A method to impregnate wet soil samples, producing high-quality thin sections.

[120.031]Mineral soils with different moisture content and texture were impregnated successfully by the method described. The water present in the soil sample is replaced by acetone and the acetone-saturated sample is impregnated by FitzPatrick's method (1970) (using acetone as thinner of the polyester resin Synolith 544). Shrinkage is minimal and the thin sections are of high quality. It should be possible to correlate thin section data obtained by this method with physical data obtained from undisturbed material. Micromorphologically, a better understanding of the plasmic fabrics should be possible. (Abstract retrieved from CAB Abstracts by CABI’s permission

Gravitational Waves in Bianchi Type-I Universes I: The Classical Theory

The propagation of classical gravitational waves in Bianchi Type-I universes is studied. We find that gravitational waves in Bianchi Type-I universes are not equivalent to two minimally coupled massless scalar fields as it is for the Robertson-Walker universe. Due to its tensorial nature, the gravitational wave is much more sensitive to the anisotropy of the spacetime than the scalar field is and it gains an effective mass term. Moreover, we find a coupling between the two polarization states of the gravitational wave which is also not present in the Robertson-Walker universe.Comment: 34 papers, written in ReVTeX, submitted to Physical Review

Hotspot mixing:A framework for heterodyne mixing in superconducting hot-electron bolometers

We propose a framework to interpret heterodyne mixing in superconducting hot-electron bolometers. The physical conversion process of the mixer is the result of an electronic hotspot, of which the length, and consequently the resistance, oscillates at the intermediate frequency. On the basis of this concept, we calculate the (un)pumped current–voltage relation, the dc voltage responsivity, and the mixer conversion efficiency

How Demanding Is Volunteer Work at a Crisis Line?:An Assessment of Work- and Organization-Related Demands and the Relation With Distress and Intention to Leave

Background: Crisis line services, run by volunteers, offer a listening ear 24/7 to people who cannot or do not want to use professional help. Although previous studies have identified various potential stressors crisis line volunteers face, as yet a comprehensive assessment is lacking with regards to the frequency and perceived stressfulness of work- and organization-related demands, and their relationship with distress and a volunteer's intention to leave. Objective: To identify the frequency and impact of particular stressful situations (demands). In addition, to examine the extent to which these demands are associated with volunteers' demographics, distress and intention to leave the crisis line service. Method: In a cross-sectional study among 543 volunteers of a Dutch crisis line service the participants filled out a questionnaire about their experience of a large number of work- and organization-related demands and their perceived stressfulness. To calculate the impact of demands, the occurrence and stressfulness were multiplied. In addition, work-related distress, intention to leave the crisis line service as well as a number of demographics and work-related characteristics were assessed. Results: Work-related demands with the highest impact on volunteers were calls from people with psychiatric problems and suicidal intentions. “Having no time for a break” was the organization-related demand with the highest impact on volunteers. Eighteen percentage of the volunteers scored moderate or high on distress and 4% had the intention to leave the crisis line service within 1 year. Most work- and organization-related demands were positively associated with volunteers' distress and intention to leave the organization. Being older, being male and spending more hours per week volunteering were significantly, positively correlated with work-related demands. The total explained variance for distress was 16% and for intention to leave 13%. Conclusion: Although most crisis line volunteers experienced low impact from work- and organization-related demands, these demands were significantly related to experienced distress and the intention to leave crisis line service. For volunteers with moderate to high distress it can be useful to implement interventions aimed at increasing personal resources to help them deal with the challenges of the work at the crisis line

Replicating Nanostructures on Silicon by Low Energy Ion Beams

We report on a nanoscale patterning method on Si substrates using self-assembled metal islands and low-energy ion-beam irradiation. The Si nanostructures produced on the Si substrate have a one-to-one correspondence with the self-assembled metal (Ag, Au, Pt) nanoislands initially grown on the substrate. The surface morphology and the structure of the irradiated surface were studied by high-resolution transmission electron microscopy (HRTEM). TEM images of ion-beam irradiated samples show the formation of sawtooth-like structures on Si. Removing metal islands and the ion-beam induced amorphous Si by etching, we obtain a crystalline nanostructure of Si. The smallest structures emit red light when exposed to a UV light. The size of the nanostructures on Si is governed by the size of the self-assembled metal nanoparticles grown on the substrate for this replica nanopatterning. The method can easily be extended for tuning the size of the Si nanostructures by the proper choice of the metal nanoparticles and the ion energy in ion-irradiation. It is suggested that off-normal irradiation can also be used for tuning the size of the nanostructures.Comment: 12 pages, 7 figures, regular paper submitted to Nanotechnolog

The Right to Informed Choice. A Study and Opinion Poll of Women Who Were or Were Not Given the Option of a Sterilisation with Their Caesarean Section

BACKGROUND: In The Netherlands, caesarean sections (CSs) are rarely combined with tubal occlusion (TO), partly because discussing CS/TO near delivery is considered unethical and earlier hypothetical counselling--i.e. suppose you happen to need a CS--is rare. This results in more unintended pregnancies and is inconsistent with informed choice. We explored whether TO should indeed not be made routinely available to eligible women. METHODS AND FINDINGS: A questionnaire was mailed to 515 Para ≥2 who underwent in the past ≥1 CS. 498 (96.7%) responded. They were on average 35.3 years old, had 2.5 children, had undergone 1.6 CSs, and 3.3 years had passed since their index delivery, either a CS (393) or vaginal birth (105) after a previous CS. 87% of the 498 believed that pregnant mothers with ≥1 children should be routinely counselled about CS/TO. Indeed, 58% and 85% respectively, thought women/couples expecting their second or third child should still be given the TO option days before delivery, if omitted earlier. Counselled women, 138/498 (27.8%), were far more often satisfied than those without CS/TO option. 33/393 had a CS/TO. None indicated regret in the questionnaire. Another 119 also would have elected a CS/TO if given that option. Therefore, 152 (38.7%) of 393 Para ≥2 had or would have liked a concurrent TO. 118/119 wrote they still regretted missing this opportunity. The exception's husband had had a vasectomy. 100/119 were good TO candidates: they were ≥28 years when they delivered an apparently healthy baby of ≥37 weeks. The current contraceptive use of these 100 suggests that this group will have at least 8 unintended pregnancies before age 50. CONCLUSION: The experiences and opinions of previous potential candidates for a CS/TO do not support the reluctance of Dutch obstetricians to counsel pregnant Para ≥1 about the TO option for a (potential) CS

The Influence of an Adsorbate Layer on Adatom Diffusion and Island Nucleation: Fe on Si(111)-√3 x √3-Au

Using scanning tunneling microscopy, the influence of a thin Au layer on the diffusion of Fe adatoms and the subsequent island nucleation on a Si(111) surface is investigated. The adsorbate induces thestructure that increases the surface mobility of subsequently deposited Fe atoms, resulting in the formation well-defined nanoclusters. Surprisingly, the domain walls—inherent to the reconstruction—do not influence the surface diffusion, which demonstrates that the passivation is of much more importance for the self-assembly than the surface corrugation. Using the decoupling of the diffusion and nucleationonthe surface and the reactionwiththe surface and conventional nucleation theory, the activation energy for surface diffusionEd = 0.61 eV and the critical cluster sizei = 3 are determined, which reveal the microscopic details of the diffusion and nucleation processes

Clinical performance of a novel textile interface for neonatal chest electrical impedance tomography

Objective: Critically ill neonates and infants might particularly benefit from continuous chest electrical impedance tomography (EIT) monitoring at the bedside. In this study a textile 32-electrode interface for neonatal EIT examination has been developed and tested to validate its clinical performance. The objectives were to assess ease of use in a clinical setting, stability of contact impedance at the electrode–skin interface and possible adverse effects. Approach: Thirty preterm infants (gestational age: 30.3 ± 3.9 week (mean ± SD), postnatal age: 13.8 ± 28.2 d, body weight at inclusion: 1727 ± 869 g) were included in this multicentre study. The electrode–skin contact impedances were measured continuously for up to 3 d and analysed during the initial 20-min phase after fastening the belt and during a 10 h measurement interval without any clinical interventions. The skin condition was assessed by attending clinicians. Main results: Our findings imply that the textile electrode interface is suitable for long-term neonatal chest EIT imaging. It does not cause any distress for the preterm infants or discomfort. Stable contact impedance of about 300 Ohm was observed immediately after fastening the electrode belt and during the subsequent 20 min period. A slight increase in contact impedance was observed over time. Tidal variation of contact impedance was less than 5 Ohm. Significance: The availability of a textile 32-electrode belt for neonatal EIT imaging with simple, fast, accurate and reproducible placement on the chest strengthens the potential of EIT to be used for regional lung monitoring in critically ill neonates and infants

Effect of routine suction on lung aeration in critically ill neonates and young infants measured with electrical impedance tomography

oai:repository.mdx.ac.uk:y1752Endotracheal suctioning is a widely used procedure to remove secretions from the airways of ventilated patients. Despite its prevalence, regional effects of this maneuver have seldom been studied. In this study, we explore its effects on regional lung aeration in neonates and young infants using electrical impedance tomography (EIT) as part of the large EU-funded multicenter observational study CRADL. 200 neonates and young infants in intensive care units were monitored with EIT for up to 72 h. EIT parameters were calculated to detect changes in ventilation distribution, ventilation inhomogeneity and ventilation quantity on a breath-by-breath level 5–10 min before and after suctioning. The intratidal change in aeration over time was investigated by means of regional expiratory time constants calculated from all respiratory cycles using an innovative procedure and visualized by 2D maps of the thoracic cross-section. 344 tracheal suctioning events from 51 patients could be analyzed. They showed no or very small changes of EIT parameters, with a dorsal shift of the center of ventilation by 0.5% of the chest diameter and a 7% decrease of tidal impedance variation after suctioning. Regional time constants did not change significantly. Routine suctioning led to EIT- detectable but merely small changes of the ventilation distribution in this study population. While still a measure requiring further study, the time constant maps may help clinicians interpret ventilationmechanics in specific cases