Spitzer/MIPS Imaging of NGC 650: Probing the History of Mass Loss on the Asymptotic Giant Branch

We present the far-infrared (IR) maps of a bipolar planetary nebula (PN), NGC 650, at 24, 70, and 160 micron taken with the Multiband Imaging Photometer for Spitzer (MIPS) on-board the Spitzer Space Telescope. While the two-peak emission structure seen in all MIPS bands suggests the presence of a near edge-on dusty torus, the distinct emission structure between the 24 micron map and the 70/160 micron maps indicates the presence of two distinct emission components in the central torus. Based on the spatial correlation of these two far-IR emission components with respect to various optical line emission, we conclude that the 24 micron emission is largely due to the [O IV] line at 25.9 micron arising from highly ionized regions behind the ionization front, whereas the 70 and 160 micron emission is due to dust continuum arising from low-temperature dust in the remnant asymptotic giant branch (AGB) wind shell. The far-IR nebula structure also suggests that the enhancement of mass loss at the end of the AGB phase has occurred isotropically, but has ensued only in the equatorial directions while ceasing in the polar directions. The present data also show evidence for the prolate spheroidal distribution of matter in this bipolar PN. The AGB mass loss history reconstructed in this PN is thus consistent with what has been previously proposed based on the past optical and mid-IR imaging surveys of the post-AGB shells.Comment: 9 pages in the emulated ApJ format with 6 figures, to appear in Ap

A 0.45V continuous time-domain filter using asynchronous oscillator structures

This paper presents a novel oscillator based filter structure for processing time-domain signals with linear dynamics that extensively uses digital logic by construction. Such a mixed signal topology is a key component for allowing efficient processing of asynchronous time encoded signals that does not necessitate external clocking. A miniaturized primitive is introduced as analogue time-domain memory that can be modelled, synthesized, and incorporated in closed loop mixed signal accelerators to realize more complex linear or non-linear computational systems. This is contextualized by demonstrating a compact low power filter operating at 0.45 V in 65 nm CMOS. Simulation results are presented showing an excess of 50 dB dynamic range with a FOM of 7fJ/pole which promises an order of magnitude improvement on state-of-the-art filters in nanometre CMOS

A 0.5V time-domain instrumentation circuit with clocked and unclocked ΔΣ operation

This paper presents a time-domain instrumentation circuit with exceptional noise efficiency directed at using nanometre CMOS for next generation neural interfaces. Current efforts to realize closed loop neuromodulation and high fidelity BMI prosthetics rely extensively on digital processing which is not well integrated with conventional analogue instrumentation. The proposed time-domain topology employs a differential ring oscillator that is put into feedback using a chopper stabilized low noise transconductor and capacitive feedback. This realization promises better digital integration by extensively using time encoded digital signals and seamlessly allows both clocked & unclocked ΔΣ behavior which is useful on-chip characterization and interfacing with synchronous systems. A 0.5V instrumentation system is implemented using a 65nm TSMC technology to realize a highly compact footprint that is 0.006mm2 in size. Simulation results demonstrate an excess of 55 dB dynamic range with 3.5 Vrms input referred noise for the given 810nW total system power budget corresponding to an NEF of 1.64

Continuous-time micropower interface for neural recording applications

This paper presents a novel amplifier architecture intended for low power neural recording applications. By using continuous-time signal representation, the proposed topology predominantly leverages digital topologies taking advantage of efficient techniques used in time domain systems. This includes higher order feedback dynamics that allow direct analogue signal quantization and near ideal integrator structures for noise shaping. The system implemented in 0.18 μ m standard CMOS demonstrates the capability for low noise instrumentation with a bandwidth of 6 kHz and highly linear full dynamic range. Simulation results indicate 1.145 μW budget from 0.5 V supply voltage with an input referred thermal noise of 7.7 μVrms

Koolide liikumisprogramm: sotsiaalsed praktikad ja eneseesitus

Uurisin oma magistritöös, mis kannab pealkirja „Koolide liikumisprogramm: sotsiaalsed praktikad ja eneseesitus“, sotsiaalse muutuse programmi nimega Liikuma Kutsuv Kool. Tänapäeva laste vähene füüsiline aktiivsus on keerukas probleem, mille lahendusvõimalust nähakse seniste liikumispraktikate muutmises. Minu analüüsitud sekkumisprogramm on võtnud sihiks praktikate muutuse koolikeskkonnas. 2016. aastal alustanud programm piloteerib kümnes koolis, katsetades erinevaid liikumisaktiivsust soodustavaid sekkumismetoodikaid, toetades ja koolitades koolide meeskondi, juhtkondi, klassiõpetajaid ja õpilasi, pakkudes koolidele nõustamist ning spordi- ja mänguvahendeid. Programmi eesmärk on muuta pilootkoolides koolikultuuri nii, et see hakkaks soosima paremaid liikumispraktikaid, ning laieneda seejärel ka teistesse Eesti koolidesse. Oma töös olen tegelenud nelja küsimusega: (1) Millised on liikumisaktiivsust soodustavate sekkumiste rõhuasetused ja senised praktikamuutused? (2) Kes on sekkumisega seotud praktikate olulisemad osapooled? (3) Kuidas toimib võrgustik sotsiaalse muutuse toetajana? (4) Milline on eneseesituse roll sekkumisprogrammis? Esimesed kolm uurimisküsimust kaardistavad sekkumisprogrammi tegevustest moodustuvat “välja”, tuginedes peamiselt sotsiaalsete praktikate teooriale. Neljas uurimisküsimus analüüsib seda välja, inspireerituna sotsioloog Erving Goffmani loodud eneseesituse-teooriast ning sotsiaalset interaktsiooni organiseerivatest dramaturgilistest printsiipidest. Töös olen analüüsinud üpriski mahukat andmevaramut, kus leidub eri meetodeil kogutud andmeid alates isiklikest uurimispäevikutest ja vaatlusraportitest kuni erinevate dokumentide ja küsimustikeni. Tööst järeldub, et programm on edukalt sekkunud kümne üpris erinevate eeltingimustega kooli toimimisse. Iga kool on moodustanud meeskonna, kes toetudes sekkumisprogrammi soovitustele on teinud suhteliselt autonoomsed otsused, millised uued praktikad koolis kasutusele võtta ja milliseid olemasolevaid praktikaid teisendada, samuti valinud vahendid, mille abil muutusi teostada. Sõltuvalt kooli eeltingimustest ja meeskonna senistest tegevusest on igas koolis toimunud muutused liikumispraktikate sotsiomateriaalses võrgustikus. Eelkõige on muutusi tunda kooliruumis: koridorides on rohkem 94 pingpongilaudu, võimlauksed on avatud ja vanemad ei sõida autodega enam treppi. Hoiakute, arusaamade ja teiste tähendustega seotud muutusi on koolikeskkonnas esmapilgul raskem märgata, kuid minu analüüs osutab, et programm on kaasa toonud nihke selles, milliste praktikatega vahetundi seostatakse. Koos uute tähendustega on tekkinud ka hulk uusi oskusi, alates õpilaste oskusest mängida kitsas koridoris sulgpalli kuni õpetajate oskuseni see koridor muretult läbida. Ülaltoodud muutused puudutavad pea kõiki osapooli. Sekkumisprogramm on taganud kompleksse võrgustikulise tegevuse, kus on ühendatud erineva tausta ja võimekustega organisatsioonidest moodustunud koalitsioon, projektimeeskond ning pilootkoolide esindajad. See võrgustik toetab pilootkoolide meeskondi nii inspiratsiooni, normide ümberkujundamise kui argise eeskujuga. Seetõttu on võrgustikune tegevus programmis osalt toimima hakanud kui sotsiaalsete muutuste kiirendi. Liikuma Kutsuv Kool on sekkumise katselava, mille toimimises on mõjurina ilmnenud ka eneseesitus. Uute praktikate loomine koolis, nende kohandumine, toimivate praktikate muutmine, võrgustikutegevus, koolis toimuvate tegevuste tutvustamine või raporteerimine ning programmimeeskonna enesegi tegevus eeldavad kommunikatiivseid tegevusi, mille oluliseks aspektiks on sageli eneseesitus. Sotsiaalse muutuse programmi jaoks on tõhusam selline eneseesitus, mis näitab koolikeskkonna argielu, selles tehtud katsetusi, tähenduslikke hetki muutuste protsessis ja laseb vaatajal ka tegevustest osa saada.http://hdl.handle.net/10062/5686

Ilokano To Go: Development and Usability of an Ilokano Vocabulary Mobile App

An Ilokano vocabulary mobile application was developed using MIT's App Inventor and a usability study was conducted on the app as part of the graduation requirements of the Learning Design and Technology Master's program at the University of Hawaii at Manoa.About 90% of the Philippine population living in Hawaii today is Ilokano or are descendants of Ilokano immigrants. Considered the language of the Philippine diaspora, Ilokano, or Ilocano, is currently being offered as a language course at several institutions in Hawaii. The courses follow a structured program, using textbooks that offer lessons and exercises based on real-world experiences. Although the students have a variety of resources available to them, the researcher found no mobile applications developed to learn Ilokano vocabulary. To assist students in their efforts, a mobile language learning application titled “Ilokano To Go” was developed and a usability study conducted. The purpose of this usability study was to develop and evaluate the ease of use of a beginner- intermediate Ilokano vocabulary development mobile app for students at a large university in Hawaii. The study included two iterations of usability testing and examined aspects of usability such as aesthetics, navigability, and usefulness. A pre-survey, usability protocol, observation checklist, and a post-survey helped to identify usability issues in the mobile application. The mobile application was well received by study participants, and changes relevant to its ease of use were made after each iteration of testing