191207 Microbial Ecology of Point-of-Use Drinking Water Filters

Title:
Microbial Ecology of Point-of-Use Drinking Water Filters

Speaker:
吳佳真 (Chia-Chen Wu), PhD, Wayne State University

Time:
12/07 (Sat.) 5 pm PST, 6 pm MST, 7 pm CST, 8 pm EST
12/08 (Sun.) 9 am Taiwan

Keywords:
Environmental Engineering, Environmental microbiology and toxicology, Drinking water microbiome, Pseudomonas aeruginosa, E. coli

Abstract:
Commercial activated carbon block (ACB) point-of-use (PoU) drinking water filters are widely used to remove chemicals of concern from tap water. ACB PoU filters, however, are an incubator of bacteria because they remove disinfectant residual and adsorb organic compounds that can serve as bacterial substrates. Bacterial growth in ACB PoU filters raises questions about whether waterborne bacteria that pose health risks can be enriched, such as enteric-related bacteria, opportunistic pathogens, and antibiotic resistant gene (ARG)-carrying bacteria. To understand how ACB PoU filters change the microbial ecology of drinking water, studies were conducted using both laboratory-based manifold systems that received Ann Arbor tap water, and filters deployed in the field in response to the Flint water crisis. This presentation will show the mechanisms of bacteria colonization in the ACB PoU filters and discuss the overall risks involved in using the filter as the sole treatment barrier for tap water.

191130 Metallurgy of Quasicrystals

Title:
Metallurgy of Quasicrystals

Speaker:
黃中人 (Jhong-Ren Huang), PhD candidate, 日本東北大學 (Tohoku University)

Time:
11/30 (Sat.) 8 pm PST, 9 pm MST, 10 pm CST, 11 pm EST
12/01 (Sun.) 12 pm Taiwan

Keywords:
Materials science, Metallurgy, Quasicrystals, Crystallography

Abstract:
準結晶 (Quasicrystals) 既不屬於傳統晶體 (Crystals) ，也不屬於非晶態物質 (Amorphous)，因而被稱為「第三種固態物質狀態」。準結晶在電子繞射圖譜具有清晰的繞射斑點，卻展現出違反傳統結晶學上定義的旋轉對稱 (5-fold symmetry) 並缺乏直移對稱性 (Translational symmetry)。一般而言，準結晶多由金屬元素組成，由於其特殊的幾何對稱性，其性質迴異於典型金屬，因而吸引許多不同領域的研究人員投入這項新型態物質的研究。本演講將從傳統結晶學的角度出發，對準結晶的發現到結晶定義的革命進行概述；並基於冶金學的角度深入描述其形成與結晶穩定性與準結晶研究的現階段問題與未來展望。

191123 Better Intelligence If and Only If Better Compression

Title:
Better Intelligence If and Only If Better Compression

Speaker:
王富民 (Fumin Wang), PhD, DeepMind

Time:
11/23 (Sat.) 5 pm PST, 6 pm MST, 7 pm CST, 8 pm EST
11/24 (Sun.) 9 am Taiwan

Keywords:
Machine learning, Information theory, Minimum description length principle, Rissanen bound, Kolmogorov complexity

Abstract:
In the theory of Artificial General Intelligence by Hutter and others, the optimal behavior of a rational agent is equivalent to compressing its observations. A similar statement is Occam's Razor, i.e. the simplest answer is usually the correct answer. In this talk, we provide a compression program that is stronger than zip, 7z, and tar.gz, and show how it can be used to make intelligent decisions. In particular, we apply it to DNA and protein codes and use the resulting complexity measures to reconstruct the phylogeny tree of the mammalian class, as well as that of the SARS virus.

191116 Hidden Monopole Dark Matter via Axion Portal and its Implications for Direct Detection Searches and Beam-Dump Experiments

Title:
Hidden Monopole Dark Matter via Axion Portal and its Implications for Direct Detection Searches and Beam-Dump Experiments

Speaker:
何書宇 (Shu-Yu Ho), PhD student, 日本東北大學 (Tohoku University)

Time:
11/16 (Sat.) 7 pm PST, 8 pm MST, 9 pm CST, 10 pm EST
11/17 (Sun.) 11 am Taiwan

Keywords:
Physics, Particle Cosmology

Abstract:
我們考慮隱性磁單極暗物質 (hidden monopole dark matter) 透過軸子傳輸 (axion portal) 與核子作用。我們發現允許的參數空間可以讓磁單極暗物質和軸子被未來的實驗給探測，像是PICO-500 (暗物質直接探測實驗) 和SHiP (束轉儲實驗)。

191109 Cosmic Rays or Turbulence Can Suppress Cooling Flows

Title:
Cosmic Rays or Turbulence Can Suppress Cooling Flows

Speaker:
蘇恭毅 (Kung-Yi Su), PhD, CCA Flatiron Institute

Time:
11/09 (Sat.) 7 pm PDT, 8 pm MDT, 9 pm CDT, 10 pm EDT
11/10 (Sun.) 11 am Taiwan

Keywords:
Astronomy, Galaxy, AGN feedback, Cooling flows, Cosmic rays, Turbulence

Abstract:
The quenching "maintenance" and related "cooling flow" problems are important in galaxies from Milky Way mass through clusters. We investigate this in halos (1e12-1e14 solar mass), using non-cosmological high-resolution hydrodynamic simulations with the FIRE2 (Feedback In Realistic Environments) stellar feedback model. We first focus the various proposed "non-AGN" solution mechanisms, including Type Ia supernovae (SNe), AGB winds, cosmic rays (CR) from SNe, magnetic fields, conduction, or morphological quenching, and show that they do not substantially reduce cooling flows nor maintain "quenched". This all supports the idea that additional physics, e.g., AGN feedback, must be important in massive galaxies, but even the qualitative form of this energetic input remains uncertain. We, therefore, tested different scenarios including thermal heating, momentum injection, cosmic ray injection, or turbulent stirring of the intra-cluster medium (ICM). We explore which scenarios can quench without violating observational constraints on energetics or ICM gas. We show that turbulent stirring or CR injection, can both maintain a low-SFR halo for Gyr timescales with modest energy input, by providing a non-thermal pressure which stably lowers the core density and cooling rates. Turbulent stirring also mixes condensed core gas into the hot halo. Pure thermal heating or nuclear isotropic momentum injection require larger energy and require fine-tuning to avoid overheating/gas expulsion.