Ultra Low Power Analog Circuits for Wireless Sensor Node System.

This thesis will discuss essential analog circuit blocks required in ultra-low power wireless sensor node systems. A wireless sensor network system requires very high energy and power efficiency which is difficult to achieve with traditional analog circuits. First, 5.58nW real time clock using a DLL (Delay Locked Loop)-assisted pulse-driven crystal oscillator is discussed. In this circuit, the operational amplifier used in the traditional circuit was replaced with pulsed drivers. The pulse was generated at precise timing by a DLL. The circuit parts operate in different supply levels, generated on chip by using a switched capacitor network. The circuit was tested at different supply voltage and temperature. Its frequency characteristic along with power consumption were measured and compared to the traditional circuit. Next, a Schmitt trigger based pulse-driven crystal oscillator is discussed. In the first chapter, a DLL was used to generate a pulse with precise timing. However, testing results and recent study showed that the crystal oscillator can sustain oscillation even with inaccurate pulse timing. In this chapter, pulse location is determined by the Schmitt trigger. Simulation results show that this structure can still sustain oscillation at different process corners and temperature. In the next chapter, a sub-nW 8 bit SAR ADC (Successive Approximation Analog-to-Digital Converter) using transistor-stack DAC (Digital-to-Analog Converter) is discussed. To facilitate design effort and reduce the layout dependent effect, a conventional capacitive DAC was replaced with transistor-stack DAC with a 255:1 multiplexer. The control logic was designed with both TSPC (True Single Phase Clock) and CMOS logic to minimize transistor count. The ADC was implemented in a 65nm CMOS process and tested at different sampling rates and input signal frequency. Its linearity and power consumption was measured. Also, a similar design was implemented and tested using 180nm CMOS process as part of a sensor node system. Lastly, a multiple output level voltage regulator using a switched capacitor network for low-cost system is discussed.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111626/1/dmyoon_1.pd

Adjoint Reidemeister torsions from wrapped M5-branes

We introduce a vanishing property of adjoint Reidemeister torsions of a cusped hyperbolic 3-manifold derived from the physics of wrapped M5-branes on the manifold. To support our physical observation, we present a rigorous proof for the figure-eight knot complement with respect to all slopes. We also present numerical verification for several knots

Ginseng and Its Active Components Ginsenosides Inhibit Adipogenesis in 3T3-L1 Cells by Regulating MMP-2 and MMP-9

The growth and development of adipose tissue are believed to require adipogenesis, angiogenesis, and extracellular matrix remodeling. As our previous study revealed that ginseng reduces adipose tissue mass in part by decreasing matrix metalloproteinase (MMP) activity in obese mice, we hypothesized that adipogenesis can be inhibited by ginseng and its active components ginsenosides (GSs). Treatment of 3T3-L1 adipocytes with Korean red ginseng extract (GE) inhibited lipid accumulation and the expression of adipocyte-specific genes (PPARγ, C/EBPα, aP2, and leptin). GE decreased both the mRNA levels and activity of MMP-2 and MMP-9 in 3T3-L1 cells. These effects were further inhibited by total GSs (TGSs) and individual GSs. TGSs and individual GSs also significantly decreased MMP-2 and MMP-9 reporter gene activities in the presence of phorbol 12-myristate 13-acetate (PMA), the MMP inducer. Among the GSs, Rb1 most effectively inhibited MMP activity. In addition, PMA treatment attenuated the inhibitory actions of GE and GSs on adipogenesis. Moreover, GE and GSs reduced the expression of NF-κB and AP-1, the transcription factors of MMP-2 and MMP-9. These results demonstrate that ginseng, in particular GSs, effectively inhibits adipogenesis and that this process may be mediated in part through the suppression of MMP-2 and MMP-9. Thus, ginseng and GSs likely have therapeutic potential for controlling adipogenesis

High-energy and durable lithium metal batteries using garnet-type solid electrolytes with tailored lithium-metal compatibility

Lithium metal batteries using solid electrolytes are considered to be the next-generation lithium batteries due to their enhanced energy density and safety. However, interfacial instabilities between Li-metal and solid electrolytes limit their implementation in practical batteries. Herein, Li-metal batteries using tailored garnet-type Li7-xLa3-aZr2-bO12 (LLZO) solid electrolytes is reported, which shows remarkable stability and energy density, meeting the lifespan requirements of commercial applications. We demonstrate that the compatibility between LLZO and lithium metal is crucial for long-term stability, which is accomplished by bulk dopant regulating and dopant-specific interfacial treatment using protonation/etching. An all-solid-state with 5 mAh cm(-2) cathode delivers a cumulative capacity of over 4000 mAh cm(-2) at 3 mA cm(-2), which to the best of our knowledge, is the highest cycling parameter reported for Li-metal batteries with LLZOs. These findings are expected to promote the development of solid-state Li-metal batteries by highlighting the efficacy of the coupled bulk and interface doping of solid electrolytes. Lithium-metal batteries (LMBs) have attracted intense interest but the instability issues limit its practical deployment. Here, the authors report a durable LMB with high energy density using a garnet-type solid electrolyte with a tailored Li-metal compatibility

Carbon-free high-performance cathode for solid-state Li-O-2 battery

The development of a cathode for solid-state lithium-oxygen batteries has been hindered in practice by a low capacity and limited cycle life despite their potential for high energy density. Here, a previously unexplored strategy is proposed wherein the cathode delivers a specific capacity of 200 milliampere hour per gram over 665 discharge/charge cycles, while existing cathodes achieve only similar to 50 milliampere hour per gram and similar to 100 cycles. A highly conductive ruthenium-based composite is designed as a carbon-free cathode by first-principles calculations to avoid the degradation associated with carbonaceous materials, implying an improvement in stability during the electrochemical cycling. In addition, water vapor is added into the main oxygen gas as an additive to change the discharge product from growth-restricted lithium peroxide to easily grown lithium hydroxide, resulting in a notable increase in capacity. Thus, the proposed strategy is effective for developing reversible solid-state lithium-oxygen batteries with high energy density

Interaction between adipocyte and AgRP neurons regulates weight loss in Activity-Based Anorexia

Anorexia Nervosa (AN) is an eating disorder observed primarily in girls and women. AN is characterized by a low body mass index, hypophagia, and hyperactivity. While AN has one of the highest mortality and relapse rates of all psychiatric disorders, there are no approved pharmacological treatments for AN. However, a recent GWAS study revealed eight metabolic gene loci associated with the development of AN, suggesting a metabolic origin of the development of AN. In the clinical setting, weight regain is one crucial aspect of treating AN.In contrast, obesity patients face weight loss resistance. Recent work shows that obesity alters the metabolite profile of most tissues. Such metabolic profile returns to normal upon weight loss for all tissues except adipose tissues. Such an aspect of obesity is attributed to the metabolic memory of adipose tissues. We sought to introduce metabolic memory of obese adipose tissue in Activity-Based Anorexia (ABA), an animal model of AN's hyperactivity and hypophagia aspect, by transplanting adipose tissues into ABA mice. Our previous study found that obese adipose tissue recipients lose body weight slower than control adipose tissue recipients when subjected to the ABA paradigm. We therefore hypothesized that behavioral benefits to adipose tissue transplantation shown in the ABA paradigm stemmed from its communication to the brain. Here, we show that neonatal ablation of Agouti-Related Peptide (AgRP) neurons significantly disrupts the weight loss resistance introduced by obese adipose transplantation in ABA

Fine Tactile Representation of Materials for Virtual Reality

The most important aspect of virtual reality (VR) is the degree by which a user can feel and experience virtual space as though it is reality. Until recently, the experience of VR had to be satisfied with operations using a separate controller along with the visual and auditory elements. However, for a far more realistic VR environment, users should be able to experience the delicacy of tactile materials. This study proposes tactile technology, which is inexpensive and easy to use. To achieve this, we analyzed the unique patterns of materials through image filtering and designed a computing model to deliver realistic vibrations to the user. In addition, we developed and tested a haptic glove so that the texture of the material can be sensed in a VR environment

FlowWiki: A wiki based platform for ad hoc collaborative workflows

Traditional workflow management systems provide rich capabilities for designing, executing, and monitoring well-defined collaborative processes. Yet, for many occasions of collaboration, we do not often have sufficient information about who will participate, what activities people will carry out, and how the entire workflow will change. Accordingly, the problem of managing flexible workflows has been receiving increasing attention during the last decade. This paper presents a novel approach by which collaborative workflows can be configured independently as needed by participants and managed in an ad hoc way. Motivated by the emerging paradigm of collective intelligence, the proposed platform, named FlowWiki, provides a set of useful mechanisms to enable dynamic collaborations without requiring prescribed collaboration model. FlowWiki is an extension of conventional wiki system, and it aims for flexibly managing collaborative workflows by allowing on-demand workflow configuration and event-driven interactions. (C) 2010 Elsevier B.V. All rights reserved.Porcel C, 2010, KNOWL-BASED SYST, V23, P32, DOI 10.1016/j.knosys.2009.07.007DREILING A, 2010, GRAVITY COLLABORATIVFang CF, 2009, KNOWL-BASED SYST, V22, P271, DOI 10.1016/j.knosys.2009.01.003TRUONG HL, 2009, LECT NOTES COMPUT SC, V5460, P260Yang JM, 2009, KNOWL-BASED SYST, V22, P105, DOI 10.1016/j.knosys.2008.07.004Rosenberg F, 2008, IEEE INTERNET COMPUT, V12, P24, DOI 10.1109/MIC.2008.98CUBRIC M, 2007, WIKISYM 07, P11HECK M, 2007, INFOWORLD, V29, P20RICHARDSON L, 2007, RESTFUL WEB SERVICESVOSSEN G, 2007, UNLEASHING WEB 2 0 CBrambilla M, 2006, ACM T SOFTW ENG METH, V15, P360, DOI 10.1145/1178625.1178627Charoy F, 2006, LECT NOTES COMPUT SC, V4103, P205EBERSBACH A, 2006, WIKI WEB COLLABORATIMCAFEE AP, 2006, MIT SLOAN MANAGE REV, V47, P20MIERS D, 2006, ACM QUEUE, V4, P40PAPAZOGLOU MP, 2006, E BUSINESS ORG TECHNPesic M, 2006, LECT NOTES COMPUT SC, V4103, P169TOLKSDORF R, 2006, P 2006 INT S WIK, P79YAN J, 2006, IEEE T SYSTEMS MAN A, V36Wang MH, 2005, KNOWL-BASED SYST, V18, P257, DOI 10.1016/j.knosys.2004.04.012Sadiq SW, 2005, INFORM SYST, V30, P349, DOI 10.1016/j.is.2004.05.002REICHERT M, 2005, P 21 INT C DAT ENGDustdar S, 2004, DISTRIB PARALLEL DAT, V15, P45, DOI 10.1023/B:DAPD.0000009431.20250.56GOLDFARB CF, 2004, XML HDBSHAN EY, 2004, WORKFLOW HDB, P103Chung PWH, 2003, KNOWL-BASED SYST, V16, P149IVANOVIC M, 2003, 1 BALK C INF, P58VANDERAALST WMP, 2002, WORKFLOW MANAGEMENTCasati F, 2001, INFORM SYST, V26, P143Noll J, 2001, J NETW COMPUT APPL, V24, P39, DOI 10.1006/jnca.2000.0122HEYLIGHEN F, 1999, COMPUTATIONAL MATH T, V5, P253Casati F, 1998, DATA KNOWL ENG, V24, P211NUTT G, 1996, DISTRIBUTED SYSTEMS, V3, P276, DOI 10.1088/0967-1846/3/4/007BLUMENTHAL R, 1995, P 1995 ACM C ORG COM, P130BOGIA DP, 1995, P C ORG COMP SYST 95, P148