Granular convection observed by magnetic resonance imaging

Vibrations in a granular material can spontaneously produce convection rolls reminiscent of those seen in fluids. Magnetic resonance imaging provides a sensitive and noninvasive probe for the detection of these convection currents, which have otherwise been difficult to observe. A magnetic resonance imaging study of convection in a column of poppy seeds yielded data about the detailed shape of the convection rolls and the depth dependence of the convection velocity. The velocity was found to decrease exponentially with depth; a simple model for this behavior is presented here.     

Galileo at Io: results from high-resolution imaging

During late 1999/early 2000, the solid state imaging experiment on the Galileo spacecraft returned more than 100 high-resolution (5 to 500 meters per pixel) images of volcanically active Io. We observed an active lava lake, an active curtain of lava, active lava flows, calderas, mountains, plateaus, and plains. Several of the sulfur dioxide-rich plumes are erupting from distal flows, rather than from the source of silicate lava (caldera or fissure, often with red pyroclastic deposits). Most of the active flows in equatorial regions are being emplaced slowly beneath insulated crust, but rapidly emplaced channelized flows are also found at all latitudes. There is no evidence for high-viscosity lava, but some bright flows may consist of sulfur rather than mafic silicates. The mountains, plateaus, and calderas are strongly influenced by tectonics and gravitational collapse. Sapping channels and scarps suggest that many portions of the upper approximately 1 kilometer are rich in volatiles.     

Long-term elevation of atmospheric CO(2) concentration and the carbon exchange rates of saplings of Pinus taeda L. and Liquidambar styraciflua L

The relationship between carbon exchange rate (CER) and internal CO(2) concentration was measured in leaves of saplings of Liquidambar styraciflua L. (sweetgum) and Pinus taeda L. (loblolly pine) grown from seed for more than 14 months at atmospheric CO(2) concentrations of either 350 or 500 microl l(-1). An elevated concentration of CO(2) during growth reduced CER at any given internal CO(2) concentration in sweetgum, but not in loblolly pine. Stomatal limitation of CER showed little response to concentration of CO(2) during measurement, but was higher in both species when grown at 500 than at 350 microl l(-1) CO(2). The net effect of a long-term increase in CO(2) concentration from 350 to 500 microl l(-1) was an increase in CER of loblolly pine, but a slight decrease in CER of sweetgum. It is suggested that the depression of CER in sweetgum resulted from a reduction in the activity of ribulose-1,5-bisphosphate carboxylase-oxygenase.     

Evaluation of lung function in pigs either experimentally or naturally infected with Chlamydiaceae

This study evaluated the influence of chlamydial infections on lung function in conventionally raised pigs. Eight pigs aged 39-44 days were included in an aerogeneous challenge model (4 were exposed to Chlamydia suis; 4 served as controls). Nineteen pigs aged 5-27 weeks without clinical symptoms (but partly PCR-positive for chlamydial species) were examined over 6 months. For lung function testing, impulse oscillometry was used. In total, all 27 pigs underwent 465 lung function tests. Variables of ventilation (respiratory rate, tidal volume, minute volume), respiratory impedance (expressed as resistance and reactance within the frequency range 3-15 Hz), and model derived resistance of proximal and distal airways were measured. Experimental exposure to C. suis significantly affected lung function. Early distal airway obstruction (3-5 days after infection) was followed by an obstruction of proximal airways (7 days after infection). The breathing pattern was significantly changed (decreased tidal volume; increased respiratory rate). In symptom-free pigs having a naturally acquired presence of different chlamydial species in the respiratory system, no deterioration in lung function could be determined up to the age of 6 months. In conclusion, the consequences of respiratory chlamydial infections appear to vary from clinical inapparence to severe respiratory distress.     

Evaluation of lung function in pigs either experimentally or naturally infected with Chlamydiaceae

This study evaluated the influence of chlamydial infections on lung function in conventionally raised pigs. Eight pigs aged 39–44 days were included in an aerogeneous challenge model (4 were exposed to Chlamydia suis; 4 served as controls). Nineteen pigs aged 5–27 weeks without clinical symptoms (but partly PCR-positive for chlamydial species) were examined over 6 months. For lung function testing, impulse oscillometry was used. In total, all 27 pigs underwent 465 lung function tests. Variables of ventilation (respiratory rate, tidal volume, minute volume), respiratory impedance (expressed as resistance and reactance within the frequency range 3–15 Hz), and model derived resistance of proximal and distal airways were measured. Experimental exposure to C. suis significantly affected lung function. Early distal airway obstruction (3–5 days after infection) was followed by an obstruction of proximal airways (7 days after infection). The breathing pattern was significantly changed (decreased tidal volume; increased respiratory rate). In symptom-free pigs having a naturally acquired presence of different chlamydial species in the respiratory system, no deterioration in lung function could be determined up to the age of 6 months. In conclusion, the consequences of respiratory chlamydial infections appear to vary from clinical inapparence to severe respiratory distress.     

Correlation of helical and incremental high-resolution thin-section computed tomographic and histomorphometric quantitative evaluation of an acute inflammatory response of lungs in dogs

OBJECTIVE: To compare quantitative densitometric computed tomography (CT), morphometric, and histologic data of normal lungs in dogs with similar parameters obtained after induction of an acute inflammatory response and determine whether CT densitometry correlated with histopathologic changes. ANIMALS: 6 healthy adult dogs. PROCEDURE: After initial CT, 1 mL of 0.1 M hydrochloric acid (HCI) and 3 mL of autologous blood were instilled into the right middle (RM) and caudal segment of the left cranial (LCCd) lung lobes, respectively. Immediately and 24 hours after instillation, CT was repeated. At 24 hours, dogs were euthanatized and lungs were fixed and sampled for morphometric and histologic evaluation. The CT data were compared with lung morphology and morphometry by use of unpaired t tests. Comparison with lungs from control dogs was performed using Spearman rank correlation coefficients. RESULT: Mean Hounsfield units (HU) from control and baseline HU from experimental dogs were identical. Immediately after instillation of HCI or blood, there was increased attenuation in both lobes. Autologous blood initially induced severe changes that almost completely resolved at 24 hours; HCI induced severe changes at 24 hours. Significant increases in percentage of parenchymal airspace and alveolar diameter resulted in decreased surface area-to-volume ratio in lobes receiving HCl. Histologic scores were significantly higher in the RM lobe, compared with controls. CONCLUSIONS AND CLINICAL RELEVANCE: Computed tomography attenuation correlated well with histomorphometry and histologic findings in this model. Lung lesions after autologous blood were transient and of limited severity. Lesions induced by HCl were severe; alterations in morphometric and histologic parameters were reflected in CT attenuation measurements.     

Undesirable reactions of domestic pigeons to vaccination against paramyxovirus type 1

Subcutaneous vaccination of fancy and racing pigeons with inactivated oil-based vaccines protects against all clinical manifestations caused by the Paramyxovirus type 1. Correct application of the vaccine may occasionally result in the development of granulomas or abscess-like lesions on the site of vaccine application. Although protected against disease as proven by challenge experiments, a variable proportion of vaccinated pigeons do not react with the formation of detectable serum antibodies. The pathogenesis of granuloma and abscess-like lesion developments and the failure to form humoral antibodies are presently not understood. Questions relating to legal liability of vaccinating veterinarians are briefly discussed.     

Use of a supraplastron approach to the coelomic cavity for repair of an esophageal tear in a loggerhead sea turtle

A juvenile loggerhead sea turtle (Caretta caretta) was referred for removal of a fishhook lodged in the coelomic portion of the esophagus. Attempts at manual and endoscopic extraction were unsuccessful and resulted in a 6-cm tear in the coelomic portion of the esophagus. A supraplastron approach was made to the coelomic cavity, allowing access to and repair of the esophageal tear. The turtle recovered well and was able to be released to the wild. The surgical approach was associated with less trauma and shorter healing and rehabilitation times, compared with traditional plastron osteotomy.