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16:00 IWF (Göttingen) English 2002

Yellow Loosestrife and Hair-legged Mining Bees (Lysimachia and Macropis)

Close interrelations between plants and animals have developed during evolution. One form of symbiosis is common in South America and Africa and is extremely fascinating: some flowering plants don't offer nectar or pollen, but a fatty oil. These flowers are called "oil flowers". This interrelation is hardly known in Europe although it occurs between bees (Macropis) and their host plant, the Yellow loosestrife (Lysimachia). The film was shot in their natural habitat at the banks of the Rhine backwaters. By means of macrography and slow-motion all phases of the bees' complex collecting behaviour are documented, including their nests. The flower structure is explained in detail. The film exemplarily introduces the basic mechanisms of a plant-animal interaction and the close connection between form and function in an ecosystem.
  • Published: 2002
  • Publisher: IWF (Göttingen)
  • Language: English
17:48 IWF (Göttingen) English 2002

Malpighiaceae and their Pollinators

Close interrelations between plants and animals have developed during evolution. In Brazil one can find an extremely fascinating symbiosis: some flowering plants don't offer nectar or pollen, but a fatty oil. These flowers are called "oil flowers". The film shows the tight link between bees (Centridini) and their host plants (Malpighiaceae) in their natural habitat. By means of macrography and slow-motion all phases of the bees' complex collecting behaviour are documented, including microscopic shots of the bees' legs and their larvae. The flower structure is explained in detail. The film exemplarily introduces the basic mechanisms of a plant-animal interaction and the close connection between form and function in an ecosystem.
  • Published: 2002
  • Publisher: IWF (Göttingen)
  • Language: English
13:16 IWF (Göttingen) English 2002

Pollination of Angelonia hirta (Scrophulariaceae)

Close interrelations between plants and animals have developed during evolution. In the garden and pastureland of Northeast Brazil one can study a fascinating symbiosis: some flowering plants don't offer nectar or pollen, but a fatty oil. They are called "oil flowers". The film documents the close interdependence between the bees (Centris) and plants (Scrophulariaceae) in their natural habitat. By means of macrography and slow-motion all phases of the bees' complex collecting behaviour are documented, including microscopic shots of the bees' legs. The flower structure is explained in detail. The film exemplarily introduces the basic mechanisms of a plant-animal interaction and the close connection between form and function in an ecosystem.
  • Published: 2002
  • Publisher: IWF (Göttingen)
  • Language: English
18:01 IWF (Göttingen) German 1998

Reifung neutrophiler Granulozyten

The differentiation of living cells from promyelocytes to segmented neutrophils is observed for several days in vitro and portrayed by means of time-lapse, phase-contrast microscopy. Furthermore, granulocyte stages that have been stained and fixed according to Pappenheim, the method also used for medical diagnostic purposes, are presented. A proliferation diagram illustrates the coexistence of maturing and resting granuloblast populations. The majority of these microcinematographic images were made in the sixties. The cover-slip cultures that were specially developed by the author enabled the first long-term observations of human hematopoietic cells using phase-contrast technology, which was very new at that time.
  • Published: 1998
  • Publisher: IWF (Göttingen)
  • Language: German
16:00 IWF (Göttingen) German 2002

Gilbweiderich und Schenkelbiene

Zwischen Pflanze und Tier haben sich im Verlauf der Evolution enge Wechselbeziehungen entwickelt. Eine Symbiose kommt gehäuft in Südamerika und Afrika vor und ist besonders faszinierend: Bei dieser bieten Blütenpflanzen den Bienen nicht - wie gewöhnlich - Nektar oder Pollen an, sondern ein fettes Öl. Man nennt sie deshalb "Ölblumen". Diese Wechselbeziehung ist in Europa kaum bekannt, obwohl sie auch hier vorkommt: zwischen Bienen der Gattung Macropis und ihrer Wirtspflanze, dem Gilbweiderich (Lysimachia vulgaris). Die Aufnahmen entstanden an den Ufern der Altarme des Rheins in der natürlichen Umgebung beider Partner. Mittels Spezialtechnik (Makro- und Zeitdehneraufnahmen) werden alle Phasen des komplexen Sammelverhaltens der Bienen sichtbar gemacht; Aufnahmen der Bodennester ergänzen das Material. Der Blütenaufbau wird detailliert vorgestellt. Damit vermittelt der Film beispielhaft die Grundmechanismen von Pflanze-Tier-Interaktionen und die enge Verknüpfung von Form und Funktion in einem Ökosystem.
  • Published: 2002
  • Publisher: IWF (Göttingen)
  • Language: German
17:51 IWF (Göttingen) German 2002

Malpighiaceen und ihre Bestäuber

Zwischen Pflanze und Tier haben sich im Verlauf der Evolution enge Wechselbeziehungen entwickelt. In einem Naturreservat in Brasilien läßt sich eine besonders faszinierende Symbiose beobachten: Bei dieser bieten Blütenpflanzen den Bienen nicht - wie gewöhnlich - Nektar oder Pollen an, sondern ein fettes Öl. Man nennt sie deshalb "Ölblumen". Der Film zeigt, wie eng sich Bienen (solitär lebende Centridini) und Pflanzen (Vertreter der Malpighiaceen) ergänzen. Die Aufnahmen entstanden in einer Forschungsstation in der natürlichen Umgebung beider Partner. Mittels Spezialtechnik (Makro- und Zeitdehneraufnahmen) werden alle Phasen des komplexen Sammelverhaltens der Bienen sichtbar gemacht; Rasteraufnahmen der Bienenbeine und Aufnahmen der Larvenbrut ergänzen das Material. Der Blütenaufbau wird detailliert vorgestellt. Damit vermittelt der Film beispielhaft die Grundmechanismen von Pflanze-Tier-Interaktionen und die enge Verknüpfung von Form und Funktion in einem Ökosystem.
  • Published: 2002
  • Publisher: IWF (Göttingen)
  • Language: German
13:12 IWF (Göttingen) German 2002

Bestäubung von Angelonia hirta (Scrophulariaceae)

Zwischen Pflanze und Tier haben sich im Verlauf der Evolution enge Wechselbeziehungen entwickelt. In der Garten- oder Weidelandschaft Nordost-Brasiliens läßt sich eine besonders faszinierende Symbiose beobachten: Bei dieser bieten Blütenpflanzen den Bienen nicht - wie gewöhnlich - Nektar oder Pollen an, sondern ein fettes Öl. Man nennt sie deshalb "Ölblumen". Der Film zeigt, wie eng sich beide Partner - Bienen der Gattung Centris und Pflanzen der Art Angelonia hirta - ergänzen. Die Aufnahmen entstanden in der natürlichen Umgebung beider Partner. Mittels Spezialtechnik (Makro- und Zeitdehneraufnahmen) werden alle Phasen des komplexen Sammelverhaltens der Bienen sichtbar gemacht; Rasteraufnahmen der Bienenbeine ergänzen die Bewegtbilder. Der Blütenaufbau wird detailliert vorgestellt. Damit vermittelt der Film beispielhaft die Grundmechanismen von Pflanze-Tier-Interaktionen und die enge Verknüpfung von Form und Funktion in einem Ökosystem.
  • Published: 2002
  • Publisher: IWF (Göttingen)
  • Language: German
47:05 IWF (Göttingen) German 2002

Ölblumen und ölsammelnde Bienen

The DVD contains the IWF films W 7047 "Malpighiaceae and their Pollinators", W 7048 "Pollination of Angelonia hirta (Scrophulariaceae)" and W 7049 "Loosestrife and Bee (Macropis)".
  • Published: 2002
  • Publisher: IWF (Göttingen)
  • Language: German
02:14 IWF (Göttingen) English 2003

Stabilization Using a Spinning Top

In an impressive demonstration, the precession effect is used to stabilize a very top-heavy device. A man tries to balance while sitting on a steel bar which can rotate freely around its horizontal axis. A top consisting of a lead-filled bicycle rim driven by an electric motor is attached to this bar with a joint allowing the top to be tilted away and towards the man, but not sideways. The center of mass of man and top are far above the bar. As long as the top is at rest, the man has to keep his feet on the floor to avoid tipping over. With the top spinning, pushing or pulling its axis will make the top precess, i.e. to move sideways. This motion can be used to balance the top-heavy system.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: English
02:03 IWF (Göttingen) English 2003

Angular Momentum as a Vector

A ventilator which can rotate freely around a vertical axis can be used to demonstrate that the angular momentum is a vector. A ventilator is mounted so that it can rotate freely around a vertical axis. It can also be tilted so that the air is blown either horizontally or upward. Upon turning on the ventilator, both the propeller and the driven air jet receive an angular momentum. Its vector points in the direction of the jet, parallel to the axis of the propeller. The ventilator receives an equal angular momentum in the opposite direction (opposite sense of rotation). The experiment is carried out for two different orientations of the ventilator.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: English
00:57 IWF (Göttingen) English 2003

Precession of a Spinning Wheel

A spinning top (gyroscope) does not follow a torque in the same way as, for example, a top at rest. Rather, it moves sideways, it "precesses". This startling behavior will be shown here. The top is a bicycle wheel with its rim filled with lead wire. It can be suspended on a rope dangling from the ceiling. The wheel is spun while holding its axle horizontal. Then, one end of the axle is attached to the rope. The weight of the wheel and the tension in the rope together cause a torque which, however, does not turn the axle into the vertical position, as would happen if the wheel were not spinning. Instead, the axle, which indicates the direction of the wheels angular momentum, circles on a horizontal plane around the point on which it is suspended. This sideways motion of a top under the influence of a torque is called "precession".
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: English
13:39 IWF (Göttingen) German 1997

Experimentelle Tragsicherheitsbewertung - Spannbetonbrücke Baiersdorf, Main-Donau-Kanal

Optical damage on the bridge was the reason to start measuring load-carrying capacity. On-line real-time methods were developed to measure critical capacity without danger or damage.
  • Published: 1997
  • Publisher: IWF (Göttingen)
  • Language: German
03:28 IWF (Göttingen) English 2004

Amperes Law

A long induction coil wound on a flexible hose is used to explore the magnetic field near current carrying conductors and also near a permanent magnet.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
01:33 IWF (Göttingen) English 2004

Induction motor

Eddy currents induced in an aluminum disk in a moving inhomogeneous field tend to move the disk along with the field. This is the principle of the induction motor.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
02:31 IWF (Göttingen) English 2004

Resolving power

It is shown that in an optical image the individual light spots are diffraction patterns caused by the opening of the imaging lens. The resulting limit of the angular resolution is demonstrated with the aid of two pairs of holes with different separations.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
02:41 IWF (Göttingen) English 2004

Eddy current brake

Forces are demonstrated which arise when an electric conductor moves through an inhomogeneous magnetic field.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
02:28 IWF (Göttingen) English 2004

Electromagnet

It will be shown that in a small electromagnet surprisingly large forces can be generated. However, these forces decrease drastically with the introduction of only a small gap between the pole faces.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
01:55 IWF (Göttingen) English 2004

Rotating magnetic field

A rotating magnetic field results from the superposition of two magnetic fields oriented perpendicularly to each other, which vary sinusoidally with equal frequency, but with a phase difference, ideally of 90 degrees.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
01:21 IWF (Göttingen) English 2004

Spherical aberration

The imaging error called "spherical aberration" is demonstrated by imaging a small coil of a light bulb.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
01:03 IWF (Göttingen) English 2004

Paramagnetic matter

Paramagnetic matter gets pulled into regions of a large magnetic field. For the demonstration, liquid oxygen is poured into a shallow container placed in front of an electromagnet with non-parallel faces.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
01:58 IWF (Göttingen) English 2004

Astigmatism

The imaging error called astigmatism occurs when light travels not parallel to the axis of the lens, but under an angle. Instead of image points, extended lines or streaks are formed.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
01:48 IWF (Göttingen) English 2004

Cone of reflected light

The reflection of light is demonstrated using a polished steel tube. The reflected light has the shape of a cone.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
00:47 IWF (Göttingen) English 2004

Perspective

Two-dimensional images of three-dimensional structures have a perspective, that is a certain ratio of size and distance for things which lie behind each other. The perspective depends on the position of the centers of the projection, which in imaging lie in the centers of the entrance- and exit-pupils. Using the images of two objects positioned at different distances from the imaging lens, the perspective and its changes will be shown.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
01:21 IWF (Göttingen) English 2003

Dynamic Stability of a Bicycle Chain

Belts made of soft material which are flexible while at rest, in this case a chain made of metal links, can become quite rigid, independent of their shape, when their tangential velocity is sufficiently large. This phenomenon is called "dynamic stability". Through the radial forces the chain stiffens, and after it gets thrown off the toothed wheel, it roles along the floor, jumps over a wooden beam, and collapses into its shapeless form only after coming to rest on the rug after colliding with the wall. It is clearly seen how the stiff chain deforms somewhat as it hits the beam. Note also how long the chain continues to rotate on the rug near the end of the experiment, before it finally comes to rest and collapses.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: English
01:16 IWF (Göttingen) English 2004

Bent light ray

A trough contains a sugar solution with a vertical concentration gradient, so that its index of refraction decreases with increasing height. A laser light beam enters the trough, tilted slightly against the horizontal direction. As it moves through the liquid, it is bent, as can be observed through scattering.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
02:42 IWF (Göttingen) English 2003

Conservation of Angular Momentum Using a Rotating Chair

Conservation of angular momentum around the vertical axis of a rotating chair. A man sitting on a rotating chair with very little friction uses weights, a spinning wheel, and a wooden hammer with a long handle to demonstrate the vector nature of the angular momentum as well as its conservation in the absence of external torques. This setup allows to limit the observation to a single (the vertical) component of the angular momentum.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: English
01:04 IWF (Göttingen) English 2003

Action = Reaction

A demonstration that forces between two bodies always occur in pairs: They are opposite in direction and equal in magnitude. These facts were summarized by Newton with the statement "action = reaction". Two people are standing on flat carts on a level floor, a few meters apart. The forces are exerted by means of a rope. The experiment shows that in both cases the forces are equal in magnitude and opposite in direction, in short: action = reaction. It also shows that the total momentum of the system is conserved.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: English
01:45 IWF (Göttingen) English 2004

Chromatic aberration

Chromatic aberration occurs in imaging as result of the wavelength dependence of the index of refraction. It will be demonstrated on a special example.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
02:46 IWF (Göttingen) English 2004

Polarized light

The plane of polarization of a light beam which has been polarized by passing it through a Nicol prism is made visible through scattering in a slightly milky liquid.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
00:40 IWF (Göttingen) English 2003

Elastic Collision in Slow Motion

Elastic collision between two bodies in slow motion through the proper choice of the experimental conditions. It will be shown that during the collision the kinetic energy is briefly converted into potential energy and then back into kinetic energy. The slow collision, achieved through the proper choice of masses and spring constants, demonstrates clearly the transformation from kinetic to potential energy, and back again, as is characteristic for elastic collisions. This experiment also demonstrates the conservation of linear momentum.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: English
00:45 IWF (Göttingen) English 2003

Conservation of Linear Momentum

According to the law of the conservation of momentum, which states that in every closed system the sum of the individual momenta stays constant. They can be exchanged inside the system. Three examples will be shown. In all three cases, the total momentum of the closed system remains constant.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: English
06:27 IWF (Göttingen) English 2004

Experiments with Water Waves

Some of the fundamental properties of waves are demonstrated using surface waves in a water trough.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
01:21 IWF (Göttingen) English 2003

Measurement of the Electric Field of the Earth

The electric field of the earth will be determined. A parallel plate capacitor of area 1 m2 is attached to the end of a long bamboo pole. The capacitor is connected to a ballistic galvanometer calibrated to measure current pulses (charges). On a balcony outside the lecture hall, the capacitor is held with its plates horizontal.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: English
01:27 IWF (Göttingen) English 2004

Model of a Travelling Wave

The connection between circular motion, phase difference and wave propagation is shown with the help of a series of beads arranged to form a right-handed helix.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
03:04 IWF (Göttingen) English 2004

Induction in conductors at rest

A changing magnetic field generates an electric field.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
03:10 IWF (Göttingen) English 2004

Induction in conductors in motion

A conductor moving in a magnetic field experiences an electric field.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: English
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