442 research outputs found
Two-surface wave decay: improved analytical theory and effects on electron acceleration
Two-surface wave decay (TSWD), i.e. the parametric excitation of electron
surface waves, was recently proposed as an absorption mechanism in the
interaction of ultrashort, intense laser pulses with solid targets. We present
an extension of the fluid theory of TSWD to a warm plasma which treats boundary
effects consistently. We also present test-particle simulations showing
localized enhancement of electron acceleration by TSWD fields; this effect
leads to a modulation of the current density entering into the target and may
seed current filamentation instabilities.Comment: 4 figures, submitted to Appl.Phys.B (special issue from HFSW X
conference, Biarritz, France, Oct 12-15 2003); slightly revised tex
Government and Self-Government of Science - Constitutional Safeguards of Scientific Research and Teaching
Assessment of management effect on grasslands characteristics in an area of the Apennines (North Italy)
In many regions of Europe, semi-natural grasslands not properly utilized face different
threats, concerning changes in botanical composition and structural evolution, which can lead to
a reduction of the qualitative value of forage biomass or, in the mid-long term, forest recovery.
The present paper assesses various semi-natural grasslands within a mountain public property
located in Tuscany (North Apennines, Italy) subjected to different types of utilization. Some of
them are managed through cattle grazing during summer, whereas some others are only
periodically mowed and utilization is performed only by wildlife occurring in the area. The paper
analyses the importance of resource management and its impact on botanical composition and on
qualitative value of forage production. Data collection of studied areas was conducted by means
of vegetation assessment performed with a fast procedure that simplifies the botanical
composition sampling. Results show the relevance of some environmental factors on grasslands
evolution and on their composition (such as altitude and slope) and the importance of
management on grassland quality and on level of shrub encroachment
T2 lesion location really matters: a 10 year follow-up study in primary progressive multiple sclerosis
Objectives: Prediction of long term clinical outcome in patients with primary progressive multiple sclerosis (PPMS) using imaging has important clinical implications, but remains challenging. We aimed to determine whether spatial location of T2 and T1 brain lesions predicts clinical progression during a 10-year follow-up in PPMS.
Methods: Lesion probability maps of the T2 and T1 brain lesions were generated using the baseline scans of 80 patients with PPMS who were clinically assessed at baseline and then after 1, 2, 5 and 10 years. For each patient, the time (in years) taken before bilateral support was required to walk (time to event (TTE)) was used as a measure of progression rate. The probability of each voxel being ‘lesional’ was correlated with TTE, adjusting for age, gender, disease duration, centre and spinal cord cross sectional area, using a multiple linear regression model. To identify the best, independent predictor of progression, a Cox regression model was used.
Results: A significant correlation between a shorter TTE and a higher probability of a voxel being lesional on T2 scans was found in the bilateral corticospinal tract and superior longitudinal fasciculus, and in the right inferior fronto-occipital fasciculus (p<0.05). The best predictor of progression rate was the T2 lesion load measured along the right inferior fronto-occipital fasciculus (p=0.016, hazard ratio 1.00652, 95% CI 1.00121 to 1.01186).
Conclusion: Our results suggest that the location of T2 brain lesions in the motor and associative tracts is an important contributor to the progression of disability in PPMS, and is independent of spinal cord involvement
GERD in elderly patients: surgical treatment with Nissen-Rossetti laparoscopic technique, outcome.
BACKGROUND: The gastro-esophageal reflux disease (GERD) is one of the most frequent disease of the upper gastro-entheric tract. Surgical treatment is reserved to selected patients, affected by severe forms of disease and/or without compliance to medical therapy. In 95%-60% of the patients submitted to surgical antireflux intervention, a notable improvement of the quality of life is observed. Functional evaluations performed on pre and post – surgical pHmetric and manometric examination have provided new acquisitions about improvements in the restoration of anatomical and functional integrity of the esophagus-gastric antireflux barrier. METHODS: 45 elderly patients with GERD were recruited in a 27 months period. All patients were subjected to laparoscopic Nissen-Rossetti 360° fundoplication. The subjects had a pre-surgical evaluation with: • 24 hours pHmetry, • esophageal manometry, The same evaluation was repeated 1 month and 6 months after surgical intervention. RESULTS: In our series all patients get benefit from surgical treatment, with an improvement of pHmetric and manometric parameters and a regression of complications of GERD such as Barrett's metaplasia. In 8.33% of patients a PPI therapy was necessary, after the surgical intervention, to control symptoms. CONCLUSIONS: The role of surgery in GERD concerns selected patients. Nissen-Rossetti mini-invasive approach is performed with an acceptable percentage of complications (3%-10%). This technique is associated with a good control of GERD symptoms in a short and middle term and with an improvement of functional parameters, such as pHmetric and manometric
Assessing whether artificial intelligence is an enabler or an inhibitor of sustainability at indicator level
"Since the early phase of the artificial-intelligence (AI) era expectations towards AI are high, with experts believing that AI paves the way for managing and handling various global challenges. However, the significant enabling and inhibiting influence of AI for sustainable development needs to be assessed carefully, given that the technology diffuses rapidly and affects millions of people worldwide on a day-to-day basis. To address this challenge, a panel discussion was organized by the KTH Royal Institute of Technology, the AI Sustainability Center and MIT Massachusetts Institute of Technology, gathering a wide range of AI experts. This paper summarizes the insights from the panel discussion around the following themes: The role of AI in achieving the Sustainable Development Goals (SDGs) AI for a prosperous 21st century Transparency, automated decision-making processes, and personal profiling and Measuring the relevance of Digitalization and Artificial Intelligence (D&AI) at the indicator level of SDGs. The research-backed panel discussion was dedicated to recognize and prioritize the agenda for addressing the pressing research gaps for academic research, funding bodies, professionals, as well as industry with an emphasis on the transportation sector. A common conclusion across these themes was the need to go beyond the development of AI in sectorial silos, so as to understand the impacts AI might have across societal, environmental, and economic outcomes. The recordings of the panel discussion can be found at: https://www.kth.se/en/2.18487/evenemang/the-role-of-ai-in-achieving-the-sdgs-enabler-or-inhibitor-1.1001364?date=2020â 08â 20&length=1&orglength=185&orgdate=2020â 06â 30 Short link: https://bit.ly/2Kap1tE © 2021"The authors acknowledge the KTH Sustainability Office and the KTH Digitalization Platform for their provided funding, which enabled the organization of this panel discussion. SG acknowledges the funding provided by the German Federal Ministry for Education and Research (BMBF) for the project “digitainable”. SDL acknowledges support through the Spanish Governmen
Cell Membrane-Coated Magnetic Nanocubes with a Homotypic Targeting Ability Increase Intracellular Temperature due to ROS Scavenging and Act as a Versatile Theranostic System for Glioblastoma Multiforme
In this study, hybrid nanocubes composed of magnetite (Fe3O4) and manganese dioxide (MnO2), coated with U-251 MG cell-derived membranes (CM-NCubes) are synthesized. The CM-NCubes demonstrate a concentration-dependent oxygen generation (up to 15%), and, for the first time in the literature, an intracellular increase of temperature (6 \ub0C) due to the exothermic scavenging reaction of hydrogen peroxide (H2O2) is showed. Internalization studies demonstrate that the CM-NCubes are internalized much faster and at a higher extent by the homotypic U-251 MG cell line compared to other cerebral cell lines. The ability of the CM-NCubes to cross an in vitro model of the blood-brain barrier is also assessed. The CM-NCubes show the ability to respond to a static magnet and to accumulate in cells even under flowing conditions. Moreover, it is demonstrated that 500 \ub5g mL 121 of sorafenib-loaded or unloaded CM-NCubes are able to induce cell death by apoptosis in U-251 MG spheroids that are used as a tumor model, after their exposure to an alternating magnetic field (AMF). Finally, it is shown that the combination of sorafenib and AMF induces a higher enzymatic activity of caspase 3 and caspase 9, probably due to an increment in reactive oxygen species by means of hyperthermia
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