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Proposed changes to Coors Procelain Co. recipe for fueled reactor tubes (Memo to Mr. Bob L. Mornin)
Because of various evaluation studies on fuel stability, it is proposed that Coors Porcelain Company change their recipe for fueled tubes. Specifically, zirconyl nitrate should be used. in addition to uranyl nitrate. The detailed changes to be made are provided
Broadband 300-GHz Power Amplifier MMICs in InGaAs mHEMT Technology
In this article, we report on compact solid-state power amplifier (SSPA) millimeter-wave monolithic integrated circuits (MMICs) covering the 280â330-GHz frequency range. The technology used is a 35-nm gate-length InGaAs metamorphic highelectron- mobility transistor (mHEMT) technology. Two power amplifier MMICs are reported, based on a compact unit amplifier cell, which is parallelized two times using two different Wilkinson power combiners. The Wilkinson combiners are designed using elevated coplanar waveguide and air-bridge thin-film transmission lines in order to implement low-loss 70-Ω lines in the back-endof-line of this InGaAs mHEMT technology. The five-stage SSPA MMICs achieve a measured small-signal gain around 20 dB over the 280â335-GHz frequency band. State-of-the-art output power performance is reported, achieving at least 13 dBm over the 286â310-GHz frequency band, with a peak output power of 13.7 dBm (23.4 mW) at 300 GHz. The PA MMICs are designed for a reduced chip width while maximizing the total gate width of 512 ÎŒm in the output stage, using a compact topology based on cascode and common-source devices, improving the output power per required chip width significantly
Parsing the Effects of Demography, Climate and Management on Recurrent Brucellosis Outbreaks in Elk
Zoonotic pathogens can harm human health and wellâbeing directly or by impacting livestock. Pathogens that spillover from wildlife can also impair conservation efforts if humans perceive wildlife as pests. Brucellosis, caused by the bacterium Brucella abortus, circulates in elk and bison herds of the Greater Yellowstone Ecosystem and poses a risk to cattle and humans. Our goal was to understand the relative effects of climatic drivers, host demography and management control programmes on disease dynamics. Using \u3e20 years of serologic, demographic and environmental data on brucellosis in elk, we built stochastic compartmental models to assess the influences of climate forcing, herd immunity, population turnover and management interventions on pathogen transmission. Data were collected at feedgrounds visited in winter by freeâranging elk in Wyoming, USA. Snowpack, hypothesized as a driver of elk aggregation and thus brucellosis transmission, was strongly correlated across feedgrounds. We expected this variable to drive synchronized disease dynamics across herds. Instead, we demonstrate asynchronous epizootics driven by variation in demographic rates. We evaluated the effectiveness of testâandâslaughter of seropositive female elk at two feedgrounds. Testâandâslaughter temporarily reduced herdâlevel seroprevalence but likely reduced herd immunity while removing few infectious individuals, resulting in subsequent outbreaks once the intervention ceased. We simulated an alternative strategy of removing seronegative female elk and found it would increase herd immunity, yielding fewer infections. We evaluated a second experimental treatment wherein feeding density was reduced at one feedground, but we found no evidence for an effect despite a decade of implementation. Synthesis and applications. Positive serostatus is often weakly correlated with infectiousness but is nevertheless used to make management decisions including lethal removal in wildlife disease systems. We show how this can have adverse consequences whereas efforts that maintain herd immunity can have longerâterm protective effects. Climatic drivers may not result in synchronous disease dynamics across populations unless vital rates are also similar because demographic factors have a large influence on disease patterns
Adaptive Optics for Astronomy
Adaptive Optics is a prime example of how progress in observational astronomy
can be driven by technological developments. At many observatories it is now
considered to be part of a standard instrumentation suite, enabling
ground-based telescopes to reach the diffraction limit and thus providing
spatial resolution superior to that achievable from space with current or
planned satellites. In this review we consider adaptive optics from the
astrophysical perspective. We show that adaptive optics has led to important
advances in our understanding of a multitude of astrophysical processes, and
describe how the requirements from science applications are now driving the
development of the next generation of novel adaptive optics techniques.Comment: to appear in ARA&A vol 50, 201
Number partitioning as random energy model
Number partitioning is a classical problem from combinatorial optimisation.
In physical terms it corresponds to a long range anti-ferromagnetic Ising spin
glass. It has been rigorously proven that the low lying energies of number
partitioning behave like uncorrelated random variables. We claim that
neighbouring energy levels are uncorrelated almost everywhere on the energy
axis, and that energetically adjacent configurations are uncorrelated, too.
Apparently there is no relation between geometry (configuration) and energy
that could be exploited by an optimization algorithm. This ``local random
energy'' picture of number partitioning is corroborated by numerical
simulations and heuristic arguments.Comment: 8+2 pages, 9 figures, PDF onl
Biomedical research leaders: report on needs, opportunities, difficulties, education and training, and evaluation.
The National Association of Physicians for the Environment (NAPE) has assumed a leadership role in protecting environmental health in recent years. The Committee of Biomedical Research Leaders was convened at the recent NAPE Leadership Conference: Biomedical Research and the Environment held on 1--2 November 1999, at the National Institutes of Health, Bethesda, Maryland. This report summarizes the discussion of the committee and its recommendations. The charge to the committee was to raise and address issues that will promote and sustain environmental health, safety, and energy efficiency within the biomedical community. Leaders from every important research sector (industry laboratories, academic health centers and institutes, hospitals and care facilities, Federal laboratories, and community-based research facilities) were gathered in this committee to discuss issues relevant to promoting environmental health. The conference and this report focus on the themes of environmental stewardship, sustainable development and "best greening practices." Environmental stewardship, an emerging theme within and outside the biomedical community, symbolizes the effort to provide an integrated, synthesized, and concerted effort to protect the health of the environment in both the present and the future. The primary goal established by the committee is to promote environmentally responsible leadership in the biomedical research community. Key outcomes of the committee's discussion and deliberation were a) the need for a central organization to evaluate, promote, and oversee efforts in environmental stewardship; and b) immediate need to facilitate efficient information transfer relevant to protecting the global environment through a database/clearinghouse. Means to fulfill these needs are discussed in this report
Evolutionarily conserved regulation of hypocretin neuron specification by Lhx9
Loss of neurons that express the neuropeptide hypocretin (Hcrt) has been implicated in narcolepsy, a debilitating disorder characterized by excessive daytime sleepiness and cataplexy. Cell replacement therapy, using Hcrt-expressing neurons generated in vitro, is a potentially useful therapeutic approach, but factors sufficient to specify Hcrt neurons are unknown. Using zebrafish as a high-throughput system to screen for factors that can specify Hcrt neurons in vivo, we identified the LIM homeobox transcription factor Lhx9 as necessary and sufficient to specify Hcrt neurons. We found that Lhx9 can directly induce hcrt expression and we identified two potential Lhx9 binding sites in the zebrafish hcrt promoter. Akin to its function in zebrafish, we found that Lhx9 is sufficient to specify Hcrt-expressing neurons in the developing mouse hypothalamus. Our results elucidate an evolutionarily conserved role for Lhx9 in Hcrt neuron specification that improves our understanding of Hcrt neuron development
SmartOTPs: An Air-Gapped 2-Factor Authentication for Smart-Contract Wallets
With the recent rise of cryptocurrencies' popularity, the security and
management of crypto-tokens have become critical. We have witnessed many
attacks on users and providers, which have resulted in significant financial
losses. To remedy these issues, several wallet solutions have been proposed.
However, these solutions often lack either essential security features,
usability, or do not allow users to customize their spending rules.
In this paper, we propose SmartOTPs, a smart-contract wallet framework that
gives a flexible, usable, and secure way of managing crypto-tokens in a
self-sovereign fashion. The proposed framework consists of four components
(i.e., an authenticator, a client, a hardware wallet, and a smart contract),
and it provides 2-factor authentication (2FA) performed in two stages of
interaction with the blockchain. To the best of our knowledge, our framework is
the first one that utilizes one-time passwords (OTPs) in the setting of the
public blockchain. In SmartOTPs, the OTPs are aggregated by a Merkle tree and
hash chains whereby for each authentication only a short OTP (e.g., 16B-long)
is transferred from the authenticator to the client. Such a novel setting
enables us to make a fully air-gapped authenticator by utilizing small QR codes
or a few mnemonic words, while additionally offering resilience against quantum
cryptanalysis. We have made a proof-of-concept based on the Ethereum platform.
Our cost analysis shows that the average cost of a transfer operation is
comparable to existing 2FA solutions using smart contracts with
multi-signatures
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