McMath-Hulbert Observatory [Lake Angelus, MI]

Observatory is near Lake Angelus, Mich. (five miles north of Pontiac). 24" reflecting telescope began operations in July 1930; also included a 10 1/2" reflector. Established and deeded to the university by Robert R. McMath, Francis McMath, and Judge Henry S. Hulbert. An additional 50' tower telescope was added in 1935/ 1946 and 70' tower telescope and office building added in 1940. Image is photograph of a painting.

The doctrines and discipline of the Methodist Episcopal church.

Prefetory letter signed: William M'Kendree, Enoch George, Robert R. Roberts... (and others)

Die pragmatische und humanistische Stromung in der modernen englischen Philosophie.

Thesis (doctoral)--Universitat Jena.

Constitutional provisions, statutes and public regulations governing railroads and other common carriers in the state of Virginia. January 1, 1909.

Robert R. Prentis, chairman.

Physical and chemical data on sediments deposited in the Missouri and the Mississippi River flood plains during the July through August 1993 flood /

Mode of access: Internet.

An oration, delivered before the American Philosophical Society, held in Philadelphia on the 27th of February, 1786; containing an enquiry into the influence of physical causes upon the moral faculty ...

Microfilmed for preservation

The molecular basis for the lack of immunostimulatory activity of vertebrate DNA

Macrophages and B cells are activated by unmethylated CpG-containing sequences in bacterial DNA. The lack of activity of self DNA has generally been attributed to CpG suppression and methylation, although the role of methylation is in doubt. The frequency of CpG in the mouse genome is 12.5% of Escherichia coli, with unmethylated CpG occurring at similar to3% the frequency of E. coli. This suppression of CpG alone is insufficient to explain the inactivity of self DNA; vertebrate DNA was inactive at 100 mug/ml, 3000 times the concentration at which E. coli DNA activity was observed. We sought to resolve why self DNA does not activate macrophages. Known active CpG motifs occurred in the mouse genome at 18% of random occurrence, similar to general CpG suppression. To examine the contribution of methylation, genomic DNAs were PCR amplified. Removal of methylation from the mouse genome revealed activity that was 23-fold lower than E. coli DNA, although there is only a 7-fold lower frequency of known active CpG motifs in the mouse genome. This discrepancy may be explained by G-rich sequences such as GGAGGGG, which potently inhibited activation and are found in greater frequency in the mouse than the E. coli genome. In summary, general CpG suppression, CpG methylation, inhibitory motifs, and saturable DNA uptake combined to explain the inactivity of self DNA. The immunostimulatory activity of DNA is determined by the frequency of unmethylated stimulatory sequences within an individual DNA strand and the ratio of stimulatory to inhibitory sequences.

Two-axis temperature-insensitive accelerometer based on multicore fiber Bragg gratings

We report a compact two-dimensional accelerometer based upon a simple fiber cantilever constructed from a short length of multicore optical fiber. Two-axis measurement is demonstrated up to 3 kHz. Differential measurement between fiber Bragg gratings written in the multicore fiber provides temperature- insensitive measurements.

A class of perfect fluids in general relativity

This thesis is concerned with exact solutions of Einstein's field equations of general relativity, in particular, when the source of the gravitational field is a perfect fluid with a purely electric Weyl tensor. General relativity, cosmology and computer algebra are discussed briefly. A mathematical introduction to Riemannian geometry and the tetrad formalism is then given. This is followed by a review of some previous results and known solutions concerning purely electric perfect fluids. In addition, some orthonormal and null tetrad equations of the Ricci and Bianchi identities are displayed in a form suitable for investigating these space-times. Conformally flat perfect fluids are characterised by the vanishing of the Weyl tensor and form a sub-class of the purely electric fields in which all solutions are known (Stephani 1967). The number of Killing vectors in these space-times is investigated and results presented for the non-expanding space-times. The existence of stationary fields that may also admit 0, 1 or 3 spacelike Killing vectors is demonstrated. Shear-free fluids in the class under consideration are shown to be either non-expanding or irrotational (Collins 1984) using both orthonormal and null tetrads. A discrepancy between Collins (1984) and Wolf (1986) is resolved by explicitly solving the field equations to prove that the only purely electric, shear-free, geodesic but rotating perfect fluid is the Godel (1949) solution. The irrotational fluids with shear are then studied and solutions due to Szafron (1977) and Allnutt (1982) are characterised. The metric is simplified in several cases where new solutions may be found. The geodesic space-times in this class and all Bianchi type 1 perfect fluid metrics are shown to have a metric expressible in a diagonal form. The position of spherically symmetric and Bianchi type 1 space-times in relation to the general case is also illustrated.

Fiber Bragg gratings of type I in SMF-28 and B/Ge fibre and type IIA B/Ge fibre under gamma radiation up to 0.54 MGy

The sensitivities of type I and IIA fibre Bragg gratings written to different reflectivities in SMF-28 and B/Ge fibres to ionizing radiation up to 0.54MGy are investigated. The Bragg wavelength shows a small and rapid increase at the start of irradiation followed by either a plateau (type I) or a decrease (type IIA).

Two-axis accelerometer based on multicore fibre Bragg gratings

We report an accelerometer based upon a simple fibre cantilever constructed from a short length of multicore fibre(MCF) containing fibre Bragg gratings (FBGs). Two-axis measurement is demonstrated up to 3 kHz.

Radial deformation measurement of a cylinder under compression using multicore fibre

A multicore fibre (MCF) sensor to measure the radial deformation of a compliant cylinder under compression is presented. The sensor is connectorised and need not be permanently bonded to the test object. A differential measurement technique using FBGs written into the MCF makes the sensor temperature insensitive. FBG measurement of axial strain of a cylinder under compression is also reported.

Dynamic two-axis curvature measurement using multicore fiber Bragg gratings interrogated by arrayed waveguide gratings

We describe the use of arrayed waveguide gratings (AWGs) in the interrogation of fiber Bragg gratings (FBGs) for dynamic strain measurement. The ratiometric AWG output was calibrated in a static deflection experiment over a ±200 με range. Dynamic strain measurement was demonstrated with a FBG in a conventional single-mode fiber mounted on the surface of a vibrating cantilever and on a piezoelectric actuator, giving a resolution of 0.5 με at 2.4 kHz. We present results of this technique extended to measure the dynamic differential strain between two FBG pairs within a multicore fiber. An arbitrary cantilever oscillation of the multicore fiber was determined from curvature measurements in two orthogonal axes at 1125 Hz with a resolution of 0.05 m-1. © 2006 Optical Society of America.

Pitch and roll sensing using fibre Bragg gratings in multicore fibre

We report the first use of a multicore fibre incorporating fibre Bragg grating strain sensors in each core as a fibre optic pitch and roll sensor. A length of four-core fibre supported at one end forms a cantilever. The differential strains between opposite grating pairs depend on the fibre’s orientation in pitch (in the vertical plane) and roll (azimuth) with respect to gravity. Resolutions of ±2◦ in roll and ±15◦ in pitch were measured.