The Particle Finite Element Method, a lagrangian finite element method based on a continuous
Delaunay
re-triangulation of the domain, is used to study machining of Ti6Al4V. In this work the method is ...revised and applied to study the influence of the cutting speed on the cutting force and the chip formation process. A parametric methodology for the detection and treatment of the rigid tool contact is presented. The adaptive insertion and removal of particles are developed and employed in order to sidestep the difficulties associated with mesh distortion, shear localization as well as for resolving the fine-scale features of the solution. The performance of PFEM is studied with a set of different two-dimensional orthogonal cutting tests. It is shown that, despite its Lagrangian nature, the proposed combined finite element-particle method is well suited for large deformation metal cutting problems with continuous chip and serrated chip formation.
When James Parkinson described the classical symptoms of the disease he could hardly foresee the evolution of our understanding over the next two hundred years. Nowadays, Parkinson's disease is ...considered a complex multifactorial disease in which genetic factors, either causative or susceptibility variants, unknown environmental cues, and the potential interaction of both could ultimately trigger the pathology. Noteworthy advances have been made in different fields from the clinical phenotype to the decoding of some potential neuropathological features, among which are the fields of genetics, drug discovery or biomaterials for drug delivery, which, though recent in origin, have evolved swiftly to become the basis of research into the disease today. In this review, we highlight some of the key advances in the field over the past two centuries and discuss the current challenges focusing on exciting new research developments likely to come in the next few years. Also, the importance of pre-motor symptoms and early diagnosis in the search for more effective therapeutic options is discussed.
Edelfosine is the prototype molecule of a family of anticancer drugs collectively known as synthetic alkyl-lysophospholipids. This drug holds promise as a selective antitumor agent, and a number of ...preclinical assays are in progress. In this study, we observe the accumulation of edelfosine in brain tissue after its oral administration in Compritol® and Precirol® lipid nanoparticles (LN). The high accumulation of edelfosine in brain was due to the inhibition of P-glycoprotein by Tween® 80, as verified using a P-glycoprotein drug interaction assay. Moreover, these LN were tested
in vitro against the C6 glioma cell line, which was later employed to establish an
in vivo xenograft mouse model of glioma.
In vitro studies revealed that edelfosine-loaded LN induced an antiproliferative effect in C6 glioma cell line. In addition,
in vivo oral administration of drug-loaded LN in NMRI nude mice bearing a C6 glioma xenograft tumor induced a highly significant reduction in tumor growth (
p
<
0.01) 14
days after the beginning of the treatment. Our results showed that Tween® 80 coated Compritol® and Precirol® LN can effectively inhibit the growth of C6 glioma cells
in vitro and suggest that edelfosine-loaded LN represent an attractive option for the enhancement of antitumor activity on brain tumors
in vivo.
Tween® 80 coated lipid nanoparticles are encouraged as promising systems for brain disease treatment. They accumulate in brain by P-gp inhibition and reduce the tumor growth of gliomas
in vivo.
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Background and aims Carpobrotus edulis invades coastal areas throughout the world, decreasing plant diversity and hampering restoration efforts by changing soil properties. Some of its effects on ...soils are known but there is a knowledge gap about the effects in rocky areas and micronutrients that we aimed to fill for dunes and rocky habitats with temperate-humid climate. Methods We compared invaded vs non-invaded paired plots in two dune and two rocky areas by measuring 18 variables in litter and 24 in soils (0–5 and 5–10 cm layers). Results Invasion effects increased with the accumulated alien necromass, decreased with soil depth and are substrate-dependent: soil pH, AI, Fe and P increased in dunes, while these variables and Mg, Cu and Zn decreased in rocky sites. Carpobrotus necromass is richer in Mg and Ca and poorer in AI, Co, Cu, Fe, Ni and Zn than native necromass. Conclusions Invader effects on soils are largely mediated by its necromass, which has contrasting characteristics with the autochthonous necromass. Carpobrotus edulis ability to discriminate against Al uptake, while favouring Mg and Ca uptake, and its lower requirement (or higher resorption) of key micronutrients (Co, Cu, Fe, Ni, Zn) than native vegetation could partly explain its invasiveness.
The construction engineering and management sector is facing rapid technological disruption due to the extensive adoption of digital tools. The main aim of this research was to assess the accuracy ...and usefulness of web-based instruments used for the evaluation and mensuration of built environment characteristics. Through on-site visits and two web-based tools, a digital management system based on fuzzy logic was used to evaluate the functional service life of two heritage timber buildings in Valdivia (Chile). The assessments of 40 professional experts (4 on-site visual inspections and 36 virtual inspections) were compared to evaluate the relative accuracy and usefulness of the on-site and web-based instruments. Web-based audits, which used Google Street View and Google Maps, tended to agree strongly with on-site audits on the functional degradation of the timber structures (vulnerabilities and external hazard affections). While web-based tools do not offer a perfect substitute for on-site audits, they do allow for preliminary audits to be performed accurately from remote locations, potentially saving time and cost and increasing the effectiveness of subsequent on-site visits. The study findings may be useful to industry stakeholders in understanding the early impacts of the use of new remote digital inspection tools on the construction industry.
We present late-time optical spectroscopy taken with the Large Binocular Telescope's Multi-Object Double Spectrograph, an improved All-Sky Automated Survey for SuperNovae pre-discovery non-detection, ...and late-time Swift observations of the nearby (d = 193 Mpc, z = 0.0436) tidal disruption event (TDE) ASASSN-14ae. Our observations span from ∼20 d before to ∼750 d after discovery. The proximity of ASASSN-14ae allows us to study the optical evolution of the flare and the transition to a host-dominated state with exceptionally high precision. We measure very weak Hα emission 300 d after discovery (L
H α ≃ 4 × 1039 erg s−1) and the most stringent upper limit to date on the Hα luminosity ∼750 d after discovery (L
H α ≲ 1039 erg s−1), suggesting that the optical emission arising from a TDE can vanish on a time-scale as short as 1 yr. Our results have important implications for both spectroscopic detection of TDE candidates at late times, as well as the nature of TDE host galaxies themselves.
Wildfires are increasing worldwide and, therefore, the extents of their on‐ and off‐site impacts are particularly important on soil erosion and nutrient cycles. To mitigate post‐fire erosion, ...mulching is increasingly being used, but its effects on the nitrogen (N) cycle are poorly known. To fill this gap of knowledge, gross N fluxes were modelled with Ntrace to compare with unburnt soils (US) the effects of intermediate (BI) and high severity (BH) burning, and post‐fire straw mulching (BIM and BHM). Two wildfires, two‐time points after the fire and 20 soil‐treatment combinations were studied. The mineralization of soil organic N to NH4+ (MSON) increased in BI (1.9–6.9×) with respect to US, with no clear trends observed in BH and mulched treatments. In most soils, NH4+ immobilisation in labile (INH4lab$$ {I}_{{\mathrm{NH}}_4\mathrm{lab}} $$) and recalcitrant soil organic matter (SOM) (INH4rec$$ {I}_{{\mathrm{NH}}_4\mathrm{rec}} $$) was more important than abiotic NH4+ fixation (ANH4$$ {A}_{{\mathrm{NH}}_4} $$) and together were larger (3.5–11×) in BI than in US, while contrasting results were found depending on time after a fire (BH, BHM, BIM) and wildfire characteristics (BHM, BIM). Autotrophic nitrification (ONH4$$ {O}_{{\mathrm{NH}}_4} $$) was included in the best model for all soils, whereas heterotrophic nitrification (OSON) was undetectable in most BH soils. Total nitrification (ONH4$$ {O}_{{\mathrm{NH}}_4} $$ + OSON) decreased with time after the fire in BH, increased in US and BI, and was differently affected by mulching depending on fire severity and time from the fire. While NO3− immobilisation (INO3$$ {I}_{{\mathrm{NO}}_3} $$) was frequently modelled only for BI soils, the dissimilatory NO3− reduction to NH4+ (DNRA) was retained in the best models for all soils and it was reduced by soil burning, whereas a short‐lived increase was induced by mulching. Denitrification (LNO3$$ {L}_{{\mathrm{NO}}_3} $$), modelled for most soils, was negatively affected by burning and positively by mulching. In summary, wildfires tended to increase MSON and INH4lab$$ {I}_{{\mathrm{NH}}_4\mathrm{lab}} $$, decrease DNRA and LNO3$$ {L}_{{\mathrm{NO}}_3} $$ and had no clear influence on INO3$$ {I}_{{\mathrm{NO}}_3} $$ and nitrification. These effects are usually mitigated by mulching which, however, tended to enhance nitrification.
Highlights
Direction and magnitude of changes in soil gross N fluxes depend on fire severity.
Usually, wildfires increased MSON and INH4lab$$ {I}_{{\mathrm{NH}}_4\mathrm{lab}} $$, and decreased DNRA and LNO3$$ {L}_{{\mathrm{NO}}_3} $$.
No clear post‐fire trend was found for INO3$$ {I}_{{\mathrm{NO}}_3} $$ and nitrification.
Fire effects on gross N fluxes are (partially) counterbalanced by mulching.
Chemistry plays a key role in many astrophysical situations regulating the cooling and the thermal properties of the gas, which are relevant during gravitational collapse, the evolution of discs and ...the fragmentation process. In order to simplify the usage of chemical networks in large numerical simulations, we present the chemistry package krome, consisting of a python pre-processor which generates a subroutine for the solution of chemical networks which can be embedded in any numerical code. For the solution of the rate equations, we make use of the high-order solver DLSODES, which was shown to be both accurate and efficient for sparse networks, which are typical in astrophysical applications. krome also provides a large set of physical processes connected to chemistry, including photochemistry, cooling, heating, dust treatment and reverse kinetics. The package presented here already contains a network for primordial chemistry, a small metal network appropriate for the modelling of low metallicities environments, a detailed network for the modelling of molecular clouds, a network for planetary atmospheres, as well as a framework for the modelling of the dust grain population. In this paper, we present an extended test suite ranging from one-zone and 1D models to first applications including cosmological simulations with enzo and ramses and 3D collapse simulations with the flash code. The package presented here is publicly available at http://kromepackage.org/ and https://bitbucket.org/krome/krome_stable.
The Largest M Dwarf Flares from ASAS-SN Schmidt, Sarah J.; Shappee, Benjamin J.; van Saders, Jennifer L. ...
Astrophysical journal/The Astrophysical journal,
05/2019, Letnik:
876, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The All-sky Automated Survey for Supernovae (ASAS-SN) is the only project in existence to scan the entire sky in optical light approximately every day, reaching a depth of g ∼ 18 mag. Over the course ...of its first 4 yr of transient alerts (2013-2016), ASAS-SN observed 53 events classified as likely M dwarf flares. We present follow-up photometry and spectroscopy of all 53 candidates, confirming flare events on 47 M dwarfs, one K dwarf, and one L dwarf. The remaining four objects include a previously identified T Tauri star, a young star with outbursts, and two objects too faint to confirm. A detailed examination of the 49 flare star light curves revealed an additional six flares on five stars, resulting in a total of 55 flares on 49 objects ranging in V-band contrast from ΔV = −1 to −10.2 mag. Using an empirical flare model to estimate the unobserved portions of the flare light curve, we obtain lower limits on the V-band energy emitted during each flare, spanning -35, which are among the most energetic flares detected on M dwarfs. The ASAS-SN M dwarf flare stars show a higher fraction of H emission, as well as stronger H emission, compared to M dwarfs selected without reference to activity, consistent with belonging to a population of more magnetically active stars. We also examined the distribution of tangential velocities, finding that the ASAS-SN flaring M dwarfs are likely to be members of the thin disk and are neither particularly young nor old.
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