e. as competing endogenous RNAs (ceRNAs), able to reduce the amount of miRNAs available to target messenger RNAs (mRNAs).ResultsWe propose a computational approach to explore the ability of lncRNAs to act as ceRNAs by protecting mRNAs from miRNA repression. A seed match analysis was performed to validate the underlying regression model. We built normal and cancer networks of miRNA-mediated sponge interactions (MMI-networks) using breast cancer expression data provided by The Cancer Genome Atlas.ConclusionsOur study highlights a marked rewiring in the ceRNA program between normal and pathological breast tissue, documented by its “on/off” switch from normal to cancer, and vice-versa. This mutually exclusive activation confers an interesting character to ceRNAs as potential oncosuppressive, or oncogenic, protagonists in cancer. At the heart of this phenomenon is the lncRNA PVT1, as illustrated by both the width of its antagonist mRNAs in normal-MMI-network, and the relevance of the latter in breast cancer. Interestingly, PVT1 revealed a net binding preference towards the mir-200 family as the bone of contention with its rival mRNAs.

Traditional Nets Interfere with the Uptake of Long-Lasting Insecticidal Nets in the Peruvian Amazon: The Relevance of Net Preference for Achieving High Coverage and Use

BackgroundWhile coverage of long-lasting insecticide-treated nets (LLIN) has steadily increased, a growing number of studies report gaps between net ownership and use. We conducted a mixed-methods social science study assessing the importance of net preference and use after Olyset® LLINs were distributed through a mass campaign in rural communities surrounding Iquitos, the capital city of the Amazonian region of Peru.MethodsThe study was conducted in the catchment area of the Paujil and Cahuide Health Centres (San Juan district) between July 2007 and November 2008. During a first qualitative phase, participant observation and in-depth interviews collected information on key determinants for net preference and use. In a second quantitative phase, a survey among recently confirmed malaria patients evaluated the acceptability and use of both LLINs and traditional nets, and a case control study assessed the association between net preference/use and housing structure (open vs. closed houses).ResultsA total of 10 communities were selected for the anthropological fieldwork and 228 households participated in the quantitative studies. In the study area, bed nets are considered part of the housing structure and are therefore required to fulfil specific architectural and social functions, such as providing privacy and shelter, which the newly distributed Olyset® LLINs ultimately did not. The LLINs' failure to meet these criteria could mainly be attributed to their large mesh size, transparency and perceived ineffectiveness to protect against mosquitoes and other insects, resulting in 63.3% of households not using any of the distributed LLINs. Notably, LLIN usage was significantly lower in houses with no interior or exterior walls (35.2%) than in those with walls (73.8%) (OR = 5.2, 95CI [2.2; 12.3], p<0.001).ConclusionNet preference can interfere with optimal LLIN use. In order to improve the number of effective days of LLIN protection per dollar spent, appropriate quantitative and qualitative methods for collecting information on net preference should be developed before any LLIN procurement decision is made.

Intermolecular C–H Amination of Complex Molecules: Insights into the Factors Governing the Selectivity

Transition-metal-catalyzed C-H amination via nitrene insertion allows the direct transformation of a C-H into a C-N bond. Given the ubiquity of C-H bonds in organic compounds, such a process raises the problem of regio- and chemoselectivity, a challenging goal even more difficult to tackle as the complexity of the substrate increases. Whereas excellent regiocontrol can be achieved by the use of an appropriate tether securing intramolecular addition of the nitrene, the intermolecular C-H amination remains much less predictable. This study aims at addressing this issue by capitalizing on an efficient stereoselective nitrene transfer involving the combination of a chiral aminating agent 1 with a chiral rhodium catalyst 2. Allylic C-H amination of terpenes and enol ethers occurs with excellent yields as well as with high regio-, chemo-, and diastereoselectivity as a result of the combination of steric and electronic factors. Conjugation of allylic C-H bonds with the π-bond would explain the chemoselectivity observed for cyclic substrates. Alkanes used in stoichiometric amounts are also efficiently functionalized with a net preference for tertiary equatorial C-H bonds. The selectivity, in this case, can be rationalized by steric and hyperconjugative effects. This study, therefore, provides useful information to better predict the site of C-H amination of complex molecules.

An exploratory study of treated-bed nets in Timor-Leste: patterns of intended and alternative usage

BackgroundThe Timor-Leste Ministry of Health has recently finalized the National Malaria Control Strategy for 2010-2020. A key component of this roadmap is to provide universal national coverage with long-lasting insecticide-treated nets (LLINs) in support of achieving the primary goal of reducing both morbidity and mortality from malaria by 30% in the first three years, followed by a further reduction of 20% by end of the programme cycle in 2020 [1]. The strategic plan calls for this target to be supported by a comprehensive information, education and communication (IEC) programme; however, there is limited prior research into household and personal usage patterns to assist in the creation of targeted, effective, and socio-culturally specific behaviour change materials.MethodsNine separate focus group discussions (FGDs) were carried out in Dili, Manatuto, and Covalima districts, Democratic Republic of Timor-Leste, in July 2010.These focus groups primarily explored themes of perceived malaria risk, causes of malaria, net usage patterns within families, barriers to correct and consistent usage, and the daily experience of users (both male and female) in households with at least one net. Comprehensive qualitative analysis utilized open source analysis software.ResultsThe primary determinants of net usage were a widespread perception that nets could or should only be used by pregnant women and young children, and the availability of sufficient sleeping space under a limited number of nets within households. Both nuisance biting and disease prevention were commonly cited as primary motivations for usage, while seasonality was not a significant factor. Long-term net durability and ease of hanging were seen as key attributes in net design preference. Very frequent washing cycles were common, potentially degrading net effectiveness. Finally, extensive re-purposing of nets (fishing, protecting crops) was both reported and observed, and may significantly decrease availability of nighttime sleeping space for all family members if distributed nets do not remain within the household.ConclusionsEmphasizing that net usage is acceptable and important for all family members regardless of age or gender, and addressing the complex behavioural economics of alternative net usages could have significant impacts on malaria control efforts in Timor-Leste, as the country's programmes make progress towards universal net coverage.

Update on the role of palliative oxygen

Breathlessness remains a frequent and burdensome symptom for individuals with life-limiting symptoms in both malignant and nonmalignant settings. As oxygen therapy is frequently given as part of the management of breathlessness and is associated with costs, treatment burden and potential dangers, it is timely to review the efficacy and appropriateness of palliative oxygen therapy. Despite the widespread use of oxygen therapy in clinical and community settings, data supporting this approach is sparse. The benefits of long-term oxygen therapy for severely hypoxaemic people with chronic obstructive pulmonary disease are proven; however, mounting evidence suggests that oxygen does not confer additional benefit over medical air for the relief of refractory breathlessness in people with mild or absent hypoxaemia. On the basis of the findings of this review, the routine use of palliative oxygen therapy without detailed assessment of pathogenesis and reversibility of symptoms cannot be justified. Promoting self-management strategies, such as cool airflow across the face, exercise and psychological support for patients and carers, should be considered before defaulting to oxygen therapy. If palliative oxygen therapy is considered for individuals with transient or mild hypoxaemia, a therapeutic trial should be conducted with clinical review after 3 days to assess the net clinical benefit and patient preference.

Dopamine and effort-based decision making

Motivational theories of choice focus on the influence of goal values and strength of reinforcement to explain behavior. By contrast relatively little is known concerning how the cost of an action, such as effort expended, contributes to a decision to act. Effort-based decision making addresses how we make an action choice based on an integration of action and goal values. Here we review behavioral and neurobiological data regarding the representation of effort as action cost, and how this impacts on decision making. Although organisms expend effort to obtain a desired reward there is a striking sensitivity to the amount of effort required, such that the net preference for an action decreases as effort cost increases. We discuss the contribution of the neurotransmitter dopamine (DA) toward overcoming response costs and in enhancing an animal's motivation toward effortful actions. We also consider the contribution of brain structures, including the basal ganglia and anterior cingulate cortex, in the internal generation of action involving a translation of reward expectation into effortful action.

A single-layer perceptron with PROMETHEE methods using novel preference indices

The Preference Ranking Organization METHods for Enrichment Evaluations (PROMETHEE) methods, based on the outranking relation theory, are used extensively in multi-criteria decision aid (MCDA). In particular, preference indices with weighted average aggregation representing the intensity of preference for one pattern over another pattern are measured by various preference functions. The higher the intensity, the stronger the preference is indicated. For MCDA, to obtain the ranking of alternatives, compromise operators such as the weighted average aggregation, or the disjunctive operators are often employed to aggregate the performance values of criteria. The compromise operators express the group utility or the majority rule, whereas the disjunctive operators take into account the strongly opponent or agreeable minorities. Since these two types of operators have their own unique features, it is interesting to develop a novel aggregator by integrating them into a single aggregator for a preference index. This study aims to develop a novel PROMETHEE-based single-layer perceptron (PROSLP) for pattern classification using the proposed preference index. The assignment of a class label to a pattern is dependent on its net preference index, which is obtained by the proposed perceptron. Computer simulations involving several real-world data sets reveal the classification performance of the proposed PROMETHEE-based SLP. The proposed perceptron with the novel preference index performs well compared to that with the original one.

Integrating multicriteria PROMETHEE II method into a single-layer perceptron for two-class pattern classification

PROMETHEE methods based on the outranking relation theory are extensively used in multicriteria decision aid. A preference index representing the intensity of preference for one pattern over another pattern can be measured by various preference functions. The higher the intensity, the stronger the preference is indicated. In contrast to traditional single-layer perceptrons (SLPs) with the sigmoid function, this paper develops a novel PROMETHEE II-based SLP using concepts from the PROMETHEE II method involving pairwise comparisons between patterns. The assignment of a class label to a pattern is dependent on its net preference index, which the proposed perceptron obtains. Specially, this study designs a genetic-algorithm-based learning algorithm to determine the relative weights of respective criteria in order to derive the preference index for any pair of patterns. Computer simulations involving several real-world data sets reveal the classification performance of the proposed PROMETHEE II-based SLP. The proposed perceptron performs well compared to the other well-known fuzzy or non-fuzzy classification methods.

A cluster randomized controlled cross-over bed net acceptability and preference trial in Solomon Islands: community participation in shaping policy for malaria elimination

BackgroundA key component of the malaria elimination strategy in Solomon Islands (SI) is widespread coverage of long-lasting insecticidal nets (LLINs). The success of this strategy is dependent on LLIN acceptability and compliance. There has been unresolved debate among policy makers and donors as to which type of LLIN would be most appropriate for large-scale distribution in SI, and anecdotal reports of a lack of acceptability of certain brands of LLINs. A cluster randomized controlled crossover bed net acceptability and preference trial was therefore carried out from July to September, 2008 to inform policy and to facilitate community engagement and participation in the selection of the most appropriate LLIN for use in SI.MethodA three-stage sampling method was used to randomly select the study population from Malaita Province, SI. Three brands of LLINs were assessed in this study: Olyset®, PermaNet® and DuraNet®. Bed net acceptability and preference were evaluated through surveys at three defined time points after short and longer-term trial of each LLIN.ResultsThe acceptability of PermaNet® after short-term use (96.5%) was significantly greater than Olyset® (67.3%, p < 0.001) and DuraNet® (69.8%, p < 0.001). The acceptability of DuraNet® and Olyset® after short-term use was not significantly different at the 5% level. LLINs that were perceived not to prevent mosquito bites were significantly less acceptable than LLINs that were perceived to prevent mosquito bites (OR 0.15; 95%CI 0.03 to 0.6). LLINs that allow a pleasant night's sleep (OR 6.3; 95%CI:3.3-12.3) and have a soft texture (OR 5.7; 95%CI:1.9-20.5) were considered more acceptable than those that did not. Olyset®'s acceptability decreased over time and this was due to net wrinkling/shrinkage after washing resulting in reduced efficiency in preventing mosquito bites. The increase in DuraNet® acceptability was a result of a reduction in minor adverse events following longer-term use.ConclusionThis research was conducted to inform LLIN procurement as part of the national malaria control and elimination programme in SI. The success of malaria elimination in the Pacific and elsewhere relies on provision of acceptable interventions, consideration of local-level realities and engagement of communities in strategy development.Trial RegistrationsClinical trials ACTRN12608000322336

Dissociative Adsorption of Methane on Surface Oxide Structures of Pd−Pt Alloys

The dissociative adsorption of methane on variously oxidized Pd, Pt and Pd-Pt surfaces is investigated using density-functional theory, as a step towards understanding the combustion of methane on these materials. For Pd-Pt alloys, models of surface oxide structures are built on the basis of known oxides on Pd and Pt. The methane adsorption energy presents large variations depending on the oxide structure and composition. Adsorption is endothermic on the bare Pd(111) metal surface as well as on stable thin layer oxide structures such as the ($\sqrt{5}\times\sqrt{5}$) surface oxide on Pd(100) and the PtO$_2$-like oxide on Pt(111). Instead, large adsorption energies are obtained for the (100) surface of bulk PdO, for metastable mixed Pd$_{1-x}$Pt$_x$O$_{4/3}$ oxide layers on Pt(100), and for Pd-Pt(111) surfaces covered with one oxygen monolayer. In the latter case, we find a net thermodynamic preference for a direct conversion of methane to methanol, which remains adsorbed on the oxidized metal substrates via weak hydrogen-bond interactions.

The Sex Composition of Two-Children Families: Heterogeneity and Selection for the Third Child: Comment on Stansfield and Carlton (2009)

The Sex Composition of Two-Children Families: Heterogeneity and Selection for the Third Child: Comment on Stansfield and Carlton (2009) Michel Garenne The study presented by Stansfield and Carlton (2009) (in this issue of Human Biology, pp. 3–11) raises several issues about the sex ratio at birth and family composition and focuses on the sex composition of two-children families in the context of family limitation. Under the assumption of homogeneity (each couple has the same probability of bearing a male or a female each time), the number of male and female children ever born is provided by a binomial distribution: For one birth: p for one male and (1 − p) for one female. For two births: p2 for two males, 2p(1 − p) for one male and one female, and (1 − p)2 for two females. For three births: p3 for three males, 3p2(1 − p) for two males and one female, 3p(1 − p)2 for two females and one male, and (1 − p)3 for three females. Using French vital registration data, Malinvaud (1955) showed that there was heterogeneity and asymmetry in the probability of bearing a boy or a girl, most likely for biological reasons. We have reanalyzed the same data set and have estimated the extent of the heterogeneity (Garenne 2009a).With an average of p = 0.51440, the coefficient of variation is σ/p = 0.09007, and the skewness equals −0.58605. The same coefficient of variation and the same skewness could be applied to U.S. data, with p = 0.51187 (U.S. vital registration data for 1987–2002). Under the assumption of heterogeneity, the formulas listed earlier still apply but p is replaced with E(p), p2 with E(p2), and p3 with E(p3), which are all values that can be derived from the coefficient of variation and the skewness. The distribution of two-children families in the population depends on these sex distributions of births and on parity progression ratios (an), that is, on the probability of having (n + 1) births given n births already. In populations practicing contraception, parity progression ratios might depend on family composition, that is, on the number of previous males and females already born, for behavioral reasons. For the United States, published values of parity progression ratios, on average for all family compositions, are a0 = 0.846, a1 = 0.659, and a2 = 0.309 (Frejka and Sardon 2007). Altogether, if we assume the sex ratio at birth observed in the U.S. vital registration, the heterogeneity observed in France, and a constant parity progression ratio, then we are not able to fit the 1987–1993 National Health Interview Survey (NHIS) data on the distribution of sexes in two-children families. There are too many balanced families of one boy and one girl (51.4% observed against 49.5% expected, P <10–13) and not enough two-girl families (22.2% observed against [End Page 97] 24.0% expected, P <10–99), whereas the proportion of two-boy families was as expected (P = 0.095) (Table 1). This has already been noted by Will Lassek and Stansfield and Carlton (2009). Click for larger view View full resolution Table 1. Observed and Expected Distribution of Two-Children Families Under Various Assumptions, United States We solved the equations and found that the data could be fitted by assuming differential parity progression ratios: a2 = 0.282 when one boy and one girl are already born, a2 = 0.308 when two boys are already born, and a2 = 0.361 when two girls are already born. This shows that U.S. families seem to have a net preference for stopping after two children when they have a balanced family (one boy and one girl) and are more likely to have a third child if they already have two girls than if they already have two boys. This pattern of differential parity progression ratios produces a deficit of females in two-children families, simply by selection bias. The sex ratio becomes 1.088 instead of 1.049 for all births combined. This could explain the...

ONIOM investigation of nucleotide selectivity in phosphodiesterases 3 and 4

AbstractThe cyclic nucleotide phosphodiesterases (PDEs) are drug‐targeted enzymes that down regulate cyclic nucleotide concentrations in the cell by catalyzing the hydrolysis of the O3′‐phosphorous bond, yielding the noncyclic nucleotides. Selectivity for cAMP versus cGMP (cyclic 3′,5′‐adenosine/‐guanosine monophosphate) as the favored substrate is primarily attributed to the orientation of a conserved glutamine residue which binds to the adenine/guanine ring. We use ONIOM hybrid quantum methods to accurately describe substrate binding within the catalytic sites of the cAMP‐specific PDE4 and the cGMP‐inhibited, dual‐specific PDE3 in order to understand subtle aspects of substrate selectivity. We estimate PDE4's net preference for cAMP binding to be about 16 kcal/mol; the cause of cAMP's known preference resides both in its fixed glutamine orientation (Gln 369 in PDE4D) and in the differential free energy of solvation, which disfavors the binding of cGMP relative to cAMP by about 15 kcal/mol. Also, we discuss the contributing role played by Asn 321, held in place by a partner Asp 167, in the deselection of cGMP by PDE4. PDE3's conserved glutamine (Gln 988 in PDE3B) is free to take on either a cGMP‐favorable or cAMP‐favorable orientation. We find that enthalpies of binding favor cGMP for PDE3, but only by the same amount as free energies of solvation disfavor cGMP binding. Comparison of the PDE3‐cAMP and ‐cGMP complexes and energetics reveals cAMP to be more susceptible to the attack of the hydroxide nucleophile in PDE3. We identify a key threonine residue (Thr 952) as responsible for PDE3's kinetic relative disfavor of cGMP hydrolysis by causing Gln 988 to tilt out of cGMP's purine plane. Our results are consistent with the PDE3's kinetic specificity for cAMP hydrolysis and the known competitive inhibition of PDE3 by cGMP. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008

Mapping the Bounds of Incoherence: How Far Can You Go and How Does It Affect Your Brand?

Consumers often have to evaluate products comprising a combination of attributes that is not expected by them, given their beliefs about how attributes normally co-vary in the product category. Such an attribute combination implies that the claimed level of a product attribute is then different from what the consumer might infer, given the level of another attribute, resulting in what we call product incoherence. We develop a model to calibrate the effect of incoherence on perceptions, uncertainty, preference, and ultimately purchase. Our model can allow managers to determine consumers’ acceptance for different positions in the multiattribute space, so they can optimize their product’s positioning. Our model implies that a product that combines positively valued attributes might increase some elements of preference for the product, but if those attributes occur in unexpected combinations, incoherence will also increase uncertainty which in turn might lower other elements of preference. The net risk-adjusted preference for a product in our model accommodates both the benefit from the expected attribute levels and the uncertainty associated with incoherence. We derive implications from the model and provide an empirical test that supports those implications.

Effect of Metal Ions (Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) and Water Coordination on the Structure of Glycine and Zwitterionic Glycine

Interactions between metal ions and amino acids are common both in solution and in the gas phase. Here, the effect of metal ions and water on the structure of glycine is examined. The effect of metal ions (Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) and water on structures of Gly.Mn+(H2O)m and GlyZwitt.Mn+(H2O)m (m = 0, 2, 5) complexes have been determined theoretically by employing the hybrid B3LYP exchange-correlation functional and using extended basis sets. Selected calculations were carried out also by means of CBS-QB3 model chemistry. The interaction enthalpies, entropies, and Gibbs energies of eight complexes Gly.Mn+ (Mn+ = Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) were determined at the B3LYP density functional level of theory. The computed Gibbs energies DeltaG degrees are negative and span a rather broad energy interval (from -90 to -1100 kJ mol(-1)), meaning that the ions studied form strong complexes. The largest interaction Gibbs energy (-1076 kJ mol(-1)) was computed for the NiGly2+ complex. Calculations of the molecular structure and relative stability of the Gly.Mn+(H2O)m and GlyZwitt.Mn+(H2O)m (Mn+ = Li+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+; m = 0, 2, and 5) systems indicate that in the complexes with monovalent metal cations the most stable species are the NO coordinated metal cations in non-zwitterionic glycine. Divalent cations Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+ prefer coordination via the OO bifurcated bonds of the zwitterionic glycine. Stepwise addition of two and five water molecules leads to considerable changes in the relative stability of the hydrated species. Addition of two water molecules at the metal ion in both Gly.Mn+ and GlyZwitt.Mn+ complexes reduces the relative stability of metallic complexes of glycine. For Mn+ = Li+ or Na+, the addition of five water molecules does not change the relative order of stability. In the Gly.K+ complex, the solvation shell of water molecules around K+ ion has, because of the larger size of the potassium cation, a different structure with a reduced number of hydrogen-bonded contacts. This results in a net preference (by 10.3 kJ mol(-1)) of the GlyZwitt.K+H2O5 system. Addition of five water molecules to the glycine complexes containing divalent cations Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+ results in a net preference for non-zwitterionic glycine species. The computed relative Gibbs energies are quite high (-10 to -38 kJ mol(-1)), and the NO coordination is preferred in the Gly.Mn+(H2O)5 (Mn+ = Mg2+, Ca2+, Ni2+, Cu2+, and Zn2+) complexes over the OO coordination.