Different types of atomic force microscopy ~AFM! probes were characterized under ultrahigh vacuum conditions and at low temperatures. Properties of AFM probes, such as the resonance frequency, the spring constant and quality factor of cantilevers, depend on temperature. A typical shift in the resonance...

A new method of direct and continuous measurement of the spring constant of single molecule or molecular complex is elaborated. To that end the standard force spectroscopy technique with functionalized tips and samples is combined with a small dithering of the tip. The change of the dithering amplitude...

The experimental results of the direct measurement of the absolute value of interaction force between the fiber probe of a scanning near-field optical microscope (SNOM) operated in shear force mode and a sample, which were performed using combined SNOM-atomic force microscope setup, are discussed for...

As our knowledge of biological processes advances, we are increasingly aware that cells actively position sub-cellular organelles and other constituents to control a wide range of biological processes. Many studies quantify the position and motion of, for example, fluorescently labeled proteins, protein...

Upon entering a cell, alphaherpesvirus capsids are transported toward the minus ends of microtubules and ultimately deposit virus DNA within the host nucleus. The virus proteins that mediate this centripetal transport are unknown but are expected to be either viral tegument proteins, which are a group...

Molecular motors move many intracellular cargos along microtubules. Recently, it has been hypothesized that in vivo cargo velocity can be used to determine the number of engaged motors. We use theoretical and experimental approaches to investigate these assertions, and find that this hypothesis is inconsistent...

Noise is a major problem in analyzing tracking data of cargos moved by molecular motors. We use Bayesian statistics to incorporate what is known about the noise in parsing the trajectory of a cargo into a series of constant velocity segments. Tracks with just noise and no underlying motion are fit with...

Molecular motor proteins are crucial for the proper distribution of organelles and vesicles in cells. Much of our current understanding of how motors function stems from studies of single motors moving cargos in vitro. More recently, however, there has been mounting evidence that the cooperation of multiple...

The forces of a photonic force microscope based on optical tweezers are determined using the Boltzmann distribution of thermally driven position fluctuations. As a fundamental method, only a minimum of information about the system is required, i.e. the solution’s temperature. This calibration method...

A quadrant photodiode placed in the back-focal plane of the microscope of a laser trap provides a high-resolution position sensor.We show that in addition to the lateral displacement of a trapped sphere, its axial position can be measured by the ratio of the intensity of scattered laser light to the...