title: Demand equations for qualitatively different foods under fixed-ratioschedules: a comparison of three data conversions

authors: Foster, T. Mary

subjects: fixed-ratio schedules

abstract: Concurrent schedules were used to establish 6 hens’ preferences for three foods. The resulting biases suggested wheat was preferred over honey-puffed and puffed wheat, and puffed wheat was the least preferred food. The hens then responded under fixed-ratio schedules for each food in 40-min (excluding reinforcer time) sessions, with the response requirement doubling each session until no reinforcers were received. At the smaller ratios, the less preferred the food, the faster the hens’ overall response rates (mainly as a result of shorter postreinforcement pauses) and the more reinforcers they received. The relations between the logarithms of the number of reinforcers obtained (consumption) and the response ratio (price) were well fitted by curvilinear demand functions. Wheat produced the smallest initial consumption (ln L), followed by honey-puffed and puffed wheat, respectively. The response requirement at which the demand functions predicted maximal responding (Pmax) were larger for wheat than for the other foods. Normalizing consumption and price, as suggested by Hursh and Winger (1995), moved the data for the three foods towards a single demand function; however, the Pmax values were generally largest for puffed wheat. The results of normalization, as suggested by Hursh and Silberberg (2008), depended on the k value used. The parameter k is related to the range of the data, and the same k value needs to be used for all data sets that are compared. A k value of 8.0 gave significantly higher essential values (smaller a values) for puffed wheat as compared to honey-puffed wheat and wheat, and the Pmax values, in normalized standard price units, were largest for puffed wheat. Normalizing demand by converting the puffed and honey-puffed wheat reinforcers to wheat equivalents (by applying the bias parameter from the concurrent-schedules procedure) maintained separate demand functions for the foods. Those for wheat had the smallest rates of change in elasticity (a) and, in contrast to the other analyses, the largest Pmax values. Normalizing demand in terms of concurrentschedule preference appears to have some advantages and to merit further investigation.

text: Demand equations for qualitatively different foods under fixed-ratioschedules: a comparison of three data conversions Concurrent schedules were used to establish 6 hens’ preferences for three foods. The resulting biases suggested wheat was preferred over honey-puffed and puffed wheat, and puffed wheat was the least preferred food. The hens then responded under fixed-ratio schedules for each food in 40-min (excluding reinforcer time) sessions, with the response requirement doubling each session until no reinforcers were received. At the smaller ratios, the less preferred the food, the faster the hens’ overall response rates (mainly as a result of shorter postreinforcement pauses) and the more reinforcers they received. The relations between the logarithms of the number of reinforcers obtained (consumption) and the response ratio (price) were well fitted by curvilinear demand functions. Wheat produced the smallest initial consumption (ln L), followed by honey-puffed and puffed wheat, respectively. The response requirement at which the demand functions predicted maximal responding (Pmax) were larger for wheat than for the other foods. Normalizing consumption and price, as suggested by Hursh and Winger (1995), moved the data for the three foods towards a single demand function; however, the Pmax values were generally largest for puffed wheat. The results of normalization, as suggested by Hursh and Silberberg (2008), depended on the k value used. The parameter k is related to the range of the data, and the same k value needs to be used for all data sets that are compared. A k value of 8.0 gave significantly higher essential values (smaller a values) for puffed wheat as compared to honey-puffed wheat and wheat, and the Pmax values, in normalized standard price units, were largest for puffed wheat. Normalizing demand by converting the puffed and honey-puffed wheat reinforcers to wheat equivalents (by applying the bias parameter from the concurrent-schedules procedure) maintained separate demand functions for the foods. Those for wheat had the smallest rates of change in elasticity (a) and, in contrast to the other analyses, the largest Pmax values. Normalizing demand in terms of concurrentschedule preference appears to have some advantages and to merit further investigation.

year: 2009

title: Effect of deer velvet on sexual function in men and their partners: A double-blind, placebo-controlled study

authors: Conaglen, Helen M.

subjects: sexual function

abstract: The use of alternative medicines and herbal remedies is an increasing trend in Western societies. For years, people have taken products made of deer velvet for their alleged beneficial effects on sexual function. There has been no scientific investigation of the effects of deer velvet powder on the sexual functioning of human males. This study investigated sexual function in men during a 12-week double-blind, placebo-controlled trial of deer velvet. Thirty-two volunteer male participants, aged 45–65 years, and their partners, were randomly assigned to either the deer velvet or placebo study group. The males took capsules containing ground deer velvet or placebo everyday for 12 weeks. Two sexual function questionnaires (the International Index of Erectile Function and the Brief Index of Sexual Function for Women) used at pre- and posttreatment assessed changes in sexual functioning in males and their partners. Blood tests at baseline, and end of study, determined levels of sex-related hormones in male participants. There were no significant differences in the sexual behavior of the men taking deer velvet compared with the men taking placebo capsules. There were no significant hormone changes from baseline to the end of the study in either group of men. We conclude that in normal males there was no advantage in taking deer velvet to enhance sexual function. All alternative health products or nutritional supplements should be subjected to randomized placebo-controlled trials to determine efficacy.

text: Effect of deer velvet on sexual function in men and their partners: A double-blind, placebo-controlled study The use of alternative medicines and herbal remedies is an increasing trend in Western societies. For years, people have taken products made of deer velvet for their alleged beneficial effects on sexual function. There has been no scientific investigation of the effects of deer velvet powder on the sexual functioning of human males. This study investigated sexual function in men during a 12-week double-blind, placebo-controlled trial of deer velvet. Thirty-two volunteer male participants, aged 45–65 years, and their partners, were randomly assigned to either the deer velvet or placebo study group. The males took capsules containing ground deer velvet or placebo everyday for 12 weeks. Two sexual function questionnaires (the International Index of Erectile Function and the Brief Index of Sexual Function for Women) used at pre- and posttreatment assessed changes in sexual functioning in males and their partners. Blood tests at baseline, and end of study, determined levels of sex-related hormones in male participants. There were no significant differences in the sexual behavior of the men taking deer velvet compared with the men taking placebo capsules. There were no significant hormone changes from baseline to the end of the study in either group of men. We conclude that in normal males there was no advantage in taking deer velvet to enhance sexual function. All alternative health products or nutritional supplements should be subjected to randomized placebo-controlled trials to determine efficacy.

year: 2003

title: Role of tephra in dating Polynesian settlement and impact, New Zealand

authors: Lowe, David J.

subjects: tephrochronology

abstract: Tephrochronology in its original sense is the use of tephra layers as time-stratigraphic marker beds to establish numerical or relative ages (Lowe and Hunt, 2001). Tephra layers have been described and studied in New Zealand for more than 160 years (the German naturalist and surgeon Ernst Dieffenbach described ‘recognizable’ tephra sections in his 1843 book Travels in New Zealand), and the first isopach map, showing fallout from the deadly plinian basaltic eruption of Mt Tarawera on 10 June 1886, was published in 1888 (Lowe, 1990; Lowe et al., 2002). More recently, a wide range of tephra-related paleoenvironmental research has been undertaken (e.g., Lowe and Newnham, 1999; Newnham and Lowe, 1999; Newnham et al., 1999, 2004; Shane, 2000), including new advances in the role of tephra in linking and dating sites containing evidence for abrupt climatic change (e.g., Newnham and Lowe, 2000; Newnham et al., 2003). Here we focus on the use of tephrochronology in dating the arrival and impacts of the first humans in New Zealand, a difficult problem for which this technique has proven to be of critical importance.

text: Role of tephra in dating Polynesian settlement and impact, New Zealand Tephrochronology in its original sense is the use of tephra layers as time-stratigraphic marker beds to establish numerical or relative ages (Lowe and Hunt, 2001). Tephra layers have been described and studied in New Zealand for more than 160 years (the German naturalist and surgeon Ernst Dieffenbach described ‘recognizable’ tephra sections in his 1843 book Travels in New Zealand), and the first isopach map, showing fallout from the deadly plinian basaltic eruption of Mt Tarawera on 10 June 1886, was published in 1888 (Lowe, 1990; Lowe et al., 2002). More recently, a wide range of tephra-related paleoenvironmental research has been undertaken (e.g., Lowe and Newnham, 1999; Newnham and Lowe, 1999; Newnham et al., 1999, 2004; Shane, 2000), including new advances in the role of tephra in linking and dating sites containing evidence for abrupt climatic change (e.g., Newnham and Lowe, 2000; Newnham et al., 2003). Here we focus on the use of tephrochronology in dating the arrival and impacts of the first humans in New Zealand, a difficult problem for which this technique has proven to be of critical importance.

year: 2004