Dynamic range of nanotube- and nanowire-based electromechanical systems

Nanomechanical resonators with high aspect ratio, such as nanotubes and nanowires are of interest due to their expected high sensitivity. However, a strongly nonlinear response combined with a high thermomechanical noise level limits the useful linear dynamic range of this type of device. We derive the equations governing this behavior and find a strong dependence [[proportional]dsqrt((d/L)[sup 5])] of the dynamic range on aspect ratio

Curvaton Scenario with Affleck-Dine Baryogenesis

We discuss the curvaton scenario with the Affleck-Dine baryogenesis. In this scenario, non-vanishing baryonic entropy fluctuation may be generated even without primordial fluctuation of the Affleck-Dine field. Too large entropy fluctuation is inconsistent with the observations and hence constraints on the curvaton scenario with the Affleck-Dine baryogenesis are obtained. We calculate the baryonic entropy fluctuation (as well as other cosmological density fluctuations) in this case and derive constraints. Implications to some of the models of the curvaton are also discussed.Comment: 16 pages,2 figure

The Past Has Ears (PHE): XR Explorations of Acoustic Spaces as Cultural Heritage

Hearing is one of our most pervasive senses. There is no equivalent to closing our eyes, or averting our gaze, for the ears. When we think about great architectural achievements in European history, such as ancient amphitheatres or Gothic cathedrals, their importance is strongly tied to their acoustic environment. The acoustics of a heritage site is an intangible consequence of the space's tangible construction and furnishings. Inspired by the project's namesake (Phe, for the constellation Phoenix), and the relatively recent res at Cathedrale de Notre Dame de Paris and Teatro La Fenice opera hall, the PHE project focuses on virtual reconstruction of heritage sites, bringing them back from the ashes. In addressing the intangible acoustic heritage of architectural sites, three main objectives have been identied for this research project: Documentation, Modelling, and Presentation. In parallel, three heritage sites are participating as case studies: Tindari Theatre (IT), Notre-Dame de Paris Cathedral (FR), and The Houses of Parliament (UK). The acoustics of a space is immersive, spatial, and due to the nature of auditory perception egocentric, in contrast to visual perception of an object, which can be observed from outside". Consequently, presentation methods for communicating acoustic heritage must represent the spatially immersive and listener-centric nature of acoustics. PHE will lead development of a museum grade hardware/software prototype for the presentation of immersive audio experiences adaptable to multiple platforms, from on-site immersive speaker installations, to mobile XR via smartphone applications

Studying individual differences in spatial cognition through differential item functioning analysis

Background: In the field of spatial cognition, the study of individual differences represents a typical research topic. Gender and age have been prominently investigated. A promising statistical technique used to identify the different responses to items in relation to different group memberships is the Differential Item Functioning Analysis (DIF). The aim of the present study was to investigate the DIF of the Landmark positioning on a Map (LPM) task, across age groups (young and elderly) and gender, in a sample of 400 healthy human participants. Methods: LPM is a hometown map completion test based on well-known and familiar landmarks used to assess allocentric mental representations. DIF was assessed on LPM items two times: on categorical (i.e., positions) and coordinate (i.e., distances) scores, separately. Results: When positions and distances were difficult to assess with respect to the intended reference point, the probability to endorse the items seemed to get worse for the elderly compared to the younger participants. Instead other features of landmarks (high pleasantness, restorativeness) seemed to improve the elderly performance. A gender-related improvement of probability to endorse distance estimation of some landmarks, favoring women, emerged, probably associated with their repeated experiences with those landmarks. Overall, the complexity of the task seemed to have a differential impact on young and elderly people while gender-oriented activities and places seemed to have a differential impact on men and women. Conclusions: For the first time DIF was applied to a spatial mental representation task, based on the schematic sketch maps of the participants. The application of DIF to the study of individual differences in spatial cognition should become a systematic routine to early detect differential items, improving knowledge, as well as experimental control, on individual differences

Effect of breastfeeding promotion interventions on cost-effectiveness of rotavirus immunization in Indonesia

BACKGROUND: Rotavirus infection has been reported to be responsible for the majority of severe diarrhea in children under-5-years-old in Indonesia. Breast milk is considered to give protection against rotavirus infection. Increasing breastfeeding promotion programs could be an alternative target to reduce the incidence of rotavirus diarrhea. This study aims to investigate the effect of breastfeeding promotion interventions on cost-effectiveness of rotavirus immunization in Indonesia, focusing on breastfeeding education and support interventions.METHODS: An age-structured cohort model was developed for the 2011 Indonesia birth cohort. We compared four interventions in scenarios: (i) base-case (I₀) reflecting the current situation for the population of under-5-years-old, (ii) with an additional breastfeeding education intervention (I₁), (iii) with a support intervention on initiation and duration (I₂) and (iv) with both of these two interventions combined (I₃). The model applied a 5-years time horizon, with 1 month analytical cycles for children less than 1 year of age and annually thereafter. Monte Carlo simulations were used to examine the economic acceptability and affordability of rotavirus vaccination.RESULTS: Rotavirus immunization would effectively reduce severe cases of rotavirus during the first 5 years of a child's life even assuming various breastfeeding promotion interventions. The total yearly vaccine cost would amount to US$64 million under the market vaccine price. Cost-effectiveness would increase to US$ 153 per quality-adjusted-life-year (societal perspective) with an optimal breastfeeding promotion intervention. Obviously, this is much lower than the 2011 Gross Domestic Product (GDP) per capita of US$ 3,495. Affordability results showed that at the market vaccine price, rotavirus vaccination could be affordable for the Indonesian health system.CONCLUSIONS: Rotavirus immunization would be a highly cost-effective public health intervention for Indonesia even under various breastfeeding promotion interventions based on the WHO's criteria for cost-effectiveness in universal immunization.</p

The road more travelled: The differential effects of spatial experience in young and elderly participants

Our spatial mental representations allow us to give refined descriptions of the environment in terms of the relative locations and distances between objects and landmarks. In this study, we investigated the effects of familiarity with the everyday environment, in terms of frequency of exploration and mode of transportation, on categorical and coordinate spatial relations, on young and elderly participants, controlling for socio-demographic factors. Participants were tested with a general anamnesis, a neuropsychological assessment, measures of explorations and the Landmark Positioning on a Map task. The results showed: (a) a modest difference in performance with categorical spatial relations; (b) a larger difference in coordinate spatial relations; (c) a significant moderating effect of age on the relationship between familiarity and spatial relations, with a stronger relation among the elderly than the young. Ceteris paribus, the role of direct experience with exploring their hometown on spatial mental representations appeared to be more important in the elderly than in the young. This advantage appears to make the elderly wiser and likely protects them from the detrimental effects of aging on spatial mental representations

Nanowire-based very-high-frequency electromechanical resonator

Fabrication and readout of devices with progressively smaller size, ultimately down to the molecular scale, is critical for the development of very-high-frequency nanoelectromechanical systems (NEMS). Nanomaterials, such as carbon nanotubes or nanowires, offer immense prospects as active elements for these applications. We report the fabrication and measurement of a platinum nanowire resonator, 43 nm in diameter and 1.3 µm in length. This device, among the smallest NEMS reported, has a fundamental vibration frequency of 105.3 MHz, with a quality factor of 8500 at 4 K. Its resonant motion is transduced by a technique that is well suited to ultrasmall mechanical structures

The attitudes of healthy children and researchers towards the challenges of involving children in research:an exploratory study

BACKGROUND: A growing trend in research is to involve co-researchers. It is referred to as Patient and Public Involvement (PPI) and comprises three groups: the patients, the public, and the researchers. Like in adult public involvement, healthy children can also be considered as 'the public'. Paediatric patients and researchers experienced in conducting child-inclusive research are often asked about their attitudes towards the challenges they encounter. This is not the case for healthy children and researchers without such experience. Our aim was to investigate the attitudes of these children and researchers towards the challenges encountered during child-inclusive research. METHODS: This was an exploratory study. We interviewed healthy children and adult researchers without prior experience in child-inclusive research. We recruited the children through a foundation for young researchers and the adult researchers from two hospitals, both in Groningen, the Netherlands. We audio recorded the interviews, and they were transcribed verbatim. We analysed the data using qualitative content analysis. RESULTS: We interviewed five adult researchers and seven healthy children, aged 9 to 14 years. Both groups thought that it was best to involve children in paediatric research from as early a stage as possible. The children assumed that no prior training would be needed because they had already been trained at school. The researchers' attitudes varied regarding training children beforehand. Both groups thought that researchers did not need prior training on how to involve children if they worked with children on a daily basis. The children felt that recognition and a modest financial reward was appropriate. Adult researchers were cautious about rewarding the children. They feared it might render the children less intrinsically motivated. CONCLUSION: Our study indicated that young and adult researchers have clear attitudes towards the challenges encountered during child-inclusive research. Young researchers could help adult researchers to find solutions to these challenges, even if they have no prior experience in child-inclusive research. Adult researchers who acknowledge the importance of child-inclusive research represent a significant step towards meaningful involvement of children. Our results imply that children could be involved in the decision-making process concerning the challenges encountered in child-inclusive research

Longevity of supersymmetric flat directions

We examine the fate of supersymmetric flat directions. We argue that the non-perturbative decay of the flat direction via preheating is an unlikely event. In order to address this issue, first we identify the physical degrees of freedom and their masses in presence of a large flat direction VEV (Vacuum Expectation Value). We explicitly show that the (complex) flat direction and its fermionic partner are the only light {\it physical} fields in the spectrum. If the flat direction VEV is much larger than the weak scale, and it has a rotational motion, there will be no resonant particle production at all. The case of multiple flat directions is more involved. We illustrate that in many cases of physical interest, the situation becomes effectively the same as that of a single flat direction, or collection of independent single directions. In such cases preheating is not relevant. In an absence of a fast non-perturbative decay, the flat direction survives long enough to affect thermalization in supersymmetric models as described in hep-ph/0505050 and hep-ph/0512227. It can also ``terminate'' an early stage of non-perturbative inflaton decay as discussed in hep-ph/0603244.Comment: 9 revtex pages, v3: expanded discussion on two flat directions, minor modifications, conclusions unchange

Basins of attraction of a nonlinear nanomechanical resonator

We present an experiment that systematically probes the basins of attraction of two fixed points of a nonlinear nanomechanical resonator and maps them out with high resolution. We observe a separatrix which progressively alters shape for varying drive strength and changes the relative areas of the two basins of attraction. The observed separatrix is blurred due to ambient fluctuations, including residual noise in the drive system, which cause uncertainty in the preparation of an initial state close to the separatrix. We find a good agreement between the experimentally mapped and theoretically calculated basins of attraction