Thermally induced mixing of water dominated interstellar ices

Despite considerable attention in the literature being given to the desorption behaviour of smaller volatiles, the thermal properties of complex organics, such as ethanol (C2H5OH), which are predicted to be formed within interstellar ices, have yet to be characterized. With this in mind, reflection absorption infrared spectroscopy (RAIRS) and temperature programmed desorption (TPD) have been used to probe the adsorption and desorption of C2H5OH deposited on top of water (H2O) films of various thicknesses grown on highly oriented pyrolytic graphite (HOPG) at 98 K. Unlike many other molecules detected within interstellar ices, C2H5OH has a comparable sublimation temperature to H2O and therefore gives rise to a complicated desorption pro. le. RAIRS and TPD show that C2H5OH is incorporated into the underlying ASW film during heating, due to a morphology change in both the C2H5OH and H2O ices. Desorption peaks assigned to C2H5OH co-desorption with amorphous, crystalline (CI) and hexagonal H2O-ice phases, in addition to C2H5OH multilayer desorption are observed in the TPD. When C2H5OH is deposited beneath ASW films, or is co-deposited as a mixture with H2O, complete co-desorption is observed, providing further evidence of thermally induced mixing between the ices. C2H5OH is also shown to modify the desorption of H2O at the ASW-CI phase transition. This behaviour has not been previously reported for more commonly studied volatiles found within astrophysical ices. These results are consistent with astronomical observations, which suggest that gas-phase C2H5OH is localized in hotter regions of the ISM, such as hot cores

The adsorption and desorption of ethanol ices from a model grain surface

Reflection absorption infrared spectroscopy (RAIRS) and temperature programed desorption (TPD) have been used to probe the adsorption and desorption of ethanol on highly ordered pyrolytic graphite (HOPG) at 98 K. RAIR spectra for ethanol show that it forms physisorbed multilayers on the surface at 98 K. Annealing multilayer ethanol ices (exposures > 50 L) beyond 120 K gives rise to a change in morphology before crystallization within the ice occurs. TPD shows that ethanol adsorbs and desorbs molecularly on the HOPG surface and shows four different species in desorption. At low coverage, desorption of monolayer ethanol is observed and is described by first-order kinetics. With increasing coverage, a second TPD peak is observed at a lower temperature, which is assigned to an ethanol bilayer. When the coverage is further increased, a second multilayer, less strongly bound to the underlying ethanol ice film, is observed. This peak dominates the TPD spectra with increasing coverage and is characterized by fractional-order kinetics and a desorption energy of 56.3 +/- 1.7 kJ mol(-1). At exposures exceeding 50 L, formation of crystalline ethanol is also observed as a high temperature shoulder on the TPD spectrum at 160 K. (c) 2008 American Institute of Physics

An App to Help Young People Self-Manage When Feeling Overwhelmed (ReZone): Protocol of a Cluster Randomized Controlled Trial

Background: The association between behavioral difficulties and academic attainment is well established. Recent policy advising schools on managing behavior has promoted the early identification of behavioral difficulties. There is also increasing research into mHealth interventions to provide support for emotional and behavioral difficulties for young people. Objective: The primary aim of the proposed research is to examine the effectiveness of an mHealth intervention, ReZone, in reducing emotional and behavioral difficulties in young people. Methods: The protocol is a cluster trial of 12 classes with N=120 students with classes randomized to ReZone or management as usual. Multilevel modeling will be used to compare ReZone versus management as usual accounting for classroom-level variation. Results: Baseline data collection started in February 2017 and ended in April 2017. Follow-up data collection started in April 2017 and ended in June 2017. Conclusions: The proposed research will provide evidence as to whether ReZone is effective at helping young people to self-manage when feeling overwhelmed

The effects of methanol on the trapping of volatile ice components

The evaporation of icy mantles, which have been formed on the surface of dust grains, is acknowledged to give rise to the rich chemistry that has been observed in the vicinity of hot cores and corinos. It has long been established that water ice is the dominant species within many astrophysical ices. However, other molecules found within astrophysical ices, particularly methanol, can influence the desorption of volatile species from the ice. Here we present a detailed investigation of the adsorption and desorption of methanol-containing ices, showing the effect that methanol has on the trapping and release of volatiles from model interstellar ices. OCS and CO2 have been used as probe molecules since they have been suggested to reside in water-rich and methanol-rich environments. Experiments show that methanol fundamentally changes the desorption characteristics of both OCS and CO2, leading to the observation of mainly codesorption of both species with bulk water ice for the tertiary ices and causing a lowering of the temperature of the volcano component of the desorption. In contrast, binary ices are dominated by standard volcano desorption. This observation clearly shows that codepositing astrophysically relevant impurities with water ice, such as methanol, can alter the desorption dynamics of volatiles that become trapped in the pores of the amorphous water ice during the sublimation process. Incorporating experimental data into a simple model to simulate these processes on astrophysical timescales shows that the additional methanol component releases larger amounts of OCS from the ice mantle at lower temperatures and earlier times. These results are of interest to astronomers as they can be used to model the star formation process, hence giving information about the evolution of our Universe

Patient and Public Involvement in Youth Mental Health Research: Protocol for a Systematic Review of Practices and Impact

Various health settings have advocated for involving patients and members of the public (PPI) in research as a means to increase quality and relevance of the produced knowledge. However, youth PPI has been an understudied area. This protocol paper describes a new project that aims to summarize what is known about PPI with young people in mental health research. In line with the Preferred Reporting Items for Systematic reviews and Meta-Analyses Statement guidelines we will identify and appraise suitable articles and extract and synthesize relevant information including at least two reviewers at each stage of the process. Results will be presented in two systematic reviews that will describe (a) how youth PPI has been conducted (Review1) and (b) what impact youth PPI had on the subsequent research and on stakeholders (Review2). To our knowledge, this is the first set of reviews that uses a critical appraisal tool, which is co-developed with children and young people. Findings from this project will provide valuable insights and set out the key steps to adopting adequate PPI methods when involving children and young people in mental health research

Contact and temperature effects in Gunn oscillators.

This study is concerned with contact properties of longitudinal and transverse (planar) Gunn devices. A description is given of the fabrication techniques developed for these devices. The transverse structure allows non-parallel electrodes to be used and also the addition of extra electrodes. Frequency tuning was investigated for both concentric electrode and three terminal devices. Tuning ranges of several GHz were observed by variation of anode bias voltage from concentric electrode diodes operating in the transit-time mode. The three terminal devices, which had a Schottky Barrier electrode between the cathode and anode, produced up to 2 GHz electronic tuning with variation of the bias voltage on the third electrode. Cavity controlled operation considerably reduced these tuning ranges. Two domain paths were possible for the three terminal devices and the tuning mechanisms for these are discussed. The frequency drift with ambient temperature was studied on longitudinal devices. These had n+ GaAs contacts to eliminate the overriding negative slope caused by alloyed metal contacts. At full power output, frequency drift rates were between -1 and -2 MHz/°C in a lambda/2 coaxial cavity. However by decoupling the load to reduce the power by about 2 dB, average drift rates were reduced to less than 100 KHz/°C. These results were attributed to the delayed domain and quenched domain modes respectively. Fourier analysis of the current waveform for each mode gave qualitative agreement with experiment

Contact and temperature effects in Gunn oscillators.

This study is concerned with contact properties of longitudinal and transverse (planar) Gunn devices. A description is given of the fabrication techniques developed for these devices. The transverse structure allows non-parallel electrodes to be used and also the addition of extra electrodes. Frequency tuning was investigated for both concentric electrode and three terminal devices. Tuning ranges of several GHz were observed by variation of anode bias voltage from concentric electrode diodes operating in the transit-time mode. The three terminal devices, which had a Schottky Barrier electrode between the cathode and anode, produced up to 2 GHz electronic tuning with variation of the bias voltage on the third electrode. Cavity controlled operation considerably reduced these tuning ranges. Two domain paths were possible for the three terminal devices and the tuning mechanisms for these are discussed. The frequency drift with ambient temperature was studied on longitudinal devices. These had n+ GaAs contacts to eliminate the overriding negative slope caused by alloyed metal contacts. At full power output, frequency drift rates were between -1 and -2 MHz/°C in a lambda/2 coaxial cavity. However by decoupling the load to reduce the power by about 2 dB, average drift rates were reduced to less than 100 KHz/°C. These results were attributed to the delayed domain and quenched domain modes respectively. Fourier analysis of the current waveform for each mode gave qualitative agreement with experiment

Surface science investigations of the role of CO2 in astrophysical ices

We have recorded reflection–absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) data for a range of CO2-bearing model astrophysical ices adsorbed on a graphitic dust grain analogue surface. Data have been recorded for pure CO2, for CO2 adsorbed on top of amorphous solid water, for mixed CO2:H2O ices and for CO2 adsorbed on top of a mixed CH3OH:H2O ice. For the TPD data, kinetic parameters for desorption have been determined, and the trapping behaviour of the CO2 in the H2O (CH3OH) ice has been determined. Data of these types are important as they can be used to model desorption in a range of astrophysical environments. RAIR spectra have also shown the interaction of the CO2 with H2O and CH3OH and can be used to compare with astronomical observations, allowing the accurate assignment of spectra