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Showing papers by "University of Arkansas published in 2008"


Journal ArticleDOI
TL;DR: This work draws from the vast body of research on the technology acceptance model (TAM) to develop a comprehensive nomological network of the determinants of individual level IT adoption and use and present a research agenda focused on potential pre- and postimplementation interventions that can enhance employees' adopted and use of IT.
Abstract: Prior research has provided valuable insights into how and why employees make a decision about the adoption and use of information technologies (ITs) in the workplace. From an organizational point of view, however, the more important issue is how managers make informed decisions about interventions that can lead to greater acceptance and effective utilization of IT. There is limited research in the IT implementation literature that deals with the role of interventions to aid such managerial decision making. Particularly, there is a need to understand how various interventions can influence the known determinants of IT adoption and use. To address this gap in the literature, we draw from the vast body of research on the technology acceptance model (TAM), particularly the work on the determinants of perceived usefulness and perceived ease of use, and: (i) develop a comprehensive nomological network (integrated model) of the determinants of individual level (IT) adoption and use; (ii) empirically test the proposed integrated model; and (iii) present a research agenda focused on potential pre- and postimplementation interventions that can enhance employees' adoption and use of IT. Our findings and research agenda have important implications for managerial decision making on IT implementation in organizations.

5,246 citations


Journal ArticleDOI
TL;DR: Investigation of the persuasive impact and detectability of normative social influence shows that normative messages can be a powerful lever of persuasion but that their influence is underdetected.
Abstract: The present research investigated the persuasive impact and detectability of normative social influence. The first study surveyed 810 Californians about energy conservation and found that descriptive normative beliefs were more predictive of behavior than were other relevant beliefs, even though respondents rated such norms as least important in their conservation decisions. Study 2, a field experiment, showed that normative social influence produced the greatest change in behavior compared to information highlighting other reasons to conserve, even though respondents rated the normative information as least motivating. Results show that normative messages can be a powerful lever of persuasion but that their influence is underdetected.

1,493 citations


Journal ArticleDOI
TL;DR: A model is developed that employs behavioral intention, facilitating conditions, and behavioral expectation as predictors of the three conceptualizations of system use that explains 65 percent, 60 percent, and 60 percent of the variance in duration, frequency, and intensity ofSystem use respectively.
Abstract: Employees' underutilization of new information systems undermines organizations' efforts to gain benefits from such systems. The two main predictors of individual-level system use in prior research-behavioral intention and facilitating conditions-have limitations that we discuss. We introduce behavioral expectation as a predictor that addresses some of the key limitations and provides a better understanding of system use. System use is examined in terms of three key conceptualizations: duration, frequency, and intensity. We develop a model that employs behavioral intention, facilitating conditions, and behavioral expectation as predictors of the three conceptualizations of system use. We argue that each of these three determinants play different roles in predicting each of the three conceptualizations of system use. We test the proposed model in the context of a longitudinal field study of 321 users of a new information system. The model explains 65 percent, 60 percent, and 60 percent of the variance in duration, frequency, and intensity of system use respectively. We offer theoretical and practical implications for our findings.

726 citations


Journal ArticleDOI
TL;DR: The findings confirmed the theoretical argument that the strength of intention to predict continuance was weakened by a high level of IS habit, and presented strong support for the theoretical links of IS continuance model, and for the new moderating effect.

480 citations


Journal ArticleDOI
03 Oct 2008-Science
TL;DR: Science-based policy is essential for guiding an environmentally sustainable approach to cellulosic biofuels and it is important to have a strategy that acknowledges the role of science in promoting sustainability.
Abstract: Science-based policy is essential for guiding an environmentally sustainable approach to cellulosic biofuels.

441 citations


Journal ArticleDOI
TL;DR: The results suggest that team history may be necessary but not sufficient for teams to overcome the problems with the use of lean digital networks as a communication environment, but may present a window of opportunity for social capital to develop, which in turn allows teams to perform just as well as in either communication environment.
Abstract: To understand the impact of social capital on knowledge integration and performance within digitally enabled teams, we studied 46 teams who had a history and a future working together. All three dimensions of their social capital (structural, relational, and cognitive) were measured prior to the team performing two tasks in a controlled setting, one face-to-face and the other through a lean digital network. Structural and cognitive capital were more important to knowledge integration when teams communicated through lean digital networks than when they communicated face-to-face; relational capital directly impacted knowledge integration equally, regardless of the communication media used by the team. Knowledge integration, in turn, impacted team decision quality, suggesting that social capital influences team performance in part by increasing a team’s ability to integrate knowledge. These results suggest that team history may be necessary but not sufficient for teams to overcome the problems with the use of lean digital networks as a communication environment. However, team history may present a window of opportunity for social capital to develop, which in turn allows teams to perform just as well as in either communication environment.

404 citations


Journal ArticleDOI
TL;DR: This study introduces change detection based on object/neighbourhood correlation image analysis and image segmentation techniques and found that object‐based change classifications incorporating the OCIs or the NCIs produced more accurate change detection classes than other change detection results.
Abstract: This study introduces change detection based on object/neighbourhood correlation image analysis and image segmentation techniques. The correlation image analysis is based on the fact that pairs of brightness values from the same geographic area (e.g. an object) between bi-temporal image datasets tend to be highly correlated when little change occurres, and uncorrelated when change occurs. Five different change detection methods were investigated to determine how new contextual features could improve change classification results, and if an object-based approach could improve change classification when compared with per-pixel analysis. The five methods examined include (1) object-based change classification incorporating object correlation images (OCIs), (2) object-based change classification incorporating neighbourhood correlation images (NCIs), (3) object-based change classification without contextual features, (4) per-pixel change classification incorporating NCIs, and (5) traditional per-pixel change classification using only bi-temporal image data. Two different classification algorithms (i.e. a machine-learning decision tree and nearest-neighbour) were also investigated. Comparison between the OCI and the NCI variables was evaluated. Object-based change classifications incorporating the OCIs or the NCIs produced more accurate change detection classes (Kappa approximated 90%) than other change detection results (Kappa ranged from 80 to 85%).

403 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used the theory of Planned Behavior (TPB) as a framework to determine factors that influence digital piracy (the illegal copying/downloading of copyrighted software and media files).
Abstract: This study focuses on one of the newer forms of software piracy, known as digital piracy, and uses the Theory of Planned Behavior (TPB) as a framework to attempt to determine factors that influence digital piracy (the illegal copying/downloading of copyrighted software and media files). This study examines factors, which could determine an individual's intention to pirate digital material (software, media, etc.). Past piracy behavior and moral obligation, in addition to the prevailing theories of behavior (Theory of Planned Behavior), were studied to determine the influence on digital piracy intention. Based on the results of this study, planned behavioral factors in addition to past piracy behavior and moral obligation were found to influence an individual's intention to pirate digital material. Attitude, past piracy behavior, perceived behavior control, and moral obligation explained 71 percent of the intention to pirate variance. Using these results, a better understanding of why individuals pirate is presented and can be used to help combat digital piracy.

318 citations


Journal ArticleDOI
TL;DR: The SPI film incorporated with the combined GSE, nisin, and EDTA demonstrated the greatest inhibitory activity against Listeria monocytogenes, which has potential applications to maintain shelf life, and improve safety of ready-to-eat food products.

288 citations


Journal ArticleDOI
TL;DR: It is found that the majority of existing links are associated to weak trade relationships; the weighted WTW is only weakly disassortative; and countries holding more intense trade relationships are more clustered.
Abstract: This paper studies the topological properties of the World Trade Web (WTW) and its evolution over time by employing a weighted-network analysis. We show that the WTW, viewed as a weighted network, displays statistical features that are very different from those obtained by using a traditional binary-network approach. In particular, we find that: (i) the majority of existing links are associated to weak trade relationships; (ii) the weighted WTW is only weakly disassortative; (iii) countries holding more intense trade relationships are more clustered.

280 citations


Journal ArticleDOI
TL;DR: NMR techniques were applied to distinguish the bonded and free alkylamine ligands in an equilibrated adsorption/desorption system for the CdSe-amine nanocrystal-ligand pair and these constants are well consistent with the existing experimental observations.
Abstract: With CdSe nanocrystals stabilized with very weak ligands (pyridine) as the starting materials, NMR techniques were applied to distinguish the bonded and free alkylamine ligands in an equilibrated adsorption/desorption system for the CdSe−amine nanocrystal−ligand pair. NMR and photoluminescence (PL) measurements were further correlated to identify the linear relationship between PL intensity and the surface ligand coverage of the amine-coated CdSe nanocrystals. For 3.5 nm CdSe nanocrystals and octylamine ligands, the chemical equilibrium constant (K) of the CdSe−amine nanocrystal−ligand adsorption/desorption process was found to be around 50−100, and the corresponding ΔrGo was calculated as 9.8−11.5 kJ/mol. With a proposed mathematic method, the corresponding chemical kinetic constants for the desorption (kd) and adsorption (ka) processes were measured to be 0.01 s-1 and 0.5 L mol-1 s-1, respectively. K, kd, and ka obtained here are generally 2−4 magnitudes different from those estimated in literature. Ana...

Journal ArticleDOI
TL;DR: In this article, the authors examine potential explanations of why consumers have difficulty making personal financial decisions that will most beneficial in the long run, and find that consumers who express higher levels of future orientation are more likely to participate in a retirement plan.
Abstract: This research examines potential explanations of why consumers have difficulty making personal financial decisions that will be most beneficial in the long run. Within the decision context of retirement savings, results from an experiment suggest that self-regulatory state, future orientation, and financial knowledge can influence consumer evaluations and intentions related to retirement investments (i.e., a 401(k) plan). Findings suggest that consumers who express higher levels of future orientation are more likely to participate in a retirement plan, an effect moderated by self-regulatory state. Results also suggest that financial knowledge and orientation toward the future can interact to influence the likelihood of 401(k) plan participation. Among consumers with a basic level of financial knowledge, future-oriented consumers expressed a greater likelihood to participate in a retirement plan than less future–oriented consumers. However, in the absence of knowledge, consumers’ orientation toward the future did not influence the likelihood of 401(k) plan participation.

Journal ArticleDOI
TL;DR: A foreign incursion of similar strains of the wheat yellow rust fungus, Puccinia striiformis f.
Abstract: Rust fungi can overcome the effect of host resistance genes rapidly, and spores can disperse long distance by wind. Here we demonstrate a foreign incursion of similar strains of the wheat yellow rust fungus, Puccinia striiformis f. sp. tritici, in North America, Australia and Europe in less than 3 years. One strain defined by identity at 15 virulence loci and 130 amplified fragment length polymorphism (AFLP) fragments was exclusive to North America (present since 2000) and Australia (since 2002). Another strain of the same virulence phenotype, but differing in two AFLP fragments, was exclusive to Europe (present since 2000-2001) as well as Western and Central Asia and the Red Sea Area (first appearance unknown). This may be the most rapid spread of an important crop pathogen on the global scale. The limited divergence between the two strains and their derivatives, and the temporal-spatial occurrence pattern confirmed a recent spread. The data gave evidence for additional intercontinental dispersal events in the past, that is, many isolates sampled before 2000 in Europe, North America and Australia had similar AFLP fingerprints, and isolates from South Africa, which showed no divergence in AFLP, differed by only two fragments from particular isolates from Central Asia, West Asia and South Europe, respectively. Previous research has demonstrated that isolates of the two new strains produced up to two to three times more spores per day than strains found in USA and Europe before 2000, suggesting that increased aggressiveness at this level may accelerate global spread of crop pathogens.

Journal ArticleDOI
30 Apr 2008-PLOS ONE
TL;DR: The apparent discrepancy between microwear and functional anatomy is consistent with the idea that P. boisei presents a hominin example of Liem's Paradox, wherein a highly derived morphology need not reflect a specialized diet.
Abstract: The Plio-Pleistocene hominin Paranthropus boisei had enormous, flat, thickly enameled cheek teeth, a robust cranium and mandible, and inferred massive, powerful chewing muscles. This specialized morphology, which earned P. boisei the nickname ‘‘Nutcracker Man’’, suggests that this hominin could have consumed very mechanically challenging foods. It has been recently argued, however, that specialized hominin morphology may indicate adaptations for the consumption of occasional fallback foods rather than preferred resources. Dental microwear offers a potential means by which to test this hypothesis in that it reflects actual use rather than genetic adaptation. High microwear surface texture complexity and anisotropy in extant primates can be associated with the consumption of exceptionally hard and tough foods respectively. Here we present the first quantitative analysis of dental microwear for P. boisei. Seven specimens examined preserved unobscured antemortem molar microwear. These all show relatively low complexity and anisotropy values. This suggests that none of the individuals consumed especially hard or tough foods in the days before they died. The apparent discrepancy between microwear and functional anatomy is consistent with the idea that P. boisei presents a hominin example of Liem’s Paradox, wherein a highly derived morphology need not reflect a specialized diet.

Journal ArticleDOI
TL;DR: In neonates with symptomatic congenital CMV disease, valganciclovir oral solution provides plasma concentrations of ganciclovIR comparable to those achieved with administration of intravenous gancallovir, and the results of the present study cannot be extrapolated to extemporaneously compounded liquid formulations of valganCiclovirs.
Abstract: Background. Intravenous ganciclovir administered for 6 weeks improves hearing outcomes in infants with symptomatic congenital cytomegalovirus (CMV) disease involving the central nervous system. Methods. Twenty-four subjects received antiviral therapy for 6 weeks. Serial pharmacokinetic assessments were performed after administration ofvalganciclovir oral solution and of intravenous ganciclovir. Results. On the basis of a previous pharmacokinetic study of the use of intravenous ganciclovir in this population, a target AUC 12 (area under the concentration-time curve over a 12-h period) of 27 mg X h/L was defined. The median dose of oral valganciclovir administered in the present trial was 16 mg/kg, which produced a geometric mean AUC 12 of 27.4 mg X h/L. The bioavailability of valganciclovir was 41.1%. Of the 18 subjects who had detectable CMV in whole blood at baseline or during therapy, 11 had <4 log viral DNA copies/mL at baseline, and 7 had 3≥4 log viral DNA copies/mL at baseline; subjects who started the study with the higher viral burden experienced greater decreases in viral load but did not clear virus during the 42-day course of therapy. Neutropenia of grade 3 or 4 developed in 38% of subjects. Conclusions. In neonates with symptomatic congenital CMV disease, valganciclovir oral solution provides plasma concentrations of ganciclovir comparable to those achieved with administration of intravenous ganciclovir. The results of the present study cannot be extrapolated to extemporaneously compounded liquid formulations of valganciclovir.

Journal ArticleDOI
TL;DR: In this paper, the trade-off between child quantity and quality by exploiting exogenous variation in fertility under son preferences was estimated by exploiting the exogenous variations in fertility for the first child's gender.
Abstract: This study estimates the trade-off between child quantity and quality by exploiting exogenous variation in fertility under son preferences. Under son preferences, both sibling size and fertility timing are determined depending on the first child’s gender, which is random as long as parents do not abort girls at their first childbearing. For the sample South Korean households, I find strong evidence of unobserved heterogeneity in preferences for child quantity and quality across households. The trade-off is not as strong as observed cross-sectional relationships would suggest. However, even after controlling for unobserved heterogeneity, a greater number of siblings have adverse effects on per-child investment in education, in particular, when fertility is high.

Journal ArticleDOI
TL;DR: For instance, this paper found that adolescents who had lower levels of peer acceptance, number of friends, and friendship quality had higher teacher-reported maladjustment, while having high levels of friendship quality was an important buffer against adjustment problems.
Abstract: The unique contributions of peer acceptance, friendship, and victimization to adjustment were examined. How these relational systems moderate the influence of one another to influence adjustment was also investigated. Friendship quality, a unique aspect of friendship, was expected to be especially important for adjustment when other relational systems were poor. A total of 238 fifth to eighth graders (boys = 109) participated in the survey-style paradigm. Youth participants completed measures assessing their friendships and peer relationships. Teachers provided assessments of adjustment. Adolescents who had lower levels of peer acceptance, number of friends, and friendship quality had greater teacher-reported maladjustment. Friendship quality was also an important buffer against adjustment problems when peer acceptance and number of friends were low.The outcomes of this article suggest that an approach that includes examining the quality of adolescents’ friendships, peer interactions, and interactive models of relationship dimensions are informative for understanding adolescents’ general adjustment.

Journal ArticleDOI
21 Mar 2008-Science
TL;DR: GenBank, the public repository for nucleotide and protein sequences, is a critical resource for molecular biology, evolutionary biology, and ecology as discussed by the authors, and some attention has been drawn to sequence errors ([1][1]), common annotation errors also reduce the value of this database.
Abstract: GenBank, the public repository for nucleotide and protein sequences, is a critical resource for molecular biology, evolutionary biology, and ecology. While some attention has been drawn to sequence errors ([1][1]), common annotation errors also reduce the value of this database. In fact, for

Journal ArticleDOI
TL;DR: An overview of various transduction systems, such as electrochemical, optical, piezoelectric, and nanomechanics methods, which have been reported in the literature in the design and fabrication of immunosensors for pesticide detection are presented.

Journal ArticleDOI
TL;DR: The data suggest that this Lactobacillus-based probiotic culture may be efficacious for reduction of Salmonella Enteritidis in neonatal chicks.

Journal ArticleDOI
TL;DR: In this article, postharvest application of UV-C radiation can decrease decay caused by ripe rot in blueberries and may enhance antioxidant levels, but no clear treatment effects were seen in total phenolic content.

Journal ArticleDOI
TL;DR: In this article, eight recent trade books written by NOS experts addressing the nature of science for the general public were examined to locate the historical examples included, and these historical vignettes were extracted and analyzed to determine the kinds of examples used and the focus of the science discipline from which the example comes.
Abstract: Increasingly widespread agreement exists that the nature of science (NOS) must be an integral element of the K-12 science curriculum with emerging consensus on what specific NOS elements should be the focus of such instruction. In this study reported, eight recent trade books written by NOS experts addressing the nature of science for the general public were examined to locate the historical examples included. These historical vignettes were extracted and analyzed to determine the kinds of examples used and the focus of the science discipline from which the example comes. The analysis has revealed that these authors have collectively provided approximately 80 historical vignettes in fields ranging from astronomy to physics, with some cited repeatedly from one book to another. In addition, the entire set of examples was then linked to important NOS notions providing an instructional resource for use by teachers, textbook writers and curriculum developers.

Journal ArticleDOI
TL;DR: In this article, a coherent coupling between surface plasmon polaritons (SPP) and quantum well excitons in a hybrid metal-semiconductor nanostructure is reported.
Abstract: We report measurements of a coherent coupling between surface plasmon polaritons (SPP) and quantum well excitons in a hybrid metal-semiconductor nanostructure. The hybrid structure is designed to optimize the radiative exciton-SPP interaction which is probed by low-temperature, angle-resolved, far-field reflectivity spectroscopy. As a result of the coupling, a significant shift of $\ensuremath{\sim}7\text{ }\text{ }\mathrm{meV}$ and an increase in broadening by $\ensuremath{\sim}4\text{ }\text{ }\mathrm{meV}$ of the quantum well exciton resonance are observed. The experiments are corroborated by a phenomenological coupled-oscillator model predicting coupling strengths as large as 50 meV in structures with optimized detunings between the coupled exciton and SPP resonances. Such a strong interaction can, e.g., be used to enhance the luminescence yield of semiconductor quantum structures or to amplify SPP waves.

Journal ArticleDOI
TL;DR: The theory of core self-evaluation (CSE) has provided organizational scholars with a framework for describing disposition-based effects on work attitudes and behaviors as mentioned in this paper, but there are potential weaknesses concerning how it is conceptualized and used.
Abstract: The theory of core self-evaluation (CSE) has provided organizational scholars with a framework for describing disposition-based effects on work attitudes and behaviors. Although the CSE construct has been useful for predicting various phenomena, there are potential weaknesses concerning how it is conceptualized and used. We review limitations regarding CSE theory, its measurement, and specific traits, and provide recommendations for addressing them. Key recommendations include strengthening the theory underlying CSE, specifying CSE as an aggregate construct with causal indicators, representing CSE as a multidimensional construct rather than a scale score, and incorporating a trait that reflects approach motivation. Theoretical and empirical evidence that relate to our recommendations are presented. Copyright © 2007 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this paper, the authors discuss three theoretical models from met expectations research in the fields of organizational behavior and consumer psychology, based on the fundamental arguments in the models, they term these models: disconfirmation, ideal point, and experiences only.

Journal ArticleDOI
TL;DR: Blackberries were evaluated by high-performance liquid chromatography-electrospray ionization-mass spectrometry and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometer to identify the ellagitannins present in flesh, torus, and seeds to determine the presence of several possible isomeric forms of ellag itannins previously unidentified in fruit.
Abstract: Blackberries ( Rubus sp.) were evaluated by high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF-MS) to identify the ellagitannins present in flesh, torus (receptacle tissue), and seeds. Most ellagitannins were present (or detectable) only in seed tissues. Ellagitannins identified by HPLC-ESI-MS in the seeds included pedunculagin, casuarictin/potentillin, castalagin/vescalagin, lambertianin A/sanguiin H-6, lambertianin C, and lambertianin D. For several of the ellagitannins, isomeric separation was also obtained. The MALDI-TOF-MS analysis was primarily utilized to evaluate and identify high molecular mass (>1000 Da) ellagitannins. The MALDI analysis verified the presence of the ellagitannins identified by HPLC-ESI-MS including lambertianin A/sanguiin H-6, lambertianin C, and lambertianin D, but the analysis also indicated the presence of several other compounds that were most likely ellagitannins based on the patterns observed in the masses (i.e., loss or addition of a gallic acid moiety to a known ellagitannin). This study determined the presence of several possible isomeric forms of ellagitannins previously unidentified in fruit and presents a possible analytical HPLC method for the analysis of the major ellagitannins present in the fruit.

Journal ArticleDOI
TL;DR: It is believed that SVWs are beginning to shape the knowledge-based and glo balized societies and economies of tomorrow, and researchers will need to build new theories and concepts for SVWs to explore the frontiers between reality and virtuality.
Abstract: Today's social virtual worlds (SVW) are beginning to realize Stephenson's vision of the metaverse: a future massive network of interconnected digital worlds. Tens of millions of people already use these kinds of environments to communicate, collaborate, and do business. Big companies are also moving into these digital realms. Thus, in a context in which the Web is becoming increasingly social, we believe that SVWs are beginning to shape the knowledge-based and glo balized societies and economies of tomorrow. Obviously, an urgent need exists to further understand SVWs and their implications for theory and practice. This article constitutes a first attempt to bring researchers into some of the business, social, technical, legal, and ethical issues related to SVWs. We anticipate that researchers will need to build new theories and concepts for SVWs, to explore the frontiers between reality and virtuality.

Journal ArticleDOI
TL;DR: The Chinese genebank contains 23,587 soybean landraces collected from 29 provinces and seven clusters were inferred, providing the first molecular evidence for the hypotheses that the origin of cultivated soybean is the Yellow River region.
Abstract: The Chinese genebank contains 23,587 soybean landraces collected from 29 provinces. In this study, a representative collection of 1,863 landraces were assessed for genetic diversity and genetic differentiation in order to provide useful information for effective management and utilization. A total of 1,160 SSR alleles at 59 SSR loci were detected including 97 unique and 485 low-frequency alleles, which indicated great richness and uniqueness of genetic variation in this core collection. Seven clusters were inferred by STRUCTURE analysis, which is in good agreement with a neighbor-joining tree. The cluster subdivision was also supported by highly significant pairwise F st values and was generally in accordance with differences in planting area and sowing season. The cluster HSuM, which contains accessions collected from the region between 32.0 and 40.5°N, 105.4 and 122.2°E along the central and downstream parts of the Yellow River, was the most genetically diverse of the seven clusters. This provides the first molecular evidence for the hypotheses that the origin of cultivated soybean is the Yellow River region. A high proportion (95.1%) of pairs of alleles from different loci was in LD in the complete dataset. This was mostly due to overall population structure, since the number of locus pairs in LD was reduced sharply within each of the clusters compared to the complete dataset. This shows that population structure needs to be accounted for in association studies conducted within this collection. The low value of LD within the clusters can be seen as evidence that much of the recombination events in the past have been maintained in soybean, fixed in homozygous self-fertilizing landraces.

Journal ArticleDOI
TL;DR: This article is a state‐of‐knowledge overview on CVS in adults and is intended to provide a framework for management and further investigations into CVD in adults.
Abstract: Cyclic vomiting syndrome (CVS) was initially described in children but can occur in all age groups. Cyclic vomiting syndrome is increasingly recognized in adults. However, the lack of awareness of CVS in adults has led to small numbers of diagnosed patients and a paucity of published data on the causes, diagnosis and management of CVS in adults. This article is a state-of-knowledge overview on CVS in adults and is intended to provide a framework for management and further investigations into CVS in adults.

Journal ArticleDOI
TL;DR: The jets of icy particles and water vapor issuing from the south pole of Enceladus are evidence for activity driven by some geophysical energy source, and it is possible that a liquid water environment exists beneath the south polar cap, which may be conducive to life.
Abstract: The jets of icy particles and water vapor issuing from the south pole of Enceladus are evidence for activity driven by some geophysical energy source. The vapor has also been shown to contain simple organic compounds, and the south polar terrain is bathed in excess heat coming from below. The source of the ice and vapor, and the mechanisms that accelerate the material into space, remain obscure. However, it is possible that a liquid water environment exists beneath the south polar cap, which may be conducive to life. Several theories for the origin of life on Earth would apply to Enceladus. These are (1) origin in an organic-rich mixture, (2) origin in the redox gradient of a submarine vent, and (3) panspermia. There are three microbial ecosystems on Earth that do not rely on sunlight, oxygen, or organics produced at the surface and, thus, provide analogues for possible ecologies on Enceladus. Two of these ecosystems are found deep in volcanic rock, and the primary productivity is based on the consumption by methanogens of hydrogen produced by rock reactions with water. The third ecosystem is found deep below the surface in South Africa and is based on sulfur-reducing bacteria consuming hydrogen and sulfate, both of which are ultimately produced by radioactive decay. Methane has been detected in the plume of Enceladus and may be biological in origin. An indicator of biological origin may be the ratio of non-methane hydrocarbons to methane, which is very low (0.001) for biological sources but is higher (0.1-0.01) for nonbiological sources. Thus, Cassini's instruments may detect plausible evidence for life by analysis of hydrocarbons in the plume during close encounters.