Association of molecules using a resonantly modulated magnetic field

We study the process of associating molecules from atomic gases using a magnetic field modulation that is resonant with the molecular binding energy. We show that maximal conversion is obtained by optimising the amplitude and frequency of the modulation for the particular temperature and density of the gas. For small modulation amplitudes, resonant coupling of an unbound atom pair to a molecule occurs at a modulation frequency corresponding to the sum of the molecular binding energy and the relative kinetic energy of the atom pair. An atom pair with an off-resonant energy has a probability of association which oscillates with a frequency and time-varying amplitude which are primarily dependent on its detuning. Increasing the amplitude of the modulation tends to result in less energetic atom pairs being resonantly coupled to the molecular state, and also alters the dynamics of the transfer from continuum states with off-resonant energies. This leads to maxima and minima in the total conversion from the gas as a function of the modulation amplitude. Increasing the temperature of the gas leads to an increase in the modulation frequency providing the best fit to the thermal distribution, and weakens the resonant frequency dependence of the conversion. Mean-field effects can alter the optimal modulation frequency and lead to the excitation of higher modes. Our simulations predict that resonant association can be effective for binding energies of order $h \times 1$ MHz.Comment: 8 pages latex, figures revised, references updated and typos correcte

Estimating Risks of Heat Strain by Age and Sex: A Population-Level Simulation Model

Individuals living in hot climates face health risks from hyperthermia due to excessive heat. Heat strain is influenced by weather exposure and by individual characteristics such as age, sex, body size, and occupation. To explore the population-level drivers of heat strain, we developed a simulation model that scales up individual risks of heat storage (estimated using Myrup and Morgan’s man model “MANMO”) to a large population. Using Australian weather data, we identify high-risk weather conditions together with individual characteristics that increase the risk of heat stress under these conditions. The model identifies elevated risks in children and the elderly, with females aged 75 and older those most likely to experience heat strain. Risk of heat strain in males does not increase as rapidly with age, but is greatest on hot days with high solar radiation. Although cloudy days are less dangerous for the wider population, older women still have an elevated risk of heat strain on hot cloudy days or when indoors during high temperatures. Simulation models provide a valuable method for exploring population level risks of heat strain, and a tool for evaluating public health and other government policy interventions

Unlicensed driving among California high school seniors

The driving behaviors and characteristics of unlicensed teenage drivers have been little explored. For this study of behaviors of unlicensed California teen drivers, 2,144 high school seniors at 13 school sites in California completed a written survey. Unlicensed driving was ascertained by combining survey questions about licensing and driving. Data were analyzed to examine characteristics of unlicensed drivers compared with licensed drivers, and to examine risk behaviors among the unlicensed drivers. A total of 12.4 percent (n = 265) of students reported driving a motor vehicle without a driver’s license or permit, while two-thirds of surveyed students had either a license or a permit, and the remainder did not drive. Unlicensed drivers were primarily male (56 percent) and Latino (67 percent); unlicensed drivers were more likely than others to attend a school with a lower-income population. Licensed and unlicensed drivers reported similar rates of driving after alcohol or other drug use. Licensed drivers were more likely than unlicensed drivers to report having been in a crash, but this difference was no longer significant after adjustment for risk behaviors. Unlicensed driving was fairly common in this sample, but did not appear to represent an excess risk relative to licensed drivers

Creative approaches to reimagining patient and public involvement (PPI) in cancer research

This study investigates the role of Patient and Public Involvement (PPI) in cancer research through interviews with patient representatives, researchers, and professionals with personal cancer experience, aiming to identify challenges and opportunities in current PPI practices. It emphasises the need for effective communication, diverse participation, and a co-creative approach. The work delves not only into the 'how' but also the 'why', offering recommendations that hope to contribute to ongoing discussions and practices

The unconventional cytoplasmic sensing mechanism for ethanol chemotaxis in Bacillus subtilis

Motile bacteria sense chemical gradients using chemoreceptors, which consist of distinct sensing and signaling domains. The general model is that the sensing domain binds the chemical and the signaling domain induces the tactic response. Here, we investigated the unconventional sensing mechanism for ethanol taxis in Bacillus subtilis. Ethanol and other short-chain alcohols are attractants for B. subtilis. Two chemoreceptors, McpB and HemAT, sense these alcohols. In the case of McpB, the signaling domain directly binds ethanol. We were further able to identify a single amino-acid residue Ala431 on the cytoplasmic signaling domain of McpB, that when mutated to a serine, reduces taxis to ethanol. Molecular dynamics simulations suggest ethanol binds McpB near residue Ala431 and mutation of this residue to serine increases coiled-coil packing within the signaling domain, thereby reducing the ability of ethanol to bind between the helices of the signaling domain. In the case of HemAT, the myoglobin-like sensing domain binds ethanol, likely between the helices encapsulating the heme group. Aside from being sensed by an unconventional mechanism, ethanol also differs from many other chemoattractants because it is not metabolized by B. subtilis and is toxic. We propose that B. subtilis uses ethanol and other short-chain alcohols to locate prey, namely alcohol-producing microorganisms