A new hierarchy for automaton semigroups

We define a new strict and computable hierarchy for the family of automaton semigroups, which reflects the various asymptotic behaviors of the state-activity growth. This hierarchy extends that given by Sidki for automaton groups, and also gives new insights into the latter. Its exponential part coincides with a notion of entropy for some associated automata. We prove that the Order Problem is decidable when the state-activity is bounded. The Order Problem remains open for the next level of this hierarchy, that is, when the state-activity is linear. Gillibert showed that it is undecidable in the whole family. The former results are implemented and will be available in the GAP package FR developed by the first author.Comment: 12 pages, accepted and presented at CIAA 201

Generic properties in some classes of automaton groups

We prove, for various important classes of Mealy automata, that almost all generated groups have an element of infinite order. In certain cases, it also implies other results such as exponential growth

A characterization of those automata that structurally generate finite groups

Antonenko and Russyev independently have shown that any Mealy automaton with no cycles with exit--that is, where every cycle in the underlying directed graph is a sink component--generates a fi- nite (semi)group, regardless of the choice of the production functions. Antonenko has proved that this constitutes a characterization in the non-invertible case and asked for the invertible case, which is proved in this paper

Superporous nanocarbon materials upcycled from polyethylene terephthalate waste for scalable energy storage

Plastic pollution is becoming a universal threat affecting wildlife, marines, the atmosphere, soil, and human wellbeing. The insufficient waste management traditions, along with a growth in the "throw-away" and "single -use" culture, exacerbate the problem. Meanwhile, the fast-growing energy storage industry, such as the lithium -ion battery (LIB), requires renewable resources to provide a steady and reliable production supply chain. This work introduces a scalable industrial mature route to transform polyethylene terephthalate (PET) plastic waste into a superporous activated carbon material for rechargeable LIBs. We characterized the analytical properties of the waste-derived carbon material and used it to develop LIB anodes. Then, we generated carbon-silicon com-posite anodes by impregnating silicon nanoparticles (SiNPs) into the superporous connected architecture network. We conducted density functional-based tight-binding (DFTB+) quantum chemical calculations to elucidate the binding interactions between PET and SiNPs. By implementing electrochemical impedance spec-troscopy (EIS), galvanostatic intermittent titration technique (GITT), and differential capacity analysis (DCA), we investigated the root causes of the degradation mechanisms of the material. Finally, our techno-economical study highlights the merits of a sustainable approach for transferring waste materials into valuable products such as energy storage. This work can create further research and development for recycling plastic wastes towards scalable stationary battery storage with the benefits of environmental sustainability and circular economics

Obese and female adolescents skip breakfast more than their non-obese and male peers

We examined the association between overweight/gender and skipping breakfast among adolescent students in Tehran city using a cross-sectional study and a multistage random sampling method. All educational zones in Tehran city were covered during the educational year of 2000-01. In total, 2321 students aged 11-16 years (1068 male; 1263 female) participated in the study. Weight and height were measured and body mass index (BMI; kg/m2) was calculated. Overweight, pre-obesity and obesity were defined as BMI � 85 th , 85 th to 95 th , and � 95 th percentile of age-sex-specific BMI reference values, respectively. Self-reported frequency of breakfast consumption was categorized as usual/always, often, and rarely/never (5-7, 2-4 and 0-1 times/wk, respectively). Student's t and Chi-square tests were employed to analyze the data. Statistical inferences were made at α = 0.05. In boys and girls, the mean ± standard deviation of BMI was 19.8 ± 4.0 and 20.6 ± 4.1 kg/m2, the 18.8 and 23.1 were overweight, and 7.3 and 8.3 were obese, respectively. There was a significant difference in the frequency of breakfast consumption between obese and normal male students (P < 0.001). Differences between pre-obese and normal, and obese and normal female students were also significant (P < 0.002 and P < 0.001, respectively). A significant difference was found in the frequency of breakfast consumption between male and female adolescents in all three categories (P < 0.001). These results suggest that obese and female adolescents are more likely to skip breakfast than their normal and male peers and are therefore at higher risk for growth deficits and low educational performance. Preventive/educational programs are urgently needed in this age group. © 2007 Versita Warsaw and Springer-Verlag

Initial Commitment to Pre-Exposure Prophylaxis and Circumcision for HIV Prevention amongst Indian Truck Drivers

Studies of HIV prevention interventions such as pre-exposure prophylaxis (PREP) and circumcision in India are limited. The present study sought to investigate Indian truck-drivers initial commitment to PREP and circumcision utilizing the AIDS Risk Reduction Model. Ninety truck-drivers completed an in-depth qualitative interview and provided a blood sample for HIV and HSV-2 testing. Truck-drivers exhibited low levels of initial commitment towards PREP and even lower for circumcision. However, potential leverage points for increasing commitment were realized in fear of infecting family rather than self, self-perceptions of risk, and for PREP focusing on cultural beliefs towards medication and physicians. Cost was a major barrier to both HIV prevention interventions. Despite these barriers, our findings suggest that the ARRM may be useful in identifying several leverage points that may be used by peers, health care providers and public health field workers to enhance initial commitment to novel HIV prevention interventions in India