Effect of random disorder and spin frustration on the reentrant spin glass phase and ferromagnetic phase in stage-2 Cu_{0.93}Co_{0.07}Cl_{2} graphite intercalation compound near the multicritical point

Stage-2 Cu$_{0.93}$Co$_{0.07}$Cl$_{2}$ graphite intercalation compound magnetically behaves like a reentrant ferromagnet near the multicritical point ($c_{MCP} \approx 0.96$). It undergoes two magnetic phase transitions at $T_{RSG}$ ($= 6.64 \pm 0.05$ K) and $T_{c}$ ($= 8.62 \pm 0.05$ K). The static and dynamic nature of the ferromagnetic and reentrant spin glass phase has been studied using DC and AC magnetic susceptibility. Characteristic memory phenomena of the DC susceptibility are observed at $T_{RSG}$ and $T_{c}$. The nonlinear AC susceptibility $\chi_{3}^{\prime}$ has a positive local maximum at $T_{RSG}$, and a negative local minimum at $T_{c}$. The relaxation time $\tau$ between $T_{RSG}$ and $T_{c}$ shows a critical slowing down: $\tau$ with $x = 13.1 \pm 0.4$ and $\tau_{0}^{*} = (2.5 \pm 0.5) \times 10^{-13}$ sec. The influence of the random disorder on the critical behavior above $T_{c}$ is clearly observed: $\alpha = -0.66$, $\beta = 0.63$, and $\gamma = 1.40$. The exponent of $\alpha$ is far from that of 3D Heisenberg model.Comment: 15 pages, 16 figures, submitted to Phys. Rev.

Coexisting cryptic species of the Litoditis marina complex (Nematoda) show differential resource use and have distinct microbiomes with high intraspecific variability

Differences in resource use or in tolerances to abiotic conditions are often invoked as potential mechanisms underlying the sympatric distribution of cryptic species. Additionally, the microbiome can provide physiological adaptations of the host to environmental conditions. We determined the intra-and interspecific variability of the microbiomes of three cryptic nematode species of the Litoditis marina species complex that co-occur, but show differences in abiotic tolerances. Roche 454 pyrosequencing of the microbial 16S rRNA gene revealed distinct bacterial communities characterized by a substantial diversity (85-513 OTUs) and many rare OTUs. The core microbiome of each species contained only very few OTUs (2-6), and four OTUs were identified as potentially generating tolerance to abiotic conditions. A controlled experiment in which nematodes from two cryptic species (Pm1 and Pm3) were fed with either an E. coli suspension or a bacterial mix was performed, and the 16S rRNA gene was sequenced using the MiSeq technology. OTU richness was 10-fold higher compared to the 454 data set and ranged between 1118 and 7864. This experiment confirmed the existence of species-specific microbiomes, a core microbiome with few OTUs, and high interindividual variability. The offered food source affected the bacterial community and illustrated different feeding behaviour between the cryptic species, with Pm3 exhibiting a higher degree of selective feeding than Pm1. Morphologically similar species belonging to the same feeding guild (bacterivores) can thus have substantial differences in their associated microbiomes and feeding strategy, which in turn may have important ramifications for biodiversity-ecosystem functioning relationships

Supervised Domain Adaptation using Graph Embedding

Getting deep convolutional neural networks to perform well requires a large amount of training data. When the available labelled data is small, it is often beneficial to use transfer learning to leverage a related larger dataset (source) in order to improve the performance on the small dataset (target). Among the transfer learning approaches, domain adaptation methods assume that distributions between the two domains are shifted and attempt to realign them. In this paper, we consider the domain adaptation problem from the perspective of dimensionality reduction and propose a generic framework based on graph embedding. Instead of solving the generalised eigenvalue problem, we formulate the graph-preserving criterion as a loss in the neural network and learn a domain-invariant feature transformation in an end-to-end fashion. We show that the proposed approach leads to a powerful Domain Adaptation framework; a simple LDA-inspired instantiation of the framework leads to state-of-the-art performance on two of the most widely used Domain Adaptation benchmarks, Office31 and MNIST to USPS datasets.Comment: 7 pages, 3 figures, 3 table

Modelling and Editing Cross-Modal Synchronization on a Label Web Canvas

We present how the open-source web framework Dezrann enables users to hear, study, and annotate music by interacting with synchronized views such as image scores, rendered scores, videos, and representations of audio as waveforms or spectrograms. We encode as unit conversions the cross-modal synchronization between these music representations. Composing these conversions allows us to conveniently translate musical time, audio time, and graphical positions, as well as to synchronize annotation labels across views. Uses of the Dezrann platform or of some of its components include corpus annotation for musicology or computer music research, music education, as well as collaborative score edition and correction in the CollabScore project

Nurturing shared leaders through internship

The Faculty of Social Sciences (the Faculty) of the University of Hong Kong has offered the very first credit-bearing internships in social sciences amongst all local tertiary institutions. Since September 2009, all students in the discipline have to complete 24 credits (equivalent to 4 courses) of off-campus experiential learning, with 12 credits in local internships and another 12 credits in global internships. In June 2012, the Faculty launched the pilot project of Service Leadership Internship (SLI) under the funding of the Li & Fung Service Leadership Initiative, which supports service leadership training in all eight of Hong Kong’s tertiary institution. The SLI took place in the summer 2012 where student interns worked as a team (groups of 3 – 5) to initiate, develop and implement (a) service task(s). By making use of the interns’ multi-disciplinary knowledge, the student interns contributed as shared leaders and helped community partners to generate innovative solutions to authentic problems under different projects. The Faculty also provided a series of support mechanisms to prepare the interns for the SLI projects. For example, an academic tutor was assigned to take care of each SLI project. Also, a series of workshops using the social cognitive approach were organized so as to enhance the interns’ social and personal competence as shared leaders and at the same time understand the construct of leaderships and social responsibilities through experiential learning and discussions. By completing the pre-workshop readings and actively participating in the workshops, interns internalized the core values of leadership such as enhanced self-awareness, became more competent as shared leaders and developed social responsibilities as an active member of the society. Booster sessions were also provided as a platform for small group sharing and problem-solving. In this paper presentation, the overall structure of the SLI, an overview of the content of the internship training and some of the learning outcome of the interns will be shared. The learning experiences in the pilot project will also help us plan for the upcoming summer of SLI 2013. A revised approach on SLI with an expanded participation of community partners will also be shared with the audience

EuCd2_2As2_2: a magnetic semiconductor

EuCd$_2$As$_2$ is now widely accepted as a topological semimetal in which a Weyl phase is induced by an external magnetic field. We challenge this view through firm experimental evidence using a combination of electronic transport, optical spectroscopy and excited-state photoemission spectroscopy. We show that the EuCd$_2$As$_2$ is in fact a semiconductor with a gap of 0.77 eV. We show that the externally applied magnetic field has a profound impact on the electronic band structure of this system. This is manifested by a huge decrease of the observed band gap, as large as 125~meV at 2~T, and consequently, by a giant redshift of the interband absorption edge. However, the semiconductor nature of the material remains preserved. EuCd$_2$As$_2$ is therefore a magnetic semiconductor rather than a Dirac or Weyl semimetal, as suggested by {\em ab initio} computations carried out within the local spin-density approximation.Comment: Accepted for publication in Physical Review Letter