Anomalous exchange interaction between intrinsic spins in conducting graphene systems

We address the nature and possible observable consequences of singular one-electron states that appear when strong defects are introduced in the metallic family of graphene, namely, metallic carbon nanotubes and nanotori. In its simplest form, after creating two defects on the same sublattice, a state may emerge at the Fermi energy presenting very unusual properties: It is unique, normalizable, and features a wave function equally distributed around both defects. As a result, the exchange coupling between the magnetic moments generated by the two defects is anomalous. The intrinsic spins couple ferromagnetically, as expected, but do not present an antiferromagnetic excited state at any distance. We propose the use of metallic carbon nanotubes as a novel electronic device based on this anomalous coupling between spins which can be useful for the robust transmission of magnetic information at large distances.Comment: 5 pages 5 fugure

Environmental Tobacco Smoke Exposure in Relation to Family Characteristics, Stressors and Chemical Co-Exposures in California Girls.

Childhood environmental tobacco smoke (ETS) exposure is a risk factor for adverse health outcomes and may disproportionately burden lower socioeconomic status groups, exacerbating health disparities. We explored associations of demographic factors, stressful life events, and chemical co-exposures, with cotinine levels, among girls in the CYGNET Study. Data were collected from families of girls aged 6-8 years old in Northern California, through clinic exams, questionnaires and biospecimens (n = 421). Linear regression and factor analysis were conducted to explore predictors of urinary cotinine and co-exposure body burdens, respectively. In unadjusted models, geometric mean cotinine concentrations were higher among Black (0.59 ug/g creatinine) than non-Hispanic white (0.27), Asian (0.32), or Hispanic (0.34) participants. Following adjustment, living in a rented home, lower primary caregiver education, and lack of two biologic parents in the home were associated with higher cotinine concentrations. Girls who experienced parental separation or unemployment in the family had higher unadjusted cotinine concentrations. Higher cotinine was also associated with higher polybrominated diphenyl ether and metals concentrations. Our findings have environmental justice implications as Black and socio-economically disadvantaged young girls experienced higher ETS exposure, also associated with higher exposure to other chemicals. Efforts to reduce ETS and co-exposures should account for other disparity-related factors

Anomalous Roughening in Experiments of Interfaces in Hele-Shaw Flows with Strong Quenched Disorder

We report experimental evidences of anomalous kinetic roughening in the stable displacement of an oil-air interface in a Hele-Shaw cell with strong quenched disorder. The disorder consists on a random modulation of the gap spacing transverse to the growth direction (tracks). We have performed experiments varying average interface velocity and gap spacing, and measured the scaling exponents. We have obtained beta=0.50, beta*=0.25, alpha=1.0, alpha_l=0.5, and z=2. When there is no fluid injection, the interface is driven solely by capillary forces, and a higher value of beta around beta=0.65 is measured. The presence of multiscaling and the particular morphology of the interfaces, characterized by high slopes that follow a L\'evy distribution, confirms the existence of anomalous scaling. From a detailed study of the motion of the oil--air interface we show that the anomaly is a consequence of different local velocities over tracks plus the coupling in the motion between neighboring tracks. The anomaly disappears at high interface velocities, weak capillary forces, or when the disorder is not sufficiently persistent in the growth direction. We have also observed the absence of scaling when the disorder is very strong or when a regular modulation of the gap spacing is introduced.Comment: 14 pages, 17 figure

The Asthma Cost in Oman

Objectives: This study evaluates the direct costs of treating asthma in Oman. Methods: Asthma prevalence and unit cost estimates were based on results from a panel using the Delphi technique, and were applied to the total Omani population aged 5 and older to obtain the number of people diagnosed with asthma. The estimates from the Delphi exercise were multiplied by the percentage of patients using government facilities to estimate the number of asthma patients managed in Oman. Treatment costs were also calculated using data from the Delphi exercise and the Asthma Insights and Reality for the Gulf and Near East study (reported in Omani riyals [OMR] and US dollars [USD]). Results: The prevalence of asthma was estimated to be 7.3% of adults (n = 96,470) and 12.7% of children (n = 58,344). Of these, 95% of both adults and children were estimated to be using government healthcare facilities. Inpatient visits accounted for the largest proportion of total direct costs (55%), followed by emergency room and outpatient visits (25% and 20%, respectively) and medications (<0.2%). The annual cost of treatment excluding medications, was OMR 34,273,696 (USD 89,111,609) for adults and OMR 27,014,735 (USD 70,238,311) for children. Including medications, the total annual direct cost of asthma treatment was estimated to be over OMR 61,500,294 (USD 159,900,761). Conclusion: Given the high medical expenditures associated with facility visits relative to the lower medication costs, the focus of Oman’s asthma cost savings should be on improving asthma control rather than reducing medication costs

In-Cylinder Heat Transfer Model Proposal Compatible with 1D Simulations in Uniflow Scavenged Engines

[EN] Advanced two-stroke engines are considered as powertrains for range extenders in hybrid electric vehicles due to size, simplicity, cost, and power density advantages. In-cylinder heat transfer is a phenomenon that affects the temperature of burnt gases and fresh air in an internal combustion engine. Compared to four-stroke units, this influence is more critical in two-stroke engines during the scavenging process since the gases velocity field inside the cylinder evolves rapidly in space and time. This study proposes a new convective heat transfer coefficient model beyond those based on Reynolds number calculation with the mean piston velocity. The model uses semi-empirical equations with non-dimensional numbers since it has to be integrated within the frame of a physical engine model, where thermo- and fluid dynamic properties of the gases inside the engine are solved using 0D or 1D approaches. In this particular application, the temperature deviation led to a poor prediction of trapped mass in the cylinder. The proposed convective heat transfer coefficient is calculated using a pseudo-velocity of the gases inside the cylinder based on the mass flow rates in the intake and exhaust ports during scavenging. The experimental results validate the 1D engine physical model, which is then used as initial conditions for CFD simulations. These CFD results are used to deduce the necessary conclusions for enhanced temperature predictability during scavenging, where deviations of less than 2% can be observed and an impact of up to 12% on the in-cylinder trapped mass can be seen.Climent, H.; Tiseira, A.; Gómez-Soriano, J.; Darbhamalla, A. (2023). In-Cylinder Heat Transfer Model Proposal Compatible with 1D Simulations in Uniflow Scavenged Engines. Applied Sciences. 13(6). https://doi.org/10.3390/app1306399613