545 research outputs found
An Abstract Birkhoff Normal Form Theorem and Exponential Type Stability of the 1d NLS
We study stability times for a family of parameter dependent nonlinear Schrodinger equations on the circle, close to the origin. Imposing a suitable Diophantine condition (first introduced by Bourgain), we prove a rather flexible Birkhoff Normal Form theorem, which implies, e.g., exponential and sub-exponential time estimates in the Sobolev and Gevrey class respectively
Multiple Imputation of Missing Race and Ethnicity in CDC COVID-19 Case-Level Surveillance Data
The COVID-19 pandemic has resulted in a disproportionate burden on racial and ethnic minority groups, but incompleteness in surveillance data limits understanding of disparities. CDC’s case-based surveillance system contains most COVID-19 cases in the United States. Data analyzed in this paper contain COVID-19 cases with case-level information through September 25, 2020, which represent 70.9% of all COVID-19 cases reported to CDC during the period. Case-level surveillance data are used to investigate COVID-19 disparities by race/ethnicity, sex, and age. However, demographic information on race and ethnicity is missing for a substantial percentage of COVID-19 cases (e.g., 35.8% and 47.2% of cases analyzed were missing race and ethnicity information, respectively). Our goal in this study was to impute missing race and ethnicity to derive more accurate incidence and incidence rate ratio (IRR) estimates for different racial and ethnic groups, and evaluate the results from imputation compared to complete case analysis, which involves removing cases with missing race/ethnicity information from the analysis. Two multiple imputation (MI) models were developed. Model 1 imputes race using six binary race variables, and Model 2 imputes race as a composite multinomial variable. Our evaluation found that compared with complete case analysis, MI reduced biases and improved coverage on incidence and IRR estimates for all race/ethnicity groups, except for the Non-Hispanic Multiple/other group. Our research highlights the importance of supplementing complete case analysis with additional methods of analysis to better describe racial and ethnic disparities. When race and ethnicity data are missing, multiple imputation may provide more accurate incidence and IRR estimates to monitor these disparities in tandem with efforts to improve the collection of race and ethnicity information for pandemic surveillance
Emergency Department as an epidemiological observatory of Human Mobility: the experience of the Moroccan population
We conducted a retrospective study of the accesses to the Emergency Department registered from January 2000 to December 2014 in 5 major hospitals in the Metropolitan Area of Rome. We extrapolated data relating to patients of Moroccan origin from about 5 million total accesses, so we compared with Italians data which, in the same period, came to ED.
The Moroccan population is distinguished by a larger number of diagnoses belonging to the ICD-9 code of Infectious Diseases and, more precisely, to Respiratory Infectious Diseases. There are also no differences in the assignment of such diagnoses to Moroccans with Italian citizenship, and this led to think that this could play an important role in the use of the ED and moreover that enrollment to the National Health Service may reduce its inappropriate use.
Regarding to Degenerative Disorders, the result of our analysis is quite emblematic, showing that the accesses to the ED is due to Cardiovascular Diseases: 6.33% of Italians' accesses against 1.81% of Moroccans and 2.36% of Moroccans with Italian citizenship. The main explanation for this difference is, obviously, due to the age of the population: about 60% of Moroccans who accessed to ED was less than 40 years old.
It is interesting how, in the field of ​​Cardiovascular Diseases, Moroccans have a lower percentage of diagnosis compared to Italians for acute diseases and a greater percentage of diagnoses for chronic diseases, suggesting once again that accesses to ED for migrants often is due to the inability to use the general services of the National Health Service.
In conclusion, from the point of view of the Emergency Department, Migration Medicine still has Infectious Diseases as the main reason for access. Degenerative Disorders remain a prerogative of the Italians, but we could certainly assume that the Moroccan population would develop at some point with the aging
Chapter 6: Priority Infrastructure Opportunities for CO2 Utilization, in: Carbon Dioxide Utilization Markets and Infrastructure Status and Opportunities: A First Report
Building on the analyses of carbon dioxide (CO2)-derived products, infrastructure requirements, and
policy, regulatory, and societal considerations discussed in Chapters 2 through 5, this chapter presents a
summary of priority infrastructure opportunities to enable CO2 utilization. The chapter begins by
describing options for CO2 utilization infrastructure funding based on current policy and regulatory
regimes, and considering successful examples in related industries. It then examines near-term
opportunities for CO2 utilization infrastructure investments, as well as near-term actions to enable longerterm deployment options. A primary consideration for these opportunities is the ability of CO2 utilization
to participate in a future circular carbon economy, which depends on the type of CO2 source, CO2-derived
product lifetime, and life cycle emissions of other process inputs. The chapt
Chapter 4: Infrastructure Considerations for CO2 Utilization, in: Carbon Dioxide Utilization Markets and Infrastructure Status and Opportunities: A First Report
This chapter describes considerations for developing infrastructure for carbon dioxide (CO2)
utilization, taking into account the CO2-derived products identified in Chapter 3 and the existing
infrastructure discussed in Chapter 2. Infrastructure needs throughout the CO2 utilization value chain are
examined, from capture to purification, transportation, conversion, and, where applicable, transportation
of the CO2-derived product. Requirements for enabling infrastructure, namely, clean electricity, hydrogen,
water, land, and energy storage, are also considered
Space Weathering on Near-Earth Objects investigated by neutral-particle detection
The ion-sputtering (IS) process is active in many planetary environments in
the Solar System where plasma precipitates directly on the surface (for
instance, Mercury, Moon, Europa). In particular, solar-wind sputtering is one
of the most important agents for the surface erosion of a Near-Earth Object
(NEO), acting together with other surface release processes, such as Photon
Stimulated Desorption (PSD), Thermal Desorption (TD) and Micrometeoroid Impact
Vaporization (MIV). The energy distribution of the IS-released neutrals peaks
at a few eVs and extends up to hundreds of eVs. Since all other release
processes produce particles of lower energies, the presence of neutral atoms in
the energy range above 10 eV and below a few keVs (Sputtered High-Energy Atoms
- SHEA) identifies the IS process. SHEA easily escape from the NEO, due to
NEO's extremely weak gravity. Detection and analysis of SHEA will give
important information on surface-loss processes as well as on surface elemental
composition. The investigation of the active release processes, as a function
of the external conditions and the NEO surface properties, is crucial for
obtaining a clear view of the body's present loss rate as well as for getting
clues on its evolution, which depends significantly on space weather. In this
work, an attempt to analyze the processes that take place on the surface of
these small airless bodies, as a result of their exposure to the space
environment, has been realized. For this reason a new space weathering model
(Space Weathering on NEO - SPAWN), is presented. Moreover, an instrument
concept of a neutral-particle analyzer specifically designed for the
measurement of neutral density and the detection of SHEA from a NEO is proposedComment: 36 page
Low energy high angular resolution neutral atom detection by means of micro-shuttering techniques: the BepiColombo SERENA/ELENA sensor
The neutral sensor ELENA (Emitted Low-Energy Neutral Atoms) for the ESA
cornerstone BepiColombo mission to Mercury (in the SERENA instrument package)
is a new kind of low energetic neutral atoms instrument, mostly devoted to
sputtering emission from planetary surfaces, from E ~20 eV up to E~5 keV,
within 1-D (2x76 deg). ELENA is a Time-of-Flight (TOF) system, based on
oscillating shutter (operated at frequencies up to a 100 kHz) and mechanical
gratings: the incoming neutral particles directly impinge upon the entrance
with a definite timing (START) and arrive to a STOP detector after a flight
path. After a brief dissertation on the achievable scientific objectives, this
paper describes the instrument, with the new design techniques approached for
the neutral particles identification and the nano-techniques used for designing
and manufacturing the nano-structure shuttering core of the ELENA sensor. The
expected count-rates, based on the Hermean environment features, are shortly
presented and discussed. Such design technologies could be fruitfully exported
to different applications for planetary exploration.Comment: 11 page
Observations of Mercury's northern cusp region with MESSENGER's Magnetometer
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95510/1/grl29143.pd
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