100 research outputs found
Author Correction: New perspectives on Neanderthal dispersal and turnover from Stajnia Cave (Poland)
No full textThe Author contributions section now reads:“W.N., A.N. and S.T. designed research; A.P., M.H., W.N., S.B., M.U., A.M., H.F., M.D.B., P.S., K.S., M.Ż., A.W., A.N. and S.T. performed research; A.P., M.H., W.N., S.B., M.U., A.M., H.F., M.D.B., P.S., K.S., M.Ż., A.W., A.N. and S.T. analysed data; A.P., M.H., S.T., W.N. and S.B. wrote the paper with the collaboration of all the co-authors.
Correction to: Geochemical Analysis of Cretaceous Shales from the Hazara Basin, Pakistan: Provenance Signatures and Paleo-Weathering Conditions, (J. Mar. Sci. Eng, (2022), 10, (800), 10.3390/jmse10060800)
No full textAddition of an Author In the original publication [1], there was a mistake in the authorship. Muhammad Umar should be added as the co-author. His affiliation is the Department of Earth Sciences, The University of Haripur, Haripur 22620, Pakistan. New Author Contributions Statement Conceptualization, A.G.F. and M.U.; methodology, A.G.F.; software, A.G.F. and H.T.J.; validation, A.G.F., M.U. and H.T.J.; formal analysis, A.G.F., M.U. and H.T.J.; investigation, A.G.F., M.U. and H.T.J.; resources, A.G.F. and M.U.; data curation, A.G.F. and M.U.; writing—original draft preparation, A.G.F. and M.U.; writing—review and editing, H.T.J., F.S., M.A.F.M., G.K. and A.K.J.; visualization, M.U., H.T.J., F.S. and M.A.F.M.; supervision, M.U.; project administration, M.U.; funding acquisition, G.K. and H.T.J. All authors have read and agreed to the published version of the manuscript. © 2022 by the authors. Licensee MDPI, Basel, Switzerland
Model reduced variational data assimilation for shallow water flow models
No full textIdentifying uncertain parameters in large-scale numerical flow models can be done using the variational method. However, for implementing the variational method the adjoint model have to be available, which requires highly complex computer code and maintenance and thus hampers its applications. To ease this problem, this thesis has explored several methods for efficiently identifying uncertain parameters in a large-scale tidal model of the entire European continental shelf which does not require the implementation of these complex adjoint code. In this study, as a first step an estimation method based on model reduction is developed and investigated for the estimation of diffusion coefficient in a simple 2D-advection diffusion model. Two projection based model reduction methods were considered, namely proper orthogonal decomposition (POD) and Balanced proper orthogonal decomposition (BPOD). In the POD based estimation method an ensemble of forward model simulations is used to determine an approximation of the covariance matrix of the model variability and a small number of the leading eigenvectors of this matrix is used to define a model subspace. By projecting the original model onto this subspace an approximate linear reduced model is obtained. Once the reduced model is available its adjoint can be implemented easily and the minimization problem is solved completely in reduced space with very low computational cost. BPOD is also a model reduction method which considers both inputs and outputs of the system while determining the reduce subspace. The estimation method has been extended by including BPOD procedure into the estimation procedure. Numerical results from a simple pollution model demonstrate that the POD based estimation approach successfully estimate the diffusion coefficient for both advection dominated problems as for diffusion dominated problems. Another important message in this study, although lots of effort had been made in constructing a reduced order model by the BPOD method, the minimization results demonstrated that both the POD and the BPOD methods performed similarly. Preliminary results showed the validity of the POD based model reduction methods for parameter estimation. As a next step, the POD based estimation method is used to calibrate numerical tidal models. Results from (twin) numerical experiments showed that the POD based calibration method performed very efficiently to estimate depth values in the selected regions of the model domain. The computational costs of the POD based calibration method are dominated by the generation of an ensemble of forward model simulations where the simulation period of the ensemble is equivalent to the timescale of the original model. It has also been found in the study that it is not needed to use a full simulations of the original model for the generation of the ensemble. The POD based calibration method has also been implemented for the estimation of the water depth and space varying bottom friction coefficient values in a very large-scale DCSM model. The recently designed large-scale spherical grid based water level model for the northwest European continental shelf (around 1000000 computational grid points) has been used for this purpose. This has been the first application of the POD based calibration method to a very large-scale model and with real data. Results from numerical experiments showed that the calibration method performs very efficiently. An overall improvement of more than 50\% was observed after the calibration in comparison with the initial model. The results also demonstrated that the POD based calibration method offered a very efficient minimization technique compared to the classical adjoint method without the burden of implementation of the adjoint. As a concluding step, to estimate depth values in the model DCSM, a Simultaneous perturbation stochastic approximation (SPSA) method has been used. The method uses stochastic simultaneous perturbation of all model parameters to generate a search at each iteration. SPSA is based on a highly efficient and easily implemented simultaneous perturbation approximation to the gradient. This gradient approximation for the central difference method uses only two objective function evaluations independent of the number of parameters being optimized. The results from experiments showed that SPSA has a lower convergence rate than POD based calibration method, however the computational cost in each iteration of the SPSA method is usually far less then the POD based calibration method. The results also demonstrated that the SPSA algorithm proved to be a promising optimization algorithm for model calibration for cases where adjoint code is not available for computing the gradient of the objective function.Applied mathematicsElectrical Engineering, Mathematics and Computer Scienc
ABOUT THE STATE OF THE WORLD WHEAT MARKET AT THE CURRENT STAGE
No full textThe author considers the Phillips curve in the historical aspect. In the article there is a mention that there were examples when the Phillips curve was not confirmed. Then the author goes on to describe the post-crisis economic situation. The author refers to the food problem as a global problem, which has been designated in the papers of the Club of Rome. Then the author characterizes world wheat production for the period 2003-2013. The author gives an example that shows the volatility of the wheat market (CBOT). The author explains why he uses quotations of forward contracts, and not in the spot market. The author scrutinizes the quotations of CBOT wheat futures contracts in the paper. The author substantiates the need for an econometric model in the research process of futures CBOT wheat prices. The author justifies the chosen scientific approach that defines the methods of research and research model. The author uses econometric approach in the paper. The author uses linear regression as a method of the research. The author creates the equation of linear regression using the software. The author makes a conclusion that there is a certain linear relationship between the price of the futures contract CBOT wheat and the level of unemployment in the United States during the period. The author verifies the effect of Phillips curve. Results of this paper allow the analyst to make informed pricing decisions on the organized market of wheat trade in the medium term
A Study of Reduced Order 4D-VAR with a Finite Element Shallow Water Model
No full textForecast models often depend on unknown parameters, such as model initial and boundary conditions, or other tunable parameters not necessarily having any physical meaning. Calibration of these parameters to minimize errors between forecasted and observed states is called data assimilation. A common approach in this context are variational methods, of which four dimensional data variation (4D-VAR) is studied in this thesis. In 4D-VAR, a cost function is defined that penalizes misfits between observations and the corresponding numerical model results, obtained by running the model with the chosen configuration. Performing optimization with regard to this cost function yields an improved initial parameter set. Associated with this type of methods, however, are difficulties in connection with programming the adjoint model, which is needed to compute the exact gradient of the cost function. Additionally, having to integrate the adjoint model backwards in time adds significantly to the computational cost of the data assimilation process. To avoid manual implementation of adjoint code and to reduce computational complexity, approximation of the gradient calculation is considered through the use of proper orthogonal decomposition (POD), a flexible data-driven order reduction method. To facilitate this, a finite element model of the shallow water equations is tested with both the full adjoint 4D-VAR method and two different POD-reduced approaches. Twin experiments are performed and comparisons are made in terms of accuracy, computational complexity and sensitivity to perturbation and number of observation points.Applied mathematicsElectrical Engineering, Mathematics and Computer Scienc
The laser-shoe: A new form of continuous ambulatory cueing for patients with Parkinson's disease
No full textContains fulltext :
166372.pdf (Publisher’s version ) (Open Access
The Practicalities of Assessing Freezing of Gait
No full textContains fulltext :
166369.pdf (Publisher’s version ) (Open Access)BACKGROUND: Freezing of gait (FOG) is a mysterious, complex and debilitating phenomenon in Parkinson's disease. Adequate assessment is a pre-requisite for managing FOG, as well as for assigning participants in FOG research. The episodic nature of FOG, as well as its multiple clinical expressions make its assessment challenging. OBJECTIVE: To highlight the available assessment tools and to provide practical, experience-based recommendations for reliable assessment of FOG. METHODS: We reviewed FOG assessment from history taking, questionnaires, lab and home-based measurements and examined how these methods account for presence and severity of FOG, their limits and advantages. The practicalities for their use in clinical and research practice are highlighted. RESULTS: According to the available assessment tools severity of FOG is marked by one or a combination of multiple clinical expressions including frequency, duration, triggering circumstances, response to levodopa, association with falls and fear of falling, or need for assistance to avoid falls. CONCLUSIONS: To date, a unique methodological tool that encompasses the entire complexity of FOG is lacking. Combining methods should give a better picture of FOG severity, in accordance with the precise clinical or research context. Further development of any future assessment tool requires understanding and thorough analysis of the specific clinical expressions of FOG
Development in soil-water-and nutrient management: A Study on drought tolerant of wheat genotypes using carbon isotopes discrimination
No full textDEVELOPMENT IN SOIL ??? WATER - AND NUTRIENT MANAGEMENT ANALYSIS: A STUDY ON DROUGHT TOLERANT OF WHEAT GENOTYPES USING CARBON ISOTOPES DISCRIMINATION (CID) TECHNIQUE \ud
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B. RASYID1*; M.U. SHIRAZI2; J.A. GYAMFI3; T. RAM4; H. BACHIRI5\ud
1Dept. of Soil Science, Fac. Of Agriculture, Hasanuddin University, Makassar, Indonesia\ud
2Nuclear Institute of Agriculture (NIA), Tandojam, Pakistan\ud
3 IAEA laboratories Seibersdorf, Austria\ud
4Agricultural Research and Extension Unit, Mauritius\ud
5Institut National de Recherche Agronomique en , Algeria (INRAA)\ud
*Correspondent author: [email protected]\ud
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ABSTRACT\ud
Drought tolerant analysis using carbon isotopes discrimination could be useful tool to decide a genotype with high adaptation to drought. A pot culture experiment was conducted in glass house at the International Atomic Energy Agency (IAEA) laboratories, Seibersdorf, Austria to analyze drought tolerant of wheat genotype using carbon isotopes discrimination technique. Four wheat genotypes viz., LU-26s, Bhittai, Roshan, Taifu, were tested. There were two treatments. i. Control (normal irrigation) and ii. Drought (30 % field capacity of the control treatment). Drought treatment was imposed after two weeks of germination. The experiment was continued up to 10 weeks after germination and was terminated at flowering stage. The data was recorded in terms of plant height, number of tillers, shoot dry weight and carbon isotopic ratio (??). Results showed that genotypes LU-26s was found to have best performance under drought condition, with minimum decrease in the growth parameters i.e., plant height, number of tillers and shoot dry weight. High corbon isotopes discrimination (CID) values were also observed in genotype LU-26s, showing close positive correlation between SDW and CID. It is therefore concluded that carbon isotopes discrimination can be an important criterion for the selection of wheat genotypes for drought prone areas. \ud
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Key words: Drought tolerant, Wheat genotypes, Carbon isotope discrimination.\ud
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PENGEMBANGAN ANALISIS PENGELOLAAN TANAH ??? AIR ??? DAN HARA : STUDI TOLERANSI TERHADAP KEKERINGAN BEBERAPA GENOTIPE GANDUM MENGGUNAKAN TEKNIK DISKRIMINASI KARBON ISOTOP\ud
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B. RASYID1*; M.U. SHIRAZI2; J.A. GYAMFI3; T. RAM4; H. BACHIRI5\ud
1Jurusan Ilmu Tanah, Fakultas Pertanian, Universitas Hasanuddin, Makassar, Indonesia\ud
2Nuclear Institute of Agriculture (NIA), Tandojam, Pakistan\ud
3 IAEA laboratories Seibersdorf, Austria\ud
4Agricultural Research and Extension Unit, Mauritius\ud
5Institut National de Recherche Agronomique en , Algeria (INRAA)\ud
*Alamat korespondensi: [email protected]\ud
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ABSTRAK\ud
Analisis toleransi terhadap kekeringan menggunakan diskriminasi karbon isotop merupakan teknik yang sangat baik digunakan untuk menentukan genotipe tanaman yang memiliki adaptasi tinggi terhadap kekeringan. Percobaan pot dilakukan pada rumah kaca Laboratorium Badan Tenaga Atom Internasional, Seibersdorf, Austria, untuk menganalisis toleransi beberapa jenis genotipe gandum dengan teknik diskriminasi karbon isotop. Tanaman yang dianalisis adalah empat genotipe gandum yakni LU-26s, Bhittai, Roshan, dan Taifu. Perlakuan pemberian air masing-masing: i. Kontrol (pemberian air normal), ii. Kekeringan (30% kapasitas lapang). Perlakuan kekeringan diberikan 2 (dua) minggu setelah tanam yang diteruskan hingga 10 (sepuluh) minggu setelah tanam saat tanaman memasuki fase pembungaan. Pengamatan yang dilakukan meliputi tinggi tanaman, jumlah anakan, berat kering akar dan rasio karbon isotop (d). Hasil penelitian menunjukkan bahwa genotipe LU-26s memberikan penampilan terbaik pada kondisi kering yang dapat dilihat pada nilai tinggi tanaman, jumlah anakan, dan berat kering tanaman. Pada diskriminasi karbon isotop, nilai tertinggi ditunjukkan pula oleh genotipe LU-26s, yang memberikan arti adanya korelasi positif antara berat kering tanaman dan diskriminasi karbon isotop. Karenanya dapat disimpulkan bahwa diskriminasi karbon isotop dapat menjadi criteria penting untuk seleksi genotipe gandum pada daerah yang cenderung kering.\ud
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Kata kunci: Toleransi kekeringan, Genotipe gandum, Diskriminasi karbon isotop
Low-frequency versus high-frequency stimulation of the pedunculopontine nucleus area in Parkinson's disease: a randomised controlled trial
No full textItem does not contain fulltextOBJECTIVE: To compare the influence of low-frequency (10-25 Hz) versus higher (60-80 Hz) frequency stimulation of the pedunculopontine nucleus area (PPNa) on akinaesia, freezing of gait and daytime sleepiness. METHOD: We included nine patients with Parkinson's disease (PD) and severe gait disorders. In this double-blind randomised cross-over study, patients were assessed after 24 h of PPNa stimulation. Assessments included the motor part of the Unified Parkinson's Disease Rating Scale, the Epworth Sleepiness Scale and a behavioural gait assessment. RESULTS: Compared with 60-80 Hz, 10-25 Hz PPNa stimulation led to decreased akinaesia, gait difficulties and daytime sleepiness in 7/9 patients. In one patient, these symptoms were aggravated under 10-25 Hz stimulation compared with 60-80 Hz. CONCLUSION: These results are in keeping with the benefits of chronic PPNa stimulation for gait and postural difficulties in patients with PD, and with regard to the influence of patients' clinical characteristics, differential neuronal loss in the PPNa and electrode location. We conclude that in patients with PPNa stimulation, low frequency provides a better outcome than high-frequency stimulation
OpenDA-NEMO framework for ocean data assimilation
No full textData assimilation methods provide a means to handle the modeling errors and uncertainties in sophisticated ocean models. In this study, we have created an OpenDA-NEMO framework unlocking the data assimilation tools available in OpenDA for use with NEMO models. This includes data assimilation methods, automatic parallelization, and a recently implemented automatic localization algorithm that removes spurious correlations in the model based on uncertainties in the computed Kalman gain matrix. We have set up a twin experiment where we assimilate sea surface height (SSH) satellite measurements. From the experiments, we can conclude that the OpenDA-NEMO framework performs as expected and that the automatic localization significantly improves the performance of the data assimilation algorithm by successfully removing spurious correlations. Based on these results, it looks promising to extend the framework with new kinds of observations and work on improving the computational speed of the automatic localization technique such that it becomes feasible to include large number of observations.Delft Institute of Applied MathematicsElectrical Engineering, Mathematics and Computer Scienc
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