On Packing Low-Diameter Spanning Trees

Edge connectivity of a graph is one of the most fundamental graph-theoretic concepts. The celebrated tree packing theorem of Tutte and Nash-Williams from 1961 states that every $k$-edge connected graph $G$ contains a collection $\cal{T}$ of $\lfloor k/2 \rfloor$ edge-disjoint spanning trees, that we refer to as a tree packing; the diameter of the tree packing $\cal{T}$ is the largest diameter of any tree in $\cal{T}$. A desirable property of a tree packing, that is both sufficient and necessary for leveraging the high connectivity of a graph in distributed communication, is that its diameter is low. Yet, despite extensive research in this area, it is still unclear how to compute a tree packing, whose diameter is sublinear in $|V(G)|$, in a low-diameter graph $G$, or alternatively how to show that such a packing does not exist. In this paper we provide first non-trivial upper and lower bounds on the diameter of tree packing. First, we show that, for every $k$-edge connected $n$-vertex graph $G$ of diameter $D$, there is a tree packing $\cal{T}$ of size $\Omega(k)$, diameter $O((101k\log n)^D)$, that causes edge-congestion at most $2$. Second, we show that for every $k$-edge connected $n$-vertex graph $G$ of diameter $D$, the diameter of $G[p]$ is $O(k^{D(D+1)/2})$ with high probability, where $G[p]$ is obtained by sampling each edge of $G$ independently with probability $p=\Theta(\log n/k)$. This provides a packing of $\Omega(k/\log n)$ edge-disjoint trees of diameter at most $O(k^{(D(D+1)/2)})$ each. We then prove that these two results are nearly tight. Lastly, we show that if every pair of vertices in a graph has $k$ edge-disjoint paths of length at most $D$ connecting them, then there is a tree packing of size $k$, diameter $O(D\log n)$, causing edge-congestion $O(\log n)$. We also provide several applications of low-diameter tree packing in distributed computation

Faculty perspective on competency development in higher education: An international study

The purpose of this research is to establish common ground on how faculty development should be instituted and the needs it should address on an international level, with its major focus being the development of competencies. A survey was developed and distributed to a sample of 764 university teaching professionals. Results show that 90% find that it is either important or very important to develop competencies in higher education, and that 73% find they are well or very well trained in developing and assessing competencies, particularly with regard to applying theoretical knowledge in practice, teamwork, and oral and written communication skills. The least valued competencies are found to be entrepreneurship and leadership. The most valued teaching methods are: project based learning, immersion in a professional environment, visits, field trips, and anything that closes the gap between the professional and academic worlds. University teaching staff consider the best assessment scenarios to be those that involve a certain amount of immersion in real situations, problem posing, and simulation; the optimum measurement instruments use observation techniques and rubrics. The need to create academic teaching communities is found to be of great importance. A common assessment method is also seen as a useful addition.DOI: 10.18870/hlrc.v4i4.22

Framing Analysis of Belt and Road Initiative

In 2013, Chinese president, Xi Jinping, announced the Belt and Road Initiative (BRI) to his audience in Kazakhstan. He stated that this will involve the construction of roads, railways, and even special trade corridors, among others along the ancient Silk Road in a bid to foster economic, political, and social relationship between China and partner countries. This paper focuses on analyzing how leading newspapers in Nigeria, Malaysia, and Vietnam, namely The Sun, Vanguard, The Punch, The Nation, NewStraits Times, Malay Mail, Business Insider, The Star, Saigon Times and Vietnamnet Bridge, have framed and communicated this multi-national project to their various audiences six years after Xi’s announcement. Working on 200 editorial contents published between May 2017 and March 2019 across the selected newspapers, this explores how they framed BRI. We found that while most of the reports have framed BRI positively, others are framed to reflect cautious optimism. We suggest that BRI managers should take necessary steps to engage the media, policy makers, and other stakeholders to properly educate them on the vision and mission of the initiative

Fluorescent Nanoparticle-Based Indirect Immunofluorescence Microscopy for Detection of Mycobacterium tuberculosis

A method of fluorescent nanoparticle-based indirect immunofluorescence microscopy (FNP-IIFM) was developed for the rapid detection of Mycobacterium tuberculosis. An anti-Mycobacterium tuberculosis antibody was used as primary antibody to recognize Mycobacterium tuberculosis, and then an antibody binding protein (Protein A) labeled with Tris(2,2-bipyridyl)dichlororuthenium(II) hexahydrate (RuBpy)-doped silica nanoparticles was used to generate fluorescent signal for microscopic examination. Prior to the detection, Protein A was immobilized on RuBpy-doped silica nanoparticles with a coverage of ∼5.1×102 molecules/nanoparticle. With this method, Mycobacterium tuberculosis in bacterial mixture as well as in spiked sputum was detected. The use of the fluorescent nanoparticles reveals amplified signal intensity and higher photostability than the direct use of conventional fluorescent dye as label. Our preliminary studies have demonstrated the potential application of the FNP-IIFM method for rapid detection of Mycobacterium tuberculosis in clinical samples

Local lung hypoxia determines epithelial fate decisions during alveolar regeneration.

After influenza infection, lineage-negative epithelial progenitors (LNEPs) exhibit a binary response to reconstitute epithelial barriers: activating a Notch-dependent ΔNp63/cytokeratin 5 (Krt5) remodelling program or differentiating into alveolar type II cells (AEC2s). Here we show that local lung hypoxia, through hypoxia-inducible factor (HIF1α), drives Notch signalling and Krt5pos basal-like cell expansion. Single-cell transcriptional profiling of human AEC2s from fibrotic lungs revealed a hypoxic subpopulation with activated Notch, suppressed surfactant protein C (SPC), and transdifferentiation toward a Krt5pos basal-like state. Activated murine Krt5pos LNEPs and diseased human AEC2s upregulate strikingly similar core pathways underlying migration and squamous metaplasia. While robust, HIF1α-driven metaplasia is ultimately inferior to AEC2 reconstitution in restoring normal lung function. HIF1α deletion or enhanced Wnt/β-catenin activity in Sox2pos LNEPs blocks Notch and Krt5 activation, instead promoting rapid AEC2 differentiation and migration and improving the quality of alveolar repair

The Ubiquitin Ligase Adaptor NDFIP1 Selectively Enforces a CD8⁺ T Cell Tolerance Checkpoint to High-Dose Antigen

Escape from peripheral tolerance checkpoints that control cytotoxic CD8+ T cells is important for cancer immunotherapy and autoimmunity, but pathways enforcing these checkpoints are mostly uncharted. We reveal that the HECT-type ubiquitin ligase activator, NDFIP1, enforces a cell-intrinsic CD8+ T cell checkpoint that desensitizes TCR signaling during in vivo exposure to high antigen levels. Ndfip1-deficient OT-I CD8+ T cells responding to high exogenous tolerogenic antigen doses that normally induce anergy aberrantly expanded and differentiated into effector cells that could precipitate autoimmune diabetes in RIP-OVAhi mice. In contrast, NDFIP1 was dispensable for peripheral deletion to low-dose exogenous or pancreatic islet-derived antigen and had little impact upon effector responses to Listeria or acute LCMV infection. These data provide evidence that NDFIP1 mediates a CD8+ T cell tolerance checkpoint, with a different mechanism to CD4+ T cells, and indicates that CD8+ T cell deletion and anergy are molecularly separable checkpoints.This work was funded by NIH grant U19-AI100627, by an Australian Government Research Training Program Domestic Scholarship (to M.V.W.), by a Sydney Parker Smith Postdoctoral Research Fellowship from the Cancer Council of Victoria (to J.M.M.), and by the National Health and Medical Research Council (NHMRC) through Program Grants 1016953, 1113904, and 1054925, Australia Fellowship 585490 (to C.C.G.), Senior Principal Research Fellowship 1081858 (to C.C.G.), CJ Martin Early Career Fellowship 585518 (to I.A.P.), and Independent Research Institutes Infrastructure Support Scheme Grant 361646. Florey Institute of Neuroscience and Mental Health and WEHI acknowledge the strong support from the Victorian Government and in particular funding from the Operational Infrastructure Support Grant

Continuous-flow liquid-phase dehydrogenation of 1,4-cyclohexanedione in a structured multichannel reactor

A highly selective, scalable and continuous-flow process is developed for the liquid-phase dehydrogenation of 1,4-cyclohexanedione to hydroquinone in a millimetre-scale structured multichannel reactor. The square shaped channels (3 mm × 3 mm) were filled with 10 wt% Pd/C catalyst particles and utilized for the dehydrogenation reaction in single-pass and recycle modes. For the purpose to enhance process understanding and to maximize conversion and selectivity by process optimization, Design of Experiment (DoE) methodology was utilized by studying the effect of operating parameters on the catalytic performance in kinetic regime. The results demostrated the strong influence of temperature and liquid feed flow on the conversion and selectivity, with liquid feed and N₂ flows influencing pressure drop significantly. A multi-objective optimization methodology was used to identify the optimum process window with the aid of sweet spot plots, with design space plots developed to establish acceptable boundaries for process parameters. In single-pass mode, complete conversion per pass per channel was not achievable whereas conversion increased from 59.8% in one-channel to 78.3% for two-channel-in-series while maintaining selectivity (> 99%) with intermediate hydrogen removal. However, for without intermediate H₂ removal step, selectivity was declined from > 99% in one-channel to 82.3% at the outlet of second-channel. In recycle mode, dehydrogenation reaction was resulted in almost complete conversion (> 99%) with very high selectivity (> 99%) and yield (> 98%). This combination of mm-scale multichannel reactor and DoE methodology opens the way to developing highly selective and scalable dehydrogenation proocesses in the fine chemical and pharmaceutical industries