Rotation and Radial Motion Thresholds Support a Two-Stage Model of Differential-Motion Analysis

Lower motion thresholds for rotational and radial flow have been measured for stimuli consisting of four closely packed circular apertures, each containing patches of drifting grating or plaid. Detection and direction thresholds were measured for gratings and plaids as a function of the relative orientation of the pattern components. There was a similarity between both types of threshold, supporting the existence of specialised rotation and radial-flow detectors. Further, thresholds increased with the relative component orientation for both gratings and plaids. This suggests that component information from a first stage, tuned spatiotemporally and to orientation, is being used directly to compute the optic flow in a two-stage process. A model based on this architecture is described by means of simple template receptive-field arrays with separable temporal and spatial tuning at the first stage.

Download Full-text

What drives the boom in outward FDI from India?

International Journal of Emerging Markets ◽

10.1108/ijoem-12-2017-0538 ◽

2020 ◽

Vol 15 (5) ◽

pp. 899-922 ◽

Cited By ~ 1

Author(s):

Munmi Saikia ◽

Khanindra Ch. Das ◽

Saundarjya Borbora

Keyword(s):

Prior Knowledge ◽

Design Methodology ◽

Probit Model ◽

Least Square ◽

Stage Model ◽

Outward Fdi ◽

Two Stage ◽

Content Type ◽

Ordinary Least Square ◽

Stage Process

PurposeThe Indian economy has experienced a boom in outward FDI (OFDI) in 2006. The study aims at exploring the factors that drive the boom in OFDI of Indian firms.Design/methodology/approachThe participation of a firm in OFDI is a two-stage process -first, the decision to internationalization and second, how much to invest. We employ a two-stage model to decompose the effects on the decision to internationalization from effects on how much to invest. The two-stage model has the advantage of allowing us to estimate separately the probability of internationalization by a firm – Pr(OFDI > 0) – and the expected volume of investment, E(OFDI|OFDI > 0). The former is estimated by the probit model and the latter is estimated by the ordinary least square model.FindingsThe study finds that prior experience and institutional advantage can strongly drive the internationalization of Indian multinationals. The study also examines the relative importance of two aspects of prior knowledge – length of prior knowledge and depth of prior knowledge on OFDI of Indian firms. The study finds that the depth of prior knowledge is a must influential driver of OFDI in comparison to its length.Originality/valueThe present study is a novel attempt to investigate, ‘What drives the boom in OFDI from India?’

Download Full-text

Timing of repeated movements: Test of a two-stage model

PsycEXTRA Dataset ◽

10.1037/e536982012-719 ◽

1997 ◽

Author(s):

Saul Sternberg ◽

Teresa Pantzer

Keyword(s):

Stage Model ◽

Two Stage

Download Full-text

Is oxidative stress the link in the two-stage model of pre-eclampsia?

The Lancet ◽

10.1016/s0140-6736(99)00284-6 ◽

1999 ◽

Vol 354 (9185) ◽

pp. 788-789 ◽

Cited By ~ 50

Author(s):

J Roberts

Keyword(s):

Oxidative Stress ◽

Stage Model ◽

Two Stage

Download Full-text

Two-Stage Model Averaging: An Application to Forecasting Stock Returns

SSRN Electronic Journal ◽

10.2139/ssrn.2362346 ◽

2013 ◽

Cited By ~ 1

Author(s):

Chandler Lutz

Keyword(s):

Stock Returns ◽

Model Averaging ◽

Stage Model ◽

Two Stage

Download Full-text

Nonlinear dynamics of pulsating detonation wave with two-stage chemical kinetics in the shock-attached frame

Journal of Inverse and Ill-Posed Problems ◽

10.1515/jiip-2020-0032 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Yaroslava E. Poroshyna ◽

Aleksander I. Lopato ◽

Pavel S. Utkin

Keyword(s):

Wave Propagation ◽

Detonation Wave ◽

Model Comparison ◽

Approximation Order ◽

Transition Regime ◽

Stage Model ◽

Two Stage ◽

One Dimensional ◽

Kinetics Of ◽

Detonation Wave Propagation

Abstract The paper contributes to the clarification of the mechanism of one-dimensional pulsating detonation wave propagation for the transition regime with two-scale pulsations. For this purpose, a novel numerical algorithm has been developed for the numerical investigation of the gaseous pulsating detonation wave using the two-stage model of kinetics of chemical reactions in the shock-attached frame. The influence of grid resolution, approximation order and the type of rear boundary conditions on the solution has been studied for four main regimes of detonation wave propagation for this model. Comparison of dynamics of pulsations with results of other authors has been carried out.

Download Full-text

Two-Stage Biodiesel Synthesis from Used Cooking Oil with a High Acid Value via an Ultrasound-Assisted Method

Energies ◽

10.3390/en14123703 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3703

Author(s):

Ming-Chien Hsiao ◽

Wei-Ting Lin ◽

Wei-Cheng Chiu ◽

Shuhn-Shyurng Hou

Keyword(s):

Acid Value ◽

Molar Ratio ◽

Optimal Conditions ◽

Two Stage ◽

Cooking Oil ◽

High Acid ◽

Used Cooking Oil ◽

Biodiesel Synthesis ◽

Stage Process ◽

Ultrasound Assisted

In this study, ultrasound was used to accelerate two-stage (esterification–transesterification) catalytic synthesis of biodiesel from used cooking oil, which originally had a high acid value (4.35 mg KOH/g). In the first stage, acid-catalyzed esterification reaction conditions were developed with a 9:1 methanol/oil molar ratio, sulfuric acid dosage at 2 wt %, and a reaction temperature of 60 °C. Under ultrasound irradiation for 40 min, the acid value was effectively decreased from 4.35 to 1.67 mg KOH/g, which was decreased to a sufficient level (<2 mg KOH/g) to avoid the saponification problem for the subsequent transesterification reaction. In the following stage, base-catalyzed transesterification reactions were carried out with a 12:1 methanol/oil molar ratio, a sodium hydroxide dosage of 1 wt %, and a reaction temperature of 65 °C. Under ultrasound-assisted transesterification for 40 min, the conversion rate of biodiesel reached 97.05%, which met the requirement of EN 14214 standard, i.e., 96.5% minimum. In order to evaluate and explore the improvement of the ultrasound-assisted two-stage (esterification–transesterification) process in shortening the reaction time, additional two-stage biodiesel synthesis experiments using the traditional mechanical stirring method under the optimal conditions were further carried out in this study. It was found that, under the same optimal conditions, using the ultrasound-assisted two-stage process, the total reaction time was significantly reduced to only 80 min, which was much shorter than the total time required by the conventional method of 140 min. It is worth noting that compared with the traditional method without ultrasound, the intensification of the ultrasound-assisted two-stage process significantly shortened the total time from 140 min to 80 min, which is a reduction of 42.9%. It was concluded that the ultrasound-assisted two-stage (esterification–transesterification) catalytic process is an effective and time-saving method for synthesizing biodiesel from used cooking oil with a high acid value.

Download Full-text