Radio signal scintillation caused by electron density irregularities in the ionosphere affects the accuracy and integrity of Global Navigation Satellite Systems, especially in the equatorial and ...high‐latitude regions during solar maxima. Scintillation in these two regions, nevertheless, is usually influenced by different factors and thus has different characteristics that cause different effects on GNSS signals. This paper compares the characteristics of high‐latitude and equatorial scintillation using multifrequency GPS scintillation data collected at Gakona, Alaska, Jicamarca, Peru, and Ascension Island during the 24th solar maximum. Several statistical distributions are established based on the data to characterize the intensity, duration, and occurrence frequency of scintillation. Results show that scintillation in the equatorial region is generally more severe and longer lasting, while high‐latitude scintillation is, in general, more moderate and usually dominated by phase fluctuations. Results also reveal the different impacts of solar activity, geomagnetic activity, and seasons on scintillation in different geographic locations.
Key Points
Scintillation at low latitudes is typically more severe than at high latitudes
Scintillation events are generally more severe on L2 and L5 than on L1
High‐latitude scintillation is highly correlated with geomagnetic activity
We show that applying feedback and weak measurements to a quantum system induces phase transitions beyond the dissipative ones. Feedback enables controlling essentially quantum properties of the ...transition, i.e., its critical exponent, as it is driven by the fundamental quantum fluctuations due to measurement. Feedback provides the non-Markovianity and nonlinearity to the hybrid quantum-classical system, and enables simulating effects similar to spin-bath problems and Floquet time crystals with tunable long-range (long-memory) interactions.
Nucleon–nucleon short range correlations (SRCs) in nuclei are important part of the nuclear structure and have been a subject of intensive studies in the last years. These objects represent temporary ...fluctuations in average nuclear matter density that occur when two or more nucleons separated by about 1 fm = 10
–13
cm. Inspired by recent theoretical and experimental progress in understanding of SRC we reanalyzed our data on the production of high momentum
and
mesons emitted from nuclear targets irradiated by a proton beam. One of the basic properties of SRCs is the universality which means that they are equally involved in the creation of different hadrons on different nuclei, reflecting the properties of nuclear matter. So far, the property of universality has been observed in electron–nuclear collisions for the breakup of proton–neutron correlations, as well as in proton–nuclear collisions for the production of cumulative pions with high momenta. Both processes involve only light quarks. In this letter, we report the first observation of SRC universality in kaon production on nuclei in the kinematic region of high energy–momentum transfers thereby extending the investigation of the SRC universality to the sector of strange quarks.
Background
Diet and exercise during pregnancy have been used to prevent gestational diabetes mellitus (GDM) with some success.
Objective
To examine the effectiveness of lifestyle intervention on GDM ...prevention and to identify key effectiveness moderators to improve the prevention strategy.
Search strategy
Pubmed, Scopus, Cochrane, and cross‐references were searched.
Selection criteria
Randomised controlled trials (RCTs) evaluating lifestyle interventions during pregnancy for GDM prevention.
Data collection and analysis
Two independent reviewers extracted data. A random‐effects model was used to analyse the relative risk (RR) and 95% confidence interval (95% CI). Meta‐regressions and subgroup analyses were used to investigate important moderators of effectiveness.
Main results
Forty‐seven RCTs involving 15 745 participants showed that diet and exercise during pregnancy were preventive of GDM (RR 0.77, 95% CI 0.69–0.87). Four key aspects were identified to improve the preventive effect: targeting the high‐risk population; an early initiation of the intervention; the correct intensity and frequency of exercise; and gestational weight gain management. Although 24 RCTs targeted women who were overweight or obese, body mass index (BMI) failed to predict the effectiveness of an intervention. Instead, interventions are most effective in high‐incidence populations rather than simply in women who are overweight or obese. Furthermore, exercise of moderate intensity for 50–60 minutes twice a week could lead to an approximately 24% reduction in GDM.
Conclusion
The best strategy to prevent GDM is to target the high‐risk population predicted by risk evaluation models and to control the gestational weight gain of women through intensified diet and exercise modifications early in their pregnancy.
Tweetable
Four key effectiveness moderators of lifestyle interventions for GDM prevention.
Tweetable
Four key effectiveness moderators of lifestyle interventions for GDM prevention.
The structure of nuclear matter at short internucleon distances is one of the poorly studied aspects of nuclear physics. At distances of the order of the nucleon radius, nuclear matter is represented ...by the pairs of correlated nucleons with relative momenta exceeding the Fermi momenta that emerge for a short time. Such structures, whose local density is comparable to the density of neutron stars, arise from fluctuations in the average nuclear density. One of the important characteristics of nucleon–nucleon correlations is their universality implying the independence of their properties from the nuclear mass number. Therefore, the peculiarities of these objects of nuclear structure reflect the properties of nuclear matter rather than specific nuclei. Information about the short-distance physics is extracted from the analysis of processes with high energy–momentum transfers. Until now, the property of universality has been observed in electron–nucleus collisions only for the breakup of nucleon pairs. In this paper we analyze the data on the cumulative production of pions by protons on a set of nuclear targets and for the first time have established the existence of universality of two-nucleon correlations in the production of π
+
and π
–
mesons. We have obtained evidence for the involvement of three-nucleon correlations in the production of pions beyond the kinematics of their production in interactions with two-nucleon objects.
We demonstrate in straightforward calculations that even under ideally weak noise the relaxation of bipartite open quantum systems contains elements not previously encountered in quantum noise ...physics. While additivity of decay rates is known to be generic for decoherence of a single system, we demonstrate that it breaks down for bipartite coherence of even the simplest composite systems.
Motivated by observations of snap-through phenomena in buckled elastic strips subject to clamping and lateral end translations, we experimentally explore the multi-stability and bifurcations of thin ...bands of various widths and compare these results with numerical continuation of a perfectly anisotropic Kirchhoff rod. Our choice of boundary conditions is not easily satisfied by the anisotropic structures, forcing a cooperation between bending and twisting deformations. We find that, despite clear physical differences between rods and strips, a naive Kirchhoff model works surprisingly well as an organizing framework for the experimental observations. In the context of this model, we observe that anisotropy creates new states and alters the connectivity between existing states. Our results are a preliminary look at relatively unstudied boundary conditions for rods and strips that may arise in a variety of engineering applications, and may guide the avoidance of jump phenomena in such settings. We also briefly comment on the limitations of current strip models.
•Prevailing C&D waste quantification methodologies are identified and compared.•One specific methodology cannot fulfill all waste quantification scenarios.•A relevance tree for appropriate ...quantification methodology selection is proposed.•More attentions should be paid to civil and infrastructural works.•Classified information is suggested for making an effective waste management plan.
Quantifying construction and demolition (C&D) waste generation is regarded as a prerequisite for the implementation of successful waste management. In literature, various methods have been employed to quantify the C&D waste generation at both regional and project levels. However, an integrated review that systemically describes and analyses all the existing methods has yet to be conducted. To bridge this research gap, an analytical review is conducted. Fifty-seven papers are retrieved based on a set of rigorous procedures. The characteristics of the selected papers are classified according to the following criteria - waste generation activity, estimation level and quantification methodology. Six categories of existing C&D waste quantification methodologies are identified, including site visit method, waste generation rate method, lifetime analysis method, classification system accumulation method, variables modelling method and other particular methods. A critical comparison of the identified methods is given according to their characteristics and implementation constraints. Moreover, a decision tree is proposed for aiding the selection of the most appropriate quantification method in different scenarios. Based on the analytical review, limitations of previous studies and recommendations of potential future research directions are further suggested.
•Restaurant use in COVID-19 pandemic influenced by policy and consumer behavior.•Most states in U.S. restricted in-person dining from March until June 2020.•Restaurant risk perception increased ...take-out and delivery use in June 2020.•Restaurant risk perception decreased in-person dining in June 2020.
This article investigated the influence of risk aversion and the perception of risk associated with dining inside a restaurant on restaurant utilization and expenditures in the initial re-opening phase of the COVID-19 pandemic. Consistent with economic theory, risk aversion and perception decreased the use of in-person restaurant services and increased the probability of using take-out and delivery, but had no influence on total restaurant expenditures. Risk perception had a larger effect on indoor dining compared to outdoor dining, suggesting risk averting behavior within the utilization of in-person restaurant services. These findings suggest COVID-19 concerns may influence restaurant use even after states relax their policies restricting restaurant operations. Our results also highlight the importance of developing policies to support the restaurant industry as consumers adjust to the re-opening phase of the pandemic.
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