5,168 research outputs found
Investigation into the voltammetric behaviour and detection of selenium(IV) at metal electrodes in diverse electrolyte media
The voltammetric behaviour of selenium(IV) was studied at platinum and gold electrodes in sulphuric acid, perchloric acid and potassium chloride media as a basis for its voltammetric detection. The best voltammetric behaviour was recorded at gold electrodes with perchloric acid as the supporting electrolyte. The concomitant presence of metals, such as copper or lead, and of model biomolecules, such as bovine serum albumin, in the solution resulted in a deterioration of the electrochemical response for selenium(IV). Quantitative detection of selenium(IV) by square wave anodic stripping voltammetry at both a millimetre-sized gold disc electrode and a microband electrode array revealed linear responses to selenium concentration in the ranges of 5-15 μM and 0.1-10 μM, respectively, with 60 s preconcentration. The sensitivities were 6.4 μA μM-1 cm-2 and 100 μA μM-1 cm-2 at the disc and the microband array, respectively. The detection limit at the microband electrode array was 25 nM, illustrating the potentiality of such microelectrodes for the development of mercury-free analytical methods for the trace detection of selenium(IV)
Identifikasi Kompetensi SMK Program Studi Otomotif dalam Rangka Implementasi Kebijakan Kurikulum 2013
The objective of this study was to determine; 1) the relevance of competencies in curriculum 2013 with the expectation of the school and the world of business and industry 2) the competencies expected by the school and the world of business and industry for the development of curriculum 2013, and 3) the roles of lecturers and education experts in the implementation of curriculum 2013, especially for the Department of Automotive, Vocational High Schools in Yogyakarta. The study was conducted with survey approach in the industry (authorized workshops), schools (Vocational High School), and universities (YSU and STU). The data collection was conducted using documentation, questionnaires, and interviews. The data was analysed using quantitative descriptive statistics. The results showed that: the relevance of competencies in curriculum 2013 with the expected competencies was 82% to 89%. The competencies expected by the schools and the world of business and industry consists of drawing with autocad and / or 3D max, spooring, as well as maintaining hidroulik power steering, measuring and analyzing vehicle emissions, maintaining hydraulic power steering (HPS), analyzing damage in the system of wiring diagram, and conducting damage diagnosis. The lectures' contribution in the socialization and implementation aspects were categorized as good with the mean scores of 73 and 39.5 respectively
Framework for classifying logical operators in stabilizer codes
Entanglement, as studied in quantum information science, and non-local
quantum correlations, as studied in condensed matter physics, are fundamentally
akin to each other. However, their relationship is often hard to quantify due
to the lack of a general approach to study both on the same footing. In
particular, while entanglement and non-local correlations are properties of
states, both arise from symmetries of global operators that commute with the
system Hamiltonian. Here, we introduce a framework for completely classifying
the local and non-local properties of all such global operators, given the
Hamiltonian and a bi-partitioning of the system. This framework is limited to
descriptions based on stabilizer quantum codes, but may be generalized. We
illustrate the use of this framework to study entanglement and non-local
correlations by analyzing global symmetries in topological order, distribution
of entanglement and entanglement entropy.Comment: 20 pages, 9 figure
The ground state properties of the spin-1/2 transverse Ising chain with periodically varying bonds and fields
Using continued fractions we study the ground state properties of the
spin-1/2 Ising chain in a transverse field with periodically varying
interaction strengths and external fields. We consider in detail the chain
having the period of modulation of interactions equals 2 and compare the
results obtained with those corresponding to the spin-1/2 isotropic XY chain in
a transverse field. In contrast to the behaviour of the transverse XY chain,
the transverse Ising chain does not exhibit a step-like magnetization vs. field
dependence caused by the alternation of bonds, its susceptibility exhibits a
logarithmic singularity at the field determined by interaction strengths, and
it is stable with respect to spin-Peierls dimerization.Comment: 11 pages, latex, 4 figure
Charge orderings in the atomic limit of the extended Hubbard model
The extended Hubbard model in the atomic limit (AL-EHM) on a square lattice
with periodic boundary conditions is studied with use of the Monte Carlo (MC)
method. Within the grand canonical ensemble the phase and order-order
boundaries for charge orderings are obtained. The phase diagrams include three
types of charge ordered phases and the nonordered phase. The system exhibits
very rich structure and shows unusual multicritical behavior. In the limiting
case of tij = 0, the EHM is equivalent to the pseudospin model with single-ion
anisotropy 1/2U, exchange interaction W in an effective magnetic field
(mu-1/2U-zW). This classical spin model is analyzed using the MC method for the
canonical ensemble. The phase diagram is compared with the known results for
the Blume-Capel model.Comment: 9 pages, 10 figure
Combination Rules, Charge Symmetry, and Hall Effect in Cuprates
The rule relating the observed Hall coefficient to the spin and charge
responses of the uniform doped Mott insulator is derived. It is essential to
include the contribution of holon and spinon three-current correlations to the
effective action of the gauge field. In the vicinity of the Mott insulating
point the Hall coefficient is holon dominated and weakly temperature dependent.
In the vicinity of a point of charge conjugation symmetry the holon
contribution to the observed Hall coefficient is small: the Hall coefficient
follows the temperature dependence of the diamagnetic susceptibility with a
sign determined by the Fermi surface shape. NOTE: document prepared using
REVTEX. (3 Figs, not included, available on request from: [email protected])Comment: 8 page
PENERAPAN MODEL PEMBELAJARAN COOPERATIVE SCRIPT UNTUK MENINGKATKAN KEMAMPUAN BERPIKIR KREATIF MATEMATIS SEKOLAH MENENGAH PERTAMA (SMP)
Penelitian ini bertujuan untuk menelaah mana yang lebih baik kemampuan berpikir kreatif matematis siswa antara siswa yang memperoleh pembelajaran model Cooperative Script dengan siswa yang memperoleh pembelajaran konvensional. Metode yang digunakan dalam penelitian ini adalah metode eksperimen dengan desain kelompok kontrol pretes-postes. Populasi dalam penelitian ini seluruh siswa kelas VIII SMP Nasional Bandung. Adapun sampel penelitiannya adalah dua kelas yang dipilih secara acak kelas yaitu VIII-A sebagai kelas kontrolyang di berikan perlakuan pembelajaran konvensional dan VIII-B sebagai kelas eksperimen diberikan perlakuan pembelajaran model CooperativeScript. Tes yang digunakan adalah tes uraian. Sedangkan skala sikap menggunakan Skala Likert yang berisikan pernyataan-pernyataan siswa mengenai kepercayaan diri siswa terhadap kegiatan pebelajaran yang dilakukan. Temuan penelitian ini menunjukan: 1) Peningkatan kemampuan berpikir kreatif matematis siswa yang memperoleh model pembelajaran Cooperative Script lebih baik daripada siswa yang memperoleh pembelajaran konvensional; 2) Kepercayaaan diri siswa terhadap pembelajaran matematika yang menggunakan model pembelajarn Cooperative Script lebih baik daripada siswa yang menggunakan model pembelajaran konvensional. Siswa bersikap positif terhadap pelajaran matematika, pembelajaran model Cooperative Script, dan soal-soal kemampuan berpikir kreatif matematis
The 16 November 2006 flank collapse of South-East Crater at Mount Etna, Italy: study of the deposit and hazard assessment
On 16 November 2006 a flank collapse affected the unstable Eastern slope of the South-East Crater
16 (SEC) of Mt. Etna. The collapse occurred during one of the paroxysmal events with sustained strombolian
17 activity that characterized the August-December 2006 eruption and was triggered by erosion of loose,
18 hydrothermally-altered material of the steep south-east sector of SEC from the outpour of lava. The collapse
19 produced a debris avalanche that involved both lithic and juvenile material and resulted in a deposit
20 emplaced on the Eastern flank of the volcano up to 1.2 km away from the source. The total volume of the
21 deposit was estimated to be in the order of 330,000-413,000 m3. The reconstruction of the collapse event
22 was simulated using TITAN2D, software designed to model granular avalanches and landslides. This
23 approach can be used to estimate areas that may be affected by similar collapse events in the future. The
24 area affected by the 16 November 2006 lateral collapse of SEC was a small portion of the Mt. Etna summit
25 area, but the fact that no one was killed or injured should be considered fortuitous. The summit and adjacent
26 areas of the volcano, in fact, are usually visited by many tourists who are not prepared to face this type of
27 danger. The 16 November 2006 collapse points to the need to be prepared for similar events through
28 scientific investigation (analysis of flank instability, numerical simulation of flows) and development of specific
civil protection plans
Role of multiple subband renormalization in the electronic transport of correlated oxide superlattices
Metallic behavior of band-insulator/ Mott-insulator interfaces was observed
in artificial perovskite superlattices such as in nanoscale SrTiO3/LaTiO3
multilayers. Applying a semiclassical perspective to the parallel electronic
transport we identify two major ingredients relevant for such systems: i) the
quantum confinement of the conduction electrons (superlattice modulation) leads
to a complex, quasi-two dimensional subband structure with both hole- and
electron-like Fermi surfaces. ii) strong electron-electron interaction requires
a substantial renormalization of the quasi-particle dispersion. We characterize
this renormalization by two sets of parameters, namely, the quasi-particle
weight and the induced particle-hole asymmetry of each partially filled
subband. In our study, the quasi-particle dispersion is calculated
self-consistently as function of microscopic parameters using the slave-boson
mean-field approximation introduced by Kotliar and Ruckenstein. We discuss the
consequences of strong local correlations on the normal-state free-carrier
response in the optical conductivity and on the thermoelectric effects.Comment: 11 pages, 4 figure
Some Experimental Results on the Sorption of Cs By Submicron W-10% Ta and Ta Powders. EUR 4740.
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