19,531 research outputs found
Instalação de granitos pós-tectónicos controlada por falha Varisca profunda no Norte de Portugal
Critical thinking and its importance in the present days for social workers
Critical thinking is multidimensional, it encompasses the intellectual (logic, rationality), psychological (self-awareness, empathy), sociological (in terms of socio-historical context), ethics (norms and moral evaluation) and philosophical (meaning of nature and the human being). As a competency, or set of competencies, critical thinking can be developed and assessed. In this sense, the exploratory study that we intend to present aims to contribute to the evaluation of the importance that students attribute to critical thinking, as well as to the evaluation of critical thinking as a competence in the present situation. Before the pandemic situation we conducted a study with a universe of the 1st year social work students recently graduated, whose training included the critical thinking curricular unit in their study plan, we used as a data collection technician, a questionnaire with likert scale to measure the students opinions. The results were very positive and students admit that it helped them to analyze information (the importance of details), to practice curiosity and skepticism (to ask questions and compare with other sources) and to question (particularly, their own beliefs), including problem solving or decision making. With this recent challenge, consequence of Covid-19, it was necessary to alter all the previous model and adjust it to the pandemic situation through distance learning. Due to the characteristics of this curricular unit, we understand that in addition to the contents and usual dynamic, it was important to support students in adapting to the new methods and use this situation in favor of the benefits of thinking critically. Being a new situation for all (teachers and students) systematic evaluations were made to perceive if the results of the changes introduced were promoting the desired effect. Subsequently, in a total of 6 classes, with about 35 students each, we selected a non-probabilistic sample of 2 students of each class and each student was asked to make a critical assessment of the impact of this curricular unit in their learning process. Among other results that we intend to present, the key was to achieve a balance between the need for security and the need to know other ways of doing or thinking and classifying the critical thinking skills acquired as potentialities to support the uncertainty of the moment. This is where critical reflection (especially involving others) can play a key role in building trust by analyzing strengths-based practice, but it also allows considering alternative options, points of view, increase their ability to assess and position themselves in different contexts and learn to be prepared for unexpected situations.info:eu-repo/semantics/acceptedVersio
Scanning Gate Spectroscopy of transport across a Quantum Hall Nano-Island
We explore transport across an ultra-small Quantum Hall Island (QHI) formed
by closed quan- tum Hall edge states and connected to propagating edge channels
through tunnel barriers. Scanning gate microscopy and scanning gate
spectroscopy are used to first localize and then study a single QHI near a
quantum point contact. The presence of Coulomb diamonds in the spectroscopy
con- firms that Coulomb blockade governs transport across the QHI. Varying the
microscope tip bias as well as current bias across the device, we uncover the
QHI discrete energy spectrum arising from electronic confinement and we extract
estimates of the gradient of the confining potential and of the edge state
velocity.Comment: 13 pages, 3 figure
Transport and Strong-Correlation Phenomena in Carbon Nanotube Quantum Dots in a Magnetic Field
Transport through carbon nanotube (CNT) quantum dots (QDs) in a magnetic
field is discussed. The evolution of the system from the ultraviolet to the
infrared is analyzed; the strongly correlated (SC) states arising in the
infrared are investigated. Experimental consequences of the physics are
presented -- the SC states arising at various fillings are shown to be
drastically different, with distinct signatures in the conductance and, in
particular, the noise. Besides CNT QDs, our results are also relevant to double
QD systems.Comment: 5 pages, 5 figure
Vorton Formation
In this paper we present the first analytic model for vorton formation. We
start by deriving the microscopic string equations of motion in Witten's
superconducting model, and show that in the relevant chiral limit these
coincide with the ones obtained from the supersonic elastic models of Carter
and Peter. We then numerically study a number of solutions of these equations
of motion and thereby suggest criteria for deciding whether a given
superconducting loop configuration can form a vorton. Finally, using a recently
developed model for the evolution of currents in superconducting strings we
conjecture, by comparison with these criteria, that string networks formed at
the GUT phase transition should produce no vortons. On the other hand, a
network formed at the electroweak scale can produce vortons accounting for up
to 6% of the critical density. Some consequences of our results are discussed.Comment: 41 pages; color figures 3-6 not included, but available from authors.
To appear in Phys. Rev.
High-field Electron Spin Resonance of Cu_{1-x}Zn_{x}GeO_{3}
High-Field Electron Spin Resonance measurements were made on powder samples
of Cu_{1-x}Zn_{x}GeO_{3} (x=0.00, 0.01, 0.02, 0.03 and 0.05) at different
frequencies (95, 110, 190, 220, 330 and 440 GHz) at low temperatures. The
spectra of the doped samples show resonances whose positions are dependent on
Zn concentration, frequency and temperature. The analysis of intensity
variation of these lines with temperature allows us to identify them as
originating in transitions within states situated inside the Spin Peierls gap.
A qualitative explanation of the details of the spectra is possible if we
assume that these states in the gap are associated with "loose" spins created
near the Zn impurities, as recently theoreticaly predicted. A new phenomenon of
quenching of the ESR signal across the Dimerized to Incommensurate
phase-boundary is observed.Comment: 4 pages, 5 ps figures in the text, submitted to Phys. Rev. Let
Origin of Spin Incommensurability in Hole-doped S=1 Chains
Spin incommensurability has been recently experimentally discovered in the
hole-doped Ni-oxide chain compound (G. Xu {\it
al.}, Science {\bf 289}, 419 (2000)). Here a two orbital model for this
material is studied using computational techniques. Spin IC is observed in a
wide range of densities and couplings. The phenomenon originates in
antiferromagnetic correlations ``across holes'' dynamically generated to
improve hole movement, as it occurs in the one-dimensional Hubbard model and in
recent studies of the two-dimensional extended t-J model. The close proximity
of ferromagnetic and phase-separated states in parameter space are also
discussed.Comment: RevTex, 4 pages, 4 figures (eps
Formation of quantum dots in the potential fluctuations of InGaAs heterostructures probed by scanning gate microscopy
The disordered potential landscape in an InGaAs/InAlAs two-dimensional
electron gas patterned into narrow wires is investigated by means of scanning
gate microscopy. It is found that scanning a negatively charged tip above
particular sites of the wires produces conductance oscillations that are
periodic in the tip voltage. These oscillations take the shape of concentric
circles whose number and diameter increase for more negative tip voltages until
full depletion occurs in the probed region. These observations cannot be
explained by charging events in material traps, but are consistent with Coulomb
blockade in quantum dots forming when the potential fluctuations are raised
locally at the Fermi level by the gating action of the tip. This interpretation
is supported by simple electrostatic simulations in the case of a disorder
potential induced by ionized dopants. This work represents a local
investigation of the mechanisms responsible for the disorder-induced
metal-to-insulator transition observed in macroscopic two-dimensional electron
systems at low enough density
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