Towards the mechanical characterization of abdominal wall by inverse analysis

The aim of this study is to characterize the passive mechanical behaviour of abdominal wall in vivo in an animal model using only external cameras and numerical analysis. The main objective lies in defining a methodology that provides in vivo information of a specific patient without altering mechanical properties. It is demonstrated in the mechanical study of abdomen for hernia purposes. Mechanical tests consisted on pneumoperitoneum tests performed on New Zealand rabbits, where inner pressure was varied from 0 mmHg to 12 mmHg. Changes in the external abdominal surface were recorded and several points were tracked. Based on their coordinates we reconstructed a 3D finite element model of the abdominal wall, considering an incompressible hyperelastic material model defined by two parameters. The spatial distributions of these parameters (shear modulus and non linear parameter) were calculated by inverse analysis, using two different types of regularization: Total Variation Diminishing (TVD) and Tikhonov (H1). After solving the inverse problem, the distribution of the material parameters were obtained along the abdominal surface. Accuracy of the results was evaluated for the last level of pressure. Results revealed a higher value of the shear modulus in a wide stripe along the craneo-caudal direction, associated with the presence of linea alba in conjunction with fascias and rectus abdominis. Non linear parameter distribution was smoother and the location of higher values varied with the regularization type. Both regularizations proved to yield in an accurate predicted displacement field, but H1 obtained a smoother material parameter distribution while TVD included some discontinuities. The methodology here presented was able to characterize in vivo the passive non linear mechanical response of the abdominal wall

Large-scale quantum-emitter arrays in atomically thin semiconductors

This is the final version. Available on open access from Nature Research via the DOI in this recordData availability: The data that supports the findings of this study are available from the corresponding author upon request.Quantum light emitters have been observed in atomically thin layers of transition metal dichalcogenides. However, they are found at random locations within the host material and usually in low densities, hindering experiments aiming to investigate this new class of emitters. Here, we create deterministic arrays of hundreds of quantum emitters in tungsten diselenide and tungsten disulphide monolayers, emitting across a range of wavelengths in the visible spectrum (610–680 nm and 740–820 nm), with a greater spectral stability than their randomly occurring counterparts. This is achieved by depositing monolayers onto silica substrates nanopatterned with arrays of 150-nm-diameter pillars ranging from 60 to 190 nm in height. The nanopillars create localized deformations in the material resulting in the quantum confinement of excitons. Our method may enable the placement of emitters in photonic structures such as optical waveguides in a scalable way, where precise and accurate positioning is paramount.European CommissionEuropean Research Council (ERC)Engineering and Physical Sciences Research Council (EPSRC)National Science Foundation (NSF

Charge-carrier complexes in monolayer semiconductors

The photoluminescence (PL) spectra of monolayer (1L) semiconductors feature peaks ascribed to different charge-carrier complexes. We perform diffusion quantum Monte Carlo simulations of the binding energies of these complexes and examine their response to electric and magnetic fields. We focus on quintons (charged biexcitons), since they are the largest free charge-carrier complexes in transition-metal dichalcogenides (TMDs). We examine the accuracy of the Rytova-Keldysh interaction potential between charges by comparing the binding energies of charge-carrier complexes in 1L-TMDs with results obtained using $\textit{ab initio}$ interaction potentials. Magnetic fields$<8$T change the binding energies (BEs) by$\sim0.2$ meV,T$^{-1}$, in agreement with experiments, with the BE variations of different complexes being very similar. Our results will help identify charge complexes in the PL spectra of 1L-semiconductor

Large-scale quantum-emitter arrays in atomically thin semiconductors.

Quantum light emitters have been observed in atomically thin layers of transition metal dichalcogenides. However, they are found at random locations within the host material and usually in low densities, hindering experiments aiming to investigate this new class of emitters. Here, we create deterministic arrays of hundreds of quantum emitters in tungsten diselenide and tungsten disulphide monolayers, emitting across a range of wavelengths in the visible spectrum (610-680 nm and 740-820 nm), with a greater spectral stability than their randomly occurring counterparts. This is achieved by depositing monolayers onto silica substrates nanopatterned with arrays of 150-nm-diameter pillars ranging from 60 to 190 nm in height. The nanopillars create localized deformations in the material resulting in the quantum confinement of excitons. Our method may enable the placement of emitters in photonic structures such as optical waveguides in a scalable way, where precise and accurate positioning is paramount

Evidence on the Human Health Effects of Low-Level Methylmercury Exposure

Background: Methylmercury (MeHg) is a known neuro-toxicant. Emerging evidence indicates it may have adverse effects on the neuro-logic and other body systems at common low levels of exposure. Impacts of MeHg exposure could vary by individual susceptibility or be confounded by bene-ficial nutrients in fish containing MeHg. Despite its global relevance, synthesis of the available literature on low-level MeHg exposure has been limited

Asthma Symptoms, Lung Function, and Markers of Oxidative Stress and Inflammation in Children Exposed to Oil Refinery Pollution

none12mixedF. Rusconi; CATELAN, DOLORES; G. Accetta; M. Peluso; R. Pistelli; F. Barbone; E. Di Felice; A. Munnia; P. Murgia; L. Paladini; A. Serci; BIGGERI, ANNIBALEF., Rusconi; Catelan, Dolores; G., Accetta; M., Peluso; R., Pistelli; F., Barbone; E., Di Felice; A., Munnia; P., Murgia; L., Paladini; A., Serci; Biggeri, Annibal

Amino-terminal dimerization of an erythropoietin mimetic peptide results in increased erythropoietic activity

AbstractBackground: Erythropoietin (EPO), the hormone involved in red blood cell production, activates its receptor by binding to the receptor's extracellular domain and presumably dimerizing two receptor monomers to initiate signal transduction. EPO-mimetic peptides, such as EMP1, also bind and activate the receptor by dimerization. These mimetic peptides are not as potent as EPO, however. The crystal structure of the EPO receptor (EBP) bound to EMP1 reveals the formation of a complex consisting of two peptides bound to two receptors, so we sought to improve the biological activity of EPO-mimetic peptides by constructing covalent dimers of EMP1 and other peptide mimetics linked by polyethylene glycol (PEG).Results: The potency of the PEG-dimerized EPO peptide mimetics both in vitro and in vivo was improved up to 1,000-fold compared to the corresponding peptide monomers. The dinners were constructed using peptide monomers which have only one reactive amine per molecule, allowing us to conclude that the increase in potency can be attributed to a structure in which two peptides are linked through their respective amino termini to the difunctional PEG molecule. In addition, an inactive peptide was converted into a weak agonist by PEG-induced dimerization.Conclusions: The potency of previously isolated peptides that are modest agonists of the EPO receptor was dramatically increased by PEG-induced dimerization. The EPO receptor is thought to be dimerized during activation, so our results are consistent with the proposed 2:2 receptor : peptide stoichiometry. The conversion of an inactive peptide into an agonist further supports the idea that dimerization can mediate receptor activation

A partitioned model order reduction approach to rationalise computational expenses in multiscale fracture mechanics

We propose in this paper an adaptive reduced order modelling technique based on domain partitioning for parametric problems of fracture. We show that coupling domain decomposition and projection-based model order reduction permits to focus the numerical effort where it is most needed: around the zones where damage propagates. No \textit{a priori} knowledge of the damage pattern is required, the extraction of the corresponding spatial regions being based solely on algebra. The efficiency of the proposed approach is demonstrated numerically with an example relevant to engineering fracture.Comment: Submitted for publication in CMAM

Collecting household water usage data: telephone questionnaire or diary?

<p>Abstract</p> <p>Background</p> <p>Quantitative Microbial Risk Assessment (QMRA), a modelling approach, is used to assess health risks. Inputs into the QMRA process include data that characterise the intensity, frequency and duration of exposure to risk(s). Data gaps for water exposure assessment include the duration and frequency of urban non-potable (non-drinking) water use. The primary objective of this study was to compare household water usage results obtained using two data collection tools, a computer assisted telephone interview (CATI) and a 7-day water activity diary, in order to assess the effect of different methodological survey approaches on derived exposure estimates. Costs and logistical aspects of each data collection tool were also examined.</p> <p>Methods</p> <p>A total of 232 households in an Australian dual reticulation scheme (where households are supplied with two grades of water through separate pipe networks) were surveyed about their water usage using both a CATI and a 7-day diary. Householders were questioned about their use of recycled water for toilet flushing, garden watering and other outdoor activities. Householders were also questioned about their water use in the laundry. Agreement between reported CATI and diary water usage responses was assessed.</p> <p>Results</p> <p>Results of this study showed that the level of agreement between CATI and diary responses was greater for more frequent water-related activities except toilet flushing and for those activities where standard durations or settings were employed. In addition, this study showed that the unit cost of diary administration was greater than for the CATI, excluding consideration of the initial selection and recruitment steps.</p> <p>Conclusion</p> <p>This study showed that it is possible to successfully 'remotely' coordinate diary completion providing that adequate instructions are given and that diary recording forms are well designed. In addition, good diary return rates can be achieved using a monetary incentive and the diary format allows for collective recording, rather than an individual's estimation, of household water usage. Accordingly, there is merit in further exploring the use of diaries for collection of water usage information either in combination with a mail out for recruitment, or potentially in the future with Internet-based recruitment (as household Internet uptake increases).</p

Nutrient intake during pregnancy and adherence to dietary recommendations: The mediterranean phime cohort

Few studies provide a detailed description of dietary habits during pregnancy, despite the central role of nutrition for the health of the mother and offspring. This paper describes the dietary habits, energy and nutrient intake in pregnant women from four countries belonging to the Mediterranean PHIME cohort (Croatia, Greece, Italy and Slovenia) and evaluates their adherence to the European Food Safety Authority (EFSA) recommendations. A total of 1436 women were included in the present analysis. Maternal diet was assessed using a food frequency questionnaire (FFQ). The mean macro and micronutrient intakes were estimated and compared with the dietary reference values (DRVs). The percentage distribution of the 16 food groups in the total intake of each macronutrient was estimated. All women shared a similar diet during pregnancy; almost all the women in the four countries exceeded the DRV for sugars, and the total fat intake was above the DRV in most women in all the countries, as was the contribution of saturated fatty acids (SFAs) to the total energy intake. In all four countries, we observed an increased risk of micronutrient deficiency for iron, folate and vitamin D. Shared guidelines, implemented at both the national and European level, are essential to improve the maternal nutritional status during pregnancy