665 research outputs found
Seeing Earth's Orbit in the Stars: Parallax and Aberration
During the 17th century the idea of an orbiting and rotating Earth became
increasingly popular, but opponents of this view continued to point out that
the theory had observable consequences that had never, in fact, been observed.
Why, for instance, had astronomers failed to detect the annual parallax of the
stars that must occur if Earth orbits the Sun? To address this problem,
astronomers of the 17th and18th centuries sought to measure the annual parallax
of stars using telescopes. None of them succeeded. Annual stellar parallax was
not successfully measured until 1838, when Friedrich Bessel detected the
parallax of the star 61 Cygni. But the early failures to detect annual stellar
parallax led to the discovery of a new (and entirely unexpected) phenomenon:
the aberration of starlight. This paper recounts the story of the discovery of
stellar aberration. It is accompanied by a set of activities and computer
simulations that allow students to explore this fascinating historical episode
and learn important lessons about the nature of science.Comment: 10 pages, 5 figures, submitted to The Physics Teache
Use of the Inverse Approach to Investigate the Stresses in Rough Elastohydrodynamic Contacts
The inverse approach, described in detail in a companion paper, is applied to two contacts. Th
Internet Predictions
More than a dozen leading experts give their opinions on where the Internet is headed and where it will be in the next decade in terms of technology, policy, and applications. They cover topics ranging from the Internet of Things to climate change to the digital storage of the future. A summary of the articles is available in the Web extras section
Competition of crystal field splitting and Hund's rule coupling in two-orbital magnetic metal-insulator transitions
Competition of crystal field splitting and Hund's rule coupling in magnetic
metal-insulator transitions of half-filled two-orbital Hubbard model is
investigated by multi-orbital slave-boson mean field theory. We show that with
the increase of Coulomb correlation, the system firstly transits from a
paramagnetic (PM) metal to a {\it N\'{e}el} antiferromagnetic (AFM) Mott
insulator, or a nonmagnetic orbital insulator, depending on the competition of
crystal field splitting and the Hund's rule coupling. The different AFM Mott
insulator, PM metal and orbital insulating phase are none, partially and fully
orbital polarized, respectively. For a small and a finite crystal
field, the orbital insulator is robust. Although the system is nonmagnetic, the
phase boundary of the orbital insulator transition obviously shifts to the
small regime after the magnetic correlations is taken into account. These
results demonstrate that large crystal field splitting favors the formation of
the orbital insulating phase, while large Hund's rule coupling tends to destroy
it, driving the low-spin to high-spin transition.Comment: 4 pages, 4 figure
Patient/Family Education for Newly Diagnosed Pediatric Oncology Patients
There is a paucity of data to support evidence-based practices in the provision of patient/family education in the context of a new childhood cancer diagnosis. Since the majority of children with cancer are treated on pediatric oncology clinical trials, lack of effective patient/family education has the potential to negatively affect both patient and clinical trial outcomes. The Children’s Oncology Group Nursing Discipline convened an interprofessional expert panel from within and beyond pediatric oncology to review available and emerging evidence and develop expert consensus recommendations regarding harmonization of patient/family education practices for newly diagnosed pediatric oncology patients across institutions. Five broad principles, with associated recommendations, were identified by the panel, including recognition that (1) in pediatric oncology, patient/family education is family-centered; (2) a diagnosis of childhood cancer is overwhelming and the family needs time to process the diagnosis and develop a plan for managing ongoing life demands before they can successfully learn to care for the child; (3) patient/family education should be an interprofessional endeavor with 3 key areas of focus: (a) diagnosis/treatment, (b) psychosocial coping, and (c) care of the child; (4) patient/family education should occur across the continuum of care; and (5) a supportive environment is necessary to optimize learning. Dissemination and implementation of these recommendations will set the stage for future studies that aim to develop evidence to inform best practices, and ultimately to establish the standard of care for effective patient/family education in pediatric oncology
State Transition Algorithm
In terms of the concepts of state and state transition, a new heuristic
random search algorithm named state transition algorithm is proposed. For
continuous function optimization problems, four special transformation
operators called rotation, translation, expansion and axesion are designed.
Adjusting measures of the transformations are mainly studied to keep the
balance of exploration and exploitation. Convergence analysis is also discussed
about the algorithm based on random search theory. In the meanwhile, to
strengthen the search ability in high dimensional space, communication strategy
is introduced into the basic algorithm and intermittent exchange is presented
to prevent premature convergence. Finally, experiments are carried out for the
algorithms. With 10 common benchmark unconstrained continuous functions used to
test the performance, the results show that state transition algorithms are
promising algorithms due to their good global search capability and convergence
property when compared with some popular algorithms.Comment: 18 pages, 28 figure
Empiricism Without the Senses: How the Instrument Replaced the Eye
On receiving news of Galileo’s observations of the four satellites of Jupiter and the rugged face of the moon through his newly invented perspicillum, Kepler in great excitement exclaimed: Therefore let Galileo take his stand by Kepler’s side. Let the former observe the moon with his face turned skyward, while the latter studies the sun by looking down at a screen (lest the lens injure his eyes). Let each employ his own device, and from this partnership may there some day arise an absolutely perfect theory of the distances. This Hollywood-like scene of the two astronomers marching hand in hand toward the dawn of a new scientific era was no attempt by Kepler to appropriate Galileo’s success or to diminish the novelty of the telescope. On the contrary, Kepler repeatedly asserted how short sighted he was in misjudging the potential for astronomical observations inherent in lenses, and how radically Galileo’s instrument transformed the science of astronomy. It was a deep sense of recognition that beyond their different scientific temperaments and projects, they shared a common agenda of a new mode of empirical engagement with the phenomenal world: the instrument. For Kepler and Galileo, empirical investigation was no longer a direct engagement with nature, but an essentially mediated endeavor. The new instruments were not to assist the human senses, but to replace them
Организация деятельности педагога по совершенствованию умений диалогической речи у детей старшего дошкольного возраста.
В работе рассмотрены основы психического и речевого развития детей старшего дошкольного возраста, охарактеризованы лингво-методические основы развития диалогической речи у старшего дошкольного возраста, раскрыто содержание деятельности педагога по совершенствованию умений диалогической речи у детей старшего дошкольного возраста, разработан комплекс педагогических мероприятий по теме исследования
Simplified tabu search with random-based searches for bound constrained global optimization
This paper proposes a simplified version of the tabu search algorithm that solely uses randomly generated direction vectors in the exploration and intensification search procedures, in order to define a set of trial points while searching in the neighborhood of a given point. In the diversification procedure, points that are inside any already visited region with a relative small visited frequency may be accepted, apart from those that are outside the visited regions. The produced numerical results show the robustness of the proposed method. Its efficiency when compared to other known metaheuristics available in the literature is encouraging.FCT - Fundação para a Ciência e a Tecnologia(UIDB/00013/2020); FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020, UIDB/00013/2020 and UIDP/00013/2020 of CMAT-UM
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