1,606 research outputs found
An exact master equation for the system-reservoir dynamics under the strong coupling regime and non-Markovian dynamics
In this paper we present a method to derive an exact master equation for a
bosonic system coupled to a set of other bosonic systems, which plays the role
of the reservoir, under the strong coupling regime, i.e., without resorting to
either the rotating-wave or secular approximations. Working with phase-space
distribution functions, we verify that the dynamics are separated in the
evolution of its center, which follows classical mechanics, and its shape,
which becomes distorted. This is the generalization of a result by Glauber, who
stated that coherent states remain coherent under certain circumstances,
specifically when the rotating-wave approximation and a zero-temperature
reservoir are used. We show that the counter-rotating terms generate
fluctuations that distort the vacuum state, much the same as thermal
fluctuations.Finally, we discuss conditions for non-Markovian dynamics
Intraseasonal sea level variability in the Persian Gulf
Author Posting. © American Meteorological Society, 2021. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 51(5), (2021): 1687â1704, https://doi.org/10.1175/JPO-D-20-0296.1.Satellite observations are used to establish the dominant magnitudes, scales, and mechanisms of intraseasonal variability in ocean dynamic sea level (ζ) in the Persian Gulf over 2002â15. Empirical orthogonal function (EOF) analysis applied to altimetry data reveals a basinwide, single-signed intraseasonal fluctuation that contributes importantly to ζ variance in the Persian Gulf at monthly to decadal time scales. An EOF analysis of Gravity Recovery and Climate Experiment (GRACE) observations over the same period returns a similar large-scale mode of intraseasonal variability, suggesting that the basinwide intraseasonal ζ variation has a predominantly barotropic nature. A linear barotropic theory is developed to interpret the data. The theory represents Persian Gulf average ζ (¯ζ) in terms of local freshwater flux, barometric pressure, and wind stress forcing, as well as ζ at the boundary in the Gulf of Oman. The theory is tested using a multiple linear regression with these freshwater flux, barometric pressure, wind stress, and boundary ζ quantities as input and ¯ζ as output. The regression explains 70% ± 9% (95% confidence interval) of the intraseasonal ¯ζ variance. Numerical values of regression coefficients computed empirically from the data are consistent with theoretical expectations from first principles. Results point to a substantial nonisostatic response to surface loading. The Gulf of Oman ζ boundary condition shows lagged correlation with ζ upstream along the Indian subcontinent, Maritime Continent, and equatorial Indian Ocean, suggesting a large-scale Indian Ocean influence on intraseasonal ¯ζ variation mediated by coastal and equatorial waves and hinting at potential predictability. This study highlights the value of GRACE for understanding sea level in an understudied marginal sea.The authors acknowledge support from NASA through the Sea Level Change Team (Grant 80NSSC20K1241) and GRACE Follow-On Science Team (Grant 80NSSC20K0728). The authors appreciate comments from two anonymous reviewers that improved the manuscript
Leveling Up to Immersive Dispute Resolution (IDR) in 3-D Virtual Worlds: Learning and Employing Key IDR Skills to Resolve In-World Developer-Participant Conflicts
Effects of Grazing Season on Physico-Chemical Characteristics and Fatty Acids of Nutritional Interest of Caciocavallo Palermitano Cheese
The aim of this work was to evaluate, in the different production seasons of the year, the physico-chemical quality of an artisanal cheese traditionally obtained from autochthonous grazing cows, with particular reference to fatty acids (FA) of nutritional interest that play an important role in the risk or prevention of some human pathologies. For this purpose, cheeses were sampled in 11 farms, repeating the samplings in 3 different periods of the year (summer, autumnâwinter, and spring) when the productive conditions of the pastures varied. The cheeses produced in the spring period, when cows ingest a greater amount of grazed forage, resulted in a more adequate composition of the main FA, which are recognized as having a health effect, such as α-linolenic, trans-vaccenic, rumenic, docosapentaenoic (DPA) and docosahexaenoic (DHA) acids. Branched-chain FA were found in greater quantities in spring cheeses, as well as in summer ones. The FA composition of cheeses produced in the different seasons was reflected in some nutritional indexes that also resulted as more suitable in cheeses obtained in the spring period. The positive effects induced on the FA profile of cheeses are presumably linked to the diet of autochthonous cows, which is mainly based on forage from natural pastures. Therefore, the results obtained confirm the benefits of grazing, which is able to guarantee the production of healthier cheeses for consumers
Path Integral Approach to Strongly Nonlinear Composite
We study strongly nonlinear disordered media using a functional method. We
solve exactly the problem of a nonlinear impurity in a linear host and we
obtain a Bruggeman-like formula for the effective nonlinear susceptibility.
This formula reduces to the usual Bruggeman effective medium approximation in
the linear case and has the following features: (i) It reproduces the weak
contrast expansion to the second order and (ii) the effective medium exponent
near the percolation threshold are , , where is the
nonlinearity exponent. Finally, we give analytical expressions for previously
numerically calculated quantities.Comment: 4 pages, 1 figure, to appear in Phys. Rev.
Preschool wheezing and gastro-esophageal reflux: âcausal or casual coincidence? update from literature
Gastroesophageal reflux (GER) and wheeze are two common conditions in children. GER has been advocated as a causative factor for explaining recurrent to persistent respiratory symptoms at any age. This association very often means that many children with cough, wheezing, or recurrent respiratory infections receive empirical anti-reflux medications. The causal relationship is still largely discussed. Compared to the large number of studies in infants and adolescents, literature on the relationship between GER and wheeze in preschool children is scarce and inconclusive. The aim of the present narrative review was to summarize what is known so far, and what the literature has proposed in the last 20 years, on the relationship between preschool wheezing and GER. In preschool children with respiratory symptoms there is a high rate of positivity of reflux testing, for this reason pH-MII testing and endoscopy are recommended. Flexible bronchoscopy may be useful to exclude anatomical abnormalities as the cause of wheezing in infancy and preschool years. Several biomarkers, as well as empirical anti-reflux therapy, have been proposed for the diagnosis of GER-related airway diseases, but the conclusions of these studies are controversial or even conflicting. There is a great need for future clinical trials to confirm or rule out the association
Cultivating compliance: governance of North Indian organic basmati smallholders in a global value chain
Focusing on a global value chain (GVC) for organic basmati rice, we study how farmersâ practices are governed through product and process standards, organic certification protocols, and contracts with buyer firms. We analyze how farmersâ entry into the GVC reconfigures their agencements (defined as heterogeneous arrangements of human and nonhuman agencies which are associated with each other). These reconfigurations entail the severance of some associations among procedural and material elements of the agencements and the formation of new associations, in order to produce cultivation practices that are accurately described by the GVCâs standards and protocols. Based on ethnography of two farmers in Uttarakhand, North India, we find that the same standards were enacted differently on the two farmersâ fields, producing variable degrees of (selective) compliance with the âofficialâ GVC standards. We argue that the disjuncture between the âofficialâ scripts of the standards and actual cultivation practices must be nurtured to allow farmersâ agencements to align their practices with local sociotechnical relations and farm ecology. Furthermore, we find that compliance and disjuncture were facilitated by many practices and associations that were officially ungoverned by the GVC
Ornithological bibliography of the Azores
Only scientific publications up to 1980 are included in this bibliography. Other old narrations containing information on Azorean ornithology are being assembled for future publication. Certain unpublished works will also be dealt with. The part for consultation has been arranged in three sections. The first presents a numbered list of papers and books in chronological
order up to 1980. Last minute alterations obliged us to eliminate some items and to use «bis» for repeated numbers in some cases. The second section consists of the list of papers under their authors in alphabetical order. Finally, the third section consists of an index of the scientific names of the species cited.
The index contains three types of entries:
- The names of the genera, in capital letters, followed by the specific and subspecific names, which lead to their numbers in the chronological list. The latter are accompanied by the relevant page numbers, in brackets. - The names of the species, in small letters in bold-faced type,
lead to the names of the genera. - The names of the subspecies, in normal small letters, lead to the genera and species. Example: Fringilla coelebs moreletti entered under FRINGILLA, coelebs and moreletti, with the
bibliographical references only under the complete name. Papers of NÂșs. 17, 41, 72, 74, 76 have not been consulted by us; all other works are available in our library
How is New England coastal sea level related to the Atlantic meridional overturning circulation at 26 degrees N?
Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters, 46(10), (2019): 5351-5360, doi: 10.1029/2019GL083073.Monthly observations are used to study the relationship between the Atlantic meridional overturning circulation (AMOC) at 26° N and sea level (ζ) on the New England coast (northeastern United States) over nonseasonal timescales during 2004â2017. Variability in ζ is anticorrelated with AMOC on intraseasonal and interannual timescales. This anticorrelation reflects the stronger underlying antiphase relationship between ageostrophic Ekmanârelated AMOC transports due to local zonal winds across 26° N and ζ changes arising from local wind and pressure forcing along the coast. These distinct local atmospheric variations across 26° N and along coastal New England are temporally correlated with one another on account of largeâscale atmospheric teleconnection patterns. Geostrophic AMOC contributions from the Gulf Stream through the Florida Straits and upperâmidâocean transport across the basin are together uncorrelated with ζ. This interpretation contrasts with past studies that understood ζ and AMOC as being in geostrophic balance with one another.This work was supported by NSF awards OCEâ1558966, OCEâ1834739, and OCEâ1805029; NASA contract NNH16CT01C; and the J. Lamar Worzel Assistant Scientist Fund and the Penzance Endowed Fund in Support of Assistant Scientists at the Woods Hole Oceanographic Institution. Helpful comments from Magdalena Andres and two anonymous reviewers are acknowledged. Tideâgauge sea level data were provided by the Permanent Service for Mean Sea Level (www.psmsl.org). Observations of the overturning circulation were taken from the RAPID data download page (www.rapid.ac.uk/data.php). Time series of the North Atlantic Oscillation and Arctic Oscillation were downloaded from the National Oceanic and Atmospheric Administration Earth System Research Laboratory Physical Sciences Division website (www.esrl.noaa.gov/psd/). Reanalysis wind stress and air pressure fields were provided by the Community Storage Server at Woods Hole Oceanographic Institution (http://cmip5.whoi.edu/).2019-11-0
Models and applications for risk assessment and prediction of Asian soybean rust epidemics.
Asian rust of soybean [Glycine max (L.) Merril] is one of the most important fungal diseases of this crop worldwide. The recent introduction of Phakopsora pachyrhizi Syd. & P. Syd in the Americas represents a major threat to soybean production in the main growing regions, and significant losses have already been reported. P. pachyrhizi is extremely aggressive under favorable weather conditions, causing rapid plant defoliation. Epidemiological studies, under both controlled and natural environmental conditions, have been done for several decades with the aim of elucidating factors that affect the disease cycle as a basis for disease modeling. The recent spread of Asian soybean rust to major production regions in the world has promoted new development, testing and application of mathematical models to assess the risk and predict the disease. These efforts have included the integration of new data, epidemiological knowledge, statistical methods, and advances in computer simulation to develop models and systems with different spatial and temporal scales, objectives and audience. In this review, we present a comprehensive discussion on the models and systems that have been tested to predict and assess the risk of Asian soybean rust. Limitations, uncertainties and challenges for modelers are also discussed
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