Academic literature on the topic 'Effetto inversione'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Effetto inversione.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Effetto inversione"
1
McBroome, Jakob, David Liang, and Russell Corbett-Detig. "Fine-Scale Position Effects Shape the Distribution of Inversion Breakpoints in Drosophila melanogaster." Genome Biology and Evolution 12, no. 8 (May 21, 2020): 1378–91. http://dx.doi.org/10.1093/gbe/evaa103.
Full textAbstract:
Abstract Chromosomal inversions are among the primary drivers of genome structure evolution in a wide range of natural populations. Although there is an impressive array of theory and empirical analyses that have identified conditions under which inversions can be positively selected, comparatively little data are available on the fitness impacts of these genome structural rearrangements themselves. Because inversion breakpoints can disrupt functional elements and alter chromatin domains, the precise positioning of an inversion’s breakpoints can strongly affect its fitness. Here, we compared the fine-scale distribution of low-frequency inversion breakpoints with those of high-frequency inversions and inversions that have gone to fixation between Drosophila species. We identified a number of differences among frequency classes that may influence inversion fitness. In particular, breakpoints that are proximal to insulator elements, generate large tandem duplications, and minimize impacts on gene coding spans which are more prevalent in high-frequency and fixed inversions than in rare inversions. The data suggest that natural selection acts to preserve both genes and larger cis-regulatory networks in the occurrence and spread of rearrangements. These factors may act to limit the availability of high-fitness arrangements when suppressed recombination is favorable.
2
Coyne, J. A., W. Meyers, A. P. Crittenden, and P. Sniegowski. "The fertility effects of pericentric inversions in Drosophila melanogaster." Genetics 134, no. 2 (June 1, 1993): 487–96. http://dx.doi.org/10.1093/genetics/134.2.487.
Full textAbstract:
Abstract Heterozygotes for pericentric inversions are expected to be semisterile because recombination in the inverted region produces aneuploid gametes. Newly arising pericentric inversions should therefore be quickly eliminated from populations by natural selection. The occasional polymorphism for such inversions and their fixation among closely related species have supported the idea that genetic drift in very small populations can overcome natural selection in the wild. We studied the effect of 7 second-chromosome and 30 third-chromosome pericentric inversions on the fertility of heterokaryotypic Drosophila melanogaster females. Surprisingly, fertility was not significantly reduced in many cases, even when the inversion was quite large. This lack of underdominance is almost certainly due to suppressed recombination in inversion heterozygotes, a phenomenon previously observed in Drosophila. In the large sample of third-chromosome inversions, the degree of underdominance depends far more on the position of breakpoints than on the inversion's length. Analysis of these positions shows that this chromosome has a pair of "sensitive sites" near cytological divisions 68 and 92: these sites appear to reduce recombination in a heterozygous inversion whose breakpoints are nearby. There may also be "sensitive sites" near divisions 31 and 49 on the second chromosome. Such sites may be important in initiating synapsis. Because many pericentric inversions do not reduce the fertility of heterozygotes, we conclude that the observed fixation or polymorphism of such rearrangements in nature does not imply genetic drift in very small populations.
3
Crow, Taylor, James Ta, Saghi Nojoomi, M. Rocío Aguilar-Rangel, Jorge Vladimir Torres Rodríguez, Daniel Gates, Rubén Rellán-Álvarez, Ruairidh Sawers, and Daniel Runcie. "Gene regulatory effects of a large chromosomal inversion in highland maize." PLOS Genetics 16, no. 12 (December 3, 2020): e1009213. http://dx.doi.org/10.1371/journal.pgen.1009213.
Full textAbstract:
Chromosomal inversions play an important role in local adaptation. Inversions can capture multiple locally adaptive functional variants in a linked block by repressing recombination. However, this recombination suppression makes it difficult to identify the genetic mechanisms underlying an inversion’s role in adaptation. In this study, we used large-scale transcriptomic data to dissect the functional importance of a 13 Mb inversion locus (Inv4m) found almost exclusively in highland populations of maize (Zea mays ssp. mays). Inv4m was introgressed into highland maize from the wild relative Zea mays ssp. mexicana, also present in the highlands of Mexico, and is thought to be important for the adaptation of these populations to cultivation in highland environments. However, the specific genetic variants and traits that underlie this adaptation are not known. We created two families segregating for the standard and inverted haplotypes of Inv4m in a common genetic background and measured gene expression effects associated with the inversion across 9 tissues in two experimental conditions. With these data, we quantified both the global transcriptomic effects of the highland Inv4m haplotype, and the local cis-regulatory variation present within the locus. We found diverse physiological effects of Inv4m across the 9 tissues, including a strong effect on the expression of genes involved in photosynthesis and chloroplast physiology. Although we could not confidently identify the causal alleles within Inv4m, this research accelerates progress towards understanding this inversion and will guide future research on these important genomic features.
4
Vantassel, Joseph P., and Brady R. Cox. "SWinvert: a workflow for performing rigorous 1-D surface wave inversions." Geophysical Journal International 224, no. 2 (September 9, 2020): 1141–56. http://dx.doi.org/10.1093/gji/ggaa426.
Full textAbstract:
SUMMARY SWinvert is a workflow developed at The University of Texas at Austin for the inversion of surface wave dispersion data. SWinvert encourages analysts to investigate inversion uncertainty and non-uniqueness in shear wave velocity (Vs) by providing a systematic procedure and specific actionable recommendations for surface wave inversion. In particular, the workflow encourages the use of multiple layering parametrizations to address the inversion's non-uniqueness, multiple global searches for each parametrization to address the inverse problem's non-linearity and quantification of Vs uncertainty in the resulting profiles. While the workflow uses the Dinver module of the popular open-source Geopsy software as its inversion engine, the principles presented are of relevance to analysts using other inversion programs. To illustrate the effectiveness of the SWinvert workflow and to develop a set of benchmarks for use in future surface wave inversion studies, synthetic experimental dispersion data for 12 subsurface models of varying complexity are inverted. While the effects of inversion uncertainty and non-uniqueness are shown to be minimal for simple subsurface models characterized by broad-band dispersion data, these effects cannot be ignored in the Vs profiles derived for more complex models with band-limited dispersion data. To encourage adoption of the SWinvert workflow, an open-source Python package (SWprepost), for pre- and post-processing of surface wave inversion data, and an application on the DesignSafe-Cyberinfrastructure (SWbatch), for performing batch-style surface wave inversions with Dinver using high-performance computing, have been developed and released in conjunction with this work. The SWinvert workflow is shown to provide a methodical procedure and a powerful set of tools for performing rigorous surface wave inversions and quantifying the uncertainty in the resulting Vs profiles.
5
Mecate, Danielle, Rod Handy, Leon Pahler, Darrah Sleeth, Joemy Ramsay, and Camie Schaefer. "Temperature Inversion and Ultrafine Particulate/Near Ultrafine Particulate Matter Concentrations in the Salt Lake Valley." Technium: Romanian Journal of Applied Sciences and Technology 2, no. 7 (January 5, 2021): 422–35. http://dx.doi.org/10.47577/technium.v2i7.2263.
Full textAbstract:
Ultrafine particulate (UFP) matter exposures are associated with negative health outcomes. UFPs (<100nm) and near UFP (NUFP) matter (4.5nm - 250nm) are trapped by the bowl-like geography of the Salt Lake Valley causing winter inversions (i.e., trapped particulate matter (PM)). Enmont PUFP C100 and Grimm 1.109 particle counters were used to define NUFP concentrations during inversion (n=5) and non-inversion (n=5) days at 7 sites. NUFP concentrations served as a proxy for the UFP fraction. NUFP concentrations were log-transformed and multivariable mixed effects linear regression models determined if NUFP concentration differed between inversion and non-inversion or by length of inversion. Difference in fraction NUFP was also analyzed. The mean NUFP concentration was 1.49-fold higher during inversions (95% CI 1.11–2.02), whereas the fraction declined by 0.22 (95% CI -0.31– -0.13). Increased NUFP concentrations during inversions may lead to increased adverse health outcomes. These findings have serious implications for inversion-prone regions.
6
Mecate, Danielle, Rod Handy, Leon Pahler, Darrah Sleeth, Joemy Ramsay, and Camie Schaefer. "Temperature Inversion and Ultrafine Particulate/Near Ultrafine Particulate Matter Concentrations in the Salt Lake Valley." Technium: Romanian Journal of Applied Sciences and Technology 2, no. 7 (January 5, 2021): 422–35. http://dx.doi.org/10.47577/technium.v2i7.2263.
Full textAbstract:
Ultrafine particulate (UFP) matter exposures are associated with negative health outcomes. UFPs (<100nm) and near UFP (NUFP) matter (4.5nm - 250nm) are trapped by the bowl-like geography of the Salt Lake Valley causing winter inversions (i.e., trapped particulate matter (PM)). Enmont PUFP C100 and Grimm 1.109 particle counters were used to define NUFP concentrations during inversion (n=5) and non-inversion (n=5) days at 7 sites. NUFP concentrations served as a proxy for the UFP fraction. NUFP concentrations were log-transformed and multivariable mixed effects linear regression models determined if NUFP concentration differed between inversion and non-inversion or by length of inversion. Difference in fraction NUFP was also analyzed. The mean NUFP concentration was 1.49-fold higher during inversions (95% CI 1.11–2.02), whereas the fraction declined by 0.22 (95% CI -0.31– -0.13). Increased NUFP concentrations during inversions may lead to increased adverse health outcomes. These findings have serious implications for inversion-prone regions.
7
Miesel, L., A. Segall, and J. R. Roth. "Construction of chromosomal rearrangements in Salmonella by transduction: inversions of non-permissive segments are not lethal." Genetics 137, no. 4 (August 1, 1994): 919–32. http://dx.doi.org/10.1093/genetics/137.4.919.
Full textAbstract:
Abstract Homologous sequences placed in inverse order at particular separated sites in the bacterial chromosome (termed "permissive") can recombine to form an inversion of the intervening chromosome segment. When the same repeated sequences flank other chromosome segments ("non-permissive"), recombination occurs but the expected inversion rearrangement is not found among the products. The failure to recover inversions of non-permissive chromosomal segments could be due to lethal effects of the final rearrangement. Alternatively, local chromosomal features might pose barriers to reciprocal exchanges between sequences at particular sites and could thereby prevent formation of inversions of the region between such sites. To distinguish between these two possibilities, we have constructed inversions of two non-permissive intervals by means of phage P22-mediated transduction crosses. These crosses generate inversions by simultaneous incorporation of two transduced fragments, each with a sequence that forms one join-point of the final inversion. We constructed inversions of the non-permissive intervals trp ('34) to his ('42) and his ('42) to cysA ('50). Strains with the constructed inversions are viable and grow normally. These results show that our previous failure to detect formation of these inversions by recombination between chromosomal sequences was not due to lethal effects of the final rearrangement. We infer that the "non-permissive" character of some chromosomal segments reflects the inability of the recombination system to perform the needed exchanges between inverse order sequences at particular sites. Apparently these mechanistic problems were circumvented by the transductional method used here to direct inversion formation.
8
Smith, Craig M., and Eric D. Skyllingstad. "Effects of Inversion Height and Surface Heat Flux on Downslope Windstorms." Monthly Weather Review 139, no. 12 (December 1, 2011): 3750–64. http://dx.doi.org/10.1175/2011mwr3619.1.
Full textAbstract:
Abstract Simulations are presented focusing on the role of temperature inversions in controlling the formation and strength of downslope wind storms. Three mechanisms are examined depending on the relative height of the inversion with respect to the mountain and the stability of vertically propagating mountain waves. For low-level inversions, flows are generated that closely resemble a reduced gravity shallow water hydraulic response with a large vertical displacement of the inversion on the lee side of the mountain. For higher-level inversion cases, simulated flows more closely followed a stratified hydraulic behavior with the inversion acting as a rigid reflective lid. In the third mechanism, downslope winds were forced by a self-induced critical layer located below the inversion height. The presence of the inversion in this case had little effect on the resulting downslope winds. Observations made on the Falkland Islands show that downslope windstorms may preferentially occur in early morning even without synoptic-scale changes in atmospheric structure. Most windstorms on the Falkland Islands generally have a short jet length; rare, longer jet length storms typically occur in conjunction with a strong low-level inversion. Idealized numerical experiments tend to produce a similar response depending on the presence of strong low-level inversion and surface cooling. Results suggest that surface heating can have significant control on the flow response by reducing the low-level inversion strength, or by changing the stratification and wind velocity below the inversion, thereby preventing a strong downslope windstorm.
9
Werle, Sean F., Ed Klekowski, and Douglas G. Smith. "Inversion polymorphism in a Connecticut River Axarus species (Diptera: Chironomidae): biometric effects of a triple inversion heterozygote." Canadian Journal of Zoology 82, no. 1 (January 1, 2004): 118–29. http://dx.doi.org/10.1139/z03-227.
Full textAbstract:
The authors sampled three spatially isolated populations of a chironomid midge in the genus Axarus living in the Connecticut River both early and late in the larval life cycle of one generation. Larvae were scored for both length and inversion frequency using the polytene chromosomes from salivary gland cells. We found polymorphism for four paracentric inversions. Inversion C1–6 exhibits a geographic cline, increasing in frequency with increasing latitude but remaining stable over time. Also stable over time were two other paracentric inversions designated A1–5 and F13–20, which were present at similar frequencies in all populations. None of these inversions was associated with larval length. A complex triple inversion designated G2–7 was significantly correlated with decreased larval length and also exhibited a significant increase in frequency (within one cohort) in the two more northerly populations. We propose that this increase is due to size-selective predation eliminating larger larvae.
10
Hill, C. W., and J. A. Gray. "Effects of chromosomal inversion on cell fitness in Escherichia coli K-12." Genetics 119, no. 4 (August 1, 1988): 771–78. http://dx.doi.org/10.1093/genetics/119.4.771.
Full textAbstract:
Abstract In an effort to learn what factors might mitigate the establishment of Escherichia coli variants bearing major chromosomal rearrangements, we have examined the effects on cell growth of two inversions between rRNA operons. One of these inversions, IN(rrnD-rrnE), had been propagated in a commonly used subline of E. coli K-12 for approximately 30 yr before its discovery, a fact that illustrates the absence of obvious detrimental effects associated with the inversion. We found that culturing under conditions requiring repeated transition from stationary phase to rapid growth led to the replacement of IN(rrnD-rrnE) cells by cells that had undergone either of two types of additional chromosomal inversion: one type fully restored the wild-type order, while the other partially restored it. The partial reinversion was also between rrn operons, but it left a small transposition. The tendency for overgrowth by these revertants persisted through several rounds of periodic selection. In contrast, the other inversion, IN(rrnG-rrnE), was associated with severe, detrimental effects. The effects of IN(rrnG-rrnE) were also alleviated by full or partial reinversion. The probable relationship between the severity of the effects caused by the inversions and the degree of displacement of the replication origin is discussed. Spontaneous inversion events between rrn operons separated by 18% of the chromosome were estimated to occur at a frequency of roughly 10(-5). If extended to natural situations, the growth disadvantage together with the relatively high frequency of reinversion suggest that clones of cells with an inversion between these rrn operons would be readily overgrown by revertants.
Dissertations / Theses on the topic "Effetto inversione"
1
ORLANDI, ANDREA. "ACTION REPRESENTATION IN THE HUMAN BRAIN: ELECTROPHYSIOLOGICAL MARKERS AND NEUROFUNCTIONAL CORRELATES." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2019. http://hdl.handle.net/10281/241203.
Full textAbstract:
La presente tesi si propone di studiare i decorsi temporali e correlati neurali legati al riconoscimento del corpo e alla codifica dell’azione utilizzando studi elettrofisiologici e di neuroimaging. È stato dimostrato come la capacità di riconoscimento di un corpo diminuisca se osservato capovolto indicando di una perturbazione dei processi di elaborazione configurazionale. Nella presente tesi è stata indagata la relazione tra riconoscimento del corpo, orientamento e attenzione, utilizzando immagini di posture corporee e strutture di cubi in orientamento canonico o capovolto. È stato ipotizzato un effetto dell’inversione sulla percezione dei corpi, ma non dei cubi. L’inversione del corpo ha portato ad una elaborazione dello stimolo più lenta (N2 anteriore più tardiva) e ad un aumento della selezione attentiva (Selection Negativity e P300 più ampie) necessaria per riconoscerlo e classificarlo. La ricostruzione della sorgente (swLORETA) ha confermato un maggior reclutamento di regioni attentive prefrontali. Per i cubi non è stata riscontrata una modulazione di tali componenti per via della mancanza di un orientamento naturale. I risultati hanno indicato come il riconoscimento del corpo sia dipendente dall’orientamento.
Diversi studi hanno mostrato il coinvolgimento di regioni fronto-parieto-temporali durante l’osservazione di un’azione e l’effetto dell’expertise nel modulare l’attività di tali aree. In questo studio, lo sforzo muscolare è stato utilizzato come strumento per investigare l’effetto della pratica della danza sulla codifica dell’azione, ipotizzando una codifica maggiormente raffinata nei danzatori (vs. controlli). Gesti tecnici caratterizzati da sforzo lieve e intenso sono stati mostrati a danzatori e controlli durante un compito di immaginazione motoria. Nei danzatori sono stati riscontrati processi di elaborazione più rapidi (P2 posteriore precoce) e un coinvolgimento bilaterale della corteccia occipito-temporale (N2 posteriore e swLORETA). Gli esperti hanno anche mostrato un aumento della P300 anteriore e della Late Positivity (LP) parietale in risposta agli stimoli a sforzo intenso, indicando una codifica dell’azione più raffinata in virtù della conoscenza dei programmi motori. I controlli hanno mostrato una modulazione della LP occipitale dovuta ad un aumento dell’elaborazione delle informazioni cinematiche. La swLORETA ha indicato una maggiore attività nelle regioni visuomotorie nei danzatori, nelle regioni visive e prefrontali nei controlli. Durante il compito di immaginazione motoria è stata trovata una Anterior Negativity (AN) più ampia negli esperti. I movimenti a sforzo intenso hanno anche portato ad una AN più ampia nei controlli, mentre il risultato inverso è stato trovato nei danzatori. La swLORETA ha mostrato attività bilaterale nelle regioni visuomotorie e temporali nei danzatori e in regioni frontali superiori e mediali nei controlli. I risultati del secondo studio hanno suggerito una forte modulazione dei processi di rappresentazione dell’azione in base all’expertise acquisita e il contributo della corteccia occipito-temporale alla codifica dell’azione.
L’ultimo studio ha esplorato i correlati neurali della rappresentazione di aspetti temporali dell’azione. I volontari hanno giudicato la piacevolezza estetica di sequenze di danza riprodotte con accelerazione uniforme o variata, indicando una preferenza per le variazioni temporali. È stato ipotizzato un maggiore coinvolgimento di regioni occipito-temporali e fronto-centrali in funzione dell’accelerazione crescente. Le sequenze variate hanno attivato regioni corticali e sottocorticali, tra cui la corteccia occipito-temporale, aree premotorie e motorie supplementari, lobulo parietale inferiore, giro frontale inferiore, insula, talamo e putamen. I risultati hanno suggerito un forte effetto di risonanza motoria durante l’elaborazione di aspetti cinematici legati alle variazioni temporali.The present thesis aimed to investigate the time course and the neural substrates of body recognition and action representation using electrophysiological and neuroimaging studies. Previous evidence has shown that the presentation of a body in upside-down orientation resulted in decreased discrimination ability and increased N190 component, suggesting a disruption of configurational processing. In this thesis, the relationship between body recognition, orientation, and attention was assessed by presenting the participants with body postures and structures of cubes in either upright or inverted orientation. We predicted an effect of inversion on the perception of bodies but not cubes. The body inversion led to a slower stimulus processing (slower anterior N2) and enhanced attention allocation (larger Selection Negativity and P300) required to recognize and classify the target. Stronger recruitment of attention-related prefrontal regions was also found using swLORETA source reconstruction. No modulation of these components was shown for the cubes due to the lack of natural orientation. This first experiment provided evidence for an orientation-dependent recognition of the human body. Several studies have found the engagement of fronto-parieto-temporal regions in action perception, modulated as a function of expertise. Here, a dancer’s muscular effort was used as a tool to investigate the impact of ballet expertise on action representation. Compared to controls, a more refined and automatic effort encoding was expected in dancers due to their increased expertise with the repertoire of movement. Expert dancers and non-dancers were presented with effortful and effortless technical gestures and instructed to reproduce each of them mentally. A faster stimulus processing (faster posterior P2) and early bilateral engagement of the occipito-temporal cortex (OTC; posterior N2 and swLORETA) was found in dancers vs. controls during action observation. The experts also showed an increased anterior P300 and parietal Late Positivity (LP) in response to effortful than effortless steps. This was interpreted as an index of refined action coding due to their acquired motor knowledge. The non-experts only showed a modulation of the occipital LP likely due to enhanced processing of dance kinematics. The swLORETA indicated the recruitment of visuomotor regions in dancers, and visual and prefrontal areas in controls. During the motor imagery task a larger Anterior Negativity (AN) was found in experts compared to non-experts. Also, the effortful (vs. effortless) steps elicited a more negative AN in controls, while the opposite effect was found in ballet dancers. The swLORETA indicated bilateral recruitment of visuomotor and temporal areas in dancers and superior and medial frontal regions in controls. The evidence from the second study suggested a strong role of expertise in the modulation of the neural processes underlying action representation and an expertise-dependent contribution of the OTC to action coding during both observation and motor imagery. The final study of this thesis explored the neural correlates of action timing representation. The volunteers judged the aesthetical appraisal of videos depicting dance sequences reproduced with a uniform or varied acceleration, showing a preference for the varied version. Enhanced activity within OTC and fronto-central regions was expected as a function of increased acceleration changes. We found that the varied (vs. uniform) version of the sequences engaged a broader network of areas cortical and subcortical areas. The OTC, premotor and supplementary motor areas, inferior parietal lobule, inferior frontal gyrus, insula, thalamus, and putamen exhibited a crucial role in the representation of action timing. These results suggest a strong embodied response during the processing of dance kinematics as a function of time variation.
2
Thomas, Lisa M. "Expertise and the inversion effect." Thesis, University of Surrey, 2002. http://epubs.surrey.ac.uk/844088/.
Full textAbstract:
It has often been argued that the processing of faces is 'special' relative to the processing of other objects and there is much evidence in support of this notion. One source of evidence is the inversion effect, which occurs when faces presented upright are recognised significantly better than faces presented upside down. This effect of stimulus inversion has been shown to impair face recognition to a greater extent than for any other object class. It is this disproportionate effect that has been given as one source of evidence that face processing is special. However, other research has argued that effects of inversion can be found for non-face stimuli providing that there is sufficient development of expertise with them and that these stimuli can be defined by a common prototype. This thesis further explores this idea. Inversion effects were investigated for both prototypically and non-prototypically defined, abstract, chequerboard stimuli and compared with those for faces. When subjects learned to categorise chequerboard stimuli that were defined by a common prototype equal size inversion effects were found to those observed for faces. However, inversion effects were not observed for category training with multiple exemplars of chequerboard stimuli that were not defined by a common prototype. Together the findings are consistent with the idea that inversion effects are a general phenomenon resulting from the acquisition of category expertise with any prototype defined stimulus category. They undermine the inversion effect as a source of evidence for the specialness of face processing. Further, using a new Moving Windows technique, additional experiments investigated the underlying mechanisms responsible for the effects of inversion found for faces and chequerboards. These showed that the diagnostic image regions searched differ across the two stimulus classes. However, on the basis of the results, it is argued that the inversion effects found for both could result from impaired processing of second-order configural information.
3
Seidshazileh, Kazem. "Effect of interfacial characteristics on phase inversion." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0029/NQ63484.pdf.
Full text
4
Murali, Raghunath. "Scaling opportunities for bulk accumulation and inversion MOSFETs for gigascale integration." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/submitted/etd-02132004-173432/unrestricted/murali%5FRaghunath%5F405%5F.pdf.
Full textAbstract:
Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2004.Hess, Dennis, Committee Member; Meindl, James, Committee Chair; Allen, Phillip, Committee Member; Cressler, John, Committee Member; Davis, Jeffrey, Committee Member. Vita. Includes bibliographical references (leaves 108-119).
5
Ouloin, Martyrs. "Méthode d’inversion d’un Modèle de diffusion Mobile Immobile fractionnaire." Thesis, Avignon, 2012. http://www.theses.fr/2012AVIG0504/document.
Full textAbstract:
L’étude expérimentale du transport de soluté dans les milieux poreux montre des écarts à la loi de Fick. D’autre part, des progrès importants ont été accomplis sur le transport en milieu poreux, en supposant que les fluides (et les traceurs) en mouvement dans ces milieux sont arrêtés pendant des durées aléatoires. La matrice solide rend cette idée plausible. Nous étudions un modèle utilisant cette idée en l’associant à des durées d’immobilisation sans moyenne finie, en fait distribuées par des lois de Lévy. On arrive ainsi au modèle MIM fractionnaire, ou fractal.Ce modèle est une équation aux dérivées partielles pour la densité de traceur. Il équivaut à supposer que les particules de fluide et de traceur font des déplacements régis par un processus stochastique. Ce dernier est la limite hydrodynamique de marches au hasard fondées sur des déplacements convectifs, des sauts gaussiens, et des arrêts distribués suivant une loi de Lévy. Ces deux versions du même modèle donnent deux méthodes de simulation numérique.Nous montrons comment mettre en œuvre ces méthodes. Ceci a pour but la maîtrise d’outils de simulation, afin de comparer avec des données expérimentales pour savoir si ce modèle convient pour décrire le transport dans un milieu donné. Cette simulation, pour être efficace, nécessite la connaissance des paramètres du transport de soluté au sein du milieu donné. Ils sont difficilement mesurables et/ou identifiables en pratique. Donc, il faut pouvoir les estimer à partir de grandeurs qu’on sait mesurer directement, comme la densité d’un traceur. Pour cela, nous avons mis en place une méthode d’inversion qui permet d’extraire les paramètres du modèle MIM fractionnaire, à partir de données expérimentales. Cette méthode d’inversion est basée sur la transformation de Laplace. Elle utilise le lien entre les paramètres de transport du modèle MIM fractionnaire, et les dérivées de la transformée de Laplace des solutions de ce modèle. Ce lien est exact dans un milieu semi-infini, et seulement approché dans un milieu fini.Après avoir testé cette méthode en l’appliquant à des données numériques en essayant de retrouver leurs paramètres à "l’aveugle", nous l’appliquons à des données issues d’une expérience de traçage en milieu poreux insaturéAppealing models for mass transport in porous media assume that fluid and tracer particles can be trapped during random periods. Among them, the fractional version of the Mobile Immobile Model (f-MIM) was found to agree with several tracer test data recorded in environmental media.This model is equivalent to a stochastic process whose density probability function satisfies an advection-diffusion equation equipped with a supplementary time derivative, of non-integer order. The stochastic process is the hydrodynamic limit of random walks accumulating convective displacements, diffusive displacements, and stagnation steps of random duration distributed by a stable Lévy law having no finite average. Random walk and fractional differential equation provide complementary simulation methods.We describe that methods, in view of having tools for comparing the model with tracer test data consisting of time concentration curves. An other essential step in this direction is finding the four parameters of the fractional equation which make its solutions fit at best given sets of such data. Hence, we also present an inversion method adapted to the f-MIM. This method is based on Laplace transform. It exploits the link between model's parameters and Laplace transformed solutions to f-MIM equation. The link is exact in semi-infinite domains. After having checked inverse method's efficiency for numerical artificial data, we apply it to real tracer test data recorded in non-saturated porous sand
6
Civile, Ciro. "The face inversion effect and perceptual learning : features and configurations." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/13564.
Full textAbstract:
This thesis explores the causes of the face inversion effect, which is a substantial decrement in performance in recognising facial stimuli when they are presented upside down (Yin,1969). I will provide results from both behavioural and electrophysiological (EEG) experiments to aid in the analysis of this effect. Over the course of six chapters I summarise my work during the four years of my PhD, and propose an explanation of the face inversion effect that is based on the general mechanisms for learning that we also share with other animals. In Chapter 1 I describe and discuss some of the main theories of face inversion. Chapter 2 used behavioural and EEG techniques to test one of the most popular explanations of the face inversion effect proposed by Diamond and Carey (1986). They proposed that it is the disruption of the expertise needed to exploit configural information that leads to the inversion effect. The experiments reported in Chapter 2 were published as in the Proceedings of the 34th annual conference of the Cognitive Science Society. In Chapter 3 I explore other potential causes of the inversion effect confirming that not only configural information is involved, but also single feature orientation information plays an important part in the inversion effect. All the experiments included in Chapter 3 are part of a paper accepted for publication in the Quarterly Journal of Experimental Psychology. Chapter 4 of this thesis went on to attempt to answer the question of whether configural information is really necessary to obtain an inversion effect. All the experiments presented in Chapter 4 are part of a manuscript in preparation for submission to the Quarterly Journal of Experimental Psychology. Chapter 5 includes some of the most innovative experiments from my PhD work. In particular it offers some behavioural and electrophysiological evidence that shows that it is possible to apply an associative approach to face inversion. Chapter 5 is a key component of this thesis because on the one hand it explains the face inversion effect using general mechanisms of perceptual learning (MKM model). On the other hand it also shows that there seems to be something extra needed to explain face recognition entirely. All the experiments included in Chapter 5 were reported in a paper submitted to the Journal of Experimental Psychology; Animal Behaviour Processes. Finally in Chapter 6 I summarise the implications that this work will have for explanations of the face inversion effect and some of the general processes involved in face perception.
7
Hobiger, Manuel. "Polarisation des ondes de surface : caractérisation, inversion et application à l'étude de l'aléa sismique." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00577887.
Full textAbstract:
L'aléa sismique d'un site donné peut être largement influencé par des effets de site. Afin d'évaluer ces effets, la structure locale du sous-sol ainsi que les propriétés du champ d'onde doivent être étudiées. Les ondes de surface (ondes de Love et de Rayleigh) s'avèrent utiles, leurs propriétés (courbes de dispersion, ellipticité des ondes de Rayleigh) étant directement liées à la structure du sous-sol. Le paramètre clé pour l'identification du type d'onde est la polarisation. Dans la première partie de la thèse, de nouvelles méthodes pour l'estimation de paramètres de polarisation d'ondes de surface sont développées. Deux méthodes, DELFI et RayDec, estiment l'ellipticité des ondes de Rayleigh à partir d'enregistrements d'un seul capteur sismique. La troisième méthode, MUSIQUE, est basée sur la méthode MUSIC et utilise les enregistrements multi-composantes de réseaux sismiques afin de distinguer ondes de Love et ondes de Rayleigh et d'estimer leurs propriétés. Dans la deuxième partie de la thèse, une étude théorique de l'inversion de courbes d'ellipticité montre quelles parties de ces courbes véhiculent les informations importantes sur la structure du sol et comment l'inversion peut être améliorée. Le schéma d'inversion résultant est alors testé en l'appliquant à des données réelles mesurées pour 14 sites européens. Finalement, 22 séismes enregistrés par un réseau de capteurs dans la vallée de Santa Clara en Californie sont analysés par MUSIQUE. La répartition azimutale, les courbes de dispersion, la courbe d'ellipticité et les énergies des différents types d'ondes sont analysées et soulignent l'importance des ondes de surface diffractées dans le champ d'ondes enregistré.
8
Ng, Chun Wai. "On the inversion and accumulation layer mobilities in N-channel trench DMOSFETS /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202005%20NG.
Full text
9
Brown, Andrew Paul. "Synthetic titanomagnetite : the effect of ball-milling, maghemitization and inversion." Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388658.
Full text
10
Goodall, Harrison M. III. "The Effect of Inversion and Motor Expertise on Body Compatibility." Scholarship @ Claremont, 2016. http://scholarship.claremont.edu/pomona_theses/159.
Full textAbstract:
Previous studies have established that when a subject’s attention is directed to a specific body part, the subject is able to move that body part faster than a body part their attention was not drawn to. This is known as the body compatibility effect, and it has been shown that this effect only occurs when viewing upright images of the human body. In this study, we presented control subjects and expert acrobats with inverted and upright stimuli. We hypothesized that the amount of time the acrobats spent inverted would result in the acrobats exhibiting body compatibility effects for both upright and inverted stimuli. Compatibility effects were observed in the upright condition for both groups, but neither group exhibited any compatibility effects in the inverted position. Unexpectedly the acrobats responded significantly faster to incongruent trials compared to the control subjects, leading to the conclusion that there must be some form of priming occurring concurrently with the body compatibility task allowing the acrobats to respond faster than the control participants.
Books on the topic "Effetto inversione"
1
Bagheri, Mehran. Four-terminal MOSFET modeling including non-quasistatic and moderate inversion effects. Ann Arbor, MI: University Microfilms International, 1986.
Find full text
2
El Salvador, inversión en educación y crecimiento económico. Antiguo Cuscatlán, Dpto. de La Libertad, El Salvador: Universidad Dr. José Matías Delgado, Centro de Investigaciones en Ciencias y Humanidades, 2012.
Find full text
3
García, Alberto Vaquero. Inversión educativa y mercado de trabajo en Galicia: Un escenario de luces y sombras. Vigo: Universidade de Vigo, 2005.
Find full text
4
Encuentro Nacional por la Educación (1st 1993 Lima, Peru?). Educación, inversión para el desarrollo: I Encuentro Nacional por la Educación. [Lima?]: Instituto Peruano de Administración de Empresas, 1993.
Find full text
5
1972-, Felices Guillermo, and Inter-American Development Bank. Social Programs and Sustainable Development Department, eds. Inversión en la calidad de la educación pública en el Perú y su efecto sobre la fuerza de trabajo y la pobreza. Washington, D.C: Banco Interamericano de Desarrollo, Departamento de Programas Sociales y Desarrollo Sostenible, 1997.
Find full text
6
Clark, Andy. Strange Inversions. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199367511.003.0013.
Full textAbstract:
Strange inversions occur when things work in ways that turn received wisdom upside down. Hume offered a strangely inverted story about causation, and Darwin, about apparent design. Dennett suggests that a strange inversion also occurs when we project our own reactive complexes outward, painting our world with elusive properties like cuteness, sweetness, blueness, sexiness, funniness, and more. Such properties strike us as experiential causes, but they are (Dennett argues) really effects—a kind of shorthand for whole sets of reactive dispositions rooted in the nuts and bolts of human information processing. Understanding the nature and origins of that strange inversion, Dennett believes, is thus key to understanding the nature and origins of human experience itself. This paper examines this claim, paying special attention to recent formulations that link that strange inversion to the emerging vision of the brain as a Bayesian estimator, constantly seeking to predict the unfolding sensory barrage.
7
Thompson, Peter. About Face. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780199794607.003.0091.
Full textAbstract:
Inverting the eyes and the mouth in a smiling face renders the expression grotesque. However, when this image is itself rotated through 180 degrees, the grotesque expression is no longer apparent—the smiling expression returns. This illusion, first shown with the face of the then UK prime minister Margaret Thatcher, has been explained as showing the detrimental effects of inversion on configural or holistic processing of faces. This explanation is, however, not entirely satisfactory and the illusion is still not fully understood. Variants and relevant parameters of the effect are explored, as are related concepts of inversion, expression, and face perception.
8
Meriläinen, Lea, and Heli Paulasto. Embedded Inversion as an Angloversal. Edited by Markku Filppula, Juhani Klemola, and Devyani Sharma. Oxford University Press, 2014. http://dx.doi.org/10.1093/oxfordhb/9780199777716.013.26.
Full textAbstract:
This chapter discusses angloversals (i.e., similar nonstandard features) across L1 and L2 varieties and learner English with a special focus on embedded inversion (EI), with the aim of bringing together research into World Englishes and learner English. The chapter examines whether EI is similar in L1, L2, and learner Englishes and, hence, indicative of a development that is taking place in Englishes throughout the world. The use of EI is analysed in terms of the emerging commonalities as well as variety-specific or L1-specific uses. The findings show that EI may be found in different types of Englishes, but apparent similarities also conceal patterns of contact-induced variation. This is interpreted as evidence for the interplay between universal tendencies and transfer effects.
9
Effects of adhesive spray and prewrap on taped ankle inversion before and after exercise. 1992.
Find full text
10
Dunlop, Storm. 1. The atmosphere. Oxford University Press, 2017. http://dx.doi.org/10.1093/actrade/9780199571314.003.0001.
Full textAbstract:
‘The atmosphere’ describes the different layers of the atmosphere and the boundaries between them—troposphere, tropopause, stratosphere, mesopause, mesosphere, ionosphere, and thermosphere—and explains why temperature generally declines with increased altitude: a decrease in pressure causes a parcel of air to expand and cool. The change in temperature with altitude is known as the lapse rate and any decrease or increase in lapse rate is known as an inversion. The inversion at the top of the troposphere is a major feature, always present in the atmosphere. The measuring and charting of atmospheric pressure using barometers is described along with the composition of the atmosphere and the greenhouse effect is explained.
Book chapters on the topic "Effetto inversione"
1
Singh, Gurvachan. "Inversion Effects." In Encyclopedia of Animal Cognition and Behavior, 1–4. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-319-47829-6_806-1.
Full text
2
Singh, Gurvachan. "Inversion Effects." In Encyclopedia of Animal Cognition and Behavior, 3677–80. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-319-55065-7_806.
Full text
3
Ellenbroek, Bart, Alfonso Abizaid, Shimon Amir, Martina de Zwaan, Sarah Parylak, Pietro Cottone, Eric P. Zorrilla, et al. "Effect Inversion." In Encyclopedia of Psychopharmacology, 456. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-540-68706-1_1106.
Full text
4
First, Michael B., Elizabeth Spencer, Elizabeth Spencer, Sander Begeer, Brynn Thomas, Danielle Geno Kent, Maria Fusaro, et al. "Inversion Effect." In Encyclopedia of Autism Spectrum Disorders, 1653. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4419-1698-3_100752.
Full text
5
Ward, Tracey, Raphael Bernier, Cora Mukerji, Danielle Perszyk, James C. McPartland, Ellen Johnson, Susan Faja, et al. "Facial Inversion Effect." In Encyclopedia of Autism Spectrum Disorders, 1227. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4419-1698-3_100577.
Full text
6
Chaudhry, Amit. "Nanoscale Effects: Inversion Layer Quantization." In Fundamentals of Nanoscaled Field Effect Transistors, 37–60. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-6822-6_3.
Full text
7
Porter, Michael B., Sergio M. Jesus, Yann Stéphan, Xavier Démoulin, and Emanuel Coelho. "Tidal Effects on Source Inversion." In Experimental Acoustic Inversion Methods for Exploration of the Shallow Water Environment, 107–23. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-011-4112-3_7.
Full text
8
Smith, J. F., O. Diachok, R. Heitmeyer, and E. Livingston. "Stochastic Bathymetric Effects on Matched Field Processing." In Full Field Inversion Methods in Ocean and Seismo-Acoustics, 273–78. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-015-8476-0_44.
Full text
9
Miller, Mary Frances, and Marianne Barabasz. "Effects of Restricted Environmental Stimulation on Inversion Perception." In Recent Research in Psychology, 105–12. New York, NY: Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4613-9701-4_8.
Full text
10
Kawaji, S., and J. Wakabayashi. "Quantum Galvanomagnetic Properties of n-Type Inversion Layers on Si(100) Mosfet." In Quantum Hall Effect: A Perspective, 127–34. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-010-9709-3_10.
Full textConference papers on the topic "Effetto inversione"
1
Klemm, H., and H. Wagner. "Effects of Wavelet Uncertainty on Seismic Inversions." In First EAGE Conference on Seismic Inversion. European Association of Geoscientists & Engineers, 2020. http://dx.doi.org/10.3997/2214-4609.202037007.
Full text
2
Kuroda, H., M. Katsuragawa, K. Muroo, and Y. Tanaka. "Population Inversions between n = 5, 4, 3 and 2 levels of He-like Al Plasma Observed by Spatially Resolved X-ray Spectroscopy." In Short Wavelength Coherent Radiation: Generation and Applications. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/swcr.1988.swlos67.
Full textAbstract:
Population inversions between N=5, 4 and 3 levels are observed in a 100ps Laser-produced plasma. As a results/ XUV of 42Å~46 Å, 130Å and 305Å corresponding to 3-2, 4-3 and 5-4 transitions are observed experimentally. Relative population densities are determined by measuring the intensities of spatially resolved X-ray line spectra of 6.635Å, 6.314Å and 6.18Å corresponding to the 3-1, 4-1 and 5- 1 transitions, which are normalized by their oscillation strengths. Careful absorption was paid to rule out the effect of reabsorption. Populations were inverted at the region located 50~100μm from the target surface. Laser light was focused into 50μm diameter and amount of inversion was clearly increased when laser intensities was increased. As to the 5-4 and 4-3 inversion, similar result was observed in silicon target, however inversion between n=3 and 2 was not confirmed at these laser intensities. XUV gains are very promising especially as to 5 4 and 4-3 transitions in both target.
3
Aristimuno, J., J. Fernandez-Concheso, and Y. Del Moro. "Effect of Simultaneous and Facies-based inversions on Geomechanical properties estimations in an Unconventional Reservoir." In Second EAGE Conference on Seismic Inversion. European Association of Geoscientists & Engineers, 2022. http://dx.doi.org/10.3997/2214-4609.202229033.
Full text
4
Lehn, Waldemar H. "Superior mirages from optical ducts with gravity waves." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.thz2.
Full textAbstract:
Superior mirages of great complexity are frequently seen under arctic temperature inversions. A mirage group observed at Resolute Bay, Canada, over a horizontal range crossing ~70 km of sea ice shows clearly identifiable sequences of five simultaneous images, alternating between erect and inverted. The marked similarity between these images and the solar Novaya Zemlya effect1 suggests that optical ducting is the underlying phenomenon. Two ducting models are compared. The first assumes that the inversion forms a short duct along the line of sight. If duct length and atmosphere beyond the duct are specified, the temperature profile within the duct can be computed directly, using a ray steering algorithm, and the observed image can be simulated arbitrarily closely. The duct of the second model is based on a shear-free three-layer atmosphere,2 in which the middle layer supports gravity waves propagating along the line of sight. The waves are represented as isothermal surfaces of sinusoidal form, whose amplitude decreases with vertical distance from the inversion. The waves permit some rays to escape and transmit image information across the inversion. An analysis of imaging properties as a function of wave parameters indicates whether this model is capable of generating the observed fivefold images.
5
Li, H. W., J. Gazengel, N. P. Xuan, J. L. Ferrier, J. P. Bourdin, and G. Rivoire. "Optical Image Processing : Spatial Filtering by Photorefractive Materials." In Photorefractive Materials, Effects, and Devices II. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/pmed.1990.jp5.
Full textAbstract:
The nonlinearities of photorefractive materials such as Fe:LiNbO3, BSO, BGO,… are used to filter the Fourier spectrum of an object. Image processing techniques, such as contrast inversion or contrast enhancement of amplitude objects, and phase objects visualization are thus obtained with simple optical devices and low power cw lasers.
6
Clegg, Nigel Mark, Ana Beatriz Domingues, Rosamary Ameneiro Paredes, Nicki Gardner, Vanessa Mendoza Barrón, Eliot Rowden, and David Marchant. "Mapping Complex Geological Surface Morphology During Landing Operations Using 3-D Inversion of Ultra-Deep Electromagnetic LWD Data." In Offshore Technology Conference. OTC, 2021. http://dx.doi.org/10.4043/31216-ms.
Full textAbstract:
Abstract Ultra-deep azimuthal electromagnetic (EM) logging-while-drilling (LWD) tools are frequently used during landing operations for early detection of the reservoir top. This enables alterations to the well plan before the reservoir is penetrated. To date, this approach has relied on one-dimensional (1-D) inversions that accounts only for changes in resistivity above or below the wellbore. When geology is complex, resulting in lateral changes in resistivity, 3-D inversion of EM data is required to provide increased reservoir understanding. This paper presents a case study from offshore Brazil, targeting a turbidite deposit. A complex reservoir surface was expected, as defined by seismic data for the area. Although top structure rugosity and lateral position uncertainty had been incorporated into the prognosis, the impact of surface topography on inversion results while landing was not anticipated. During real-time operations, 1-D EM inversion was used along with correlation of shallow LWD data to map the reservoir top. It was clear the geology was more complicated than depicted by the 2-D geological model constructed from the 1-D inversion and that lateral changes in surface morphology may be occurring. Post well a 3-D inversion of the EM data revealed the 3-D geological structure. During the initial approach, the 1-D inversion indicated that relief of the reservoir top was more exaggerated than expected; the well intersected a sharp peak prior to approaching the target zone. The misfit on the 1-D inversion indicated there was potential for lateral variation in resistivity, influencing the 1-D results; lateral changes can produce artefacts that obscure the subsurface structure. This was confirmed after drilling with analysis of ultra-deep azimuthal resistivity images, indicating significant changes in resistivity to the left and right of the borehole. A 3-D EM inversion was run to depict these complex subsurface geometries. The 1-D inversion results were better understood post-drill with the 3-D inversion results, which show a high point in the reservoir top to the side of the wellbore that was drilled past, but not penetrated by, the well. This high-resistivity zone had a negative effect on the 1-D inversion results and made delineation of the reservoir top difficult. Understanding lateral variations in formation and fluid boundaries can improve well placement and reservoir understanding. This knowledge can impact landing scenarios and well placement within the reservoir. Three-dimensional inversion of ultra-deep azimuthal EM LWD data in real time will provide a clearer picture of the position of resistivity changes while drilling. This will enable decisions to be made that affect the azimuthal position of a well, as well as its vertical position during drilling, thereby facilitating optimal well placement, even in complex geological environments or for infill wells requiring precise well placement.
7
Zhang, Mo, Shoubo Wang, Ram S. Mohan, Ovadia Shoham, and Haijing Gao. "Shear Effects on Phase Inversion in Oil-Water Flow." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52076.
Full textAbstract:
Oil-water dispersed flow, in which one of the phases either water or oil is dispersed into the other phase, which is the continuous phase, occurs commonly in Petroleum Industry during the production and transportation of crudes. Phase inversion occurs when the dispersed phase grows into the continuous phase and the continuous phase becomes the dispersed phase caused by changes in the composition, interfacial properties and other factors. Production equipment, such as pumps and chokes, generate shear in oil-water mixture flow, which has a strong effect on phase inversion phenomena. In this study, based on the newly acquired data on a gear pump, the relationship between phase inversion region and shear intensity are discussed and the limitation of current phase inversion prediction model is presented.
8
Savage, C. M., and M. Lindberg. "Steady-state population Inversion via quantized fields." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1988. http://dx.doi.org/10.1364/oam.1988.ms8.
Full textAbstract:
Placing an optical cavity around a two-level atom modifies the electromagnetic vacuum to which it couples. Effects such as inhibited and enhanced spontaneous emission are known to result. Recently one of us predicted a new nonclassical effect of vacuum engineering.1 A two-level transition may be laser driven into an inverted steady state. Semiclassical theory forbids this fully quantum mechanical result. Unlike squeezing and antibunching, this inversion is not a property of the linearized quantum fluctuations. We present numerical and analytical results which clarify the physics of the inversion. The maximum inversion possible is determined. We attempt to identify obstacles to the experimental realization of steady-state inversion. Multiple atoms and multiple cavity modes do not destroy the effect. A significant difficulty appears to be localizing the atoms at the cavity beamwaist until they reach steady state. The inversion may be observed via fluorescence changes as the cavity is blocked and unblocked or via the presence of a fluoresence maximum as a function of the driving field intensity.
9
René, R. M., and Ki Young Kim. "Effects of Intra‐Inversion Filtering on the Accuracy of UXO Magnetic Dipole Inversions Using Standardized Test Site Data." In Symposium on the Application of Geophysics to Engineering and Environmental Problems 2007. Environment and Engineering Geophysical Society, 2007. http://dx.doi.org/10.4133/1.2924658.
Full text
10
René, R. M., and Ki Young Kim. "Effects Of Intra-Inversion Filtering On The Accuracy Of Uxo Magnetic Dipole Inversions Using Standardized Test Site Data." In 20th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems. European Association of Geoscientists & Engineers, 2007. http://dx.doi.org/10.3997/2214-4609-pdb.179.01495-1506.
Full textReports on the topic "Effetto inversione"
1
Martinez Ballarin, Roberto. Evidence of Dopant-Type Inversion and Other Radiation Damage Effects of the CDF Silicon Detectors. Office of Scientific and Technical Information (OSTI), January 2011. http://dx.doi.org/10.2172/1249484.
Full text
2
Martinez-Ballarin, Roberto. Evidence of Dopant Type-Inversion and Other Radiation Damage Effects of the CDF Silicon Detectors. Office of Scientific and Technical Information (OSTI), June 2010. http://dx.doi.org/10.2172/1151636.
Full text
3
Chamberlin, Danielle Russell. Effect of uniaxial stress on gallium, beryllium, and copper-doped germanium hole population inversion lasers. Office of Scientific and Technical Information (OSTI), May 1998. http://dx.doi.org/10.2172/674711.
Full text
4
Liou, Yuei-An. Retrieving Ionospheric Electron Density Distribution With COSMIC Occultations: An Analysis of the Effects of Geometric and Mathematical Delays on TEC Inversions From GPS/MET Occultation Data. Fort Belvoir, VA: Defense Technical Information Center, August 2001. http://dx.doi.org/10.21236/ada627499.
Full text
5
Monetary Policy Report - January 2022. Banco de la República, March 2022. http://dx.doi.org/10.32468/inf-pol-mont-eng.tr1-2022.
Full textAbstract:
Macroeconomic summary Several factors contributed to an increase in projected inflation on the forecast horizon, keeping it above the target rate. These included inflation in December that surpassed expectations (5.62%), indexation to higher inflation rates for various baskets in the consumer price index (CPI), a significant real increase in the legal minimum wage, persistent external and domestic inflationary supply shocks, and heightened exchange rate pressures. The CPI for foods was affected by the persistence of external and domestic supply shocks and was the most significant contributor to unexpectedly high inflation in the fourth quarter. Price adjustments for fuels and certain utilities can explain the acceleration in inflation for regulated items, which was more significant than anticipated. Prices in the CPI for goods excluding food and regulated items also rose more than expected. This was partly due to a smaller effect on prices from the national government’s VAT-free day than anticipated by the technical staff and more persistent external pressures, including via peso depreciation. By contrast, the CPI for services excluding food and regulated items accelerated less than expected, partly reflecting strong competition in the communications sector. This was the only major CPI basket for which prices increased below the target inflation rate. The technical staff revised its inflation forecast upward in response to certain external shocks (prices, costs, and depreciation) and domestic shocks (e.g., on meat products) that were stronger and more persistent than anticipated in the previous report. Observed inflation and a real increase in the legal minimum wage also exceeded expectations, which would boost inflation by affecting price indexation, labor costs, and inflation expectations. The technical staff now expects year-end headline inflation of 4.3% in 2022 and 3.4% in 2023; core inflation is projected to be 4.5% and 3.6%, respectively. These forecasts consider the lapse of certain price relief measures associated with the COVID-19 health emergency, which would contribute to temporarily keeping inflation above the target on the forecast horizon. It is important to note that these estimates continue to contain a significant degree of uncertainty, mainly related to the development of external and domestic supply shocks and their ultimate effects on prices. Other contributing factors include high price volatility and measurement uncertainty related to the extension of Colombia’s health emergency and tax relief measures (such as the VAT-free days) associated with the Social Investment Law (Ley de Inversión Social). The as-yet uncertain magnitude of the effects of a recent real increase in the legal minimum wage (that was high by historical standards) and high observed and expected inflation, are additional factors weighing on the overall uncertainty of the estimates in this report. The size of excess productive capacity remaining in the economy and the degree to which it is closing are also uncertain, as the evolution of the pandemic continues to represent a significant forecast risk. margin, could be less dynamic than expected. And the normalization of monetary policy in the United States could come more quickly than projected in this report, which could negatively affect international financing costs. Finally, there remains a significant degree of uncertainty related to the duration of supply chocks and the degree to which macroeconomic and political conditions could negatively affect the recovery in investment. The technical staff revised its GDP growth projection for 2022 from 4.7% to 4.3% (Graph 1.3). This revision accounts for the likelihood that a larger portion of the recent positive dynamic in private consumption would be transitory than previously expected. This estimate also contemplates less dynamic investment behavior than forecast in the previous report amid less favorable financial conditions and a highly uncertain investment environment. Third-quarter GDP growth (12.9%), which was similar to projections from the October report, and the fourth-quarter growth forecast (8.7%) reflect a positive consumption trend, which has been revised upward. This dynamic has been driven by both public and private spending. Investment growth, meanwhile, has been weaker than forecast. Available fourth-quarter data suggest that consumption spending for the period would have exceeded estimates from October, thanks to three consecutive months that included VAT-free days, a relatively low COVID-19 caseload, and mobility indicators similar to their pre-pandemic levels. By contrast, the most recently available figures on new housing developments and machinery and equipment imports suggest that investment, while continuing to rise, is growing at a slower rate than anticipated in the previous report. The trade deficit is expected to have widened, as imports would have grown at a high level and outpaced exports. Given the above, the technical staff now expects fourth-quarter economic growth of 8.7%, with overall growth for 2021 of 9.9%. Several factors should continue to contribute to output recovery in 2022, though some of these may be less significant than previously forecast. International financial conditions are expected to be less favorable, though external demand should continue to recover and terms of trade continue to increase amid higher projected oil prices. Lower unemployment rates and subsequent positive effects on household income, despite increased inflation, would also boost output recovery, as would progress in the national vaccination campaign. The technical staff expects that the conditions that have favored recent high levels of consumption would be, in large part, transitory. Consumption spending is expected to grow at a slower rate in 2022. Gross fixed capital formation (GFCF) would continue to recover, approaching its pre-pandemic level, though at a slower rate than anticipated in the previous report. This would be due to lower observed GFCF levels and the potential impact of political and fiscal uncertainty. Meanwhile, the policy interest rate would be less expansionary as the process of monetary policy normalization continues. Given the above, growth in 2022 is forecast to decelerate to 4.3% (previously 4.7%). In 2023, that figure (3.1%) is projected to converge to levels closer to the potential growth rate. In this case, excess productive capacity would be expected to tighten at a similar rate as projected in the previous report. The trade deficit would tighten more than previously projected on the forecast horizon, due to expectations of an improved export dynamic and moderation in imports. The growth forecast for 2022 considers a low basis of comparison from the first half of 2021. However, there remain significant downside risks to this forecast. The current projection does not, for example, account for any additional effects on economic activity resulting from further waves of COVID-19. High private consumption levels, which have already surpassed pre-pandemic levels by a large margin, could be less dynamic than expected. And the normalization of monetary policy in the United States could come more quickly than projected in this report, which could negatively affect international financing costs. Finally, there remains a significant degree of uncertainty related to the duration of supply chocks and the degree to which macroeconomic and political conditions could negatively affect the recovery in investment. External demand for Colombian goods and services should continue to recover amid significant global inflation pressures, high oil prices, and less favorable international financial conditions than those estimated in October. Economic activity among Colombia’s major trade partners recovered in 2021 amid countries reopening and ample international liquidity. However, that growth has been somewhat restricted by global supply chain disruptions and new outbreaks of COVID-19. The technical staff has revised its growth forecast for Colombia’s main trade partners from 6.3% to 6.9% for 2021, and from 3.4% to 3.3% for 2022; trade partner economies are expected to grow 2.6% in 2023. Colombia’s annual terms of trade increased in 2021, largely on higher oil, coffee, and coal prices. This improvement came despite increased prices for goods and services imports. The expected oil price trajectory has been revised upward, partly to supply restrictions and lagging investment in the sector that would offset reduced growth forecasts in some major economies. Elevated freight and raw materials costs and supply chain disruptions continue to affect global goods production, and have led to increases in global prices. Coupled with the recovery in global demand, this has put upward pressure on external inflation. Several emerging market economies have continued to normalize monetary policy in this context. Meanwhile, in the United States, the Federal Reserve has anticipated an end to its asset buying program. U.S. inflation in December (7.0%) was again surprisingly high and market average inflation forecasts for 2022 have increased. The Fed is expected to increase its policy rate during the first quarter of 2022, with quarterly increases anticipated over the rest of the year. For its part, Colombia’s sovereign risk premium has increased and is forecast to remain on a higher path, to levels above the 15-year-average, on the forecast horizon. This would be partly due to the effects of a less expansionary monetary policy in the United States and the accumulation of macroeconomic imbalances in Colombia. Given the above, international financial conditions are projected to be less favorable than anticipated in the October report. The increase in Colombia’s external financing costs could be more significant if upward pressures on inflation in the United States persist and monetary policy is normalized more quickly than contemplated in this report. As detailed in Section 2.3, uncertainty surrounding international financial conditions continues to be unusually high. Along with other considerations, recent concerns over the potential effects of new COVID-19 variants, the persistence of global supply chain disruptions, energy crises in certain countries, growing geopolitical tensions, and a more significant deceleration in China are all factors underlying this uncertainty. The changing macroeconomic environment toward greater inflation and unanchoring risks on inflation expectations imply a reduction in the space available for monetary policy stimulus. Recovery in domestic demand and a reduction in excess productive capacity have come in line with the technical staff’s expectations from the October report. Some upside risks to inflation have materialized, while medium-term inflation expectations have increased and are above the 3% target. Monetary policy remains expansionary. Significant global inflationary pressures and the unexpected increase in the CPI in December point to more persistent effects from recent supply shocks. Core inflation is trending upward, but remains below the 3% target. Headline and core inflation projections have increased on the forecast horizon and are above the target rate through the end of 2023. Meanwhile, the expected dynamism of domestic demand would be in line with low levels of excess productive capacity. An accumulation of macroeconomic imbalances in Colombia and the increased likelihood of a faster normalization of monetary policy in the United States would put upward pressure on sovereign risk perceptions in a more persistent manner, with implications for the exchange rate and the natural rate of interest. Persistent disruptions to international supply chains, a high real increase in the legal minimum wage, and the indexation of various baskets in the CPI to higher inflation rates could affect price expectations and push inflation above the target more persistently. These factors suggest that the space to maintain monetary stimulus has continued to diminish, though monetary policy remains expansionary. 1.2 Monetary policy decision Banco de la República’s board of directors (BDBR) in its meetings in December 2021 and January 2022 voted to continue normalizing monetary policy. The BDBR voted by a majority in these two meetings to increase the benchmark interest rate by 50 and 100 basis points, respectively, bringing the policy rate to 4.0%.