The meteorological usefulness of a maser RF amplifier on a highly sensitive X-band weather radar receiver

An evaluation of the meteorological usefulness of a maser RF amplifier on an AN/MPS-34 X-band weather radar indicates that there are both advantages and disadvantages to its use. The problems associated with the maser used in this study included tuning problems, loss of gain through loss of liquid helium and from tilting too high, and instability of the gain of the maser with time. The problems encountered which are potentially common to all masers included logistics problems, loss of gain because of saturation of the maser, and sufficient additional sensitivity to the radar receiver system to allow the detection of thermal noise. The detection of thermal noise, predicted by theory for the system used, is the most significant result of the study. Objects at a temperature of 300 K radiate thermal noise which is easily detected by the maser-equipped AN/MPS-34 while on short pulse (MDS ≤ -100 dbm while the noise power for the MPS-34 on short pulse from objects at 300 K exceeds -108 dbm). The advantages of the maser for the detection of clouds, precipitation, fog, clear air turbulence, insects, and birds are investigated. Little advantage is gained by using the maser on sensitive radars for most forms of precipitation except light snow. For sensitive radars, there are definite advantages to using the maser for clouds and bird detection and to some extent for insect detection. An additional 12 db of gain doubles the maximum range of detection for point targets and increases the maximum range of detection for distributed targets four times. Fog and clear air turbulence both have such small reflectivities that the maser did not provide enough additional gain to make detection of these feasible. Several uses of a maser for weather radar are suggested including the study of first echoes and clouds. The addition of a maser to other wavelength radars and to radars of relatively low sensitivity are also considered

Chinese Land Reclamation in the South China Sea: Implications and Policy Options

This report assesses legal, military/operational, and diplomatic implications of the reclamation and construction activity. It surveys U.S. and Chinese statements on the situation, provides a history of reclamation activity by other nations including the United States and other South China Sea claimants, and discusses U.S. strategy and potential options for U.S. policymakers

Plastic Laminate Pulsed Power Development

The desire to move high-energy Pulsed Power systems from the laboratory to practical field systems requires the development of compact lightweight drivers. This paper concerns an effort to develop such a system based on a plastic laminate strip Blumlein as the final pulseshaping stage for a 600 kV, 50ns, 5-ohm driver. A lifetime and breakdown study conducted with small-area samples identified Kapton sheet impregnated with Propylene Carbonate as the best material combination of those evaluated. The program has successfully demonstrated techniques for folding large area systems into compact geometry's and vacuum impregnating the laminate in the folded systems. The major operational challenges encountered revolve around edge grading and low inductance, low impedance switching. The design iterations and lessons learned are discussed. A multistage prototype testing program has demonstrated 600kV operation on a short 6ns line. Full-scale prototypes are currently undergoing development and testing

2011 American College of Rheumatology recommendations for the treatment of juvenile idiopathic arthritis: Initiation and safety monitoring of therapeutic agents for the treatment of arthritis and systemic features

Guidelines and recommendations developed and/or endorsed by the American College of Rheumatology (ACR) are intended to provide guidance for particular patterns of practice and not to dictate the care of a particular patient. The ACR considers adherence to these guidelines and recommendations to be voluntary, with the ultimate determination regarding their application to be made by the physician in light of each patient’s individual circumstances. Guidelines and recommendations are intended to promote beneficial or desirable outcomes but cannot guarantee any specific outcome. Guidelines and recommendations developed or endorsed by the ACR are subject to periodic revision as warranted by the evolution of medical knowledge, technology, and practice

Subgrouping the autism "spectrum": reflections on DSM-5

DSM-5 has moved autism from the level of subgroups ("apples and oranges") to the prototypical level ("fruit"). But making progress in research, and ultimately improving clinical practice, will require identifying subgroups within the autism spectrum

Using the Light Microscopy Module (LMM) on the International Space Station (ISS), The Advanced Colloids Experiment (ACE) and MacroMolecular Biophysics (MMB)

The Light Microscopy Module (LMM) was launched to the International Space Station (ISS) in 2009 and began science operations in 2010. It continues to support Physical and Biological scientific research on ISS. During 2016, if all goes as planned, three experiments will be completed: [1] Advanced Colloids Experiments with Heated base-2 (ACE-H2) and [2] Advanced Colloids Experiments with Temperature control (ACE-T1). Preliminary results, along with an overview of present and future LMM capabilities will be presented; this includes details on the planned data imaging processing and storage system, along with the confocal upgrade to the core microscope. [1] a consortium of universities from the State of Kentucky working through the Experimental Program to Stimulate Competitive Research (EPSCoR): Stuart Williams, Gerold Willing, Hemali Rathnayake, et al. and [2] from Chungnam National University, Daejeon, S. Korea: Chang-Soo Lee, et al