Landslides on Ceres: Diversity and Geologic Context.

Landslides are among the most widespread geologic features on Ceres. Using data from Dawn's Framing Camera, landslides were previously classified based upon geomorphologic characteristics into one of three archetypal categories, Type 1(T1), Type 2 (T2), and Type 3 (T3). Due to their geologic context, variation in age, and physical characteristics, most landslides on Ceres are, however, intermediate in their morphology and physical properties between the archetypes of each landslide class. Here we describe the varied morphology of individual intermediate landslides, identify geologic controls that contribute to this variation, and provide first-order quantification of the physical properties of the continuum of Ceres's surface flows. These intermediate flows appear in varied settings and show a range of characteristics, including those found at contacts between craters, those having multiple trunks or lobes; showing characteristics of both T2 and T3 landslides; material slumping on crater rims; very small, ejecta-like flows; and those appearing inside of catenae. We suggest that while their morphologies can vary, the distribution and mechanical properties of intermediate landslides do not differ significantly from that of archetypal landslides, confirming a link between landslides and subsurface ice. We also find that most intermediate landslides are similar to Type 2 landslides and formed by shallow failure. Clusters of these features suggest ice enhancement near Juling, Kupalo and Urvara craters. Since the majority of Ceres's landslides fall in the intermediate landslide category, placing their attributes in context contributes to a better understanding of Ceres's shallow subsurface and the nature of ground ice.

The geomorphology of Ceres.

Analysis of Dawn spacecraft Framing Camera image data allows evaluation of the topography and geomorphology of features on the surface of Ceres. The dwarf planet is dominated by numerous craters, but other features are also common. Linear structures include both those associated with impact craters and those that do not appear to have any correlation to an impact event. Abundant lobate flows are identified, and numerous domical features are found at a range of scales. Features suggestive of near-surface ice, cryomagmatism, and cryovolcanism have been identified. Although spectroscopic analysis has currently detected surface water ice at only one location on Ceres, the identification of these potentially ice-related features suggests that there may be at least some ice in localized regions in the crust.

Use of a paramagnetic substance, colloidal manganese sulfide, as an NMR contrast material in rats.

Paramagnetic pharmaceuticals ( magnetopharmaceuticals ) that are suitably distributed into specific organ systems or diseased sites might be clinically useful for tissue contrast enhancement in nuclear magnetic resonance images. To determine whether an insoluble magnetopharmaceutical might be useful in such service, we investigated the effect of a colloidal preparation of manganese sulfide ( MnSC ) upon liver and lung spin-lattice relaxation times (T1) in rats following intravenous administration. NMR tissue sample measurements were made at 24 MHz, ahd showed that after MnSC treatment, liver T1 values--and to a lesser extent lung T1 values--were depressed below control values. Liver manganese content (as determined by flame atomic absorption spectrophotometry) increased in proportion to the dose of MnSC , and the reciprocal of the liver T1 values also increased in proportion to the dose of MnSC .

Alteration of gallium-67 distribution in tumor-bearing mice following treatment with methotrexate: concise communication.

The effect of methotrexate (MTX) treatment upon Ga-67 distribution was investigated. Tumor bearing mice were injected with Ga-67 citrate at varying time intervals following MTX treatment administered either as a single dose or in multiple doses. Altered Ga-67 distribution was observed following MTX therapy, the general pattern showing decreased levels in blood and increased uptake in bone. MTX therapy decreased Ga-67 uptake in liver, tumor, and muscle. The effects of MTX are related to the dose and time interval between the administrations of MTX and Ga-67. The serum of MTX-treated mice had lower unsaturated iron-binding capacities and higher levels of unbound Ga-67. Serum iron and iron binding in rats determined 20 hr after MTX therapy showed significantly higher levels of serum iron and lower levels of Ga-67 in blood, and the percent transferrin saturation was approximately 95%. These observations suggest that MTX inhibition of erythropoiesis elevates serum iron levels and decreases the availability of gallium-binding sites in serum, resulting in altered Ga-67 tissue distribution.

Comparison of Tc-99m pyrosphosphate and Tc-99m hydroxymethylene diphosphonate in acute myocardial infarction: concise communication.

A clinical comparison between a new bone seeking radiopharmaceutical, Tc-99m hydroxymethylene diphosphonate (TcHMDP) and the standard agent, Tc-99m pyrophosphate (TcPPi), was performed in 18 patients with acute myocardial infarction. Each patient was imaged initially with either TcHMDP or TcPPi, and imaged 24 hr later with the other tracer. All 18 patients had images positive for acute myocardial infarction with TcPPi, whereas 16 of 18 patients (89%) had positive studies with TcHMDP. The TcPPi images were graded significantly superior to those obtained with TcHMDP in 61% of the patients, and they were equal in 33%. In only one patient (6%) was TcHMDP better. The results indicate that compared with TcHMDP, TcPPi not only has a superior sensitivity for acute myocardial infarction but also has a significantly increased intensity of uptake in positive areas. TcPPi remains the agent of choice for myocardial infarct imaging.

Comparison of Tc-99m pyrophosphate and Tc-99m methylene diphosphonate in acute myocardial infarction: concise communication.

This study compared Tc-99m pyrophosphate (PPi) and Tc-99m methylene diphosphonate (MDP) for myocardial infarct imaging in 24 patients with diagnosed acute myocardial infarction. The radiopharmaceuticals were administered randomly and interpreted without knowledge of the sequence used. Twenty-three patients (96%) had positive Tc-99m PPi scintigrams, but only 17 (71%) had a positive Tc-99m MDP study (P less than 0.05). In addition, a comparison of the relative intensity with each agent revealed greater intensity with Tc-99m in 21 cases, equal intensity in two cases, and less intensity in only one case (p less than 0.001). These findings support the superiority of Tc-99m PPi as the agent of choice for myocardial scintigraphy in acute infarction.

Relative lesion detection ability of Tc-99m HMDP and Tc-99m MDP: concise communication.

To compare the efficacy of Tc-99m HMDP and Tc-99m MDP to define skeletal lesions, 28 adult patients were examined in a double-blind, randomized, crossover study. Each patient was imaged with both agents over a period of 7-14 days. Both quantitative and qualitative evaluations were performed on the resulting images. Both agents detected the same number of skeletal lesions, and the number of lesions detected was the same whether the imaging was performed 2 or 4 hr after injection. Relative uptake of the tracer in the lesion relative to normal bone was also the same for both agents. Lesions were easier to see at 4 hr after injection than at 2 hr, presumably because soft-tissue levels were lower. Retention of tracer in bone compared with soft tissue was greater, and image quality was judged to be better, with Tc-99m HMDP than with Tc-99m MDP.

The utility of adrenal scintigraphy in Cushing's syndrome and hyperaldosteronism.

Thirty-three adrenal scintigrams in 30 patients were reviewed to determine the utility of this noninvasive imaging technique. It was found to be very accurate in distinguishing bilateral from unilateral hyperfunction in patients who have clinical and biochemical evidence of adrenal cortical hyperfunction. The technique proved correct in 12 of 12 cases of Cushing's syndrome and 14 of 19 cases of hyperaldosteronism. Specific clinical questions were also answered in three miscellaneous cases.

Hematologic depression following therapy with strontium-89 chloride.

Initial clinical trials using strontium-89 (Sr-89) chloride for the treatment of painful skeletal metastases have observed minimal or no hematological depression secondary to the radiostrontium. A patient with marked bone marrow depression temporally related to the administration of the Sr-89 is reported, and the need for close hematological monitoring is emphasized. Bone marrow tumor replacement may predispose patients to marrow depression from radiostrontium, and such patients should be treated with caution.

Operational review: beyond the numbers game.

The first response to operational review is, traditionally, an examination of productivity indicators and a rationale for their defense. This paper describes the creative approach chosen by one hospital setting with specific reference to the occupational therapy department. The focus was placed on outcome for the child and productivity measurement. Results of the review for the occupational therapy department were positive and established a precedent for parts of the presentation when the review continued throughout the hospital. Occupational therapy managers are encouraged to become more innovative in the effective management of their departments, continuing to develop and build leadership skills for the future.

Manage or be managed: where do you stand?

Proficiency in administration is an essential component for all occupational therapists whether they are managing a caseload or directing the activities of a large department. However, more attention needs to be paid to preparing therapists for management roles by professional organizations in occupational therapy, at both provincial and national levels. Occupational therapy managers have a role to play as well. The issues are reviewed briefly and recommendations to improve the situation are made.

Principles and applications of nuclear magnetic resonance imaging.

The physics, instrumentation, and general aspects of nuclear magnetic resonance (NMR) imaging are discussed. NMR images are constructed from magnetic signals emitted by certain atomic nuclei when they are subjected to simultaneously applied magnetic fields and externally generated radiofrequency (r.f.) energy. Hydrogen (the nucleus of which is a single proton) is sensitive to NMR and sufficiently abundant in tissues to produce the signals necessary for image formation. The NMR imaging device consists of a large magnet, a radiofrequency-transmitter coil, and computer hardware. Following r.f. pulsing, the strength and origin of the magnetic signals can be determined by magnetic field gradients that are superimposed on a magnetic field. Then this spatial information can be encoded electronically and reconstructed into a cross-sectional image. NMR imaging is valuable for the diagnosis of a variety of diseases and traumas since a high level of lesion and soft tissue contrast is possible in most types of pathology. Compounds containing paramagnetic elements (magnetopharmaceuticals) may be useful to enhance tissue contrast and organ detail. The high level of tissue detail, sensitivity to pathology, and apparent lack of hazard make NMR an important addition to the existing diagnostic modalities.

Positron emission tomography: from production and distribution to drug research and clinical applications.

The radiopharmaceutical FDG has had a major impact on PET imaging in clinical medicine, particularly in the detection and staging of certain cancers. PET isotopes offer unparalleled insight into in vivo distribution of labeled drugs. PET imaging of blood flow, metabolism, and neuroreceptor characteristics may provide new perspectives on the mechanism of action and effects of drugs.

Volumetric diffusive respirator use in neonatal respiratory failure.

Six very low birthweight neonates with terminal respiratory failure due to severe hyaline membrane disease who failed to respond to conventional ventilation were offered a trial of high frequency jet ventilation using the volumetric diffusive respirator (VDR). All neonates showed improvement in pulmonary function. Two neonates were weaned successfully from high frequency ventilation. The results of this initial trial suggest that the volumetric diffusive respirator is a safe and effective method of ventilation in neonates with respiratory failure and that the survival rate in such neonates might be enhanced if treatment is introduced earlier in the disease.