848 research outputs found
Collapse and revival oscillations as a probe for the tunneling amplitude in an ultra-cold Bose gas
We present a theoretical study of the quantum corrections to the revival time
due to finite tunneling in the collapse and revival of matter wave interference
after a quantum quench. We study hard-core bosons in a superlattice potential
and the Bose-Hubbard model by means of exact numerical approaches and
mean-field theory. We consider systems without and with a trapping potential
present. We show that the quantum corrections to the revival time can be used
to accurately determine the value of the hopping parameter in experiments with
ultracold bosons in optical lattices.Comment: 10 pages, 12 figures, typos in section 3A correcte
Excitation Gap from Optimized Correlation Functions in Quantum Monte Carlo Simulations
We give a prescription for finding optimized correlation functions for the
extraction of the gap to the first excited state within quantum Monte Carlo
simulations. We demonstrate that optimized correlation functions provide a more
accurate reading of the gap when compared to other `non-optimized' correlation
functions and are generally characterized by considerably larger
signal-to-noise ratios. We also analyze the cost of the procedure and show that
it is not computationally demanding. We illustrate the effectiveness of the
proposed procedure by analyzing several exemplary many-body systems of
interacting spin-1/2 particles.Comment: 11 pages, 5 figure
Measurement of transparency ratios for protons from short-range correlated pairs
Nuclear transparency, Tp(A), is a measure of the average probability for a
struck proton to escape the nucleus without significant re-interaction.
Previously, nuclear transparencies were extructed for quasi-elastic A(e,e'p)
knockout of protons with momentum below the Fermi momentum, where the spectral
functions are well known. In this paper we extract a novel observable, the
transparency ratio, Tp(A)/T_p(12C), for knockout of high-missing-momentum
protons from the breakup of short range correlated pairs (2N-SRC) in Al, Fe and
Pb nuclei relative to C. The ratios were measured at momentum transfer Q^2 >
1.5 (GeV/c)^2 and x_B > 1.2 where the reaction is expected to be dominated by
electron scattering from 2N-SRC. The transparency ratios of the knocked-out
protons coming from 2N-SRC breakup are 20 - 30% lower than those of previous
results for low missing momentum. They agree with Glauber calculations and
agree with renormalization of the previously published transparencies as
proposed by recent theoretical investigations. The new transparencies scale as
A^-1/3, which is consistent with dominance of scattering from nucleons at the
nuclear surface.Comment: 6 pages, 4 figure
Perancangan Film Pendek Tentang Pengelolaan Waktu Sebagai Upaya Membangun Kesadaran Bagi Mahasiswa
Kita masing-masing memiliki 24 jam, 7 hari seminggu dan 52 minggu setiap tahun. Banyaknya waktu tidak begitu penting tapi lebih penting bagaimana waktu itu dikelola dari bagaimana kita memanfaatkan waktu sehingga penggunaan waktu lebih efektif sehingga mencapai hasil lebih banyak dengan waktu yang sama. Berdasarkan perolehan data kuesioner dan wawancara dari narasumber yang ahli dibidangnya di sadari bahwa permasalahan pengelolaan waktu yang memang menjadi permasalahan mahasiswa kini. Kurangnya pengelolaan waktu yang baik menyebabkan seseorang menggunakan waktunya dengan sembarangan dan sering menunda waktu. Mahasiswa yang kurang peka tentang waktu akan mempengaruhi apakah mereka memiliki suatu tujuan. Melalui permasalahan yang ada maka perancangan melakukan pendekatan dengan metode analisis deskriptif kualitatif dengan menghasilkan sebuah gagasan dengan pendekatan media visualisasi yang dikemas dalam bentuk film pendek.Setelah melakukan sebuah pengamatan di ketahui bahwa ada tiga alasan utama mengapa kita menggunakan visualisasi dalam berkomunikasi karena pesan yang disampaikan lebih menarik perhatian, lebih efisien, dan pesan visual lebih efektif.Pembuatan film pendek berjudul “Goal” digunakan sebagai media untuk menyadarkan mahasiswa dalam pengelolaan waktu dengan baik.Perancangan ini dibuat dengan pendekatan drama yang menceritakan kehidupan mahasiswa dengan cerita yang singkat
Exponential Complexity of the Quantum Adiabatic Algorithm for certain Satisfiability Problems
We determine the complexity of several constraint satisfaction problems using
the quantum adiabatic algorithm in its simplest implementation. We do so by
studying the size dependence of the gap to the first excited state of "typical"
instances. We find that at large sizes N, the complexity increases
exponentially for all models that we study. We also compare our results against
the complexity of the analogous classical algorithm WalkSAT and show that the
harder the problem is for the classical algorithm the harder it is also for the
quantum adiabatic algorithm.Comment: 9 pages, 7 figure
A Novel Interdisciplinary Course in Gerontechnology for Disseminating Computational Thinking
While specialized knowledge and skills are the hallmark of modern society, the size and complexity of contemporary problems often require cooperative effort to analyze and solve. Therefore, experiences with skills, methodologies, and tools for effective interdisciplinary collaboration and structured problem solving are vital for preparing students for future academic and professional success. Meanwhile, computational systems have permeated much of modern professional and personal life, making computational thinking an essential skill for members of modern society. However, formal training in these techniques is primarily limited to students within computer science, mathematics, management of information systems, and engineering. At Iowa State University, we have designed and offered an experimental course to develop undergraduate students’ abilities for interdisciplinary teamwork and to disseminate computational thinking skills to a broader range of students. This novel course was jointly designed and instructed by faculty from the Computer Science Department, Gerontology Program, and Graphic Design Program to incorporate diverse faculty expertise and pedagogical approaches. Students were required to interview real users to identify real-life problems, gather requirements, and assess candidate solutions, which necessitated communication both within the group and with technologically-disinclined users. In-class presentations and wiki-based project websites provided regular practice at disseminating domain expertise to larger interdisciplinary audiences. Workshops, group-based mentoring, peer learning, and guided discovery allowed non-CS majors to learn much more about computer programs and tools, and grading criteria held students individually accountable within their disciplines but also emphasized group collaboration
Challenges in monitoring and managing engineered slopes in a changing climate
Geotechnical asset owners need to know which parts of their asset network are vulnerable to climate change induced failure in order to optimise future investment. Protecting these vulnerable slopes requires monitoring systems capable of identifying and alerting to asset operators changes in the internal conditions that precede failure. Current monitoring systems are heavily reliant on point sensors which can be difficult to interpret across slope scale. This paper presents challenges to producing such a system and research being carried out to address some of these using electrical resistance tomography (ERT). Experimental results show that whilst it is possible to measure soil water content indirectly via resistivity the relationship between resistivity and water content will change over time for a given slope. If geotechnical parameters such as pore water pressure are to be estimated using this method then ERT systems will require integrating with more conventional geotechnical instrumentation to ensure correct representative information is provided. The paper also presents examples of how such data can be processed and communicated to asset owners for the purposes of asset management
The Regulation of Actin Organization by Actin-Depolymerizing Factor in Elongating Pollen Tubes
Initial Validation of a Comprehensive Assessment Instrument for Bereavement-Related Grief Symptoms and Risk of Complications:The Indicator of Bereavement Adaptation-Cruse Scotland (IBACS)
OBJECTIVE: This study assessed the validity of the Indicator of Bereavement Adaptation Cruse Scotland (IBACS). Designed for use in clinical and non-clinical settings, the IBACS measures severity of grief symptoms and risk of developing complications. METHOD: N = 196 (44 male, 152 female) help-seeking, bereaved Scottish adults participated at two timepoints: T1 (baseline) and T2 (after 18 months). Four validated assessment instruments were administered: CORE-R, ICG-R, IES-R, SCL-90-R. Discriminative ability was assessed using ROC curve analysis. Concurrent validity was tested through correlation analysis at T1. Predictive validity was assessed using correlation analyses and ROC curve analysis. Optimal IBACS cutoff values were obtained by calculating a maximal Youden index J in ROC curve analysis. Clinical implications were compared across instruments. RESULTS: ROC curve analysis results (AUC = .84, p < .01, 95% CI between .77 and .90) indicated the IBACS is a good diagnostic instrument for assessing complicated grief. Positive correlations (p < .01, 2-tailed) with all four instruments at T1 demonstrated the IBACS' concurrent validity, strongest with complicated grief measures (r = .82). Predictive validity was shown to be fair in T2 ROC curve analysis results (n = 67, AUC = .78, 95% CI between .65 and .92; p < .01). Predictive validity was also supported by stable positive correlations between IBACS and other instruments at T2. Clinical indications were found not to differ across instruments. CONCLUSIONS: The IBACS offers effective grief symptom and risk assessment for use by non-clinicians. Indications are sufficient to support intake assessment for a stepped model of bereavement intervention
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