Tripping Mechanism Research Articles

Pollination Mechanisms of Ebenus cretica

Ebenus cretica L., is an endemic plant of Crete with potential as a cut flower or flowering potted plant. It is a herbaceous perennial evergreen subshrub that flowers from April to June. It forms numerous thick racemes with an average of 50 pink or purple flowers 10 to 12 mm long. A great variability in major morphological characteristics exists among the populations of E. cretica on the island; however, color variants are very rare. Selection and breeding is a necessary prerequisite before the plant is marketable; therefore, research conducted at the TEI of Heraklion since 1994 has focused on artificial self- and cross-pollination of pink-flowered ebenus plants. It has been concluded that the zygomorphic flowers of E. cretica are pollinated by insects (bumblebees); the tripping mechanism occurs and seeds are formed by either cross- or self-pollination. For self-pollination, unripe flower racemes were enveloped in paper bags and shaken by hand or wind to release pollen; however, this method gave poor results. Best results were obtained by tripping the flowers while avoiding the introduction of foreign pollen. Self-incopatibility was not observed. Cross-pollination was achieved by emasculating flowers on the female parent, 2 to 4 days prior to the dehiscence of the anthers. The corolla is half-white and half-pink at this stage, turning to a uniform pink when the pollen is ripe. The stigma appears to be fully receptive at least 2 days before the dehiscence of the anthers. Each fertilized ovule gives one mature seed ≈3 weeks after pollination. This research indicates that breeding techniques can be applied without difficulty to E. cretica in order to develop uniform plant material and new varieties/hybrids with desirable characteristic.

Propiedades mecánicas y mecanismos de deformación en aleaciones del sistemas Fe-xMn-3,2Al-0,2C (12 ≤ x ≤ 43)

Microstructure and mechanical properties of Fe-xMn-3,2Al-0,23C alloys with 12 ≤ x ≤ 43 (mass %) at 77 and 290 K have been studied to determine the mechanisms controlling plastic deformation. Austenitic alloys (Mn ≥ 22) show an increase of elongation to failure with decreasing temperature of testing (inverse ductility). This behavior has been related to formation of deformation twins, which is favored at 77 K. Alloys with manganese content lower than 17 % present a two-phase microstructure (α' + γ). The martensite volume fraction increases as the manganese content decreases. These alloys show a loss of ductility, especially at 77 K. In contrast to asutenitic alloys, this different mechanical behavior has been associated with a TRIP mechanism (transformationinduced plasticity).

Analysis of a circuit breaker solenoid actuator system using the decoupled CAD-FE-integral technique

A decoupled three-dimensional CAD (computer-aided-design) finite-element-integral method, combined with the Runge-Kutta method, is offered to determine the dynamic characteristics and design requirements of a circuit breaker solenoid actuator, when energized from a DC supply. The model couples the electric, magnetic, and mechanical systems of the device. The presented solution takes account of the nonlinear magnetic material properties, the dimensions of the magnetic circuit, the coil parameters, and load of the trip mechanism system. The predicted dynamic characteristics from the analysis correlate closely with the results from the test performed on the actuator and demonstrate the applicability of the proposed techniques to the optimization of circuit breaker actuator performance and electromagnetic solenoid design. >

Reproductive Biology of Diploid and Triploid Apios americana (Leguminosae)

Apios americana Medicus (Leguminosae; Phaseoleae), a tuberous, herbaceous vine, consists of diploid and triploid clones which are morphologically nearly identical. Although A. americana is widespread in eastern North America and flowers profusely throughout its range, fruit set is low. In part, this is because populations north of Connecticut consist almost exclusively of sterile triploid individuals. Although triploid populations occur south of this region, diploids predominate. Fruit set is also low in diploids. We attribute this to partial self-incompatibility and to a low rate of floral visits by leaf-cutter bees (Megachile spp.), the only legitimate pollinator. Visitation is easily measured because flowers have a nonrepetitive explosive tripping mechanism which must be triggered by insects. In two Connecticut populations only 10% of 299 flowers were tripped, and on average only about one-half of these set fruit. We conclude that A. americana maintains populations by vegetative propagation, but expands its range and retains variability through sexual reproduction of diploids.

REPRODUCTIVE BIOLOGY OF DIPLOID AND TRIPLOID APIOS AMERICANA (LEGUMINOSAE)

Apios americana Medicus (Leguminosae; Phaseoleae), a tuberous, herbaceous vine, consists of diploid and triploid clones which are morphologically nearly identical. Although A. americana is widespread in eastern North America and flowers profusely throughout its range, fruit set is low. In part, this is because populations north of Connecticut consist almost exclusively of sterile triploid individuals. Although triploid populations occur south of this region, diploids predominate. Fruit set is also low in diploids. We attribute this to partial self‐incompatibility and to a low rate of floral visits by leaf‐cutter bees (Megachile spp.), the only legitimate pollinator. Visitation is easily measured because flowers have a nonrepetitive explosive tripping mechanism which must be triggered by insects. In two Connecticut populations only 10% of 299 flowers were tripped, and on average only about one‐half of these set fruit. We conclude that A. americana maintains populations by vegetative propagation, but expands its range and retains variability through sexual reproduction of diploids.

Breeding systems and pollination inVigna minima (Leguminosae, Papilionoideae)

Four types of floral breeding systems—(i) chasmogamy, (ii) aerial pseudocleistogamy, (iii) subterranean pseudocleistogamy and (iv) obligate subterranean true cleistogamy—are observed in the populations ofVigna minima inhabiting the Western Ghats (India). Five categories of phenotypes are recognized based on the number and kinds of floral breeding systems found in a given individual. The frequencies of different categories of phenotypes not only show intra- and interpopulation variation, but also fluctuate from generation to generation suggesting differences in the genetic structure of populations. This polymorphism in the breeding system of a single species is unique and may be adaptive. Obligate subterranean true cleistogamy and amphicarpy appear to be adaptations to jungle fires and soil erosion.—The flowers are of the flag-blossom type and insect visitors act as tripping agents. The tripping mechanism together with the polymorphic floral breeding system result in a balanced mixture of selfing and outcrossing. Such a recombination system may enhance the fitness ofV. minima which is essentially a colonizing species.

Siphocampylus oscitans (Campanulaceae: Lobelioideae), A New Name for Burmeistera Weberbaueri from Peru

Burmeistera weberbaueri is transferred to the genus Siphocampylus under the new name Siphocampylus oscitans. The species is noteworthy in being one of only three species of Siphocampylus known to have a dilated anther-tube orifice. As part of a reassessment of the Peruvian members of Burmeistera (Stein, 1987), it has become apparent that B. weberbaueri Zahlbr. actually belongs to the large Andean genus Siphocampylus. This paper makes the appropriate generic transfer and proposes a new name to accommodate this unusual species. Generic delimitations in Campanulaceae subfamily Lobelioideae have long been recognized as problematic (Gleason, 1925; McVaugh, 1940). Traditional systems, such as those of Presl (1836) and Wimmer (1943), rely heavily on fruit morphology for classification at the tribal level. In particular, capsular versus baccate fruit is a fundamental character used to define and align genera. Strict reliance on this dichotomy in the classification ofthe subfamily has separated close relatives, for example, capsular-fruited Siphocampylus and baccate-fruited Centropogon. Although fruit type in conjunction with other features can be reliable for clustering related groups of species, probable convergence in fruit characters suggests caution in its application. Among neotropical Lobelioideae the emphasis on fruit type, and to a lesser degree on the presence or extent of a dorsal slit in the corolla (another seemingly labile character), has yielded _genera .of convenience. -aOze of-the most natural groupings, however, appears to be the genus Burmeistera, which is characterized by baccate fruits, oblong or linear seeds, mostly nonbracteolate pedicels, entire corolla tubes, and distally open and oblique anther tubes often with little or no apical pubescence. The distally open anther tube of Burmeistera is one of its most distinctive features. In most genera of Lobelioideae the three dorsal anthers are longer than the two ventral ones and curve downward at the apex, effectively closing the mouth of the anther tube. This allows the internally released pollen to build up pressure as the style and stigma elongate, pushing pistonlike through the anther tube. The characteristic tuft of stiff hairs at the tip of the ventral anthers functions as a lever that opens the orifice slightly and allows the pressurized pollen to discharge. Presumably tripped by flower visitors, this action has been elegantly documented in Isotoma petraea by Brantjes (1983) and has been observed in the neotropical genera Centropogon and Siphocampylus (Stein, in prep.). Since the dorsal anthers in Burmeistera do not curve downward closing the anther tube, this type of regulated pollen discharge does not occur. This difference in pollen presentation probably explains the correlated feature of glabrous or only sparsely pilose anther apices in Burmeistera sect. Imberbes F. Wimmer: apical hairs there have no function as trip mechanisms. Whether the densely villous tuft at the tip of the ventral anthers in Burmeistera sect. Barbatae F. Wimmer has a functional role -in.pollen d-ischarge is not clear. Burmeistera weberbaueri was included in this genus by Zahlbruckner (1906) on the basis of floral features alone, as he had no mature fruit. This decision was probably based upon his observation of a naked and dilated anther-tube orifice, the absence of bracteoles, and the somewhat I I am grateful to Carlos Reynal for locating the type specimen at MOL and to B. E. Leuenberger for searching for type material at B. Dan H. Nicolson kindly provided advice regarding lectotypification, and Porter P. Lowry II and Peter Goldblatt made useful suggestions on-an earlier draft. Fieldwork in Peru was supported by National Science Foundation Doctoral Dissertation Improvement Grant BSR84-13912 and by a Garden Club of America Award in Tropical Botany. 2 Missouri Botanical Garden and Washington University. P.O. Box 299, St. Louis, Missouri 63166-0299, U.S.A. ANN. MissouRI BOT. GARD. 74: 491-493. 1987. This content downloaded from 207.46.13.43 on Wed, 25 May 2016 04:52:59 UTC All use subject to http://about.jstor.org/terms 492 ANNALS OF THE MISSOURI BOTANICAL GARDEN [VOL. 74 burmeisteroid corolla morphology (a short, straight tube with an abruptly ampliate throat and falcate lobes). The strongly turbinate hypanthium visible in the Field Museum type photograph suggests the mature fruit of this species to be capsular rather than baccate. Furthermore, the coriaceous and rugose texture of the leaves characterizes many members of Siphocampylus but is unknown in Burmeistera. An open anthertube orifice of the kind described by Zahlbruckner is, however, extremely rare in Siphocampylus.

An analysis of multiple captures in Permoyscus with a critique on methodology

Multiple captures obtained in Sherman traps are reported for Peromyscus maniculatus (66 intraspecific, 6 interspecific) and P. difficilis (12 intraspecific, 4 interspecific) in Colorado. Multiple capture frequency in P. maniculatus. (3.53%) was higher than in P. difficilis (1.94%), which probably resulted from the greater weights of P. difficilis. Only one case of injury or death was noted in 84 multiple captures. Multiple captures occurred in traps in which the treadles were significantly less sensitive to tripping than traps that captured single mice, which suggested that pairs of mice did not enter the traps simultaneoulsy. Adult mice were disproportionatley sampled in single captures because of the insensitivity of the tripping mechanism. For the same reason, immature mice were disproportionately sampled in multiple captures. These trap-related biases can create spurious age and sex associations within multiple captures. Trap bias should be tested explicitly before attempting to analyze multiple-capture data from single-capture traps. A "socially null" model of random encounter of traps by captured pairs fits many of the data presented here and is suggested as the appropriate null hypothesis for these analyses. If live-trapping data must be used to address questions of social behavior, the use of actual multiple-capture traps, preferably to study long-term associations between individuals, is suggested.

A simple water and plankton sampler

SUMMARY. A lightweight, free‐flushing water and plankton sampler constructed of readily available, inexpensive material is described. Easily interchangeable tubes of varying volumes allow sampling flexibility. The sampler is activated by a messenger and is shut by two plastic funnels. For analyses in highly stratified waters, the sampler can be adjusted into the horizontal position. Several samplers may be tripped in series. The sampler has proved a versatile and reliable instrument in ecological studies.The tripping mechanism may also be used to release reversing thermometers and closing nets.

On the effects of intercritical tempering on the impact energy of Fe-9Ni-0.1C

The effects of intercritical tempering on the impact energy of Fe-9Ni-0.1C have been investigated. The Charpy V-notch energy at all test temperatures between 77 and 300 K increased with increasing precipitated and retained austenite up to concentrations of austenite of ≈ 14% and then decreased. Evidence for a mechanically-induced austenite → martensite transformation in the plastic zone preceding the crack tip was obtained using Mössbauer effect scattering from the fracture surface. The contribution to the impact energy from this localized TRIP mechanism is shown to be negligible compared with the scavenging effect of the austenite, removing deleterious impurities from the martensite and increasing its toughness. The decrease in impact energy for austenite concentrations in excess of ≈ 14% is attributed to the development of a nearly continuous network of austenite in interlath and prior austenite boundaries. In the plastic zone ahead of the crack, this network is transformed into brittle, untempered martensite, providing a low energy path for the advancing crack.

A Water Sampler Employing a Solenoid Tripping Mechanism

A Water Sampler Employing a Solenoid Tripping Mechanism

Anatomical Structure of the Alfalfa Flower and an Explanation of the Tripping Mechanism

1. Eleven alfalfa selections were studied at the blossom stage of development in an attempt to relate proportion of flowers tripped by insect pollinators to certain characteristics of the blossoms. Techniques used to obtain relative measures of resistance to, and force of, tripping of the alfalfa flowers are described. 2. Detailed study of the anatomical structure of alfalfa flowers shows two major forces to be involved in the tripping mechanism. These are (a) the cohesive force between the two keel petals and (b) the pressure exerted by the sexual column from cells under tension at the juncture of the fused filaments and the keel. The former force, resulting from the interlocking of "finger-like" projections on the appressed surfaces of the keel petals, is sufficient to prevent spontaneous tripping of alfalfa flowers. Both the tenacity of this restraining force and the relative pressure exerted by the sexual column against the appressed keel petals differed in flowers from various alfalfa selections. These variations were attributed to differences in anatomical structure and makeup of the blossoms. 3. Evidence indicates that the restraining force of the adhered keel petals is more closely related to the proportion of flowers tripped by insects than is the degree of force with which the sexual column is released on tripping.

The Point-Discharge Recorder - Recording Micro-Ammeter

A description is given of a photographic-type recording micro-ammeter, constructed for use in Nigeria for a study of the earth's electrostatic field near ground level. It was used for recording the current flow from an elevated sharp point, and as this is subject to sudden changes, a high writing speed in the y-direction was required. A 24-hr. record is obtained, on a horizontally-rotating drum, with the aid of a galvanometer which rotates about a vertical axis. Timing marks are added automatically once a minute. Special attention was given to the problem of backlash. The following items are also considered in detail: the auxiliary `retrace' spring, the timing-mark trip mechanism, the magnetically-operated shutter mechanism, and the prismatic mirror. Some concluding notes are given on the performance of the instrument in the laboratory and in the field.

A Technique for Trapping and Tagging Spotted Skunks

Wildlife technicians are constantly confronted with the problem of obtaining certain data without causing atypical behavior in the species studied. It was necessary to deal with this difficulty in the current investigation of the prairie spotted skunk (Spilogale interrupta) in Iowa. For three years the writer has been engaged in research on this skunk over an area of 17 square miles in the southeastern part of the State. The work involves an intensive trapping and tagging program and has required the development and perfection of a trap and of a tagging technique which do not appear to frighten the animals or to have any great effect upon their physical condition. The spotted skunk is more like a weasel in habits than is the striped skunk, and may be more affected by man's activities. It is rapid moving and can climb trees readily. It is timid but alert and quick-tempered. It is difficult to tame. When kept in captivity for a long period it becomes accustomed to its keeper but may not willingly be touched. The species, too, appears to be more nomadic than the striped skunk (Mephitis mephitis) and is probably less inclined to have a permanent den. It is by preference nocturnal and is usually not seen abroad in daylight. Several types of traps were tried at first, such as those recommended by the United States Biological Survey (now the Fish and Wildlife Service) for the trapping of cats, but they did not prove satisfactory. The trap (P1. 20-A) finally developed is, to the writer's knowledge, novel in construction and design. The trap is made like a box with one end double and one side having a swinging door. The side door permits easy cleaning of the trap and setting of the mechanism. This door has a wire cloth insert for admitting light to the interior. All working parts of the trap are inside the box; thus fouling or tripping of the mechanism by snow, ice, water, or wind is avoided. There are no hinges in the tripping mechanism to become stiff during wet weather. There are no places where metal rests against metal or where binding may result, and consequently interfere with the sensitivity and action of the mechanism (P1. 20-B). The door (an automobile license plate thrice folded) is hung by fishline cord running through eyes fixed in the top of the box. At the trigger end of the cord a I-inch ring is attached and this ring passes over the wire lever holding up the treadle (P1. 20-B, and P1. 21-A). The metal door is heavy enough to counterbalance the treadle and being metal it cannot be chewed. 1 Journal Paper No. J-822 of the Iowa Agricultural Experiment Station, Ames, Iowa. Project No. 549. Fish and Wildlife Service (U. S. Department of the Interior), Iowa State College, Iowa State Conservation Commission, and the American Wildlife Institute cooperating. 2 Research in this project is under the supervision of Dr. Geo. O. Hendrickson, Iowa State College, and T. G. Scott, United States Fish and Wildlife Service.

THE CONTROL OF NORMAL AND "CONVULSIVE" BRAIN POTENTIALS

Brain potentials can be used within limits as an index of the action of cerebral neurones. The recorded waves are the envelope of the beats of many single neurones and their profile depends on the shape of the unit potential and the temporal relation of the many units. The isolated frog brain, with relatively few and similar neurones which can be subjected to a wide variety of experimental conditions, is especially favorable for studying the control of potentials. Mammalian brain in situ, so far as similar experiments have been made, shows like behavior. The olfactory bulb of the isolated brain gives an electrical beat, at six per second, larger and more regular than before removal from the frog. Under varied conditions, the frequency, still regular, may be shifted from one to 50 per second and the single wave from a sine to many highly skewed forms constantly repeated. Such patterns indicate strong unison of the many cells and so reproduce the potential profile of the unit. The unit beat is controlled by the metabolism of the cell, oxidative or glycolytic energy supplying the driving force. It is also controlled by a trip mechanism, presumably the cell membrane, which determines the frequency of oscillation at constant drive. Amplitude and frequency vary inversely as the trip mechanism is altered, together as metabolism is changed. Control of cell potentials mainly through metabolism is considered in the cases of: oxygen lack, narcosis, cyanide, glucose lack, insulin, B1 avitaminosis, iodoacetate, and nicotine poisoning. The action and interaction of these and subsequent agents is presented. Control mainly through the trip mechanism is considered for: altered osmotic pressure, sodium, potassium, calcium, magnesium, and hydrogen ions; for neural stimulation and, in more detail, for polarization by constant currents. Unification of the beats of the many units into synchronous or simultaneous patterns must depend on the propagation of nerve impulses or on electric fields and currents. The mechanism of unification is analyzed and tests for its effectiveness are described. The following conditions favor unison: high temperature and calcium, low potassium and sodium, diminution in afferent nerve impulses (in patterns), increased polarization (or injury potentials), the drugs nicotine and caffeine. Further analysis is made with caffeine, which leads to large repeated waves which may travel along the hemisphere. These are described in detail; and also the control of their size, shape, frequency, speed, and direction of travel by temperature and polarization. The spreading caffeine waves are not stopped by nicotine, which blocks synaptic conduction; they cross a complete transection of the hemisphere when the two halves are in good apposition and so in electrical but not neural continuity; and a caffeinized brain can augment the activity of an abutting normal one. It is concluded that, besides neural coordination of separate neurons, a strictly electrical mechanism can regulate nerve cell beats and cause a spreading activation. This may prove of considerable importance in the interpretation of normal activity, electronarcosis, and of the massed "convulsive" action of the cortex in epilepsy. A theoretical explanation of the mechanism of spread is presented. It demands the existence in brain of maintained polarization gradients in certain directions. These have been found present as predicted.

IS THE DOOR OF UTRICULARIA AN IRRITABLE MECHANISM?

The present paper deals with the question whether the door mechanism in Utricularia is an irritable one (as e.g., Mimosa is irritable) or is mechanical, and in the opening paragraphs the two views are set forth together with mention of the protagonists and their factual contributions. In particular the recently published views of Kruck have been examined and found to be inadequate.(a) The evidence for the conclusions herein presented have been drawn from a study of the posture of the door, and its exact positional relations to the threshold. The correlated anatomical facts have been studied and set forth, and it has been shown that the physical properties of the door do not change during action and that its action depends wholly on the pressure of the external medium (water) induced by the out-pumping capacity of the walls of the trap, first observed by Brocher, on the water-tightness of the door procured by the velum, as shown by Lloyd, and upon the actuation of a tripping mechanism also earlier described by the same author. There are no changes in turgor in the door cells and no reception or transmission of stimuli by the bristles, which are simply a part of the tripping mechanism.(b) Evidence has also been obtained from a study of the flexures and movements of the door, and it is shown that such could not occur if there were changes in turgor. It is further shown that the histology of the door and threshold are correlated with the position, degree and direction of the flexures.(c) It has been shown that during the flexures and movements of the door, there is no change in the position or form of the air contained in the intercellular spaces of the door, such as have been said to occur as a result of the movement of sap into these intercellular spaces.(d) Killing of the bristles does not prevent the action of the door, although it has been postulated that the bristles receive and transmit stimuli to the tissues of the door.(e) The rate of movement of the door during action is so rapid that, while it does not preclude the interpretation that it is an irritable response, it at least exposes it to grave doubt. Since the action can be repeated as rapidly and as often as the experimental conditions permit there can be no period of recovery. The action is so rapid that, if the mechanism is an irritable one, the latent period, or the period of transmission, must be very much shorter than any other case in the plant kingdom.The conclusion is therefore reached that the mechanism of the door is purely mechanical, though this is not to say that the trap is purely passive, since the physiological activity of the walls has to play its part in exhausting water from the interior, as a reduced water pressure within is necessary for the action of the door.A comparative study of 75 species of Utricularia supports this conclusion.

QUANTITATIVE STUDIES ON THE HUMAN MUSCLE TONUS

In a previous contribution, McKinley and I 1 described a new method for obtaining quantitative measurements of human muscle tonus. The principle of our technic is analogous to the usual clinical method of estimating tonus; that is, the resistance of resting, or at least voluntarily relaxed, muscles to passive stretch is determined. TECHNIC An arm of the subject to be tested is placed on a freely rotating arm rest which is driven in a horizontal position on a ball-bearing axis by the release of a weight. The internal condyle is carefully placed directly above the axis, and the forearm is passively extended or flexed by releasing a weight with a trip mechanism. The angular distance and the velocity of the moving forearm are recorded on a smoked drum with an electric time marker. To measure tonus under different conditions my associates and I have developed three methods, more or less