The Experts below are selected from a list of 732510 Experts worldwide ranked by ideXlab platform
Jukka Rantanen - One of the best experts on this subject based on the ideXlab platform.
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influence of solvent evaporation rate and formulation Factors on solid dispersion physical stability
European Journal of Pharmaceutical Sciences, 2011Co-Authors: Jian X Wu, Mingshi Yang, Frans Van Den Berg, Jari Pajander, Thomas Rades, Jukka RantanenAbstract:Abstract New chemical entities (NCEs) often show poor water solubility necessitating solid dispersion formulation. The aim of the current study is to employ design of experiments in investigating the influence of one critical Process Factor (solvent evaporation rate) and two formulation Factors (PVP:piroxicam ratio (PVP:PRX) and PVP molecular weight (PMW)) on the physical stability of PRX solid dispersion prepared by the solvent evaporation method. The results showed the rank order of an increase in Factors contributing to a decrease in the extent of PRX nucleation being evaporation rate > PVP:PRX > PMW. The same rank order was found for the decrease in the extent of PRX crystal growth in PVP matrices from day 0 up to day 12. However, after 12 days the rank became PVP:PRX > evaporation rate > PMW. The effects of an increase in evaporation rate and PVP:PRX ratio in stabilizing PRX were of the same order of magnitude, while the effect from PMW was much smaller. The findings were confirmed by XRPD. FT-IR showed that PRX recrystallization in the PVP matrix followed Ostwald’s step rule, and an increase in the three Factors all led to increased hydrogen bonding interaction between PRX and PVP. The present study showed the applicability of the Quality by Design approach in solid dispersion research, and highlights the need for multiFactorial analysis.
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influence of solvent evaporation rate and formulation Factors on solid dispersion physical stability
European Journal of Pharmaceutical Sciences, 2011Co-Authors: Mingshi Yang, Jari Pajander, Thomas Rades, Frans Van Den Berg, Jukka RantanenAbstract:Abstract New chemical entities (NCEs) often show poor water solubility necessitating solid dispersion formulation. The aim of the current study is to employ design of experiments in investigating the influence of one critical Process Factor (solvent evaporation rate) and two formulation Factors (PVP:piroxicam ratio (PVP:PRX) and PVP molecular weight (PMW)) on the physical stability of PRX solid dispersion prepared by the solvent evaporation method. The results showed the rank order of an increase in Factors contributing to a decrease in the extent of PRX nucleation being evaporation rate > PVP:PRX > PMW. The same rank order was found for the decrease in the extent of PRX crystal growth in PVP matrices from day 0 up to day 12. However, after 12 days the rank became PVP:PRX > evaporation rate > PMW. The effects of an increase in evaporation rate and PVP:PRX ratio in stabilizing PRX were of the same order of magnitude, while the effect from PMW was much smaller. The findings were confirmed by XRPD. FT-IR showed that PRX recrystallization in the PVP matrix followed Ostwald’s step rule, and an increase in the three Factors all led to increased hydrogen bonding interaction between PRX and PVP. The present study showed the applicability of the Quality by Design approach in solid dispersion research, and highlights the need for multiFactorial analysis.
Mingshi Yang - One of the best experts on this subject based on the ideXlab platform.
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influence of solvent evaporation rate and formulation Factors on solid dispersion physical stability
European Journal of Pharmaceutical Sciences, 2011Co-Authors: Jian X Wu, Mingshi Yang, Frans Van Den Berg, Jari Pajander, Thomas Rades, Jukka RantanenAbstract:Abstract New chemical entities (NCEs) often show poor water solubility necessitating solid dispersion formulation. The aim of the current study is to employ design of experiments in investigating the influence of one critical Process Factor (solvent evaporation rate) and two formulation Factors (PVP:piroxicam ratio (PVP:PRX) and PVP molecular weight (PMW)) on the physical stability of PRX solid dispersion prepared by the solvent evaporation method. The results showed the rank order of an increase in Factors contributing to a decrease in the extent of PRX nucleation being evaporation rate > PVP:PRX > PMW. The same rank order was found for the decrease in the extent of PRX crystal growth in PVP matrices from day 0 up to day 12. However, after 12 days the rank became PVP:PRX > evaporation rate > PMW. The effects of an increase in evaporation rate and PVP:PRX ratio in stabilizing PRX were of the same order of magnitude, while the effect from PMW was much smaller. The findings were confirmed by XRPD. FT-IR showed that PRX recrystallization in the PVP matrix followed Ostwald’s step rule, and an increase in the three Factors all led to increased hydrogen bonding interaction between PRX and PVP. The present study showed the applicability of the Quality by Design approach in solid dispersion research, and highlights the need for multiFactorial analysis.
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influence of solvent evaporation rate and formulation Factors on solid dispersion physical stability
European Journal of Pharmaceutical Sciences, 2011Co-Authors: Mingshi Yang, Jari Pajander, Thomas Rades, Frans Van Den Berg, Jukka RantanenAbstract:Abstract New chemical entities (NCEs) often show poor water solubility necessitating solid dispersion formulation. The aim of the current study is to employ design of experiments in investigating the influence of one critical Process Factor (solvent evaporation rate) and two formulation Factors (PVP:piroxicam ratio (PVP:PRX) and PVP molecular weight (PMW)) on the physical stability of PRX solid dispersion prepared by the solvent evaporation method. The results showed the rank order of an increase in Factors contributing to a decrease in the extent of PRX nucleation being evaporation rate > PVP:PRX > PMW. The same rank order was found for the decrease in the extent of PRX crystal growth in PVP matrices from day 0 up to day 12. However, after 12 days the rank became PVP:PRX > evaporation rate > PMW. The effects of an increase in evaporation rate and PVP:PRX ratio in stabilizing PRX were of the same order of magnitude, while the effect from PMW was much smaller. The findings were confirmed by XRPD. FT-IR showed that PRX recrystallization in the PVP matrix followed Ostwald’s step rule, and an increase in the three Factors all led to increased hydrogen bonding interaction between PRX and PVP. The present study showed the applicability of the Quality by Design approach in solid dispersion research, and highlights the need for multiFactorial analysis.
Maneesh Sahani - One of the best experts on this subject based on the ideXlab platform.
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NeurIPS - Temporal alignment and latent Gaussian Process Factor inference in population spike trains
2018Co-Authors: Lea Duncker, Maneesh SahaniAbstract:We introduce a novel scalable approach to identifying common latent structure in neural population spike-trains, which allows for variability both in the trajectory and in the rate of progression of the underlying computation. Our approach is based on shared latent Gaussian Processes (GPs) which are combined linearly, as in the Gaussian Process Factor Analysis (GPFA) algorithm. We extend GPFA to handle unbinned spike-train data by incorporating a continuous time point-Process likelihood model, achieving scalability with a sparse variational approximation. Shared variability is separated into terms that express condition dependence, as well as trial-to-trial variation in trajectories. Finally, we introduce a nested GP formulation to capture variability in the rate of evolution along the trajectory. We show that the new method learns to recover latent trajectories in synthetic data, and can accurately identify the trial-to-trial timing of movement-related parameters from motor cortical data without any supervision.
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Temporal alignment and latent Gaussian Process Factor inference in population spike trains
2018Co-Authors: Lea Duncker, Maneesh SahaniAbstract:We introduce a novel scalable approach to identifying common latent structure in neural population spike-trains, which allows for variability both in the trajectory and in the rate of progression of the underlying computation. Our approach is based on shared latent Gaussian Processes (GPs) which are combined linearly, as in the Gaussian Process Factor Analysis (GPFA) algorithm. We extend GPFA to handle unbinned spike-train data by incorporating a continuous time point-Process likelihood model, achieving scalability with a sparse variational approximation. Shared variability is separated into terms that express condition dependence, as well as trial-to-trial variation in trajectories. Finally, we introduce a nested GP formulation to capture variability in the rate of evolution along the trajectory. We show that the new method learns to recover latent trajectories in synthetic data, and can accurately identify the trial-to-trial timing of movement-related parameters from motor cortical data without any supervision.
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gaussian Process Factor analysis for low dimensional single trial analysis of neural population activity
Neural Information Processing Systems, 2008Co-Authors: John P Cunningham, G Santhanam, Stephen I Ryu, Krishna V Shenoy, Maneesh SahaniAbstract:We consider the problem of extracting smooth, low-dimensional neural trajectories that summarize the activity recorded simultaneously from tens to hundreds of neurons on individual experimental trials. Current methods for extracting neural trajectories involve a two-stage Process: the data are first "denoised" by smoothing over time, then a static dimensionality reduction technique is applied. We first describe extensions of the two-stage methods that allow the degree of smoothing to be chosen in a principled way, and account for spiking variability that may vary both across neurons and across time. We then present a novel method for extracting neural trajectories, Gaussian-Process Factor analysis (GPFA), which unifies the smoothing and dimensionality reduction operations in a common probabilistic framework. We applied these methods to the activity of 61 neurons recorded simultaneously in macaque premotor and motor cortices during reach planning and execution. By adopting a goodness-of-fit metric that measures how well the activity of each neuron can be predicted by all other recorded neurons, we found that GPFA provided a better characterization of the population activity than the two-stage methods.
Thomas Rades - One of the best experts on this subject based on the ideXlab platform.
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influence of solvent evaporation rate and formulation Factors on solid dispersion physical stability
European Journal of Pharmaceutical Sciences, 2011Co-Authors: Jian X Wu, Mingshi Yang, Frans Van Den Berg, Jari Pajander, Thomas Rades, Jukka RantanenAbstract:Abstract New chemical entities (NCEs) often show poor water solubility necessitating solid dispersion formulation. The aim of the current study is to employ design of experiments in investigating the influence of one critical Process Factor (solvent evaporation rate) and two formulation Factors (PVP:piroxicam ratio (PVP:PRX) and PVP molecular weight (PMW)) on the physical stability of PRX solid dispersion prepared by the solvent evaporation method. The results showed the rank order of an increase in Factors contributing to a decrease in the extent of PRX nucleation being evaporation rate > PVP:PRX > PMW. The same rank order was found for the decrease in the extent of PRX crystal growth in PVP matrices from day 0 up to day 12. However, after 12 days the rank became PVP:PRX > evaporation rate > PMW. The effects of an increase in evaporation rate and PVP:PRX ratio in stabilizing PRX were of the same order of magnitude, while the effect from PMW was much smaller. The findings were confirmed by XRPD. FT-IR showed that PRX recrystallization in the PVP matrix followed Ostwald’s step rule, and an increase in the three Factors all led to increased hydrogen bonding interaction between PRX and PVP. The present study showed the applicability of the Quality by Design approach in solid dispersion research, and highlights the need for multiFactorial analysis.
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influence of solvent evaporation rate and formulation Factors on solid dispersion physical stability
European Journal of Pharmaceutical Sciences, 2011Co-Authors: Mingshi Yang, Jari Pajander, Thomas Rades, Frans Van Den Berg, Jukka RantanenAbstract:Abstract New chemical entities (NCEs) often show poor water solubility necessitating solid dispersion formulation. The aim of the current study is to employ design of experiments in investigating the influence of one critical Process Factor (solvent evaporation rate) and two formulation Factors (PVP:piroxicam ratio (PVP:PRX) and PVP molecular weight (PMW)) on the physical stability of PRX solid dispersion prepared by the solvent evaporation method. The results showed the rank order of an increase in Factors contributing to a decrease in the extent of PRX nucleation being evaporation rate > PVP:PRX > PMW. The same rank order was found for the decrease in the extent of PRX crystal growth in PVP matrices from day 0 up to day 12. However, after 12 days the rank became PVP:PRX > evaporation rate > PMW. The effects of an increase in evaporation rate and PVP:PRX ratio in stabilizing PRX were of the same order of magnitude, while the effect from PMW was much smaller. The findings were confirmed by XRPD. FT-IR showed that PRX recrystallization in the PVP matrix followed Ostwald’s step rule, and an increase in the three Factors all led to increased hydrogen bonding interaction between PRX and PVP. The present study showed the applicability of the Quality by Design approach in solid dispersion research, and highlights the need for multiFactorial analysis.
Jari Pajander - One of the best experts on this subject based on the ideXlab platform.
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influence of solvent evaporation rate and formulation Factors on solid dispersion physical stability
European Journal of Pharmaceutical Sciences, 2011Co-Authors: Jian X Wu, Mingshi Yang, Frans Van Den Berg, Jari Pajander, Thomas Rades, Jukka RantanenAbstract:Abstract New chemical entities (NCEs) often show poor water solubility necessitating solid dispersion formulation. The aim of the current study is to employ design of experiments in investigating the influence of one critical Process Factor (solvent evaporation rate) and two formulation Factors (PVP:piroxicam ratio (PVP:PRX) and PVP molecular weight (PMW)) on the physical stability of PRX solid dispersion prepared by the solvent evaporation method. The results showed the rank order of an increase in Factors contributing to a decrease in the extent of PRX nucleation being evaporation rate > PVP:PRX > PMW. The same rank order was found for the decrease in the extent of PRX crystal growth in PVP matrices from day 0 up to day 12. However, after 12 days the rank became PVP:PRX > evaporation rate > PMW. The effects of an increase in evaporation rate and PVP:PRX ratio in stabilizing PRX were of the same order of magnitude, while the effect from PMW was much smaller. The findings were confirmed by XRPD. FT-IR showed that PRX recrystallization in the PVP matrix followed Ostwald’s step rule, and an increase in the three Factors all led to increased hydrogen bonding interaction between PRX and PVP. The present study showed the applicability of the Quality by Design approach in solid dispersion research, and highlights the need for multiFactorial analysis.
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influence of solvent evaporation rate and formulation Factors on solid dispersion physical stability
European Journal of Pharmaceutical Sciences, 2011Co-Authors: Mingshi Yang, Jari Pajander, Thomas Rades, Frans Van Den Berg, Jukka RantanenAbstract:Abstract New chemical entities (NCEs) often show poor water solubility necessitating solid dispersion formulation. The aim of the current study is to employ design of experiments in investigating the influence of one critical Process Factor (solvent evaporation rate) and two formulation Factors (PVP:piroxicam ratio (PVP:PRX) and PVP molecular weight (PMW)) on the physical stability of PRX solid dispersion prepared by the solvent evaporation method. The results showed the rank order of an increase in Factors contributing to a decrease in the extent of PRX nucleation being evaporation rate > PVP:PRX > PMW. The same rank order was found for the decrease in the extent of PRX crystal growth in PVP matrices from day 0 up to day 12. However, after 12 days the rank became PVP:PRX > evaporation rate > PMW. The effects of an increase in evaporation rate and PVP:PRX ratio in stabilizing PRX were of the same order of magnitude, while the effect from PMW was much smaller. The findings were confirmed by XRPD. FT-IR showed that PRX recrystallization in the PVP matrix followed Ostwald’s step rule, and an increase in the three Factors all led to increased hydrogen bonding interaction between PRX and PVP. The present study showed the applicability of the Quality by Design approach in solid dispersion research, and highlights the need for multiFactorial analysis.