Bounding the firing synchronization problem on a ring

In this paper we improve the upper and lower bounds on the complexity of solutions to the firing synchronization problem on a ring. In this variant of the firing synchronization problem the goal is to synchronize a ring of identical finite automata. Initially, all automata are in the same state except for one automaton that is designated as the initiator for the synchronization. The goal is to define the set of states and the transition function for the automata so that all machines enter a special fire state for the first time and simultaneously during the final round of the computation. In our work we present two solutions to the ring firing synchronization problem, an 8-state minimal-time solution and a 6-state non-minimal-time solution. Both solutions use fewer states than the previous best-known minimal-time automaton, a 16-state solution due to Culik. We also give the first lower bounds on the number of states needed for solutions to the ring firing synchronization problem. We show that there is no 3-state solution and no 4-state, symmetric, minimal-time solution for the ring.     

Production of Bioactive Volatiles by Different Burkholderia ambifaria Strains

Increasing evidence indicates that volatile compounds emitted by bacteria can influence the growth of other organisms. In this study, the volatiles produced by three different strains of Burkholderia ambifaria were analysed and their effects on the growth of plants and fungi, as well as on the antibiotic resistance of target bacteria, were assessed. Burkholderia ambifaria emitted highly bioactive volatiles independently of the strain origin (clinical environment, rhizosphere of pea, roots of maize). These volatile blends induced significant biomass increase in the model plant Arabidopsis thaliana as well as growth inhibition of two phytopathogenic fungi (Rhizoctonia solani and Alternaria alternata). In Escherichia coli exposed to the volatiles of B. ambifaria, resistance to the aminoglycoside antibiotics gentamicin and kanamycin was found to be increased. The volatile blends of the three strains were similar, and dimethyl disulfide was the most abundant compound. Sulfur compounds, ketones, and aromatic compounds were major groups in all three volatile profiles. When applied as pure substance, dimethyl disulfide led to increased plant biomass, as did acetophenone and 3-hexanone. Significant fungal growth reduction was observed with high concentrations of dimethyl di- and trisulfide, 4-octanone, S-methyl methanethiosulphonate, 1-phenylpropan-1-one, and 2-undecanone, while dimethyl trisulfide, 1-methylthio-3-pentanone, and o-aminoacetophenone increased resistance of E. coli to aminoglycosides. Comparison of the volatile profile produced by an engineered mutant impaired in quorum-sensing (QS) signalling with the corresponding wild-type led to the conclusion that QS is not involved in the regulation of volatile production in B. ambifaria LMG strain 19182.     

A sensor network for high frequency estimation of water quality constituent fluxes using surrogates

Characterizing spatial and temporal variability in the fluxes and stores of water and water borne constituents is important in understanding the mechanisms and flow paths that carry constituents to a stream and through a watershed. High frequency data collected at multiple sites can be used to more effectively quantify spatial and temporal variability in water quality constituent fluxes than through the use of low frequency water quality grab sampling. However, for many constituents (e.g., sediment and phosphorus) in-situ sensor technology does not currently exist for making high frequency measurements of constituent concentrations. In this paper we describe how water quality measures such as turbidity or specific conductance, which can be measured in-situ with high frequency, can be used as surrogates for other water quality constituents that cannot economically be measured with high frequency to provide continuous time series of water quality constituent concentrations and fluxes. We describe the observing infrastructure required to make high frequency estimates of water quality constituent fluxes based on surrogate data at multiple sites within a sensor network supporting an environmental observatory. This includes the supporting sensor, communication, data management, and data storage and processing infrastructure. We then provide a case study implementation in the Little Bear River watershed of northern Utah, USA, where a wireless sensor network has been developed for estimating total phosphorus and total suspended solids fluxes using turbidity as a surrogate.     

Processable Thermally Conductive Polyurethane Composite Fibers

The demand for wearable electronics has resulted in an increasing interest in the development of functional fibers, with a specific focus upon the development of electrically conductive fibers incorporable into garments. However, the production of thermally conductive fibers for heat dissipation has been largely neglected. Owing to the very rapid development of miniaturized wearable electronics, there is an increasing need for the development of thermally conductive fibers as heat sinks and thermal management processes. In this study, thermally conductive but electrically insulating boron nitride nanopowder (BNNP) fillers are used to effectively enhance the thermal conductivity and mechanical properties of elastomeric polyurethane fibers. Thermal conductivity enhancement of more than 160% is achieved at very low loadings of BNNP (less than 5 wt%) with an improvement in the mechanical properties of the unmodified fiber. These thermally conductive fibers are also incorporated into 3D textile structures as a proof of processability.     

The Content of Reality Dating Shows and Viewer Perceptions of Dating

This research utilized a content analysis of 64 hours of reality dating shows and a survey of 197 young adults to determine the extent to which the content on these shows was related to actual dating attitudes, preferred date characteristics, and dating behaviors of viewers of that genre. Results show that male viewers, those who perceived higher realism in the shows, and those with higher average viewing scores were more likely to endorse attitudes found within the programming. Dating characteristics were portrayed infrequently, and no relationship between viewing and endorsement of those characteristics was found. Viewing reality dating shows was related to self-reports of drinking alcohol and using hot tubs early in the dating relationship.     

Development and Characterization of Degradable Thiol-Allyl Ether Photopolymers

Degradable thiol-ene photopolymer networks were formed through radically mediated step-growth reactions. Variations in the network structure were used to alter the initial and temporal moduli, mass loss profiles, and equilibrium swelling ratios. Mass loss rates varied with changes in the solvent concentration, monomer molecular weight, average monomer functionality, and concentration of degradable linkages. The time required for the networks to degrade completely ranged from 1.20 ± 0.01 to 24.5 ± 0.1 days, which corresponded to hydrolysis rates of 0.18 ± 0.01 and 0.021 ± 0.0003 day⁻¹. Initial moduli also varied considerably as a function of network structure, ranging from 150 ± 35 to nearly 5000 ± 100 kPa, and initial equilibrium swelling ratios ranged from 2.5 ± 0.01 to 18.7 ± 2. Collectively, these results demonstrate how the material properties and the mass loss behavior of thiol-ene networks can be independently tuned for specific applications.     

Age of drinking onset, driving after drinking, and involvement in alcohol related motor-vehicle crashes.

This study assessed whether persons who begin drinking at younger ages are more likely to report drunk driving and alcohol-related crash involvement over the life course, even after controlling analytically for diagnosis of alcohol dependence, years of drinking alcohol, and other personal characteristics associated with the age respondents started drinking. A national survey asked 42,862 respondents the age that they started drinking, whether they drove after drinking too much, and whether they were in motor-vehicle crashes because of their drinking. This analysis focused on 27,081 (65%), who reported ever drinking in their lifetime. The earlier the age respondents started drinking, the more likely they were to report driving after drinking too much and being in a motor-vehicle crash because of their drinking even after adjusting for current/ever diagnosis of alcohol dependence, number of years respondents had been drinking, and other characteristics and behaviors associated with the age respondents started drinking. Particularly, among persons who were never alcohol-dependent, those who began drinking in each age group under 21, relative to those starting at age 21 or older, were more likely to report "ever" and "in the past year" being in a crash after drinking too much. The traffic safety benefits of delaying drinking may extend well beyond the legal drinking age of 21.