4,063 research outputs found
Multidimensional replica-exchange method for free-energy calculations
We have developed a new simulation algorithm for free-energy calculations.
The method is a multidimensional extension of the replica-exchange method.
While pairs of replicas with different temperatures are exchanged during the
simulation in the original replica-exchange method, pairs of replicas with
different temperatures and/or different parameters of the potential energy are
exchanged in the new algorithm. This greatly enhances the sampling of the
conformational space and allows accurate calculations of free energy in a wide
temperature range from a single simulation run, using the weighted histogram
analysis method.Comment: 13 pages, (ReVTeX), 9 figures. J. Chem. Phys. 113 (2000), in pres
PENGARUH MATA KULIAH PERENCANAAN PENGAJARAN FISIKA TERHADAP MATA KULIAH PENGAJARAN MIKRO PADA MAHASISWA FISIKA SEMESTER GENAP 2016/2017 FKIP UNSYIAH
Permasalahan dalam penelitian ini yaitu Bagaimanakah pengaruh mata kuliah perencanaan pngajaran fisika terhadap pengajaran mikro pada mahasiswa fisika semester genap 2016/2017 Fkip Unsyiah?. Dimana penelitian ini bertujuan untuk mengetahui pengaruh mata kuliah perencanaan pengajaram fisika terhadap pengajaran mikro pada mahasiswa fisika semester genap 2016/2017 FKIP Unsyiah. Populasi dalam penelitian ini adalah mahasiwa fisika FKIP Unsyiah semester genap 2016/2017 yang sedang melaksanakan praktik pengajaran mikro dan telah lulus dalam mata kuliah perencanaan pengajaran fiska. Teknik pengumpulan data menggunakan Studi Dokumentasi dan Observasi. Teknik analisis data menggunakan analisis statistik dengan rumus analisis regresi. Hasil penelitian diperoleh thitung > ttabel (2.56 > 1.7). Hal ini berarti ada pengaruh antara mata kuliah perencanaan fisika terhadap pengajaran mikro pada mahasiswa fisika FKIP Unsyiah tahun 2017. Disarankan untuk mahasiswa praktikan pengjaran mikro terlebih dahulu mendalami materi pada mata kuliah perencanaan pengjaran fisika.Kata Kunci : Pengaruh, perencanaan pengajaran fisika, pengajaran mikro
Diffusion in the Markovian limit of the spatio-temporal colored noise
We explore the diffusion process in the non-Markovian spatio-temporal
noise.%the escape rate problem in the non-Markovian spatio-temporal random
noise. There is a non-trivial short memory regime, i.e., the Markovian limit
characterized by a scaling relation between the spatial and temporal
correlation lengths. In this regime, a Fokker-Planck equation is derived by
expanding the trajectory around the systematic motion and the non-Markovian
nature amounts to the systematic reduction of the potential. For a system with
the potential barrier, this fact leads to the renormalization of both the
barrier height and collisional prefactor in the Kramers escape rate, with the
resultant rate showing a maximum at some scaling limit.Comment: 4pages,2figure
Detection of Macroscopic Entanglement by Correlation of Local Observables
We propose a correlation of local observables on many sites in macroscopic
quantum systems. By measuring the correlation one can detect, if any,
superposition of macroscopically distinct states, which we call macroscopic
entanglement, in arbitrary quantum states that are (effectively) homogeneous.
Using this property, we also propose an index of macroscopic entanglement.Comment: Although the index q was proposed for mixed states, it is also
applicable to pure states, on which we fix minor bugs (that will be reported
in PRL as erratum). The conclusions of the paper remain unchanged. (4 pages,
no figures.
Effective Sampling in the Configurational Space by the Multicanonical-Multioverlap Algorithm
We propose a new generalized-ensemble algorithm, which we refer to as the
multicanonical-multioverlap algorithm. By utilizing a non-Boltzmann weight
factor, this method realizes a random walk in the multi-dimensional,
energy-overlap space and explores widely in the configurational space including
specific configurations, where the overlap of a configuration with respect to a
reference state is a measure for structural similarity. We apply the
multicanonical-multioverlap molecular dynamics method to a penta peptide,
Met-enkephalin, in vacuum as a test system. We also apply the multicanonical
and multioverlap molecular dynamics methods to this system for the purpose of
comparisons. We see that the multicanonical-multioverlap molecular dynamics
method realizes effective sampling in the configurational space including
specific configurations more than the other two methods. From the results of
the multicanonical-multioverlap molecular dynamics simulation, furthermore, we
obtain a new local-minimum state of the Met-enkephalin system.Comment: 15 pages, (Revtex4), 9 figure
Role of an intermediate state in homogeneous nucleation
We explore the role of an intermediate state (phase) in homogeneous
nucleation phenomenon by examining the decay process through a doubly-humped
potential barrier. As a generic model we use the fourth- and sixth-order Landau
potentials and analyze the Fokker-Planck equation for the one-dimensional
thermal diffusion in the system characterized by a triple-well potential. In
the low temperature case we apply the WKB method to the decay process and
obtain the decay rate which is accurate for a wide range of depth and curvature
of the middle well. In the case of a deep middle well, it reduces to a
doubly-humped-barrier counterpart of the Kramers escape rate: the barrier
height and the curvature of an initial well in the Kramers rate are replaced by
the arithmetic mean of higher(or outer) and lower(or inner) partial barriers
and the geometric mean of curvatures of the initial and intermediate wells,
respectively. It seems to be a universal formula. In the case of a
shallow-enough middle well, Kramers escape rate is alternatively evaluated
within the standard framework of the mean-first-passage time problem, which
certainly supports the WKB result. The criteria whether or not the existence of
an intermediate state can enhance the decay rate are revealed.Comment: 9pages, 11figure
Exploring the Implementation of Lesson-Level UDL Principles Through an Observation Protocol
The researchers piloted an observational protocol to examine the Universal Design for Learning (UDL) principles and checkpoint strategies used during daily instruction with a small sample of general and special education teachers. Observational research on UDL has been recommended within the literature. Researchers used the high-leverage practice of explicit instruction as the anchor for the design of the observation protocol. Findings indicate there is alignment between observed UDL principles and strategies employed at the lesson level and teachers’ self-reports of the UDL principles and strategies employed. Findings also suggest that teachers are using several UDL principles within their daily instruction and that there is overlap among UDL checkpoint strategies and aligned UDL principles. Essential UDL principles that pre-service and in-service teachers are expected to deliver at the lesson level can be prioritised to ensure a developmental approach to the implementation of UDL. Implications and recommendations for future research are discussed
Dose-response relationships at different exposure levels - necessity of reevaluation in establishing no-effect levels
Moments of generalized Husimi distributions and complexity of many-body quantum states
We consider generalized Husimi distributions for many-body systems, and show
that their moments are good measures of complexity of many-body quantum states.
Our construction of the Husimi distribution is based on the coherent state of
the single-particle transformation group. Then the coherent states are
independent-particle states, and, at the same time, the most localized states
in the Husimi representation. Therefore delocalization of the Husimi
distribution, which can be measured by the moments, is a sign of many-body
correlation (entanglement). Since the delocalization of the Husimi distribution
is also related to chaoticity of the dynamics, it suggests a relation between
entanglement and chaos. Our definition of the Husimi distribution can be
applied not only to the systems of distinguishable particles, but also to those
of identical particles, i.e., fermions and bosons. We derive an algebraic
formula to evaluate the moments of the Husimi distribution.Comment: published version, 33 pages, 7 figre
Correlations of observables in chaotic states of macroscopic quantum systems
We study correlations of observables in energy eigenstates of chaotic systems
of a large size . We show that the bipartite entanglement of two subsystems
is quite strong, whereas macroscopic entanglement of the total system is
absent. It is also found that correlations, either quantum or classical, among
less than points are quite small. These results imply that chaotic states
are stable. Invariance of these properties under local operations is also
shown.Comment: 5 pages, 2 figure
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