Context Of Assimilation Research Articles

What infant-directed speech tells us about the development of compensation for assimilation

In speech addressed to adults, words are seldom realized in their canonical, or citation, form. For example, the word ‘green’ in the phrase ‘green beans’ can often be realized as ‘greem’ due to English place assimilation, where word-final coronals take on the place of articulation of neighboring velars. In such a situation, adult listeners readily ‘undo’ the assimilatory process and perceive the underlying intended lexical form of ‘greem’ (i.e. they access the lexical representation ‘green’). An interesting developmental question is how children, with their limited lexical knowledge, come to cope with phonologically conditioned connected speech processes such as place assimilation. Here, we begin to address this issue by examining the occurrence of place assimilation in the input to English-learning 18-month-olds. Perceptual and acoustic analyses of elicited speech, as well asanalysis of a corpus of spontaneous speech, all converge on the finding that caregivers do not spoon-feed their children canonical tokens of words. Rather, infant-directed speech contains just as many non-canonical realizations of words in place assimilation contexts asadult-directed speech. Implications for models of developmental speech perception are discussed.

Estimating Wheat Yield in China at the Field and District Scale from the Assimilation of Satellite Data into the Aquacrop and Simple Algorithm for Yield (SAFY) Models

Accurate yield estimation at the field scale is essential for the development of precision agriculture management, whereas at the district level it can provide valuable information for supply chain management. In this paper, Huan Jing (HJ) satellite HJ1A/B and Landsat 8 Operational Land Imager (OLI) images were employed to retrieve leaf area index (LAI) and canopy cover (CC) in the Yangling area (Central China). These variables were then assimilated into two crop models, Aquacrop and simple algorithm for yield (SAFY), in order to compare their performances and practicalities. Due to the models’ specificities and computational constraints, different assimilation methods were used. For SAFY, the ensemble Kalman filter (EnKF) was applied using LAI as the observed variable, while for Aquacrop, particle swarm optimization (PSO) was used, using canopy cover (CC). These techniques were applied and validated both at the field and at the district scale. In the field application, the lowest relative root-mean-square error (RRMSE) value of 18% was obtained using EnKF with SAFY. On a district scale, both methods were able to provide production estimates in agreement with data provided by the official statistical offices. From an operational point of view, SAFY with the EnKF method was more suitable than Aquacrop with PSO, in a data assimilation context.

Dual identity and immigrants’ protest against discrimination: The moderating role of diversity ideologies

Discrimination of immigrant groups is an important social problem in many societies around the world. This study examines the moderating role of cultural diversity beliefs on the relation between dual identity and the intention to protest against immigrants’ discrimination. An experimental study was conducted among national samples of the three main immigrant-origin groups in the Netherlands. It was found that dual identity predicted the intention to protest against discrimination more strongly within a context of multicultural recognition compared to a context of assimilation or interculturalism. This demonstrates that multicultural recognition is a facilitating condition for dual identifiers to get involved in collective action for social change.

A simple method for integrating a complex model into an ensemble data assimilation system using MPI

This paper details a strategy for modifying the source code of a complex model so that the model may be used in a data assimilation context, and gives the standards for implementing a data assimilation code to use such a model. The strategy relies on keeping the model separate from any data assimilation code, and coupling the two through the use of Message Passing Interface (MPI) functionality. This strategy limits the changes necessary to the model and as such is rapid to program, at the expense of ultimate performance. The implementation technique is applied in different models with state dimension up to .2.7 × 108 The overheads added by using this implementation strategy in a coupled ocean-atmosphere climate model are shown to be an order of magnitude smaller than the addition of correlated stochastic random errors necessary for some nonlinear data assimilation techniques.

Ultrasound evidence for place of articulation of the mora nasal /ɴ/ in Japanese

The Japanese mora nasal /ɴ/, which occurs in syllable-final position, takes its place of articulation from the following segment if there is one. However, the mora nasal in utterance-final position is often transcribed as velar, uvular, or even placeless. The present study examines the tongue shapes in Japanese using ultrasound imaging to investigate whether Japanese mora nasal /ɴ/ is placeless and to assess whether assimilation to following segments is gradient or categorical. Preliminary results from ultrasound imaging from one native speaker of Tokyo dialect showed three shapes for final /ɴ/, even though the researchers could not distinguish them perceptually. Results from assimilation contexts showed that the velar gesture for /ɴ/ was not deleted. All gestures remained and assimilation was not categorical, even though perceptually, it was. The velar gesture for /ɴ/ might be expected to be deleted before an alveolar /n/ because they are both lingual, but a blending of the two tongue gestures occurred instead. Variability in place of articulation in final position occurred even within one speaker. Categorical assimilation was not observed in any phonological environments studied. The mora nasal may vary across speakers, so further research is needed to determine whether it behaves similarly for more speakers.

Implementation of a 3D-Var system for atmospheric profiling data assimilation into the RAMS model: initial results

Abstract. This paper presents the current status of development of a three-dimensional variational data assimilation system (3D-Var). The system can be used with different numerical weather prediction models, but it is mainly designed to be coupled with the Regional Atmospheric Modelling System (RAMS). Analyses are given for the following parameters: zonal and meridional wind components, temperature, relative humidity, and geopotential height. Important features of the data assimilation system are the use of incremental formulation of the cost function, and the representation of the background error by recursive filters and the eigenmodes of the vertical component of the background error covariance matrix. This matrix is estimated by the National Meteorological Center (NMC) method. The data assimilation and forecasting system is applied to the real context of atmospheric profiling data assimilation, and in particular to the short-term wind prediction. The analyses are produced at 20 km horizontal resolution over central Europe and extend over the whole troposphere. Assimilated data are vertical soundings of wind, temperature, and relative humidity from radiosondes, and wind measurements of the European wind profiler network. Results show the validity of the analyses because they are closer to the observations (lower root mean square error (RMSE)) compared to the background (higher RMSE), and the differences of the RMSEs are in agreement with the data assimilation settings. To quantify the impact of improved initial conditions on the short-term forecast, the analyses are used as initial conditions of three-hours forecasts of the RAMS model. In particular two sets of forecasts are produced: (a) the first uses the ECMWF analysis/forecast cycle as initial and boundary conditions; (b) the second uses the analyses produced by the 3D-Var as initial conditions, then it is driven by the ECMWF forecast. The improvement is quantified by considering the horizontal components of the wind, which are measured at asynoptic times by the European wind profiler network. The results show that the RMSE is effectively reduced at the short range. The results are in agreement with the set-up of the numerical experiment.

Progress towards the assimilation of all‐sky infrared radiances: an evaluation of cloud effects

As a step toward the assimilation of cloud‐affected infrared radiances in multi‐layer cloud conditions, this study evaluates cloud effects on model first‐guess simulations (background) and observations using the Infrared Atmospheric Sounding Interferometer (IASI) radiances. It is found from an extensive statistical analysis that over oceans the magnitude of observation‐minus‐background departures (O–B) – even in the most cloud‐sensitive window channels – is typically less than 10 K for 85% of all‐sky IASI data. A parameter has been developed to express the magnitude of the cloud effect based upon observed and simulated cloudy radiances. It is shown that the variations in the standard deviation (SD) of O–B departures can be described (and thus predicted) by this cloud effect parameter – such that the probability density function (PDF) of O–B normalized with predicted O–B SD exhibits a near‐Gaussian form. It is argued that the predicted cloud effect can be used in an assimilation context to define cloud‐dependent quality controls and aid observation error assignment. Simple linear estimation theory is used to simulate the possible benefits of state‐dependent observation errors according to cloud effect.

Return Travel, Assimilation, and Cultural Maintenance: An Example of Turkish-Americans in Arizona

Within the context of diaspora studies, immigration, assimilation, and return travel, this study examines the relationships between elements of cultural integration and travel characteristics among Turkish-Americans living in the state of Arizona. The findings suggest that integration activities and characteristics have little bearing on immigrants' travel patterns to the homeland, with the exception of length of stay and the types of accommodations used while in Turkey.

Assimilation of multiple data types for improved heat flux prediction: A one-dimensional field study

Accurate latent (LE) and sensible (H) heat flux partitioning from Land Surface Models (LSMs) is important for numerical weather prediction. Land data assimilation can play a key role in improving heat flux prediction by merging information from a range of remotely sensed products with LSMs. This paper demonstrates this potential for an open grassland site in Australia via one-dimensional experiments spanning a year-long period. With a focus on how a LSM is impacted, in-situ field observations were assimilated. Data types as available from passive microwave and thermal infra-red remote sensors were tested for their impact, with individual and joint assimilation of LE and H, near-surface soil moisture, and skin temperature observations—all on time scales approximating satellite overpass intervals. Assessed against independent data from field observations, the multi-observation approach of joint near-surface soil moisture and skin temperature assimilation made the greatest improvements to LE (expressed as daily evapotranspiration; ET), being slightly better than for joint LE and H assimilation. This result questions the value of using LE and H retrievals from thermal imagery within an assimilation context. Individually, skin temperature assimilation was one of the best performers for soil temperature estimates but with degraded root-zone soil moisture estimates and minimal ET improvements. Likewise, near-surface soil moisture assimilation produced the greatest root-zone soil moisture improvement but with relatively modest ET improvement. Combined near-surface soil moisture and skin temperature assimilation balanced the improvements to both soil moisture and temperature states along with strong improvements to ET estimates, highlighting the benefits of multi-observation assimilation.

The Submerged History of the Indian Ocean in Admiring Silence

Focusing on the satirical stories that the protagonist in Admiring Silence produces, this paper investigates their function as strategies within a submerged history of migration and global movement. I argue that the stories of failed integration and a discredited historical past, when placed within a historical context of Indian Ocean cosmopolitanism, can be studied as part of the shortcoming of both a Eurocentric and an Afro-centric historiography in relation to societies of the Indian Ocean rim. The protagonist's entanglement in his own stories and his ability to move between the positions of perpetrator and victim as well as between that of the traveller and the one left behind are placed within a context of assimilation and hierarchies of dependence of Indian Ocean societies. In calling our attention to this submerged history, the novel challenges historicist understandings of change and movement and points to the global histories involved in the process of articulating modernity.

Sociomaterial actors in the assimilation gap: a case study of web service, management and IT-assimilation

This paper investigates the conditions for the assimilation of information systems (IS) and information technology (IT) in organizations and the influence of various actors in the organization and eBusiness context. To do so it draws on the literature on assimilation gap, sociomateriality and infrastructure together with a study of implementation and use of information and communication technology in and among organizations in a Swedish region. There were substantial investments in web infrastructure made on a regional level and the focus of this study is how the investments were transformed and assimilated in practices, relations and communication. Based on the empirical data from the case study, the paper extends the assimilation process into interplay among actors in organizations contexts. It describes organizations' strategies for coping with their needs for information and the actors in these processes. Two categories of actors are identified, sensemaking and sensegiving actors, as most important in assimilation of IS/IT in organizations. A sociomaterial perspective gives guidance and a better understanding of the assimilation process in terms of knowledge and interpretative frames, and how assimilation involves identity construction and negotiations among sensemaking and sensegiving actors. The contribution of this paper is a better understanding of the context of assimilation and adaptation of IT in organizations' business processes, and steps to be taken to improve readiness.

Four-Dimensional Variational Data Assimilation for the Canadian Regional Deterministic Prediction System

Abstract As a second step in the development of the Canadian Regional Data Assimilation System following Fillion et al., this study extends the approach to the four-dimensional variational data assimilation (4D-Var) context. Emphasis is first put on illustrating the importance of controlling lateral boundary conditions (LBCs). The use in the minimization of a horizontal grid over a domain exceeding the horizontal grid of the high-resolution nonlinear model is then proposed. The authors examine the performance of this 4D-Var formulation as an upcoming upgrade to the currently operational regional three-dimensional variational data assimilation (3D-Var) system. Forecast verifications against radiosonde data for 118 winter cases and 118 summer cases were performed. Results indicate a slight positive impact up to 48 h against North American radiosondes, but with a significant positive impact (especially for winds) at mid- and high latitudes during the summer. Accumulated precipitation scores over 24 h, whether during the first or second day of the forecasts, are slightly improved. The regional 4D-Var analysis system described in this study can run within current real-time “regional run” allocation for operations at the Canadian Meteorological Center (CMC). Future improvements of this system are briefly mentioned especially regarding the upcoming computer upgrade at CMC.

Assimilation of pCO2 data into a global coupled physical‐biogeochemical ocean model

As part of the CARBOOCEAN project, measurements of the partial pressure of carbon dioxide (pCO2) in the ocean have been collected since 2001. Our aim was to use these data in a data assimilation context to improve the representation of pCO2 and its associated prognostic variables in biogeochemical models. Based upon a sequential framework a new method for the assimilation of pCO2 data was developed. This method had to account for oceanic pCO2 being a derived quantity with a functional dependence on temperature, salinity, dissolved inorganic carbon (DIC), and alkalinity. Our method calculates pCO2 increments using an analysis correction technique and then converts these into increments in model variables. Temperature and salinity are assumed to be error free, and so only DIC and alkalinity are updated. Furthermore, in DIC and alkalinity space increments are taken to be perpendicular to the local line of constant pCO2. Our method was tested by assimilating pCO2 data from 2006 into the NEMO‐HadOCC biogeochemical model and then comparing the output from this model to a control with no pCO2 assimilation. While lack of data prevented the assimilation system from correcting a significant systematic error in the subpolar North Atlantic, results from this experiment showed that pCO2 assimilation, despite limited data, reduced RMS and mean errors and also brought the model closer to climatology in the subtropical North Atlantic.

"They Prepared Me to Be a Teacher, But Not a Culturally Responsive Navajo Teacher for Navajo Kids": A Tribal Critical Race Theory Analysis of an Indigenous Teacher Preparation Program

This article argues that federally-funded Indigenous teacher preparation programs housed at mainstream, predominantly White universities can be colonial and thus require significant focused work in order to ensure that they are not. The article has three interrelated objectives: first, to discuss efforts to prepare Indigenous teachers for Indigenous schools within predominantly White university teacher preparation programs; second, to examine whether these programs continue the legacy of colonization and assimilation, or advance tribal nations' goals of sovereignty and self-determination; and third, to extend the theoretical capacities of critical race theory and tribal critical race theory by using their analytic tools to make sense of particular efforts in Indigenous education. The preparation of culturally responsive Indigenous teachers for schools serving Indigenous youth is clearly needed, but this is difficult work given the larger context of imperialism, White supremacy, and assimilation that still structures our educational institutions.

Inference on core surface flow from observations and 3-D dynamo modelling

SUMMARY We show how a 3-D, self-consistent numerical model of the geodynamo can be used as the subjective prior information for the determination of Earth’s core surface flows from the geomagnetic field and its secular variation. This is achieved by estimating those parts of the numericalmodelstatevectorhiddenfromtheobservations,throughastandardKalmanfiltering (or stochastic inverse) procedure, where the Kalman gain matrix is based on the multivariate statisticsofthegeodynamomodel.Toallowforadirectcomparisonwithobservations,thefield variablesenteringthesestatisticsarescaledfollowingtwoofthescalinglawsthathaverecently come to the fore in numerical dynamo modelling, which express the dependency of the secular variation timescale and the magnetic energy density on their respective control parameters. We perform test experiments with noisy synthetic data, showing good to excellent recovery of the hidden parts of the state vector. A geomagnetic field model parent to a candidate model to the 2010 release of IGRF is then used for a core surface flow estimation. The estimated flow confirms the presence of convective columns underneath America, whereas exhibiting a high level of equatorial symmetry. We suggest that the discrete state estimation problem considered here (in connection with the classical core flow problem) could be used generically as a means to assess the degree of geophysical realism of a given geodynamo model. More generally, this study opens the way to using scaling laws and multivariate statistics from numerical models in the broader context of geomagnetic data assimilation.

The geomagnetic secular‐variation timescale in observations and numerical dynamo models

The knowledge of the spatial power spectra of the main geomagnetic field and of its secular variation makes it possible to define typical timescales τn for each spherical harmonic degree n. Investigating both observations and numerical dynamos, we show that a one‐parameter law of the form τn = τSV/n is satisfied for the non‐dipole field, given the statistical way the observed τn are expected to fluctuate. Consequently, we determine the corresponding secular‐variation timescale τSV from either instantaneous or time‐averaged spectra, leading to a value of 415 ±4555 yr for recent satellite field models. In the broader context of geomagnetic data assimilation, τSV could provide a sensible and convenient means to rescale the time axis of dynamo simulations.

The social context of assimilation: Testing implications of segmented assimilation theory

Segmented assimilation theory has been a popular explanation for the diverse experiences of assimilation among new waves of immigrants and their children. While the theory has been interpreted in many different ways, we emphasize its implications for the important role of social context: both processes and consequences of assimilation should depend on the local social context in which immigrants are embedded. We derive empirically falsifiable hypotheses about the interaction effects between social context and assimilation on immigrant children’s well-being. We then test the hypotheses using data from the National Longitudinal Study of Adolescent Health. Our empirical analyses yield two main findings. First, for immigrant adolescents living in non-poverty neighborhoods, we find assimilation to be positively associated with educational achievement and psychological well-being but also positively associated with at-risk behavior. Second, there is little empirical evidence supporting our hypotheses derived from segmented assimilation theory. We interpret these results to mean that future research would be more fruitful focusing on differential processes of assimilation rather than differential consequences of assimilation.

On the use of Advanced Microwave Sounding Unit‐A and ‐B measurements for studying the monsoon variability over West Africa

The advanced microwave sounding unit (AMSU) ‐A and ‐B sensors provide observations of humidity and temperature that are relevant for meteorological and climate studies. The use of these observations in numerical weather prediction models has increased in the past 10 years because of some improvements in data assimilation. However, an appropriate use of AMSU measurements apart from assimilation context is rather difficult and depends for the most part on how successfully the instrumental characteristics are accounted for. In particular, atmosphere humidity and temperature variations can be completely hidden by features because of the effect of the observation zenith angle. In this paper, 8 years of AMSU‐A and ‐B observations have been corrected from the observations zenith angle effect and have been used to study temperature and humidity variations over West Africa. Comparisons have been made between AMSU observations and selected atmospheric fields from European Centre for Medium‐Range Weather Forecasts analyses as well as outgoing longwave radiation estimates. It has been found that observations from AMSU‐A channel 5 can be used to monitor the heat low evolution and that AMSU‐B observations from channels 3 and 5 are well adapted to study the humidity variations in direct link with the African monsoon from intraseasonal to interannual scales.

Assimilation ideology and situational well-being among ethnic minority members

Two experimental questionnaire studies were conducted to test whether assimilation ideology affects the relationship between ethnic self-esteem and situational well-being of Turkish-Dutch participants. Social identity theory argues that ethnic identity can buffer the effects of group identity threat on well-being, and self-esteem research suggests that a positively evaluated self-aspect can form an important source of well-being. Results show that in an assimilation context, ethnic self-esteem is positively related to feelings of global self-worth and general life-satisfaction. The findings suggest that ethnic self-esteem is an important factor for well-being in an assimilation context that undermines minority group members ability to live their ethnic identity and threatens their group’s positive distinctiveness.

Superposition of local zoom models and simultaneous calibration for 1D–2D shallow water flows

We address the problem of coupling 2D shallow water equations with 1D shallow water equations (St-Venant equations), as applied to river-floodplain flows. Mathematical coupling conditions are derived classicaly from the 3D Navier–Stokes equations by integrating over the vertical wet section, when overflowing occurs. It leads to extra source terms in the 1D equations. Next we assume to be in a variational data assimilation context, then the optimal control process allows to couple both models and assimilate data simultaneously (Joint Assimilation Coupling algorithms). Two different versions of JAC algorithms are presented and compared. In a numerical test case, we superimpose the local 2D model on the 1D global model. The results show the efficiency of the present simultaneous superposition–assimilation approach.