Engineering model 8-cm thruster subsystem

An Engineering Model (EM) 8 cm Ion Thruster Propulsion Subsystem was developed for operation at a thrust level 5 mN (1.1 mlb) at a specific impulse 1 sub sp = 2667 sec with a total system input power P sub in = 165 W. The system dry mass is 15 kg with a mercury-propellant-reservoir capacity of 8.75 kg permitting uninterrupted operation for about 12,500 hr. The subsystem can be started from a dormant condition in a time less than or equal to 15 min. The thruster has a design lifetime of 20,000 hr with 10,000 startup cycles. A gimbal unit is included to provide a thrust vector deflection capability of + or - 10 degrees in any direction from the zero position. The EM subsystem development program included thruster optimization, power-supply circuit optimization and flight packaging, subsystem integration, and subsystem acceptance testing including a cyclic test of the total propulsion package

The effect of smoking, drinking and smoking cessation on morbidity and mortality in oral cancer: a controlled study

14 March 200

On the Gold Standard for Security of Universal Steganography

While symmetric-key steganography is quite well understood both in the information-theoretic and in the computational setting, many fundamental questions about its public-key counterpart resist persistent attempts to solve them. The computational model for public-key steganography was proposed by von Ahn and Hopper in EUROCRYPT 2004. At TCC 2005, Backes and Cachin gave the first universal public-key stegosystem - i.e. one that works on all channels - achieving security against replayable chosen-covertext attacks (SS-RCCA) and asked whether security against non-replayable chosen-covertext attacks (SS-CCA) is achievable. Later, Hopper (ICALP 2005) provided such a stegosystem for every efficiently sampleable channel, but did not achieve universality. He posed the question whether universality and SS-CCA-security can be achieved simultaneously. No progress on this question has been achieved since more than a decade. In our work we solve Hopper's problem in a somehow complete manner: As our main positive result we design an SS-CCA-secure stegosystem that works for every memoryless channel. On the other hand, we prove that this result is the best possible in the context of universal steganography. We provide a family of 0-memoryless channels - where the already sent documents have only marginal influence on the current distribution - and prove that no SS-CCA-secure steganography for this family exists in the standard non-look-ahead model.Comment: EUROCRYPT 2018, llncs styl

A low-power, low-cost infra-red emitter in CMOS technology

In this paper, 1 we present the design and characterization of a low-power low-cost infra-red emitter based on a tungsten micro-hotplate fabricated in a commercial 1-μm SOI-CMOS technology. The device has a 250-μm diameter resistive heater inside a 600-μm diameter thin dielectric membrane. We first present electro-thermal and optical device characterization, long term stability measurements, and then demonstrate its application as a gas sensor for a domestic boiler. The emitter has a dc power consumption of only 70 mW, a total emission of 0.8 mW across the 2.5–15-μm wavelength range, a 50% frequency modulation depth of 70 Hz, and excellent uniformity from device-to-device. We also compare two larger emitters (heater size of 600 and 1800 μm) made in the same technology that have a much higher infra-red emission, but at the detriment of higher power consumption. Finally, we demonstrate that carbon nanotubes can be used to significantly enhance the thermo-optical transduction efficiency of the emitter

SOI CMOS MEMS infra-red thermal source with carbon nanotubes coating

This abstract presents the development of a Silicon-on-Insulator (SOI) CMOS micro-electro-mechanical (MEMS) micro-hotplate based infra-red (IR) light source employing a vertically aligned multi-walled carbon nanotubes (VAMWCNTs) emission layer. Chips were batch fabricated using a standard SOI CMOS process with tungsten metalization followed by a deep reactive ion etching (DRIE) post-CMOS process. VA-MWCNTs were grown at the chip level with a proven in-situ technique. The CNTs coated devices were compared with uncoated devices. Herein we discuss the device performance in terms of power dissipation, beam collimation, thermal transient times, integrated emitted radiation and emitted radiation spectral profile.</p

First Results from the CHARA Array. II. A Description of the Instrument

The CHARA Array is a six 1-m telescope optical/IR interferometric array located on Mount Wilson California, designed and built by the Center for High Angular Resolution Astronomy of Georgia State University. In this paper we describe the main elements of the Array hardware and software control systems as well as the data reduction methods currently being used. Our plans for upgrades in the near future are also described

Clinical and neural correlates of alexithymia in posttraumatic stress disorder.

Individuals with posttraumatic stress disorder (PTSD) often exhibit deficits in emotional experience and expression, which suggests that certain individuals with PTSD may be alexithymic. In this study, in a sample of 105 individuals with PTSD, clinical correlates of alexithymia included reexperiencing, hyperarousal, numbing, dissociative symptoms, and retrospectively reported experiences of childhood emotional neglect. In a subsample of 26 individuals with PTSD related to a motor vehicle accident, functional neural responses to trauma-script imagery were associated with severity of alexithymia, including increased right posterior-insula and ventral posterior-cingulate activation and decreased bilateral ventral anterior-cingulate, ventromedial prefrontal, anterior-insula, and right inferior frontal cortex activation. Clinical and theoretical implications and future research directions are discussed

Risk factors for breast cancer in young women by oestrogen receptor and progesterone receptor status

We used data from 765 cases and 564 controls in the population-based Australian Breast Cancer Family Study to investigate whether, in women under the age of 40, the profile of risk factors differed between breast cancer subtypes defined by joint oestrogen and progesterone receptor status. As hypothesised, no significant differences were found