Additive manufacturing of glass using a filament fed process

There are many scientific and engineering applications of glass including optics, communications, electronics, and hermetic seals, there has been minimal research towards the Additive Manufacturing (AM) of transparent glass parts. The special thermal and optical properties of glasses make them hard to be printed using conventional AM techniques. In this dissertation, two different AM techniques for glass AM were developed, Selective Laser Melting (SLM) and filament fed process. Semi-transparent parts were printed with SLM process. However, the filament fed process was found to be more robust and promising for printing optically transparent glass parts. Therefore, this dissertation is focused on filament fed process for different types of glass, including soda lime glass, fused quartz and borosilicate glass. For soda lime glass, the optical quality of the best printed part was found to be as good as furnace cast glass part using the same type of filaments. Optical defects and refractive index inhomogeneity can be linked to the molten region temperature. Furthermore, the mechanism of bubble formation in soda lime glass printing was also studied. Different regimes of bubble formation were found corresponding with different process parameters. Though the melting temperature of fused quartz is very high (~2300 ⁰C), 3D fully transparent cubes with high index homogeneity were printed. For borosilicate glass, 3D fully transparent parts were printed, and the optical quality of best printed sample is as good as conventionally manufactured borosilicate glass --Abstract, page iv

TRPA1 mediates sensation of the rate of temperature change in Drosophila larvae.

Avoidance of noxious ambient heat is crucial for survival. A well-known phenomenon is that animals are sensitive to the rate of temperature change. However, the cellular and molecular underpinnings through which animals sense and respond much more vigorously to fast temperature changes are unknown. Using Drosophila larvae, we found that nociceptive rolling behavior was triggered at lower temperatures and at higher frequencies when the temperature increased rapidly. We identified neurons in the brain that were sensitive to the speed of the temperature increase rather than just to the absolute temperature. These cellular and behavioral responses depended on the TRPA1 channel, whose activity responded to the rate of temperature increase. We propose that larvae use low-threshold sensors in the brain to monitor rapid temperature increases as a protective alert signal to trigger rolling behaviors, allowing fast escape before the temperature of the brain rises to dangerous levels

A Parameterized Complexity View on Collapsing k-Cores

We study the NP-hard graph problem Collapsed k-Core where, given an undirected graph G and integers b, x, and k, we are asked to remove b vertices such that the k-core of remaining graph, that is, the (uniquely determined) largest induced subgraph with minimum degree k, has size at most x. Collapsed k-Core was introduced by Zhang et al. [AAAI 2017] and it is motivated by the study of engagement behavior of users in a social network and measuring the resilience of a network against user drop outs. Collapsed k-Core is a generalization of r-Degenerate Vertex Deletion (which is known to be NP-hard for all r >=0) where, given an undirected graph G and integers b and r, we are asked to remove b vertices such that the remaining graph is r-degenerate, that is, every its subgraph has minimum degree at most r. We investigate the parameterized complexity of Collapsed k-Core with respect to the parameters b, x, and k, and several structural parameters of the input graph. We reveal a dichotomy in the computational complexity of Collapsed k-Core for k = 3. For the latter case it is known that for all x >= 0 Collapsed k-Core is W[P]-hard when parameterized by b. We show that Collapsed k-Core is W[1]-hard when parameterized by b and in FPT when parameterized by (b+x) if k <=2. Furthermore, we show that Collapsed k-Core is in FPT when parameterized by the treewidth of the input graph and presumably does not admit a polynomial kernel when parameterized by the vertex cover number of the input graph

Computing Lens for Exploring the Historical People's Social Network

A typical social research topic is to figure out the influential people's relationship and its weights. It is very tedious for social scientists to solve those problems by studying massive literature. Digital humanities bring a new way to a social subject. In this paper, we propose a framework for social scientists to find out ancient figures' power and their camp. The core of our framework consists of signed graph model and novel group partition algorithm. We validate and verify our solution by China Biographical Database Project (CBDB) dataset. The analytic results on a case study demonstrate the effectiveness of our framework, which gets information that consists with the literature's facts and social scientists' viewpoints.Comment: accepted at SoNet 201

批评是理性对话——艾布拉姆斯与他的文学批评观 (Literary Criticism as a Rational Dialogue: M.H. Abrams and His Theoretical Orientations)

M.H. Abrams is known to Chinese readers as an influential literary critic of the Romantic Movement. This article, commissioned by Literature, a Chinese-language literary newspaper, introduces the theoretical orientations of M. H. Abrams, who passed away in April 2015 at the age of 102

Parameterized Dynamic Cluster Editing

We introduce a dynamic version of the NP-hard Cluster Editing problem. The essential point here is to take into account dynamically evolving input graphs: Having a cluster graph (that is, a disjoint union of cliques) that represents a solution for a first input graph, can we cost-efficiently transform it into a "similar" cluster graph that is a solution for a second ("subsequent") input graph? This model is motivated by several application scenarios, including incremental clustering, the search for compromise clusterings, or also local search in graph-based data clustering. We thoroughly study six problem variants (edge editing, edge deletion, edge insertion; each combined with two distance measures between cluster graphs). We obtain both fixed-parameter tractability as well as parameterized hardness results, thus (except for two open questions) providing a fairly complete picture of the parameterized computational complexity landscape under the perhaps two most natural parameterizations: the distance of the new "similar" cluster graph to (i) the second input graph and to (ii) the input cluster graph

TRPA1 mediates sensation of the rate of temperature change in Drosophila larvae

Avoidance of noxious ambient heat is crucial for animal survival. An important class of molecules that contributes to thermosensation is Transient Receptor Potential channels (thermoTRPs). ThermoTRPs are activated directly or indirectly by changes in temperatures, enabling animals to respond behaviorally to temperature fluctuations in the environment. The founding thermoTRP, mouse TRPV1, is activated by temperature higher than 42°C, and is required for avoidance of noxious heat. Other mammalian thermoTRPs are activated with different thresholds, such as mouse TRPM8 and TRPA1, which are activated directly by temperatures below ~23°C and ~17°C, respectively. The contribution of TRPs to thermosensation is evolutionarily conserved, and is well-documented in the invertebrate model organisms: C. elegans and Drosophila melanogaster. In Drosophila larvae, noxious heat is detected through direct activation of three TRPA channels: Painless, Pyrexia and TRPA1. The TRPA1 channel also enables larvae to sense small deviations above the preferred temperature. In the comfortable range, this fine thermal detection occurs through indirect activation of TRPA1 via a rhodopsin-dependent thermosensory signaling cascade. This signaling cascade may serve to lower the threshold for direct activation of TRPA1. The extensive studies on thermoTRPs in model organisms have contributed greatly to the theme that warm or hot temperatures of different thresholds are sensed by direct activation of TRP channels. However, a long-known but poorly understood phenomenon is that the rate of temperature change, rather than just the temperature threshold can affect the nociceptive response. Classic experiments on frogs performed more than 130 years ago demonstrated their high sensitivity and escape response to fast rises in heat, and indifference to slow increases in temperature. Stronger nociceptive reactions to fast temperature rises have been documented throughout the animal kingdom, in organisms as diverse as worms and humans. However, the mechanism underlying temperature rate detection is not clear. To explore the mechanism through which an animal responds differentially to slow and fast elevations in temperature, we developed Drosophila larvae as an animal model. We found that if we challenged larvae with a rapid temperature rise, a very high proportion of the animals exhibited nociceptive rolling behavior. However, if the temperature increase was gradual, the percentage of larvae that rolled was much lower, even after we exceeded temperatures that induced robust nociceptive avoidance after a fast temperature increase. We found one of the TRPA1 isoforms was the key rate-sensor, and was required for neurons in the brain to respond to the rate of temperature increase, rather than just the temperature threshold. Our results indicate that larvae use a TRPA1-dependent rate-sensing mechanism to safeguard the brain from exposure to noxious heat

Novel thick-foam ferroelectret with engineered voids for energy harvesting applications

This work reports a novel thick-foam ferroelectret which is designed and engineered for energy harvesting applications. We fabricated this ferroelectret foam by mixing a chemical blowing agent with a polymer solution, then used heat treatment to activate the agent and create voids in the polymer foam. The dimensions of the foam, the density and size of voids can be well controlled in the fabrication process. Therefore, this ferroelectret can be engineered into optimized structure for energy harvesting applications.<br/