• Energy Research
• clinical medicine close
• US close
• GB close
• AU close
• CA close

Silicon microdosimetry is a promising technology for heavy ion therapy (HIT) quality assurance, because of its sub-mm spatial resolution and capability to determine radiation effects at a cellular level in a mixed radiation field. A drawback of silicon is not being tissue-equivalent, thus the need to convert the detector response obtained in silicon to tissue. This paper presents a method for converting silicon microdosimetric spectra to tissue for a therapeutic 12C beam, based on Monte Carlo simulations. The energy deposition spectra in a 10 μm sized silicon cylindrical sensitive volume (SV) were found to be equivalent to those measured in a tissue SV, with the same shape, but with dimensions scaled by a factor κ equal to 0.57 and 0.54 for muscle and water, respectively. A low energy correction factor was determined to account for the enhanced response in silicon at low energy depositions, produced by electrons. The concept of the mean path length [Formula: see text] to calculate the lineal energy was introduced as an alternative to the mean chord length [Formula: see text] because it was found that adopting Cauchy's formula for the [Formula: see text] was not appropriate for the radiation field typical of HIT as it is very directional. [Formula: see text] can be determined based on the peak of the lineal energy distribution produced by the incident carbon beam. Furthermore it was demonstrated that the thickness of the SV along the direction of the incident 12C ion beam can be adopted as [Formula: see text]. The tissue equivalence conversion method and [Formula: see text] were adopted to determine the RBE10, calculated using a modified microdosimetric kinetic model, applied to the microdosimetric spectra resulting from the simulation study. Comparison of the RBE10 along the Bragg peak to experimental TEPC measurements at HIMAC, NIRS, showed good agreement. Such agreement demonstrates the validity of the developed tissue equivalence correction factors and of the determination of [Formula: see text].

The effect of polar solvents and polar cosolvent mixtures on the transport properties of benzocaine in polydimethylsiloxane (PDMS) was studied. Methanol, ethanol, n-propanol, and n-butanol, as well as aqueous cosolvent mixtures of each n-alkanol, were used as vehicles for benzocaine. A constant activity gradient was maintained in all diffusion studies, with the membrane exposed to saturated donor suspensions of drug, and sink conditions maintained in the receiver. In spite of the constant activity gradient, steady-state benzocaine flux was substantially enhanced with increasing n-alkanol volume fraction and reached a maximum for the pure n-alkanol in each case. At any given composition, the degree of benzocaine flux enhancement generally increased with n-alkanol carbon number. In terms of the appropriate Fick's first law expression for this system, these observations were attributed to simultaneous changes in benzocaine concentration within the PDMS membrane, the diffusion coefficient of benzocaine in PDMS, fillerless membrane volume fraction, tortuosity, and the membrane thickness. These parameters were in turn correlated with the cosolvent composition in contact with the membrane. Both membrane solubility and diffusion coefficient were found to increase substantially, but decreases in tortuosity and increases in fillerless membrane volume fraction and membrane thickness were minor.

Anthropogenically generated underwater noise in the marine environment is ubiquitous, comprising both intense impulse and continuous noise. The installation of offshore wind farms across the North Sea has triggered a range of ecological questions regarding the impact of anthropogenically produced underwater noise on marine wildlife. Our interest is on the impact on the "passive drifters," i.e., the early life stages of fish that form the basis of fish populations and are an important prey for pelagic predators. This study deals with the impact of pile driving and operational noise generated at offshore wind farms on Dicentrarchus labrax (sea bass) larvae.

BackgroundMost alcoholics experience periods of voluntary alcohol abstinence or imposed alcohol deprivation followed by a return to alcohol drinking. This study examined whether varenicline (VAR) reduces alcohol intake during a return to drinking after periods of alcohol deprivation in rats selectively bred for high alcohol drinking (the alcohol preferring or “P” rats).MethodsAlcohol‐experienced P rats were given 24‐hour access to food and water and scheduled access to alcohol (15% and 30% v/v) for 2 h/d. After 4 weeks, rats were deprived of alcohol for 2 weeks, followed by reaccess to alcohol for 2 weeks, and this pattern was repeated for a total of 3 cycles. Rats were fed either vehicle (VEH) or VAR, in doses of 0.5, 1.0, or 2.0 mg/kg BW, at 1 hour prior to onset of the daily alcohol reaccess period for the first 5 days of each of the 3 alcohol reaccess cycles.ResultsLow‐dose VAR (0.5 mg/kg BW) reduced alcohol intake during the 5 days of drug treatment in alcohol reaccess cycles 1 and 2. Higher doses of VAR (1.0 mg/kg BW and 2.0 mg/kg BW) reduced alcohol intake during the 5 days of treatment in all 3 alcohol reaccess cycles. The decrease in alcohol intake disappeared with termination of VAR treatment in all alcohol reaccess cycles.ConclusionsThe results demonstrate that VAR decreases alcohol intake during multiple cycles of alcohol reaccess following alcohol deprivation in rats and suggests that it may prevent a return to heavy alcohol drinking during a lapse from alcohol abstinence in humans with alcohol use disorder.

An alcohol-free tissue conditioner based on a n-butyl methacrylate/i-butyl methacrylate copolymer has recently been developed. The purpose of the present study was to compare some key properties of the new tissue conditioner with those of poly(ethyl methacrylate)-based conventional materials containing ethyl alcohol. The effect of a coating, which consisted of poly(ethyl methacrylate) and methyl methacrylate, was also evaluated.The new alcohol-free tissue conditioner (Fictioner) and three tissue conditioners containing ethyl alcohol (FITT, Hydro-Cast, SR-Ivoseal) were evaluated. The coated alcohol-free material was also used. Gelation characteristics, dynamic viscoelastic properties and compatibility with dental stones were measured using a displacement rheometer, dynamic viscoelastometer and profilometer, respectively. In addition, weight changes during immersion in water were determined.The working time and gelation time of the alcohol-free tissue conditioner were similar to those of the conventional materials. This alcohol-free material had significantly lower shear storage modulus and shear loss modulus, and higher loss tangent (P<0.05) than FITT and SR-Ivoseal at 0.01 and 1 Hz. The alcohol-free material maintained its inherent viscoelastic properties and exhibited only a slight change in weight during 14 days of water immersion when compared to the conventional materials. The application of the coating significantly reduced the loss of the initial viscoelastic properties and surface quality during the test periods.The coated alcohol-free tissue conditioner would be superior to the conventional materials containing ethyl alcohol in view of viscoelastic properties after gelation, compatibility with dental stones and durability.

To describe physical activity (PA) and inactivity levels of Filipino youth aged 14-16 y.PA type and patterns were assessed in an adolescent cohort enrolled in the Cebu Longitudinal Health and Nutrition Survey.A total of 1053 males (aged 15.6+/-0.5 y; body mass index (BMI)=18.6+/-2.6 kg/m(2)) and 990 females (aged 14.6+/-0.5 y; BMI=18.8+/-2.4 kg/m(2)).PA was assessed by (1) self-reported usual PA (questionnaire); (2) 24-h objective monitoring (Caltrac accelerometer); and (3) 24 h recalls of PA during the objectively monitored time frame.As measured by Caltrac, males expended 378.0+/-164.5 kcal and females 271.0+/-105.4 kcal. The measurement approaches employed agreed in expected ways, given the limitations of each. Together the approaches used indicated that the primary sources of PA for this population are chores and active commuting. In all, 40% of the sample walked to school, less than 1% rode a bicycle, 22% rode in/on motorized transport, and 37% used some combination of walking and motorized transport. Further, gender differences exist for type, frequency, and duration of physical activities performed by Filipino youth. Specifically, females report engaging in few leisure-time physical activities and more household chores. In total, 48% of Filipino youth report watching > or =2 h/day of television; relatively few youth (7%) report watching >4 h/day at this time. An 18% of males report no vigorous activities compared to 87% of females.Clear gender differences in PA patterns and levels exist in Filipino adolescents. Nonsport/exercise type activities (eg chores and active commuting) currently provide a large proportion of daily activity for both males and females, however. It is anticipated that as modernization and technological advancement continue in this developing country, these primary sources of PA will decrease.

The present study was designed to determine the short-term effects of alcohol consumption on hormonal responses and mood states in nulliparous women who have regular menstrual cycles. To this aim, we conducted a within-subjects design study in which eight women consumed a 0.4-g/kg dose of alcohol in orange juice during one test session (alcohol condition) and an equal volume of orange juice (control condition) during the other. Changes in plasma prolactin, oxytocin and cortisol levels, blood alcohol concentrations (BACs), and mood states were compared. BAC peaked at approximately 36.7+5.4 min after the consumption of the alcoholic beverage and decreased thereafter. Alcohol consumption significantly increased the area under the concentration-time curve (AUC) of prolactin (P<.01) and decreased the oxytocin AUC (P=.04) when compared to the control condition. Cortisol AUCs were not different across the two experimental conditions. Similar to that previously observed in lactating women, changes in prolactin and oxytocin paralleled changes in feelings of drunkenness. The magnitude and persistence of the alcohol-induced hormonal changes in nulliparous women were significantly less pronounced than those observed in lactating women, further highlighting the dynamics of the system under study during lactation.