Precipitation observations from high frequency spaceborne polarimetric synthetic aperture radar and ground-based radar: theory and model validation

2010 Fall.Includes bibliographical references.Global weather monitoring is a very useful tool to better understand the Earth's hydrological cycle and provide critical information for emergency and warning systems in severe cases. Developed countries have installed numerous ground-based radars for this purpose, but they obviously are not global in extent. To address this issue, the Tropical Rainfall Measurement Mission (TRMM) was launched in 1997 and has been quite successful. The follow-on Global Precipitation Measurement (GPM) mission will replace TRMM once it is launched. However, a single precipitation radar satellite is still limited, so it would be beneficial if additional existing satellite platforms can be used for meteorological purposes. Within the past few years, several X-band Synthetic Aperture Radar (SAR) satellites have been launched and more are planned. While the primary SAR application is surface monitoring, and they are heralded as "all weather'' systems, strong precipitation induces propagation and backscatter effects in the data. Thus, there exists a potential for weather monitoring using this technology. The process of extracting meteorological parameters from radar measurements is essentially an inversion problem that has been extensively studied for radars designed to estimate these parameters. Before attempting to solve the inverse problem for SAR data, however, the forward problem must be addressed to gain knowledge on exactly how precipitation impacts SAR imagery. This is accomplished by simulating storms in SAR data starting from real measurements of a storm by ground-based polarimetric radar. In addition, real storm observations by current SAR platforms are also quantitatively analyzed by comparison to theoretical results using simultaneous acquisitions by ground radars even in single polarization. For storm simulation, a novel approach is presented here using neural networks to accommodate the oscillations present when the particle scattering requires the Mie solution, i.e., particle diameter is close to the radar wavelength. The process of transforming the real ground measurements to spaceborne SAR is also described, and results are presented in detail. These results are then compared to real observations of storms acquired by the German TerraSAR-X satellite and by one of the Italian COSMO-SkyMed satellites both operating in co-polar mode (i.e., HH and VV). In the TerraSAR-X case, two horizontal polarization ground radars provided simultaneous observations, from which theoretical attenuation is derived assuming all rain hydrometeors. A C-band fully polarimetric ground radar simultaneously observed the storm captured by the COSMO-SkyMed SAR, providing a case to begin validating the simulation model. While previous research has identified the backscatter and attenuation effects of precipitation on X-band SAR imagery, and some have noted an impact on polarimetric observations, the research presented here is the first to quantify it in a holistic sense and demonstrate it using a detailed model of actual storms observed by ground radars. In addition to volumetric effects from precipitation, the land backscatter is altered when water is on or near the surface. This is explored using TRMM, Canada's RADARSAT-1 C-band SAR and Level 3 NEXRAD ground radar data. A weak correlation is determined, and further investigation is warranted. Options for future research are then proposed

Telemedicine infectious diseases consultations and clinical outcomes: A systematic review

Background: Telemedicine use is increasing in many specialties, but its impact on clinical outcomes in infectious diseases has not been systematically reviewed. We reviewed the current evidence for clinical effectiveness of telemedicine infectious diseases consultations, including outcomes of mortality, hospital readmission, antimicrobial use, cost, length of stay, adherence, and patient satisfaction. Methods: We queried Ovid MEDLINE 1946-, Embase.com 1947-, Scopus 1823-, Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov 1997- through August 5, 2019, for studies looking at clinical outcomes of infectious diseases in the setting of telemedicine use. We did not restrict by language or year of publication. Clinical outcomes searched included 30-day all-cause mortality, 30-day readmissions, patient compliance/adherence, patient satisfaction, cost or cost-effectiveness, length of hospital stay, antimicrobial use, and antimicrobial stewardship. Bias was assessed using standard methodologies. PROSPERO CRD42018105225. Results: From a search pool of 1154 studies, only 18 involved telemedicine infectious diseases consultation and our selected clinical outcomes. The outcomes tracked were heterogeneous, precluding meta-analysis, and the majority of studies were of poor quality. Overall, clinical outcomes with telemedicine infectious diseases consultation seem comparable to in-person infectious diseases consultation. Conclusions: Although in widespread use, the clinical effectiveness of telemedicine infectious diseases consultations has yet to be sufficiently studied. Further studies, or publication of previously collected and available data, are warranted to verify the cost-effectiveness of this widespread practice. Systematic review registration: PROSPERO CRD42018105225

Retrieval of surface-layer moisture fields using CSU radars

The surface-layer refractivity, i.e., the refractive index of air near the earth's surface, can be retrieved from radar by examining the phase of stationary ground targets. The index of refraction is a function of pressure, temperature, and humidity, and variations are dominated by humidity in warmer weather. Since the refractivity has a significant impact on the phase of propagating radar waves, it can be measured by observing the range integrated phase change between two stationary ground targets. This index, in turn, can be used to estimate the water vapor near the surface to explore convective storm initiation and storm evolution, and to enhance quantitative precipitation forecasts. This procedure was recently performed using the CSU-CHILL and Pawnee s-band radars, in addition to several other radars and sensors in Colorado. Estimated refractivity fields and the result of automatic stationary target identification are presented as well as phase comparisons with an x-band radar

Implementation of telemedicine infectious diseases consultation in a rural hospital using the Active Implementation Framework

In this pilot study, guided by the Active Implementation Framework, telemedicine infectious diseases consultation was provided to hospitalized inpatients at a rural Missouri hospital. Measured outcomes included the implementation outcomes of feasibility, acceptability, appropriateness, and fidelity, as well as clinical outcomes of readmissions and death

Perceptions of telemedicine and costs incurred by a visit to a general infectious diseases clinic: A survey

Background: The costs of attending in-person general infectious diseases clinics and preferences for visit type (telemedicine vs in-person) are not well known. We aimed to measure the time-related, monetary, social, and societal costs associated with travel to an in-person clinic visit and to assess patients\u27 preferences, questions, and concerns regarding telemedicine. Methods: Patients (≥18 years, living ≥25 miles from clinic at time of clinic visit) were recruited for this survey study from the general infectious diseases (ID) clinic at Washington University from June 2019 to February 2020. We calculated time and money potentially saved by telemedicine, as well as carbon dioxide emissions, with the assistance of Google Maps (low/high estimates). We also determined patient preferences regarding telemedicine for ID care. Results: Seventy-five patients completed the study. The round-trip mean travel distance was 227.2 ± 142.6 miles, mean travel time was 3.6 ± 2.0 hours to 4.5 ± 2.3 hours (low and high estimates from Google Maps), travel costs were $131.34 ±$82.27, and mean carbon dioxide emissions were 91.79 ± 57.60 kg. Fifty-eight patients (77.3%) said they would be willing to have a telemedicine visit in the future, and 30 (40.5%) said they would rather have had their visit the day the survey was completed as a telemedicine visit. Conclusions: Telemedicine has the potential to significantly reduce patient costs, both monetary and time-related, and offers substantial environmental benefits, while being an acceptable method of care delivery to most patients at a general ID clinic

Hacking Nuclear Command and Control

Executive Summary This paper will analyse the threat of cyber terrorism in regard to nuclear weapons. Specifically, this research will use open source knowledge to identify the structure of nuclear command and control centres, how those structures might be compromised through computer network operations, and how doing so would fit within established cyber terrorists' capabilities, strategies, and tactics. If access to command and control centres is obtained, terrorists could fake or actually cause one nuclear-armed state to attack another, thus provoking a nuclear response from another nuclear power. This may be an easier alternative for terrorist groups than building or acquiring a nuclear weapon or dirty bomb themselves. This would also act as a force equaliser, and provide terrorists with the asymmetric benefits of high speed, removal of geographical distance, and a relatively low cost. Continuing difficulties in developing computer tracking technologies which could trace the identity of intruders, and difficulties in establishing an internationally agreed upon legal framework to guide responses to computer network operations, point towards an inherent weakness in using computer networks to manage nuclear weaponry. This is particularly relevant to reducing the hair trigger posture of existing nuclear arsenals. All computers which are connected to the internet are susceptible to infiltration and remote control. Computers which operate on a closed network may also be compromised by various hacker methods, such as privilege escalation, roaming notebooks, wireless access points, embedded exploits in software and hardware, and maintenance entry points. For example, e-mail spoofing targeted at individuals who have access to a closed network, could lead to the installation of a virus on an open network. This virus could then be carelessly transported on removable data storage between the open and closed network. Information found on the internet may also reveal how to access these closed networks directly. Efforts by militaries to place increasing reliance on computer networks, including experimental technology such as autonomous systems, and their desire to have multiple launch options, such as nuclear triad capability, enables multiple entry points for terrorists. For example, if a terrestrial command centre is impenetrable, perhaps isolating one nuclear armed submarine would prove an easier task. There is evidence to suggest multiple attempts have been made by hackers to compromise the extremely low radio frequency once used by the US Navy to send nuclear launch approval to submerged submarines. Additionally, the alleged Soviet system known as Perimetr was designed to automatically launch nuclear weapons if it was unable to establish communications with Soviet leadership. This was intended as a retaliatory response in the event that nuclear weapons ha

Prenatal and Postnatal Dietary n-3 Fatty Acid Supplementation Alters Buffy Coat DNA Methylation Profile in Pigs

The objective of this study was to determine the effect of maternal long chain n-3 fatty acid supplementation on the DNA methylation profile of offspring buffy coats. We demonstrated several methylated regions across the genome were influenced by maternal n-3 dietary treatment. Therefore, feeding n-3 fatty acids to sows during gestation and lactation may result in a DNA methylation imprint on offspring buffy coats that persists beyond the nursery phase and may alter the phenotype of the growing pig

Reduction of carbon dioxide and organic carbonyls by hydrosilanes catalysed by the perrhenate anion

The simple perrhenate salt [N(hexyl)4][(ReO4)] acts as a catalyst for the reduction of organic carbonyls and carbon dioxide by primary and secondary hydrosilanes. In the case of CO2, this results in the formation of methanol equivalents via silylformate and silylacetal intermediates. Furthermore, the addition of alkylamines to the reaction mixture favours catalytic amine N-methylation over methanol production under certain conditions. DFT analysis of the mechanism of CO2 reduction shows that the perrhenate anion activates the silylhydride forming a hypervalent silicate transition state such that the CO2 can directly cleave a Si–H bond