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The article offers the author's insights on his dedication to become a professional comet hunter. The author discusses his early memories of learning the French language to pass an examination, his discovery on the movement of a fuzzy object, and the new comets he discovered including the Comet Shoemaker-Levy 9, which was the first comet that crashed in the planet Jupiter.

The search for buried landmines is currently a tedious and dangerous process, performed by hand to ensure the high degree of reliability required for reputable land recovery. An experimental class at MIT spent one semester working to develop new tools to increase the rate of manual landmine removal. By redefining the problem statement to address the results of a time/motion analysis, rather than directly addressing the landmine problem itself, the class conceived three new tools that use existing technologies in novel ways to increase the rate of the location and neutralization of hidden anti-personnel mines.

The discovery of Comet Shoemaker-Levy 9 in March 1993 opened an extraordinary few years in the study of the history of impacts in the solar system. This review paper offers a background that attempts to set the events of 1993 and 1994 into a historical context, and describes events leading to the discovery and the mounting of a unique and unprecedented international effort to observe the comet's collision with Jupiter. A selection of the results is presented to explore how the fate of Comet Shoemaker-Levy 9 has affected scientific and popular understanding of impacts in the solar system.

The Hubble Space Telescope made systematic observations of the split comet P/Shoemaker-Levy 9 (SL9) (P designates a periodic comet) starting in July 1993 and continuing through mid-July 1994 when the fragments plunged into Jupiter's atmosphere. Deconvolutions of Wide Field Planetary Camera images indicate that the diameters of some fragments may have been as large as approximately 2 to 4 kilometers, assuming a geometric albedo of 4 percent, but significantly smaller values (that is,1 kilometer) cannot be ruled out. Most of the fragments (or nuclei) were embedded in circularly symmetric inner comae from July 1993 until late June 1994, implying that there was continuous, but weak, cometary activity. At least a few nuclei fragmented into separate, condensed objects well after the breakup of the SL9 parent body, which argues against the hypothesis that the SL9 fragments were swarms of debris with no dominant, central bodies. Spectroscopic observations taken on 14 July 1994 showed an outburst in magnesium ion emission that was followed closely by a threefold increase in continuum emission, which may have been caused by the electrostatic charging and subsequent explosion of dust as the comet passed from interplanetary space into the jovian magnetosphere. No OH emission was detected, but the derived upper limit on the H2O production rate of approximately 10(27) molecules per second does not necessarily imply that the object was water-poor.

The Hubble Space Telescope observed the fragmented comet P/Shoemaker-Levy 9 (1993e) (P indicates that it is a periodic comet) on 1 July 1993. Approximately 20 individual nuclei and their comae were observed in images taken with the Planetary Camera. After subtraction of the comae light, the 11 brightest nuclei have magnitudes between approximately 23.7 and 24.8. Assuming that the geometric albedo is 0.04, these magnitudes imply that the nuclear diameters are in the range approximately 2.5 to 4.3 kilometers. If the density of each nucleus is 1 gram per cubic centimeter, the total energy deposited by the impact of these 11 nuclei into Jupiter's atmosphere next July will be approximately 4 x 10(30) ergs ( approximately 10(8) megatons of TNT). This latter number should be regarded as an upper limit because the nuclear magnitudes probably contain a small residual coma contribution. The Faint Object Spectrograph was used to search for fluorescence from OH, which is usually an excellent indicator of cometary activity. No OH emission was detected, and this can be translated into an upper limit on the water production rate of approximately 2 x 10(27) molecules per second.

Hydrogen nuclear magnetic resonance(NMR) was used to probe defect reactions in fused silica during 193 nm ultraviolet irradiation and thermal treatment. Hydrogen concentration and Carr–Purcell measurements indicate that the majority of hydrogen atoms are isolated and do not segregate or evolve from the fused silica during annealing or irradiation. Previously, NMR spin‐lattice relaxation measurements have revealed that a small fraction of hydrogen in fused silica exists as centers that undergo molecular motion and are consumed during annealing. Here, a detailed analysis of the NMR spin‐lattice relaxation behavior is used to support the identification of this center as a pair of adjacent silanol groups. These silanol pairs react during annealing to form a strained bond, thus increasing the susceptibility of fused silica to E’formation. Excimer laser irradiation, like thermal treatment, is shown to directly reduce the number of relaxation centers in the material. The measured dependence of spin‐lattice relaxation as a function of irradiation for identically prepared samples is consistent with silanol pair center consumption by a two‐photon process.

1 H NMR spectra were obtained for silicon dioxide films that were thermally grown under clean room conditions. Bulk hydrogen in a concentration of approximately 1.2×10 198 H/cm 3 was detected in a 1.1-μm thick wet oxide grown at 1000 o C. The relatively long (∼15 s) spin-lattice relaxation time for this sample is consistent with bulk hydrogen, while a narrow 3 kHz half-width at half maximum (HWHM) Gaussian line shape suggests that the majority of hydrogen in this film is well isolated. Thinner thermal oxides, own under a variety of conditions, were exposed to the ambient to assess the effects of sample aging

The design for a nuclear magnetic resonance (NMR) probe capable of detecting hydrogen signals at levels of

Hydrogen distribution in various solid system was studied by multiple quantum (MQ) nuclear magnetic resonance (NMR). The rate of growth of MQ coherences for bulk infinite, three-dimensional hydrogen lattice found in materials such as calcium hydride, sodium bicarbonate, and adamantane followed a universal growth curve when the time axix was scaled by a the square root of the second moment (M 2 1/2 ), while three chemically vapor deposited diamond films and a natural diamond powder sample showed a noted departure from this universal growth curve

Nuclear magnetic resonance (NMR) was used to study hydrogen in fused silica for the first time. The 1H NMR spin‐lattice relaxation time constant (T1) in synthetic fused silica was found to be strongly affected by thermal treatments, correlating with the concentration of E’ centers produced during subsequent 193‐nm excimer‐laser irradiation. In addition, the relative proportion of the two components in the NMR spectrum were affected by thermal treatment, although no change in the total hydrogen content was observed. The broad NMR component, because of its linewidth and dependence upon thermal processing, is postulated to be a direct signature of the NMR relaxation centers. These results are interpreted within the framework of a model in which pairs of silanol groups are consumed during thermal treatment, forming a strained bond which is susceptible to E’ center formation.

Hydrogen incorporated into polycrystalline diamond was found to correlate with the optical absorption in the 8 to 10 μm wavelength IR region, where transparency is desired. In this first detailed study of diamond films by 1H NMR, average concentrations were found to be

Developing and deploying "clinical practice guidelines" and "best practices" is a major strategic goal of our organization. We developed and evaluated a novel way of educating our colleagues on the office management of shoulder pain, using an interactive multimedia computer program to allow rapid access to user-selected audiovisual educational materials through a simple point and click interface.Pre- and post-testing of 30 practicing primary care providers was conducted to assess ability to evaluate and manage patients who present with shoulder pain, and a post-use survey was administered to assess clinician acceptance and confidence, ability to use as a just-in-time tool, and changes in utilization of medical resources.Pre- and post-testing demonstrated that clinicians used this tool to improve their scores in a wide variety of clinical areas including history, physical examination, diagnosis, and management of conditions causing painful shoulder above their scores using textbooks and other traditional educational materials alone. The post-use survey showed outstanding acceptance by clinicians and their reported increased confidence as well as the potential for their increased abilities to translate into significant cost savings through more focused use of radiographic studies, orthopedic consultations, and physical therapy treatments.It was concluded that "The Multimedia Reference for Office Management of Shoulder Pain" is an effective and valuable learning resource for practicing clinicians, and demonstrates the potential to use an interactive multimedia tool to augment clinical skills and promote cost effective management of patients with this common clinical problem.

Collaborative development involving both individuals and groups is often less efficient than independent development because of communication overhead and integration costs. Despite the decreased development efficiency, collaborations promise more general-purpose products because of the opportunity for integration, with negotiation and reconciliation of diverse perspectives. Collaborations are also perhaps less costly when considered in contexts where there is significant duplication of effort. Computer-facilitated collaboration can reduce the communication and integration burden such that the increased effort required to manage a successful collaboration focuses primarily on the development of shared conceptual model among the developers by requiring that the work product be independently reproducible. This reproducibility requirement incorporates formal quality assurance processes into the development process. In this paper, we describe our initial experiences developing SNOMED-RT using such a computer-facilitated collaborative process. We quantify the extra costs incurred to achieve consistency in our efforts and reproducibility of our results.

Hydrogen is a common impurity in silicon dioxide (SiO2) which can influence its optical and electronic properites. Here, nuclear magnetic resonance (NMR) is applied to study of hydrogen in these materials, despite their relatively low hydrogen content. We present results for bulk fused silica as well as thermally grown films of SiO2 on silicon. These experiments demonstrate the potential of solid state NMR for studying low hydrogen content film systems. In bulk fused silica, we have observed that although the majority of hydrogen is isolated, a small number of centers exist involving adjacent silanol pairs. These pairs react during high temperature annealing as well as during deep ultraviolet irradiation. Furthermore, the presence of these centers is related to the susceptibility of fused silica to radiation damage. The results obtained on the fused silica material are compared to SiO2 films on silicon. The NMR spectra and relaxation associated with thick (>1μm) wet SiO2 films are similar to those for the fused silica while the NMR data for thinner oxide more closely resembles those of surface water on silica gel.

An IR and multiple quantum NMR (MQNMR) study of hydrogen microstructure in three boron doped a-Si:H is discussed. The total Si-bonded H content of all films was 6.5 ± 1.0 at.% as determined by the 640 cm-1 IR wagging mode, but their boron content, which was determined by secondary ion mass spectrometry, ranged from 0.02 to 0.3 at. %. The number of correlated hydrogen, as measured at a preparation time of 600 μSwas found to be more weakly dependent on the boron content than previously observed in phosphorous-doped glow-discharge films. Upon annealing at 220 °C the MQNMR spectrum show a moderate increase in the number of correlated hydrogen in all three samples.

This paper reviews the role of past and future visual observations in cometary research. The strengths and limitations of visual observations are explored for the benefit of both investigators who might have to use them and observers who wish to make real contributions to the field. We consider the characteristics of the eye-brain combination as a detector and compare them with those of modern detectors. We specifically evaluate visual discoveries, magnitude estimates, and drawings.

This review describes the use of supersonic molecular beams or super­ sonic free jets to prepare gas phase samples for spectroscopic study under conditions where the internal degrees of freedom, the molecular vibration and rotations, have been cooled to very low temperatures. The dual objectives of preparing an isolated gas phase sample and of producing low internal temperatures have been traditionally desired by spectroscopists. However, the use of traditional techniques ultimately makes these two goals mutually exclusive. Almost arbitrarily low tem­ peratures can be achieved by the use of a proper refrigerant, but if temperatures much below the freezing point are desired, the reduced vapor pressure will require that spectroscopy be done on a solid sample. Frequently the goal of a spectroscopic study is the elucidation of those intermolecular interactions that occur in solids, and of course in these cases the low temperature solid is the sample of choice. In other cases the goal of the experiment is to study those intramolecular properties that are only slightly affected by the solid matrix surrounding the molecule of interest. In these cases the solid sample, although not ideal, is still adequate. However, there are cases where the desire is the study of properties of the isolated molecule that are completely overwhelmed in the matrix by intermolecular interactions, and in these cases the study must be carried out in the gas phase at the lowest temperature con­ sistent with adequate vapor pressure. The use of a supersonic expansion allows the preparation of internally cold, isolated, gas phase molecules and thereby retains the advantages of solid state or matrix isolation spectroscopy without the disadvantage

The microwave absorption spectrum of the OH X2Π radical has been observed in all vibrational levels up to ν = 6. Experimental details are described of the tunable cavity and parallel plate Stark-modulated spectrometers employed for transitions below and above 23 GHz, respectively. The observed line frequencies, together with those reported by other workers, have been fitted using a non-linear least-squares routine with numerical diagonalization of the Hamiltonian matrix. Pseudo high-order corrections for centrifugal distortion of the Λ-doubling are required for the ν = 0 data, which now extend to J = 19/2 in the 2Π1/2 component. The various adjustable parameters of the Hamiltonian are compared with those of other similar models. The Λ-doubling and magnetic hyperfine constants for the different vibrational levels are reported, and several line frequencies of potential astrophysical significance are predicted.

The gas phase reaction between carbonyl sulphide and the products of a microwave discharge in molecular oxygen has been studied by electron resonance. In addition to absorption lines from O 2 and SO in their ground electronic states, a four-line pattern due to SO in its excited 1 ∆ state is observed. Analysis of this spectrum yields the rotational constant B 0 for the 1 ∆ state, from which the bond length is calculated to be 1·493 Å.

The electron resonance spectrum of SO has been previously shown to arise from SO in two electronic states, the ground 3 Ʃ - and the excited 1 ∆ state. In this paper the portion of the spectrum assigned to the 3 Ʃ - state is analysed and shown to arise from three isotopic species, 32 S 16 O, 33 S 16 O, and 34 S 16 O. The analysis shows that besides the dominant interaction of the unpaired electronic spins with the magnetic field; other interactions must be taken into account to interpret the spectrum accurately. Interactions with electronic orbital angular momentum of π states mixed in by spin-orbit coupling and with rotationally induced magnetic moments have been observed. Values for parameters measuring such interactions have been determined from the spectrum, and these values lead to a resolution of the first- and second-order contributions to the zero-field molecular constants as well as an approximate value for the spin-orbit coupling constant. The hyperftne structure resulting from 33 S in 33 S 16 O has also been observed and is related to the usual hyperfine coupling constants. The expected line strengths and widths for SO have been calculated and these are compared with the observed quantities. Besides the expected lines from the isotopic SO species in the 3 Ʃ - state, several other lines have been detected. These lines are interpreted as arising from 32 S 16 O in the ground electronic state, but in the first excited vibrational level. The spectrum of vibrationally excited SO allows a value of the spin-spin coupling constant in the first excited vibrational state to be determined.

We have used solid state nuclear magnetic resonance (NMR) spectroscopy to study both “wet” and “dry” thermally grown films of SiO2 on silicon substrates. For the 5000 § wet film, grown at 1050 °C we observed a single Lorentzian line of 6 kHz HWHM (half width at half maximum). For the 500 § dry film, we observed a convolution of two lines: a) a Lorentzian of 4 kHz HWHM and b) a Gaussian of 20 kHz HWHM. The hydrogen distributions in both oxides are interpreted as a function of these lines.

The laser induced photodissociation of a number of van der Waals molecules has now been studied. Prior to this work, all of these van der Waals photodissociation reactions have been predissociations [1] involving laser excitation to a quasi-bound state. In this case the energy that will eventually be used to break the van der Waals bond is initially stored in some other vibrational mode, usually one of the vibrational modes of the chemically bound part of the molecule. After a finite period of time energy is transferred from the storage mode to the dissociating van der Waals mode, and the bond is broken.

Computer enhanced high resolution groundbased images taken during Halley’s most active phases in 1985–86 exhibit all of the coma structures seen in 1910 photographs. Improved detector technology compensated for the poor observing circumstances of the current apparition yielding a wealth of complex coma structure. This structure resulted mostly from discrete dust jet activity producing spirals, arcs, and jagged-edged envelopes. Several episodes of the “multiple nucleus” and antisunward jet phenomenon were also observed. The variation in dust jet activity during the Vega and Giotto flybys is easily seen on the groundbased images. Our images of jets in the 388 nm CN (0,0) band show that they usually do not correlate very well with visible dust jets. As in 1910, the observed expansion velocities and jet curvature indicate a rotation period near 2.2 days. Because the short period dominates the shape of the jets, detailed jet modeling will be required to detect longer term rotation components such as the proposed 7.4 day period.

This paper briefly reviews the history of electricity as motive power for oil pipe line operation and notes some of the reasons for, and the results of, its rapid development in the Southwest. Some attention is paid to the method of serving these loads from transmission lines and the tendency of modern pipe line practise is shown. The last five years have seen rapid advances in the methods of underground transportation of petroleum and the paper reviews some of the present tendencies in design of the modern oil pipe line station.

A mechanism of formation of the 1Δ state of SO is postulated, and experimental data supporting this mechanism is given. The excitation energy from the 3Σ to the 1Δ state of SO is probably less than the corresponding quantity in O2.