Search

Background Methods Results Conclusions Accessing peer support can be difficult for people with, or carers of people with, inherited intellectual disabilities. One way to improve access is to provide services online, yet few studies have explored people's experiences with online peer support programmes. We aimed to explore experiences with such programmes for communities affected by fragile X‐associated conditions.Qualitative study involving individual semi‐structured interviews with 16 people with, or carers of people with, a fragile X‐associated condition (n = 4 adult premutation carriers; n = 12 parents/carers of children/adults), who participated in at least one of three online peer support programmes: educational webinars, Facebook discussion group and small peer group sessions via Zoom. Reflexive thematic analysis was used to develop themes.Three overarching themes relating to experiences were as follows: (1) uncertainty and value of shared experiences, (2) support navigating healthcare, (3) advantages being online, but still a place for in‐person events. Educational webinars were perceived to be a valuable source of information about fragile X‐associated conditions although people had variable information needs. Facebook discussion groups enabled people to connect with others, although participants expressed some competing preferences for how the groups were organised. Zoom peer group sessions were perceived to help participants feel supported by others, but that consistency in organisation was important.Online peer support programmes were perceived to be beneficial, bridging informational gaps and facilitating social connection. However, participants believed there was still a place for in‐person events, some felt educational webinars did not always meet their needs and some had privacy concerns. [ABSTRACT FROM AUTHOR]

The strain field of the emitters of one unstressed and two electrically stressed oxide-confined GaAs-based vertical-cavity surface-emitting lasers has been analyzed. The components of the strain tensor in the optical aperture, in the quantum wells, and at the oxide edge of the lamellas have been measured by nano-beam precession electron diffraction and geometrical phase analysis. The measurements have been used to validate the simulations based on the finite element method (FEM) of the mechanical behavior of the emitters. The FEM model is used to quantify the strain caused by the lattice mismatch of the GaAs-based epitaxial layers and the volume variation of the Al 98 Ga 2 As layer due to selective oxidation. The first is calculated as a function of the misfit strain and corresponds very well to the measured values. The latter is calibrated assuming that the thickness of the oxide is expanded by 4 % in both the unstressed sample and the stressed sample with dislocations. Instead, it is contracted by 8 % for the sample where the stress test has caused further oxidation. [ABSTRACT FROM AUTHOR]

The growth and the electronic properties of sexithiophene thin films on silicon surfaces have been studied by angle resolved ultraviolet photoelectron spectroscopy while morphology and crystalline order have been assessed by atomic force microscopy and x-ray diffraction. The influence of the surface modification of the substrate as well as of the growth temperature and the growth rate were investigated in ultrahigh vacuum through controlled multistep growth sequences ranging from (sub)monolayer coverage up to thick films. Depending on the preparation, two electronically distinct sexithiophene (6T) films could be produced, as revealed by their ionization potentials which differed by ∼0.7 eV. The evolution of the electronic energy levels with film thickness is considered in terms of the concepts of interface dipole and band bending, with the latter being argued to be inappropriate. Irrespective of substrate or growth conditions the thick 6T films were found to all have the same work function of ∼0.4 eV, which is related to near vertically oriented molecules on the films surface. Against general expectations 6T grown at a low rate on the reactive Si(111) substrate and those grown at high rates on the oxide surface produces films that are more uniform and crystalline than those grown at low rates on the passive oxidized Si surfaces. The latter promotes the formation of small three-dimensional crystallites and a much poorer morphology for planar devices. [ABSTRACT FROM AUTHOR]

Introduction: The majority of Apollo 17 sample 77017 constitutes a feldspathic impactite that was recrystallized at subsolidus temperatures as a result of a basin impact [e.g., 1]. We dated this recrystallisation event at ~4.17 Ga using 147Sm-143Nd systematics [2]. On the basis of a geological investigation of craters that could have excavated sample 77017, in combination with a numerical modelling of impact-induced redistribution of basin melts, we also found that a basin-forming event--either Serenitatis or Crisium--was the most likely cause for the recrystallisation [3]. Here, we present 207Pb/206Pb data that provide a more precise recrystallization age and to further constrain the origin of the protolith. Methods: 535 mg of a fine (<20 µm) bulk fraction of split 77017,199 was used for Pb isotope analyses. Stepwise digestion, chemical separation, and isotopic analyses were adopted from [4, 5]. A Monte Carlo approach (10000 cycles) was used for blank subtraction and error propagation. Results: The sample-to-blank ratios of the Pb isotope analyses of the six digestion steps of the bulk fraction range from 0.3 x106 to 9.8 x106. Thus the effect of procedural blanks on the Pb isotope systematics is negligible. Nevertheless, a substantial terrestrial lead component was present in the first two digstion steps and a minor terrestrial component affected the penultimate step. The remaining digestion steps define a 4143 ±9 Ma (MSWD = 0.99) isochron. Additionally, further analyses of mineral fractions combined with the data originally presented in [2] now yield a 4159 ±16 Ma 147Sm-143Nd isochron (MSWD = 1.3; originally a 4170 ±80 Ma errorchron, MSWD = 8.1) when using 6 of the 9 data points. Discussion: The 40Ar/39Ar dating by [1] has established a minimum age estimate (4034 ±58 Ma; recalculated) for the metamorphic sub-solidus recrystallization of 77017. This minimum age is consistent with our 207Pb/206Pb isochron date (4143 ±9 Ma), which, more importantly, is concordant with our 147Sm-143Nd isochron date (4159 ±16 Ma) obtained on the same sample split [2]. We consider the weighted average of the two dates (4147 ± 8 Ma, MSWD = 3.0) to be the best age estimate for the recrystallisation event. Our isochron intersects within error the initial Pb isotopic composition of the LMO at the time of differentiation determined by [6]. As [6] consider this event to have taken place at 4376 ±18 Ma, this would require that the 207Pb/206Pb of the 77017-protolith did not change significantly over the next ~229 Ma until the recrystallisation event at 4147 ± 8 Ma. This in turn, requires a very low µ-value (=238U/204Pb) in the protolith, which is typical for crustal materials and suggests that little or no KREEP component is present. However, U-Th-Pb systematics of 77017 were previously obtained by [7] and on the basis of the U and Th concentrations, the authors concluded that it is possible that "77017 contains about 5-6% KREEP component" [7]. Using our 207Pb/206Pb data, we attempted to constrain whether this KREEP component could have already been present in the protolith before impact. We solved for a protolith isotopic composition that would yield an initial 207Pb/206Pb on our 77017 Pb-Pb isochron using a 2-stage model (Stage 1: bulk moon from moon formation to protolith formation, Stage 2: protolith from its formation to recrystallisation event; after [6]). Even when choosing from the possible range of parameters (time of moon formation, time of protolith formation, µ during stage 1 and 2; [6, 8]) those that produce the highest µ-value (i.e., closest to KREEP) in the protolith, this value never exceeds that of the bulk silicate moon in the respective scenario. This is indicative of crustal material that preferentially incorporated Pb. Furthermore, even the highest possible µ-value in such a 2-stage model is lower than the µ-value of 77017 (658-870) measured by [7]. We conclude that this measured µ-value of 77017, which is suggestive of the presence of a KREEP component, must result from a process (most likely addition of a KREEP component or Pb loss) that occurred during the recrystallisation of the sample or even a later event. Therefore, it seems likely that the protolith of 77017 was free of any KREEP component. A KREEP-free 77017 protolith supports our interpretation that the basin impact that led to the recrystallisation of 77017 was either Serenitatis or Crisium [3]. A 4.15 Ga age of either basin contradicts terminal lunar cataclysm models that require both basins to be ~3.9 Ga [9, and references therein]. [ABSTRACT FROM AUTHOR]