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

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 $N$. 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 $N/2$ 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