Project description:While octopuses are mostly benthic animals, and squid prefer the open waters, cuttlefish present a special intermediate stage. Although their body structure resembles that of a squid, in many cases their behavior is mostly benthic. To test cuttlefish's preference in the use of space, we trained juvenile Sepia gibba and Sepia officinalis cuttlefish to reach a shelter at the opposite side of a tank. Afterwards, rock barriers were placed between the starting point and the shelter. In one experiment, direct paths were available both through the sand and over the rocks. In a second experiment the direct path was blocked by small rocks requiring a short detour to by-pass. In the third experiment instead, the only direct path available was over the rocks; or else to reach the goal via an exclusively horizontal path a longer detour would have to be selected. We showed that cuttlefish prefer to move horizontally when a direct route or a short detour path is available close to the ground; however when faced with significant obstacles they can and would preferentially choose a more direct path requiring a vertical movement over a longer exclusively horizontal path. Therefore, cuttlefish appear to be predominantly benthic dwellers that prefer to stay near the bottom. Nonetheless, they do view and utilize the vertical space in their daily movements where it plays a role in night foraging, obstacles negotiation and movement in their home-range.
Project description:Soot emitted from incomplete combustion of hydrocarbon fuels contributes to global warming and causes human disease. The mechanism by which soot nanoparticles form within hydrocarbon flames is still an unsolved problem in combustion science. Mechanisms proposed to date involving purely chemical growth are limited by slow reaction rates, whereas mechanisms relying on solely physical interactions between molecules are limited by weak intermolecular interactions that are unstable at flame temperatures. Here, we show evidence for a reactive π-diradical aromatic soot precursor imaged using non-contact atomic force microscopy. Localization of π-electrons on non-hexagonal rings was found to allow for Kekulé aromatic soot precursors to possess a triplet diradical ground state. Barrierless chain reactions are shown between these reactive sites, which provide thermally stable aromatic rim-linked hydrocarbons under flame conditions. Quantum molecular dynamics simulations demonstrate physical condensation of aromatics that survive for tens of picoseconds. Bound internal rotors then enable the reactive sites to find each other and become chemically cross-linked before dissociation. These species provide a rapid, thermally stable chain reaction toward soot nanoparticle formation and could provide molecular targets for limiting the emission of these toxic combustion products.
Project description:Oscillation and collective behavior of diffusion flames is a fascinating phenomena. Considering candle bundles with different sizes in variable oxygen concentration, the flickering dynamics of the flames are experimentally and theoretically investigated. Trends for the flickering frequency as a function of the candle number in the bundle and oxygen concentration is revealed for various topologies of the candles packing. The collective behavior of the flames as a function of their separation distance is studied by measuring an appropriate synchronization order parameter and through the common oscillation frequency. In agreement with previous results we find a discontinuous phase transition between an in-phase synchronized state at small separation distance and a counter-phase synchronized state at larger separation distances. A previously used dynamical model is modified in order to accommodate our experimental findings.
Project description:Against a backdrop of increasing smoke-free policies, electronic cigarette use, and discussion about public health risks posed by smoking and vaping, this study examines psychosocial predictors of intentions to ask others not to use e-cigarettes (vape) and smoke - i.e., assertive communication intentions. A national sample of U.S. adults (n = 474) reported assertive communication intentions for public venues. Psychosocial correlates included perceived risks of exposure to secondhand smoke (SHSe) and secondhand vapor (SHVe), SHSe and SHVe attitudes, subjective norms, and perceived self-efficacy. Separate linear regression models were conducted for smoking and vaping assertive communication intention outcomes. Perceived risks and self-efficacy were associated with greater vaping and smoking assertive communication intentions; subjective norms were only significant for vaping assertive communication intentions. Although a majority of respondents indicated they were unlikely to intervene to voice objections about SHSe and SHVe in public venues, this study suggests that incidental or intentional messages and policies that influence perceptions of risk, norms, and efficacy could affect willingness to voice objections about others' vaping and smoking in public.
Project description:When two or more candle flames are fused by approaching them together, the resulting large flame often exhibits flickering, i.e., prolonged high-frequency oscillation in its size and luminance. In the present work, we investigate the collective behaviour of three-coupled candle flame oscillators in a triangular arrangement. The system showed four distinct types of syncronised modes as a consequence of spontaneous symmetry breaking. The modes obtained include the in-phase mode, the partial in-phase mode, the rotation mode, and an anomalous one called the "death" mode that causes a sudden stop of the flame oscillation followed by self-sustained stable combustion. We also clarified the correlation between the inter-flame distance and the frequency with which the modes occur.
Project description:Cognitive impairment is known to be a core deficit in schizophrenia. Existing treatments for schizophrenia have limited efficacy against cognitive impairment. The ubiquitous use of nicotine in this population is thought to reflect an attempt by patients to selfmedicate certain symptoms associated with the illness. Concurrently there is evidence that nicotinic receptors that have lower affinity for nicotine are more important in cognition. Therefore, a number of medications that target nicotinic acetylcholine receptors (nAChRs) have been tested or are in development. In this article we summarize the clinical evidence of nAChRs dysfunction in schizophrenia and review clinical studies testing either nicotine or nicotinic medications for the treatment of cognitive impairment in schizophrenia. Some evidence suggests beneficial effects of nAChRs based treatments for the attentional deficits associated with schizophrenia. Standardized cognitive test batteries have failed to capture consistent improvements from drugs acting at nAChRs. However, more proximal measures of brain function, such as ERPs relevant to information processing impairments in schizophrenia, have shown some benefit. Further work is necessary to conclude that nAChRs based treatments are of clinical utility in the treatment of cognitive deficits of schizophrenia.
Project description:The influence of CF3I on the burning velocity of methane-air flame is experimentally and numerically studied. Experimental results demonstrate that the inhibition effectiveness of CF3I is very close to that of CF3Br. A detailed kinetic model of flame inhibition by CF3I is presented, based on an updated version of a previous model. The kinetic model contains 1072 reactions with 115 species including 10 iodine-containing species. Modeling results demonstrate good agreement with experimental data, and both experiments and calculations show that CF3I is only slightly less effective at reducing the burning velocity than CF3Br. The flame structure predicted from numerical simulations is analyzed and shows that main reactions of the inhibition cycle of CF3I are: H+HI=H2+I; H+I+M=HI+M; I+I+M=I2+M; H+I2=HI+I; I+CH3+M=CH3I+M; H+CH3I=CH3+HI; I+HCO=HI+CO; HI+OH=H2O+I and O+HI=I+OH.
Project description:Study objectivesTo compare the prices paid for nicotine vaping products (NVPs) and supplies among current NVP users to prices paid for cigarettes among current smokers.DataThe 2016 International Tobacco Control Four Country Vaping and Smoking Survey (4CV1). Key measures included: (1) self-reported prices paid for reusable NVPs (eg, rechargeable devices with cartridges and tank system devices with e-liquids) in the 3-month period prior to the survey among current NVP users, (2) prices paid for disposable NVPs, cartridges and e-liquids purchased in the last 30 days among current NVP users and (3) self-reported prices paid for cigarettes among current smokers.ResultsDisposable NVP price was higher than the price of a comparable unit for combustible cigarettes in England (EN), USA and Canada (CA). Prefilled cartridge price was higher than the price of a comparable unit of cigarettes in USA and CA, but lower in EN and Australia. E-liquid price was consistently lower than the price of a comparable unit of cigarettes across four countries. For start-up costs, price of a rechargeable device is approximately 3-5 times higher than a pack of cigarettes in four countries.ConclusionNVP prices were generally higher than prices of combustible cigarettes, especially the high upfront NVP devices. The high upfront costs of purchasing a reusable NVP may discourage some smokers from switching to vaping. However, the average lower costs of cartridges and e-liquids relative to a package of cigarettes make switching to a NVP an attractive alternative to smoking in the long term so long as smokers switch completely to vaping.
Project description:BackgroundThe use of electronic nicotine delivery systems (ENDS), also known as vaping, is becoming popular among young adults. Few studies have explored the psychological factors that predict ENDS use and susceptibility in young adults, in addition to known demographic predictors.MethodIn a cross-sectional survey design, 521 young adults (37% male), ages 18-25 from the United States, were recruited via Amazon's Mechanical Turk (MTurk) in 2019, to answer an online survey measuring demographic characteristics and psychological characteristics related to mental health and the Big Five personality traits. The survey also included measures of ENDS ever-use, current use, and susceptibility (never users open to trying ENDS), which we predicted from the demographic and psychological measures using independent and multiple binary logistic regression analyses.ResultsOf those surveyed (n = 521), 282 (54.1%) were ENDS ever-users, 93 (17.9%) were current ENDS users, and 61 (11.7%) were ENDS susceptible; 62 (11.9%) were current smokers. Demographically, young adults lower in adulthood socioeconomic-status (SES), not pursuing education further than high school, and current smokers were more likely to be ENDS users. Psychologically, young adults higher in anxiety and lower in conscientiousness more likely to have ever-used ENDS. Lower conscientiousness further predicted current ENDS use and ENDS susceptibility.ConclusionIn this sample of MTurk workers, young adults with experience in vaping were more demographically and psychologically vulnerable than young adults with no experience in vaping. Young adults interested in vaping, but without prior experience, were less conscientious than their non-interested peers. Interventions to target vaping use should focus on economically disadvantaged young adults and those lower in conscientiousness.
Project description:Background:The effects of electronic cigarettes on the ocular surface has yet to be shown. The purpose of the study was to assess the impact of e-cigarette use on the anterior corneal surface integrity. Methods:Forty three males and 21 females with an average of 21years were required to vape 0.05ml of e-liquid of 8mg nicotine concentration. Corneal epithelial thickness (CET) and Non Invasive Keratograph Tear Break up Time (NIKBUT) measurements were obtained prior to and post vaping. The Optovue iVue optical coherence topographer was used to measure central; superior; inferior; nasal and temporal CET and NIKBUT was assessed using the Oculus Keratograph 5M. Results:There was a mean increase for central corneal epithelial thickness of 0.3448 microns. The superior CET increased by 0.2414 microns. The inferior CET increased by 0.2931microns. The nasal CET increased by 0.2069 microns. The temporal CET increased by 0.2759 microns. The mean change in NIKBUT post-vaping was an increase of 1.40 seconds. All observations occurred at p > 0.05. Conclusion:The acute effect of e-cigarette use does not impact corneal epithelial thickness and non-invasive keratography tear break up time after 10 puffs mild exposure but more research is needed to assess if this remains the case with more frequent, higher exposure.