Gravity receptors and responses

The overall process of gravity sensing and response processes in plants may be divided conveniently into at least four components or stages: Stimulus susception (a physical event, characteristically the input to the G receptor system of environmental information about the G force magnitude, its vector direction, or both); information perception (an influence of susception on some biological structure or process that can be described as the transformation of environmental information into a biologicallly meaningful change); information transport (the export, if required, of an influence (often chemical) to cells and organs other than those at the sensor location); and biological response (almost always (in plants) a growth change of some kind). Some analysts of the process identify, between information perception and information transport, an additional stage, transduction, which would emphasize the importance of a transformation from one form of information to another, for example from mechanical statolith displacement to an electric, chemical, or other alteration that was its indirect result. These four (or five) stages are temporally sequential. Even if all that occurs at each stage can not be confidently identified, it seems evident that during transduction and transport, matters dealt with are found relatively late in the information flow rather than at the perception stage. As more and more is learned about the roles played by plant hormones which condition the G responses, the mechanism(s) of perception which should be are not necessarily better understood. However, if by asking the right questions and being lucky with experiments perhaps the discovery of how some process (such as sedimentation of protoplasmic organelles) dictates what happens down stream in the information flow sequence may be made

Situated cognition and the culture of learning

Includes bibliographical references (p. 16-17

A provisional survey of the interaction between net photosynthetic rate, respiratory rate, and thallus water content in some New Zealand cryptogams

The effect of water content on photosynthetic and respiratory rates in eight lichen species and one bryophyte species were studied using an injection infrared gas analyser technique. All species snowed a strong relationship between net assimilation rate (NAR), respiration rate, and water content similar to relationships reported in published studies overseas. Species from moist habitats showed negative NAR at low water contents. Species from high-light areas showed a depression in NAR at high water contents which could be alleviated by higher light intensities. The experiments confirmed the suitability of New Zealand species for these studies

Cognitive apprenticeship : teaching the craft of reading, writing, and mathtematics

Includes bibliographical references (p. 25-27)This research was supported by the National Institute of Education under Contract no. US-NIE-C-400-81-0030 and the Office of Naval Research under Contract No. N00014-85-C-002

Charged Schrodinger Black Holes

We construct charged and rotating asymptotically Schrodinger black hole solutions of IIB supergravity. We begin by obtaining a closed-form expression for the null Melvin twist of a broad class of type IIB backgrounds, including solutions of minimal five-dimensional gauged supergravity, and identify the resulting five-dimensional effective action. We use these results to demonstrate that the near-horizon physics and thermodynamics of asymptotically Schrodinger black holes obtained in this way are essentially inherited from their AdS progenitors, and verify that they admit zero-temperature extremal limits with AdS_2 near-horizon geometries. Notably, the AdS_2 radius is parametrically larger than that of the asymptotic Schrodinger space.Comment: 22 pages, LaTe

Reversal of cardiac dysfunction by selective ET-A receptor antagonism

1. The effectiveness of a selective endothelin receptor-A (ET-A) antagonist, A-127722 (approximately 10 mg kg-1 day-1 as 200 mg kg-1 powdered food), to reverse existing cardiac remodelling and prevent further remodelling was tested in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. 2. Uninephrectomised rats (UNX) administered DOCA (25mg every 4th day sc) and 1% NaCl in drinking water for 28 days developed hypertension (systolic BP: UNX 128 6, DOCA-salt 182 5* mmHg; *P<0.05 vs UNX), left ventricular hypertrophy (UNX 1.99 0.06, DOCA-salt 3.30 0.08* mg/kg body wt), decreased left ventricular internal diameter (UNX 6.69 0.18, DOCA-salt 5.51 0.37* mm), an increased left ventricular monocyte/macrophage infiltration together with an increased interstitial collagen from 2.7 0.3 to 11.7 1.3%, increased passive diastolic stiffness (UNX 21.1 0.5, DOCA-salt 30.1 1.3*), prolongation of the action potential duration at 20% and 90% of repolarization (APD20 - UNX 6.8 1.1, DOCA-salt 10.1 1.5* msec; APD90 - UNX 34.4 3.5, DOCA-salt 64.3 10.4* msec) and vascular dysfunction (2.6 fold decrease in maximal contractile response to noradrenaline, 3.5 fold decrease in maximal relaxation response to acetylcholine). 3. Administration of A-127722 for 14 days starting 14 days after surgery attenuated the increases in systolic blood pressure (150 6** mmHg, **P<0.05 vs DOCA-salt), left ventricular wet weight (2.65 0.06** mg/kg body wt) and internal diameter (6.39 0.31** mm), prevented left ventricular monocyte/macrophage accumulation, attenuated the increased left ventricular interstitial collagen (7.6 1.3%**), reversed the increased passive diastolic stiffness (22.1 1.2**), attenuated the action potential duration prolongation (APD20 - 7.6 1.4**, APD90 - 41.5 6.9** msec) and normalized changes in vascular function. 4. ET-A receptor antagonism both reverses and prevents the cardiac and vascular remodelling in DOCA-salt hypertension and improves cardiovascular function

Blackening of photographic materials by means of low voltage cathode rays

Work undertaken was to determine the effect of cathode rays photographic materials. It was desired to find the relations between the voltage of the cathode rays and blackening, and the total charge received by the film and the blackening;Special apparatus was designed for carrying out this work, exposures being made a specially constructed vacuum chamber of brass. The apparatus differed from apparatus previously used for this type of work in that a special camera was provided which made exposures on a film moving past a slit through which the electrons entered the camera. The slit was half v-shaped, giving a variable charge on each film. Data for the relation between voltage and blackening were then taken from the curves obtained for the total charge-density curves;The conclusions are as follows: (1) the range studied, namely 2 to 20 coulombs/cm.2, the density produced by development is linear with respect to the total charge received except for the very low values where the curves have a tendency to drop rapidly. (2) In the range studied, namely 100 to 500 volts, the density produced by development is a linear function of the voltage

Noise performance of the Klapper-Kratt low delay FM detector

In this dissertation the dual differentiator version of the Klapper-Kratt FM detector family is investigated with additive Gaussian noise. Prior analysis of this new detector family has been limited to the noiseless case. The investigation was conducted both analytically and experimentally. First, the dual differentiator version of the Klapper-Kratt detector was mathematically analyzed, assuming an unmodulated carrier plus additive Gaussian noise. This analysis was verified by assembling the detector and measuring its performance in the laboratory. It was discovered that the Klapper-Kratt detector without limiter performs identically to the conventional limiter discriminator in the linear improvement region. When compared to the limiter discriminator, threshold occurs at a higher CNR in the new detector (without limiter). When a limiter is added to the Klapper-Kratt detector, the new detector exhibits the same threshold as that of the limiter discriminator. The detector was found to have extremely low delay and wide bandwidth. The analytical and experimental results were nearly identical

Small Groups and the Sabbath School

Problem: The Seventh-day Adventist Church is experiencing world-wide growth. At the same time the Church is North America and Australia is faced with a decline in the percentage of members who are attending Sabbath School. This decline over the past decade and more has occurred in Sabbath School, which normally offers members small study classes. Yet the use of small groups is recognised by church growth leaders as an important factor in helping churches grow. The purpose of this research is to enquire whether the dynamics of small groups will enhance the effectiveness of Sabbath School classes to attract and retain members. Method: A Biblical understanding of the nature of the church and her relationship with Christ was sought, in order to draw insights and emphases from the New Testament about small groups. This laid the foundation for enquiring about the role of small groups in church growth today, and the dynamics that social scientists believe operate within small groups. This study has enabled the development of a small group experiment as a dynamic learning experience to observe group growth and the impact of group experience on a Sabbath School class. Procedure: Members of the church became the personnel of both a newly formed small group and a Sabbath School class. This ministry project applied the principles of effective group development - both spiritual and social - to a series of Tuesday evening meetings over five months. Essentially the same group of people met in a small Sabbath School class for four and one-half months. Assessing instruments were given to the group members and also a control Sabbath School class. Results: There were positive indications of a growing fellowship within the small group which increased acceptance and trust as members became more willing to reveal their formerly little known selves. Participation became more balanced at group meetings, and the social interaction presented greater opportunity for members to help one another in mutual ministry. There is reason to believe that this has considerable bearing upon an increased attitude of satisfaction with Sabbath School and class interaction in particular. Members of the group have made a decided choice to continue their developing group experience and Sabbath School class beyond the term of experimentation and without the presence of the researcher. This indicates the sense of identity and belonging which has grown and can now be channelled into the task of group evangelism. Conclusion: Considerable encouragement is derived from this study which suggests that the effectiveness of Sabbath School classes can be increased by the association of class members in close proximity as a small group meeting for spiritual and social interaction. The enrichment derived from implementing small group dynamics may indicate a growing significance for the establishment of small groups within the church structure of celebration, congregation, and cell, for individual development, church maintenance, and evangelistic task