title: Components and tidal modulation of the wave field in a semi-enclosed shallow bay

authors: WinklerPrins, L

abstract: The wave fields of coastal bays are comprised of waves generated by far-off storms that enter the bay to combine with waves generated locally by winds inside the bay and regionally outside the bay. In any given location, the resultant wave field varies spatially and temporally, and affects coastal features, such as beaches in estuaries and bays (BEBs). However, wave fields in enclosed bays with tidal shoals are poorly studied, limiting the efficacy of coastal protection and restoration projects in these systems, a critical focus in light of ongoing sea level rise. Here we present observations of the wave field in Tomales Bay, a 20-km-long, narrow, semi-enclosed embayment on the wave-dominated coast of Northern California (USA) with a spring-tide range of 2.5 m. We deployed pressure sensors near several beaches along the linear axis of the bay. Low-frequency waves (4∗10−2−2.5∗10−1 Hz or 4–25-s period) were not observed further than 4 km of the mouth, delineating the “outer bay” region, where remotely generated swell and regionally generated wind waves could dominate. The wave spectrum of the landward “inner bay” was dominated by fetch-limited waves generated within the bay with frequency ≥2.5∗10−1Hz. The energy of both ocean waves and locally generated wind waves across all sites were controlled by the tide, but the former by changes in attenuation and the latter likely by modulation of wave generation. Wave energies were low at low tide and high at high tide, but high-frequency wind wave energy was increased during ebb tides while lower-frequency swell energy was reduced during ebb tides, suggesting different mechanisms of tidal influences. Thus, in addition to fluctuations in winds and the presence of ocean waves, tides exert a strong control on the wave energy spectra at coastal features in mesotidal regions. In general, events that may be impactful for BEB morphology are expected to occur when waves due to high winds or high-swell event arrive during high-tide periods. However, no such events were observed during our study and questions remain as to how rarely such events occur across the bay.

text: Components and tidal modulation of the wave field in a semi-enclosed shallow bay The wave fields of coastal bays are comprised of waves generated by far-off storms that enter the bay to combine with waves generated locally by winds inside the bay and regionally outside the bay. In any given location, the resultant wave field varies spatially and temporally, and affects coastal features, such as beaches in estuaries and bays (BEBs). However, wave fields in enclosed bays with tidal shoals are poorly studied, limiting the efficacy of coastal protection and restoration projects in these systems, a critical focus in light of ongoing sea level rise. Here we present observations of the wave field in Tomales Bay, a 20-km-long, narrow, semi-enclosed embayment on the wave-dominated coast of Northern California (USA) with a spring-tide range of 2.5 m. We deployed pressure sensors near several beaches along the linear axis of the bay. Low-frequency waves (4∗10−2−2.5∗10−1 Hz or 4–25-s period) were not observed further than 4 km of the mouth, delineating the “outer bay” region, where remotely generated swell and regionally generated wind waves could dominate. The wave spectrum of the landward “inner bay” was dominated by fetch-limited waves generated within the bay with frequency ≥2.5∗10−1Hz. The energy of both ocean waves and locally generated wind waves across all sites were controlled by the tide, but the former by changes in attenuation and the latter likely by modulation of wave generation. Wave energies were low at low tide and high at high tide, but high-frequency wind wave energy was increased during ebb tides while lower-frequency swell energy was reduced during ebb tides, suggesting different mechanisms of tidal influences. Thus, in addition to fluctuations in winds and the presence of ocean waves, tides exert a strong control on the wave energy spectra at coastal features in mesotidal regions. In general, events that may be impactful for BEB morphology are expected to occur when waves due to high winds or high-swell event arrive during high-tide periods. However, no such events were observed during our study and questions remain as to how rarely such events occur across the bay.

year: 2023-12-02

title: Body Weight as a Motivating Operation: The Effect of Body Weight on Demand for Food in Hens.

authors: Andrews, Tegan Emily Anne-Marie

abstract: Demand for wheat and puffed wheat was examined in six hens, using an ascending geometric progression of fixed-ratio schedules of reinforcement. Hens responded by pecking a key for 2-s access to food in 40-min sessions. The body weight criterion used to decide if a hen was to be placed in an experimental session differed across conditions, to determine if this would affect performance, using wheat and puffed wheat as reinforcers in different conditions. In the first experiment the hens were maintained by post-session feeding at 80 ± 5% of their free-feeding body weights. In Conditions 1 and 2 the hens were placed in a session even when they were more than 5 % above the target weight. In Conditions 3 and 4 they were placed in a session if their body weight was within the specified range, meaning there could be several days between sessions. There were clear differences resulting from food type, both in behaviour under the fixed ratio schedules, and in the resulting demand functions (with consumption measured as either number of reinforcers or weight of food obtained). Wheat resulted in lower overall response rates than puffed wheat at low fixed ratio values. The body weight criterion did not result in large effects on performance, however, the more relaxed body weight criterion gave a higher essential value for puffed wheat than for wheat (replicating Foster et al., 2009), whereas, the strict body weight criterion gave a lower essential value for puffed wheat than for wheat under the analysis proposed by Hursh and Silberberg (2008) and using number of reinforcers as the consumption measure. A second experiment replicated Jackson (2011), using the same two foods, strict body weight criteria and sessions which terminated after 40 reinforcers or 40-min. The resulting data were similar to Jackson (2011), who found similar performance for both foods. The difference between the demand functions for the two foods, with reinforcer rate as the consumption measure, were greatly reduced in comparison to Experiment 1. The essential value of the two foods was not consistently different across hens. These results suggest that the session termination criterion did affect demand.

text: Body Weight as a Motivating Operation: The Effect of Body Weight on Demand for Food in Hens. Demand for wheat and puffed wheat was examined in six hens, using an ascending geometric progression of fixed-ratio schedules of reinforcement. Hens responded by pecking a key for 2-s access to food in 40-min sessions. The body weight criterion used to decide if a hen was to be placed in an experimental session differed across conditions, to determine if this would affect performance, using wheat and puffed wheat as reinforcers in different conditions. In the first experiment the hens were maintained by post-session feeding at 80 ± 5% of their free-feeding body weights. In Conditions 1 and 2 the hens were placed in a session even when they were more than 5 % above the target weight. In Conditions 3 and 4 they were placed in a session if their body weight was within the specified range, meaning there could be several days between sessions. There were clear differences resulting from food type, both in behaviour under the fixed ratio schedules, and in the resulting demand functions (with consumption measured as either number of reinforcers or weight of food obtained). Wheat resulted in lower overall response rates than puffed wheat at low fixed ratio values. The body weight criterion did not result in large effects on performance, however, the more relaxed body weight criterion gave a higher essential value for puffed wheat than for wheat (replicating Foster et al., 2009), whereas, the strict body weight criterion gave a lower essential value for puffed wheat than for wheat under the analysis proposed by Hursh and Silberberg (2008) and using number of reinforcers as the consumption measure. A second experiment replicated Jackson (2011), using the same two foods, strict body weight criteria and sessions which terminated after 40 reinforcers or 40-min. The resulting data were similar to Jackson (2011), who found similar performance for both foods. The difference between the demand functions for the two foods, with reinforcer rate as the consumption measure, were greatly reduced in comparison to Experiment 1. The essential value of the two foods was not consistently different across hens. These results suggest that the session termination criterion did affect demand.

year: 2014

title: Perceptions, expectations and interactions: a study of teachers and pupils in five ethnically mixed primary classrooms

authors: St George, Alison

abstract: Teachers’ perceptions of their pupils, expectations for pupil general ability, teacher-pupil interaction and pupil achievement were investigated in this naturalistic study of 5 teachers and 90 pupils in their New Zealand ethnically mixed Standard 3 classrooms.
A pilot study showed that teachers at this level tended to perceive pupils in terms of constructs reflecting academic work skills, home background and personal/social attributes. Using rating scales developed from the pilot study it was apparent that the teachers had a conception of the ideal pupil. It was suggested that this influenced expectations for pupils’ ability to do well at school. Girls and Pakeha pupils were seen as being closer to the ideal pupil stereotype than boys or Polynesian pupils, and for Polynesian pupils this was reflected in lower teacher expectations. Teacher expectations tended to be borne out by standardized achievement test results and accounted for a large proportion of teacher rated achievement variance. Ethnic group made a small but significant independent contribution to achievement variance on two of the Progressive Achievement Tests and on teacher rated achievement.
Using data on teacher-pupil dyadic interaction collected with the Brophy-Good system, contrasting patterns of interaction were noted between expectation groups (high, middle and low teacher expectations). The differences were largely qualitative and there were no expectation group differences in the total number of public or private dyadic interactions. High expectation pupils initiated more contacts with the teacher, answered more open public academic questions and received a lot less criticism for work or behaviour than the other groups. The low expectation group experienced a greater proportion of teacher initiated contacts and were asked more direct public academic questions which were of the product rather than the process type. The middle expectation group generally fell in between the high and low groups, but received the most criticism and the highest proportion of process questions. Teachers appeared to be attempting to prevent inequalities in quantity of interaction and this was discussed in terms of the perception of pupil attributes. Expectation group differences in interaction were not always the same for boys and girls or for all teachers. Despite the differences in teachers’ perceptions and expectations for Polynesian and Pakeha pupils, no ethnic group differences in teacher-pupil interaction were evidenced. 
No consistent and clear-cut expectation group differences were found in pupils’ perceptions of teacher behaviour. There was a moderate positive correlation between perception of the quantity of teacher contact and observed interaction but not regarding the affective quality of teacher contacts. 
The findings were discussed in terms of the theory and research on person perception and expectation phenomena in interpersonal behaviour. Some practical implications for educational practice were commented upon.

text: Perceptions, expectations and interactions: a study of teachers and pupils in five ethnically mixed primary classrooms Teachers’ perceptions of their pupils, expectations for pupil general ability, teacher-pupil interaction and pupil achievement were investigated in this naturalistic study of 5 teachers and 90 pupils in their New Zealand ethnically mixed Standard 3 classrooms.
A pilot study showed that teachers at this level tended to perceive pupils in terms of constructs reflecting academic work skills, home background and personal/social attributes. Using rating scales developed from the pilot study it was apparent that the teachers had a conception of the ideal pupil. It was suggested that this influenced expectations for pupils’ ability to do well at school. Girls and Pakeha pupils were seen as being closer to the ideal pupil stereotype than boys or Polynesian pupils, and for Polynesian pupils this was reflected in lower teacher expectations. Teacher expectations tended to be borne out by standardized achievement test results and accounted for a large proportion of teacher rated achievement variance. Ethnic group made a small but significant independent contribution to achievement variance on two of the Progressive Achievement Tests and on teacher rated achievement.
Using data on teacher-pupil dyadic interaction collected with the Brophy-Good system, contrasting patterns of interaction were noted between expectation groups (high, middle and low teacher expectations). The differences were largely qualitative and there were no expectation group differences in the total number of public or private dyadic interactions. High expectation pupils initiated more contacts with the teacher, answered more open public academic questions and received a lot less criticism for work or behaviour than the other groups. The low expectation group experienced a greater proportion of teacher initiated contacts and were asked more direct public academic questions which were of the product rather than the process type. The middle expectation group generally fell in between the high and low groups, but received the most criticism and the highest proportion of process questions. Teachers appeared to be attempting to prevent inequalities in quantity of interaction and this was discussed in terms of the perception of pupil attributes. Expectation group differences in interaction were not always the same for boys and girls or for all teachers. Despite the differences in teachers’ perceptions and expectations for Polynesian and Pakeha pupils, no ethnic group differences in teacher-pupil interaction were evidenced. 
No consistent and clear-cut expectation group differences were found in pupils’ perceptions of teacher behaviour. There was a moderate positive correlation between perception of the quantity of teacher contact and observed interaction but not regarding the affective quality of teacher contacts. 
The findings were discussed in terms of the theory and research on person perception and expectation phenomena in interpersonal behaviour. Some practical implications for educational practice were commented upon.

year: 1978