Study for evaluation of incineration and microwave treatment of human fecal matter for spacecraft operation

Incineration and microwave treatment of human fecal matter to determine concentration ranges and identities of liquid, gaseous, and solid product

SANICLAY-T: simple thermodynamic-based anisotropic plasticity model for clays

In this work the anisotropic model for clays SANICLAY proposed by Dafalias and Taiebat (2013) is reformulated within the framework of hyper-elastoplasticity. The model, called SANICLAY-T, is fully defined by two scalar potential functions, the free energy and the rate of dissipation. It is first presented in the triaxial space and then generalised in the multiaxial one. The model reproduces exactly the original one for the case of associate flow rule, while leads to a different outcome for non-associated flow. When compared to existing hyperplastic models accounting for rotational hardening, the proposed one proves to be more versatile, as characterised by less restrictive constraints on the hardening and asymptotic behaviour of the soil. The predictive capability of the model is illustrated with reference to experimental data on natural and reconstituted clays, highlighting its merits and limitations

University Students' Online Learning During COVID-19: The Role of Grit in Academic Performance

The governmental restriction due to COVID-19 pandemic led to Italian Universities moving teaching from face-to-face, to online. This represented an unexpected transition from traditional learning to what can be considered “e-learning.” This, together with the psychological distress that may be associated with the experience of lockdown, might have affected students' performance. It was hypothesised that grit may be a protective factor in such situations. Indeed, compared to their less “gritty” peers, individuals with higher levels of grit are expected to exhibit greater persistence in the pursuit of goals despite setbacks. Within educational contexts, grit is portrayed as a potentially important influence on outcomes such as achievement level, retention and probability of graduation. A longitudinal study was conducted using an online survey in order to assess the moderated mediation effect of grit on students' achievement. One hundred seventy-six undergraduate students from two universities in the north of Italy participated in the survey. The results showed that grit affects students' grades in final exams; perceived self-efficacy in the management of complex problems had a mediation effect on grades, while psychological distress moderated the first part of the mediation process. These novel findings extended our knowledge regarding the role of grit in academic performance investigating for the first time the role of self-efficacy and psychological distress in a learning carried out entirely online

Glider observations of thermohaline staircases in the tropical North Atlantic using an automated classifier

Thermohaline staircases are stepped structures of alternating thick mixed layers and thin high-gradient interfaces. These structures can be up to several tens of metres thick and are associated with double-diffusive mixing. Thermohaline staircases occur across broad swathes of the Arctic and tropical and subtropical oceans and can increase rates of diapycnal mixing by up to 5 times the background rate, driving substantial nutrient fluxes to the upper ocean. In this study, we present an improved classification algorithm to detect thermohaline staircases in ocean glider profiles. We use a dataset of 1162 glider profiles from the tropical North Atlantic collected in early 2020 at the edge of a known thermohaline staircase region. The algorithm identifies thermohaline staircases in 97.7 % of profiles that extend deeper than 300 m. We validate our algorithm against previous results obtained from algorithmic classification of Argo float profiles. Using fine-resolution temperature data from a fast-response thermistor on one of the gliders, we explore the effect of varying vertical bin sizes on detected thermohaline staircases. Our algorithm builds on previous work by adding improved flexibility and the ability to classify staircases from profiles with noisy salinity data. Using our results, we propose that the incidence of thermohaline staircases is limited by strong background vertical gradients in conservative temperature and absolute salinity.</p

Development of form and function in peripheral auditory structures of the zebrafish (Danio rerio)

Investigations of the development of auditory form and function have, with a few exceptions, thus far been largely restricted to birds and mammals, making it difficult to postulate evolutionary hypotheses. Teleost fishes represent useful models for developmental investigations of the auditory system due to their often extensive period of posthatching development and the diversity of auditory specializations in this group. Using the auditory brainstem response and morphological techniques we investigated the development of auditory form and function in zebrafish (Danio rerio) ranging in size from 10 to 45 mm total length. We found no difference in auditory sensitivity, response latency, or response amplitude with development, but we did find an expansion of maximum detectable frequency from 200 Hz at 10 mm to 4000 Hz at 45 mm TL. The expansion of frequency range coincided with the development of Weberian ossicles in zebrafish, suggesting that changes in hearing ability in this species are driven more by development of auxiliary specializations than by the ear itself. We propose a model for the development of zebrafish hearing wherein the Weberian ossicles gradually increase the range of frequencies available to the inner ear, much as middle ear development increases frequency range in mammals

Fatigue Characterisation and Monitoring in 3D Printed Short Fibres Reinforced Polyamide

The use of fused filament fabrication technology as a competitor of the conventional manufacturing processes for end-use parts production is of a great interest. However, a deep knowledge of the mechanical properties and failure behavior of printed parts is required to safely design final usable components. The present work aims to characterize the mechanical properties of a 3D printed short carbon fiber reinforced polyamide and to investigate the relationship between its unique morphology and its failure behavior. Tensile tests were conducted on rectangular specimens printed with an alternating sequence of layers with 0°/90° and ±45° raster orientation. Fracture surfaces of failed specimens were analyzed by Scanning Electron Microscopy (SEM). Possible failure mechanisms were then inferred by surface morphology analysis. Moreover, several specimens’ geometries were designed and printed to characterize the in-plane and out-of-plane material compressive properties. Considerations about the longitudinal strength of the material were eventually drawn

Development of ultrasound detection in American shad (Alosa sapidissima)

It has recently been shown that a few fish species, including American shad (Alosa sapidissima; Clupeiformes), are able to detect sound up to 180 kHz, an ability not found in most other fishes. Initially, it was proposed that ultrasound detection in shad involves the auditory bullae, swim bladder extensions found in all members of the Clupeiformes. However, while all clupeiformes have bullae, not all can detect ultrasound. Thus, the bullae alone are not sufficient to explain ultrasound detection. In this study, we used a developmental approach to determine when ultrasound detection begins and how the ability to detect ultrasound changes with ontogeny in American shad. We then compared changes in auditory function with morphological development to identify structures that are potentially responsible for ultrasound detection. We found that the auditory bullae and all three auditory end organs are present well before fish show ultrasound detection behaviourally and we suggest that an additional specialization in the utricle (one of the auditory end organs) forms coincident with the onset of ultrasound detection. We further show that this utricular specialization is found in two clupeiform species that can detect ultrasound but not in two clupeiform species not capable of ultrasound detection. Thus, it appears that ultrasound-detecting clupeiformes have undergone structural modification of the utricle that allows detection of ultrasonic stimulation

Glider Observations of the Northwestern Iberian Margin During an Exceptional Summer Upwelling Season

Glider observations from the Northwestern Iberian Margin during the exceptionally strong 2010 summer upwelling season resolved the evolution of physical and biogeochemical variables during two upwelling events. Upwelling brought low-oxygen Eastern North Atlantic Central Water from 190 m depth onto the shelf up to a depth of 50 m. During the two observed periods of upwelling, a poleward jet developed over the shelf break. The persistent upwelling favorable winds maintained equatorward flow on the outer shelf for 2 months with no reversals during relaxation periods, a phenomenon not previously observed. During upwelling, near-surface chlorophyll a concentration increased by more than 6 mg m −3. Oxygen supersaturation in the near surface increased by more than 20%, 6 days after the chlorophyll a maximum