Z2 spin liquid in S=1/2 Heisenberg model on Kagome lattice: A projective symmetry group study of Schwinger-fermion mean-field states

With strong geometric frustration and quantum fluctuations, S=1/2 quantum Heisenberg antiferromagnets on the Kagome lattice has long been considered as an ideal platform to realize spin liquid (SL), a novel phase with no symmetry breaking and fractionalized excitations. A recent numerical study of Heisenberg S=1/2 Kagome lattice model (HKLM) show that in contrast to earlier studies, the ground state is a singlet-gapped SL with signatures of Z2 topological order. Motivated by this numerical discovery, we use projective symmetry group to classify all 20 possible Schwinger-fermion mean-field states of Z2 SLs on Kagome lattice. Among them we found only one gapped Z2 SL (which we call Z2[0,\pi]\beta state) in the neighborhood of U(1)-Dirac SL state, whose energy is found to be the lowest among many other candidate SLs including the uniform resonating-valentce-bond states. We thus propose this Z2[0,\pi]\beta state to be the numerically discovered SL ground state of HKLM.Comment: 12 pages, 2 figures, revtex4, published versio

Fostering medical students' lifelong learning skills with a dashboard, coaching and learning planning.

IntroductionTo develop lifelong learning skills, students need feedback, access to performance data, and coaching. A new medical curriculum incorporated infrastructural supports based on self-regulated learning theory and the Master Adaptive Learner framework to engage students in reflection and learning planning. This study examines students' experience with a performance dashboard, longitudinal coaching, and structured time for goal-setting.MethodsFocus groups with first-year medical students explored performance dashboard usage, coaching and learning planning. We analyzed findings using thematic analysis. Results informed development of a 29-item survey rated strongly disagree (1) to strongly agree (5) to investigate experience with the dashboard, coaching and learning goals program. The survey was distributed to one first-year medical student class. We performed descriptive statistics and factor analysis.ResultsIn three focus groups with 21 participants, students endorsed using the dashboard to access performance information but had trouble interpreting and integrating information. They valued coaches as sources of advice but varied in their perceptions of the value of discussing learning planning. Of 152 students, 114 (75%) completed the survey. Exploratory factor analysis yielded 5 factors explaining 57% of the variance: learning goals development (α = 0.88; mean 3.25 (standard deviation 0.91)), dashboard usage (α = 0.82; 3.36 (0.64)), coaching (α = 0.71; 3.72 (0.64)), employment of learning strategies (α = 0.81; 3.67 (0.79)), and reflection (α = 0.63; 3.68 (0.64)).DiscussionThe student performance dashboard provides efficient feedback access, yet students' use of this information to guide learning is variable. These results can inform other programs seeking to foster lifelong learning skills

Heart enhancers with deeply conserved regulatory activity are established early in zebrafish development.

During the phylotypic period, embryos from different genera show similar gene expression patterns, implying common regulatory mechanisms. Here we set out to identify enhancers involved in the initial events of cardiogenesis, which occurs during the phylotypic period. We isolate early cardiac progenitor cells from zebrafish embryos and characterize 3838 open chromatin regions specific to this cell population. Of these regions, 162 overlap with conserved non-coding elements (CNEs) that also map to open chromatin regions in human. Most of the zebrafish conserved open chromatin elements tested drive gene expression in the developing heart. Despite modest sequence identity, human orthologous open chromatin regions recapitulate the spatial temporal expression patterns of the zebrafish sequence, potentially providing a basis for phylotypic gene expression patterns. Genome-wide, we discover 5598 zebrafish-human conserved open chromatin regions, suggesting that a diverse repertoire of ancient enhancers is established prior to organogenesis and the phylotypic period

Low-Cost Compressive Sensing for Color Video and Depth

A simple and inexpensive (low-power and low-bandwidth) modification is made to a conventional off-the-shelf color video camera, from which we recover {multiple} color frames for each of the original measured frames, and each of the recovered frames can be focused at a different depth. The recovery of multiple frames for each measured frame is made possible via high-speed coding, manifested via translation of a single coded aperture; the inexpensive translation is constituted by mounting the binary code on a piezoelectric device. To simultaneously recover depth information, a {liquid} lens is modulated at high speed, via a variable voltage. Consequently, during the aforementioned coding process, the liquid lens allows the camera to sweep the focus through multiple depths. In addition to designing and implementing the camera, fast recovery is achieved by an anytime algorithm exploiting the group-sparsity of wavelet/DCT coefficients.Comment: 8 pages, CVPR 201

Adaptive Temporal Compressive Sensing for Video

This paper introduces the concept of adaptive temporal compressive sensing (CS) for video. We propose a CS algorithm to adapt the compression ratio based on the scene's temporal complexity, computed from the compressed data, without compromising the quality of the reconstructed video. The temporal adaptivity is manifested by manipulating the integration time of the camera, opening the possibility to real-time implementation. The proposed algorithm is a generalized temporal CS approach that can be incorporated with a diverse set of existing hardware systems.Comment: IEEE Interonal International Conference on Image Processing (ICIP),201

Multidrug-resistant Escherichia coli and Tetracycline-resistant Enterococcus faecalis in wild raptors of Alabama and Georgia, USA

Wild birds inhabit in a wide variety of environments and can travel great distances. Thus, wild birds can possibly spread antimicrobial resistance along the way, and this may represent a potential public health concern. We characterized antimicrobial resistance in fecal Escherichia coli and Enterococcus faecalis in wild raptors in the southeastern US. Cloacal samples were collected from 118 wild raptors of 17 species from 18 counties in Alabama and 15 counties in Georgia. A total of 112 E. coli and 76 E. faecalis isolates were recovered, and we found significantly more antimicrobial-resistant E. coli (20/112, 18%) than E. faecalis (6/76, 8%; P = 0.05). Five antimicrobial-resistant genes: blaTEM-1, blaCTX-M-1, tet(M), cmlA, cat, and gyrA, were identified in antimicrobial-resistant E. coli isolates. Five of 13 (38%) ampicillin-resistant E. coli harbored both bla-TEM-1 and blaCTX-M-1 genes, indicating they are extended-spectrum beta-lactamase-carrying strains. Both of the tetracycline resistance genes, tet(M) and tet(L), were identified in E. faecalis isolates. Wild raptors seem to be a reservoir host of antimicrobial-resistant E. coli and E. faecalis and may represent a hazard to animal and human health by transmission of these isolates