Propagation of Vortex Electron Wave Functions in a Magnetic Field

The physics of coherent beams of photons carrying axial orbital angular momentum (OAM) is well understood and such beams, sometimes known as vortex beams, have found applications in optics and microscopy. Recently electron beams carrying very large values of axial OAM have been generated. In the absence of coupling to an external electromagnetic field the propagation of such vortex electron beams is virtually identical mathematically to that of vortex photon beams propagating in a medium with a homogeneous index of refraction. But when coupled to an external electromagnetic field the propagation of vortex electron beams is distinctly different from photons. Here we use the exact path integral solution to Schrodingers equation to examine the time evolution of an electron wave function carrying axial OAM. Interestingly we find that the nonzero OAM wave function can be obtained from the zero OAM wave function, in the case considered here, simply by multipling it by an appropriate time and position dependent prefactor. Hence adding OAM and propagating can in this case be replaced by first propagating then adding OAM. Also, the results shown provide an explicit illustration of the fact that the gyromagnetic ratio for OAM is unity. We also propose a novel version of the Bohm-Aharonov effect using vortex electron beams.Comment: 14 pages, 2 figures, submitted to Phys Rev

Investigation of the characteristics of photoplethysmographic signals in the human oesophagus in anaesthetised patients undergoing routine surgery

The continuous monitoring of arterial blood oxygen saturation in patients with compromised peripheral perfusion is often difficult or impossible, since conventional non-invasive techniques such as pulse oximetry (SpO2) fail. Measurements of oxygen saturation are unreliable when patients are peripherally cool with low cardiac output or poor peripheral circulation. These clinical situations commonly occur after major surgery including cardiopulmonary bypass. It is suggested that the above difficulties might be overcome if the sensor were to monitor a better perfused central part of the body such as the oesophagus. A reflection probe has been constructed utilising miniaturised opto-electronic devices designed to fit into a transparent oesophageal stomach tube. A system to detect and preprocess the photoplethysmograph (PPG) signals has been developed. The PPG output is sampled and recorded by a data acquisition system and a laptop personal computer. The characteristics of the pulsatile signal in the oesophagus of anaesthetised adult patients undergoing routine elective surgery has been investigated. Preliminary results show that good quality photoplethysmograpic (PPG) signals can be measured in the human oesophagus. The oesophageal signal amplitudes were found to be approximately a factor of two greater than the amplitudes of conventional finger PPGs. The characteristics of the PPG signals obtained at various depths in the oesophagus have been studied and the results will be presented. This investigation indicates the suitability of the oesophagus as an alternative site for the reliable monitoring of oxygen saturation (SpO2) in patients with poor peripheral perfusion

Investigation of photoplethysmographic signals in the human oesophagus

The continuous monitoring of blood oxygen saturation in patients with compromised peripheral perfusion is often difficult or impossible, since conventional non-invasive techniques such as pulse oximetry fail. Measurements of oxygen saturation are unreliable when patients are peripherally cool with low cardiac output and poor peripheral circulation. These clinical situations commonly occur after major surgery including cardiopulmonary bypass. We suggest that the above difficulties might be overcome if the sensor were to monitor a more central part of the body. It is proposed to use the oesophagus as measurement site and reflection techniques on the hypothesis that this site should be better perfused. A new probe was constructed utilising miniaturised opto-electronic devices designed to fit into a transparent oesophageal stomach tube. One infrared wavelength was used in this study at 880 nm and a circuit to analyse the photoplethysmograph (PPG) signal was developed. The output PPG signals were sampled and recorded by a data acquisition system and a laptop personal computer. Initial measurements were carried out to investigate the amplitude of the pulsatile signal in the oesophagus and preliminary results are presented

Geologic Mapping in the Hesperia Planum Region of Mars

Hesperia Planum, characterized by a high concentration of mare-type wrinkle ridges and ridge rings, encompasses > 2 million square km in the southern highlands of Mars. The most common interpretation is that the plains were emplaced as "flood" lavas with total thicknesses of <3 km [4-10]. The wrinkle ridges on its surface make Hesperia Planum the type locale for "Hesperian-aged ridged plains" on Mars, and wrinkle-ridge formation occurred in more than one episode. Hesperia Planum s stratigraphic position and crater-retention age define the base of the Hesperian System. However, preliminary results of geologic mapping reveal that the whole of Hesperia Planum is unlikely to be composed of the same materials, emplaced at the same geologic time. To unravel these complexities, we are generating a 1:1.5M-scale geologic map of Hesperia Planum and its surroundings. To date, we have identified 4 distinct plains units within Hesperia Planum and are attempting to determine the nature and relative ages of these materials

Lunar Geologic Mapping: A Preliminary Map of a Portion of the LQ-10 ("Marius") Quadrangle

Since the first lunar mapping program ended in the 1970s, new topographical, multispectral, elemental and albedo imaging datasets have become available (e.g., Clementine, Lunar Prospector, Galileo). Lunar science has also advanced within the intervening time period. A new systematic lunar geologic mapping effort endeavors to build on the success of earlier mapping programs by fully integrating the many disparate datasets using GIS software and bringing to bear the most current understanding of lunar geologic history. As part of this program, we report on a 1:2,500,000-scale preliminary map of a subset of Lunar Quadrangle 10 ("LQ-10" or the "Marius Quadrangle," see Figures 1 and 2), and discuss the first-order science results. By generating a geologic map of this region, we can constrain the stratigraphic and geologic relationships between features, revealing information about the Moon s chemical and thermal evolution

Photoplethysmographic (PPG) signals recorded from the human oesophagus

Background and Goal of study: Although a major advance in clinical monitoring, pulse oximetry may fail when peripheral perfusion is poor (1). Measurement of arterial oxygen saturation (SpO2) at the cricopharyngeus has been attempted in anaesthetised patients, but readings varied with the orientation of the probe (2), and suffered from signal failure (3). We have recorded PPG signals from the lower oesophagus to determine optimal recording depth and signal qualit

Mapping Hesperia Planum, Mars

Hesperia Planum, characterized by a high concentration of mare-type wrinkle ridges and ridge rings [1-4], encompasses > 2 million km2 in the southern highlands of Mars (Fig. 1). The most common interpretation is that the plains were emplaced as flood lavas with total thicknesses of <3 km [4-10]. The wrinkle ridges on its surface make Hesperia Planum the type locale for Hesperian-aged ridged plains on Mars [e.g., 9], and recent investigations reveal that wrinkle-ridge formation occurred in more than one episode [4]. Hesperia Planum s stratigraphic position and crater-retention age [e.g., 9, 11-12] define the base of the Hesperian System. However, preliminary results of geologic mapping reveal that the whole of Hesperia Planum is unlikely to be composed of the same materials, emplaced at the same geologic time. To unravel these complexities, we are generating a 1:1.5M-scale geologic map of Hesperia Planum and its surroundings (Fig. 1). To date, we have identified 4 distinct plains units within Hesperia Planum and are attempting to determine the nature and relative ages of these materials (Fig. 2) [13-15]

Observation of Interaction of Spin and Intrinsic Orbital Angular Momentum of Light

Interaction of spin and intrinsic orbital angular momentum of light is observed, as evidenced by length-dependent rotations of both spatial patterns and optical polarization in a cylindrically-symmetric isotropic optical fiber. Such rotations occur in straight few-mode fiber when superpositions of two modes with parallel and anti-parallel orientation of spin and intrinsic orbital angular momentum (IOAM=$2\hslash$) are excited, resulting from a degeneracy splitting of the propagation constants of the modes.Comment: 6 pages, 5 figures, and a detailed supplement. Version 3 corrects a typo and adds the journal referenc