252 research outputs found
The history of nanoscience and nanotechnology: From chemical-physical applications to nanomedicine
Nanoscience breakthroughs in almost every field of science and nanotechnologies make life easier in this era. Nanoscience and nanotechnology represent an expanding research area, which involves structures, devices, and systems with novel properties and functions due to the arrangement of their atoms on the 1-100 nm scale. The field was subject to a growing public awareness and controversy in the early 2000s, and in turn, the beginnings of commercial applications of nanotechnology. Nanotechnologies contribute to almost every field of science, including physics, materials science, chemistry, biology, computer science, and engineering. Notably, in recent years nanotechnologies have been applied to human health with promising results, especially in the field of cancer treatment. To understand the nature of nanotechnology, it is helpful to review the timeline of discoveries that brought us to the current understanding of this science. This review illustrates the progress and main principles of nanoscience and nanotechnology and represents the pre-modern as well as modern timeline era of discoveries and milestones in these fields
The Non-Trapping Degree of Scattering
We consider classical potential scattering. If no orbit is trapped at energy
E, the Hamiltonian dynamics defines an integer-valued topological degree. This
can be calculated explicitly and be used for symbolic dynamics of
multi-obstacle scattering.
If the potential is bounded, then in the non-trapping case the boundary of
Hill's Region is empty or homeomorphic to a sphere.
We consider classical potential scattering. If at energy E no orbit is
trapped, the Hamiltonian dynamics defines an integer-valued topological degree
deg(E) < 2. This is calculated explicitly for all potentials, and exactly the
integers < 2 are shown to occur for suitable potentials.
The non-trapping condition is restrictive in the sense that for a bounded
potential it is shown to imply that the boundary of Hill's Region in
configuration space is either empty or homeomorphic to a sphere.
However, in many situations one can decompose a potential into a sum of
non-trapping potentials with non-trivial degree and embed symbolic dynamics of
multi-obstacle scattering. This comprises a large number of earlier results,
obtained by different authors on multi-obstacle scattering.Comment: 25 pages, 1 figure Revised and enlarged version, containing more
detailed proofs and remark
A systematic review opens the black box of âusual careâ in stroke rehabilitation control groups and finds a black hole
INTRODUCTION: In experimental trials, new methods are tested against the âbestâ or âusualâ care. To appraise control group (CG) interventions provided as âusual care,â we focused on stroke as a leading cause of disability demanding rehabilitation as a complex intervention. EVIDENCE ACQUISITION: For this methodological appraisal, we conducted a systematic review of RCTs without timespan limitation. The PICO included stroke survivors, rehabilitation, control group intervention, lower limb function. To assess the risk of bias, we used the Cochrane risk of bias tool (RoB). we identified the terminology describing the CG Program (CGP), performed a knowledge synthesis and conducted a frequency analysis of provided interventions. EVIDENCE SYNTHESIS: we included 155 publications. 13.6% of the articles did not describe the CG, and 11.6% indicated only the professionals involved. In the remaining 116 studies, three studies provided an intervention according to specific guidelines, 106 different âusual careâ CGPs were detected, with nine proposed twice and two between four and five times. The most adopted terminology to state âusual careâ was âconventional physiotherapy.â CONCLUSIONS: This study shows that usual care in CG does not actually exist, as both specific terminology and consistency within CGP contents are missing. Reporting guidelines should give better assistance on this issue. These results should be verified in other fields
Spinning particles in Taub-NUT space
The geodesic motion of pseudo-classical spinning particles in Euclidean
Taub-NUT space is analysed. The constants of motion are expressed in terms of
Killing-Yano tensors. Some previous results from the literature are corrected.Comment: LaTeX, 8 page
Modified gold nanoparticles to overcome the chemoresistance to gemcitabine in mutant p53 cancer cells
New U-Pb SHRIMP zircon ages for pre-variscan orthogneisses from Portugal and their bearing on the evolution of the Ossa-morena tectonic zone
New SHRIMP U-Pb zircon ages for the Portalegre and Alcåçovas orthogneisses document a complex pre-Variscan history for the Iberian basement in Portugal. The available geochemical and geochronological data for the Alcåçovas orthogneiss (ca. 540 Ma) tend to favor its involvement in a Cadomian orogenic event. This is consistent with the development of an active continental margin setting at the end of the Proterozoic and supports a Gondwanan provenance for the Iberian crust. On the other hand, the Ordovician emplacement age obtained for the magmatic precursors of the Portalegre orthogneisses (497 ± 10 Ma) provides additional evidence for the occurrence of rift-related magmatic activity during the Lower Paleozoic
Generalized Killing equations and Taub-NUT spinning space
The generalized Killing equations for the configuration space of spinning
particles (spinning space) are analysed. Simple solutions of the homogeneous
part of these equations are expressed in terms of Killing-Yano tensors. The
general results are applied to the case of the four-dimensional euclidean
Taub-NUT manifold.Comment: 10 pages, late
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