5,793 research outputs found
The F@ Framework of Designing Awareness Mechanisms in Instant Messaging
This paper presents our research on awareness support in Instant Messaging (IM). The paper starts with a brief overview of empirical study of IM, using an online survey and face-to-face interviews to identify user needs for awareness support. The study identified a need for supporting four aspects of awareness, awareness of multiple concurrent conversations, conversational awareness, presence awareness of a group conversation, and visibility of moment-to-moment listeners and viewers. Based on the empirical study and existing research on awareness, we have developed the F@ (read as fat) framework of awareness. F@ comprises of the abstract level and the concrete level. The former includes an in-depth description of various awareness aspects in IM, whilst the latter utilises temporal logic to formalise fundamental time-related awareness aspects. F@ helps developers gain a better understanding of awareness and thereby design usable mechanisms to support awareness. Applying F@, we have designed several mechanisms to support various aspect of awareness in IM
Dissecting Quantum Phase Transition in the Transverse Ising Model
Irrespective of the fact that a complete theoretical description of critical
phenomena in connection with phase transition has been well-established through
the renormalization group formalism, the understanding of the phase transition
itself remains incomplete. For example, the questions like why and how the
phase transition happens are still unclear. Here we provide a pattern picture
to dissect the quantum phase transition occurring in the transverse Ising model
for a finite lattice. After the validity of the pattern formulation obtained is
confirmed, the energy contributions of different patterns to the ground state
energy provide a sufficient detail to show why and how the phase transition
takes place. Furthermore, a histogram of patterns' occupancy calculated by the
projections of ground state wavefunction on the patterns also shows the
detailed process of the phase transition. Our results are not only fundamental
in understanding the mechanism of phase transition, but also of practical
interest in quantum simulation platforms.Comment: 6 pages, 4 figure
Low-Dose Exposure to Bisphenol A in Early Life
Bisphenol A (BPA) has lower estrogenic potency than 17b-estadiol. The reference dose of BPA is defined as 50 ug/kg bw/day by the Environmental Protection Agency. The lower doses of BPA than no observable effect level are considered safe. However, early life exposure to low-dose BPA may increase the risk of developing adult onset disease. The harmful effects caused by low-dose BPA in fetus and newborns can transmit to third or fourth generations. The suggested mechanism of transgeneration is epigenetic changes. In addition, simultaneous exposure to various chemicals can induce combined effects. Low-dose effects of BPA are ongoing controversy because the animal test results will be the same in humans. Epidemiologic evidences are needed to provide the human health effects from exposure to low dose of BPA
Dissecting Superradiant Phase Transition in the Quantum Rabi Model
The phase transition is both thermodynamically and quantum-mechanically
ubiquitous in nature or laboratory and its understanding is still one of most
active issues in modern physics and related disciplines. The Landau's theory
provides a general framework to describe \textit{phenomenologically} the phase
transition by the introduction of order parameters and the associated symmetry
breakings; and is also taken as starting point to explore the critical
phenomena in connection with phase transitions in renormalization group, which
provides a complete theoretical description of the behavior close to the
critical points. In this sense the microscopic mechanism of the phase
transition remains still to be uncovered. Here we make a first attempt to
explore the microscopic mechanism of the superradiant phase transition in the
quantum Rabi model (QRM). We firstly perform a diagonalization in an operator
space to obtain three fundamental patterns involved in the QRM and then analyze
explicitly their energy evolutions with increasing coupling strengths. The
characteristic behaviors found uncover the microscipic mechanism of the
superradiant phase transition: one is active to drive the happening of phase
transition, the second responses rapidly to the change of the active pattern
and wakes up the third pattern to stablize the new phase. This kind of
dissecting mechanism explains for the first time why and how happens the
superradiant phase transition in the QRM and paves a way to explore the
microscopic mechanism of the phase transitions happening popularly in nature.Comment: 6 pages, 5 figure
Pattern description of the ground state properties of the one-dimensional axial next-nearest-neighbor Ising model in a transverse field
The description and understanding of the consequences of competing
interactions in various systems, both classical and quantum, are notoriously
difficult due to insufficient information involved in conventional concepts,
for example, order parameters and/or correlation functions. Here we go beyond
these conventional language and present a pattern picture to describe and
understand the frustration physics by taking the one-dimensional (1D) axial
next-nearest-neighbor Ising (ANNNI) model in a transverse field as an example.
The system is dissected by the patterns, obtained by diagnonalizing the model
Hamiltonian in an operator space with a finite lattice size (: natural
number) and periodic boundary condition. With increasing the frustration
parameter, the system experiences successively various phases/metastates,
identified respectively as those with zero, two, four, ,
domains/kinks, where the first is the ferromagnetic phase and the last the
antiphase. Except for the ferromagnetic phase and antiphase, the others should
be metastates, whose transitions are crossing over in nature. The results
clarify the controversial issues about the phases in the 1D ANNNI model and
provide a starting point to study more complicated situations, for example, the
frustration systems in high dimensions.Comment: 6 pages, 5 figure
Novel GATA5 loss-of-function mutations underlie familial atrial fibrillation
OBJECTIVE: This study aimed to identify novel GATA5 mutations that underlie familial atrial fibrillation. METHODS: A total of 110 unrelated patients with familial atrial fibrillation and 200 unrelated, ethnically matched healthy controls were recruited. The entire coding region of the GATA5 gene was sequenced in 110 atrial fibrillation probands. The available relatives of the mutation carriers and 200 controls were subsequently genotyped for the identified mutations. The functional effect of the mutated GATA5 was characterized using a luciferase reporter assay system. RESULTS: Two novel heterozygous GATA5 mutations (p.Y138F and p.C210G) were identified in two of the 110 unrelated atrial fibrillation families. These missense mutations cosegregated with AF in the families and were absent in the 400 control chromosomes. A cross-species alignment of GATA5 protein sequence showed that the altered amino acids were completely conserved evolutionarily. A functional analysis revealed that the mutant GATA5 proteins were associated with significantly decreased transcriptional activation when compared with their wild-type counterpart. CONCLUSION: The findings expand the spectrum of GATA5 mutations linked to AF and provide novel insights into the molecular mechanism involved in the pathogenesis of atrial fibrillation, suggesting potential implications for the early prophylaxis and personalized treatment of this common arrhythmia
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