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: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: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: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 behavior of technical nanoparticles at high temperatures was measured systematically to detect morphology changes under conditions relevant to the thermal treatment of end-of-life products containing engineered nanomaterials. The focus of this paper is on laboratory experiments, where we used a Bunsen-type burner to add titania and ceria particles to a laminar premixed flame. To evaluate the influence of temperature on particle size distributions, we used SMPS, ELPI and TEM analyses. To measure the temperature profile of the flame, we used coherent anti-Stokes Raman spectroscopy (CARS). The comprehensible data records show high temperatures by measurement and equilibrium calculation for different stoichiometries and argon admixtures. With this, we show that all technical metal oxide nanoparticle agglomerates investigated reform in flames at high temperatures. The originally large agglomerates of titania and ceria build very small nanoparticles (<10 nm/"peak 2") at starting temperatures of <2200 K and <1475 K, respectively (ceria: Tmelt = 2773 K, Tboil = 3873 K/titania: Tmelt = 2116 K, Tboil = 3245 K). Since the maximum flame temperatures are below the evaporation temperature of titania and ceria, enhanced vaporization of titania and ceria in the chemically reacting flame is assumed.
Project description:The detailed chemical structures of three low-pressure (35 Torr) premixed laminar furan/oxygen/argon flames with equivalence ratios of 1.4, 1.8 and 2.2 have been investigated by using tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam mass spectrometry. About 40 combustion species including hydrocarbons and oxygenated intermediates have been identified by measurements of photoionization efficiency spectra. Mole fraction profiles of the flame species including reactants, intermediates and products have been determined by scanning burner position with some selected photon energies near ionization thresholds. Flame temperatures have been measured by a Pt-6%Rh/Pt-30%Rh thermocouple. A new mechanism involving 206 species and 1368 reactions has been proposed whose predictions are in reasonable agreement with measured species profiles for the three investigated flames. Rate-of-production and sensitivity analyses have been performed to track the key reaction paths governing furan consumption for different equivalence ratios. Both experimental and modeling results indicate that few aromatics could be formed in these flames. Furthermore, the current model has been validated against previous pyrolysis results of the literature obtained behind shock waves and the agreement is reasonable as well.
Project description:BackgroundVaping's popularity has particularly increased among young people, with its prevalence varying across different regions, including the Middle East. The health impacts of vaping, especially when initiated early, are a growing concern.AimsThis study aimed to investigate the correlates of early vaping initiation (EVI) and explored the sociodemographic characteristics and vaping motives influencing EVI among vapers from Arab countries.MethodsAn online cross-sectional survey recruited 428regular vapers, aged 18-60 who resided in Arab countries at the time of the study. Sociodemographic and vaping motives data were collected. Stepwise logistic regression was used to examine the factors associated with EVI.ResultsThe study findings revealed that older participants and expats have lower odds of EVI. Males and vapers from Qatar had around 4-5 times the odds of EVI as compared to females and those from Egypt, respectively.ConclusionTargeted social marketing and education campaigns may benefit groups at risk of EVI, including residents of Qatar, males, and those who are strongly influenced by social media or who have friends or family members who vape. Reducing EVI is particularly important, as vaping often begins at an early age, and early intervention is vital to prevent early initiation and subsequent addiction.
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.