Basic magnetic resonance imaging principles used for evaluating animal patients with neurologic disease.

The use of MRI in veterinary medicine is growing, because it provides excellent anatomic and pathologic detail. Acquiring a useful MRI study depends upon understanding basic MRI principles and choosing the correct pulse sequences. This article introduces the reader to principles of MRI, image contrast, and appropriate pulse sequence selection for imaging. Lastly, the article briefly describes diffusion imaging, magnetic resonance angiography, and chemical shift artifact. The fundamental topics addressed in this article are items that exotic animal practitioners using MRI should know and be able to put to immediate use.     

What is your diagnosis? Lingual mass in a dog

A 3.5-year-old female spayed Rat Terrier was presented for evaluation of a submucosal lingual mass. Fine-needle aspiration of the mass revealed a population of neoplastic cells composed predominantly of small, round cells and large, round to spindle-shaped cells, which occasionally had blunt cytoplasmic borders and multiple nuclei. The neoplastic cells had moderate to marked anisocytosis and anisokaryosis. The cytologic interpretation was malignant neoplasia, most likely sarcoma. Histopathologic examination of a biopsy specimen revealed an unencapsulated, poorly demarcated, moderately cellular neoplasm composed of individualized, infiltrative spindle cells. Elongate skeletal muscle cells with prominent, rectangular borders (strap cells) were observed. A morphologic diagnosis of rhabdomyosarcoma was made. Staining with phosphotungstic acid-hematoxylin revealed haphazardly arranged skeletal muscle cross-striations. Immunohistochemical staining results for vimentin, Myo D1, desmin, and myoglobin were positive, though staining intensity of tumor cells varied with the degree of differentiation. Using transmission electron microscopy, irregular, disorganized Z-bands were identified. Rhabdomyosarcomas are uncommon tumors in the dog, and rarely may involve the tongue or oral cavity. Cytologic evaluation of a rhabdomyosarcoma may reveal a pleomorphic population of cells and definitive diagnosis may require histologic examination, immunohistochemical staining, and electron microscopy.     

Drivers of consensus‐based decision‐making in international environmental regimes: Lessons from the Southern Ocean

相似文献   

Continental-scale partitioning of fire emissions during the 1997 to 2001 El Niño/La Niña period

During the 1997 to 1998 El Ni?o, drought conditions triggered widespread increases in fire activity, releasing CH4 and CO2 to the atmosphere. We evaluated the contribution of fires from different continents to variability in these greenhouse gases from 1997 to 2001, using satellite-based estimates of fire activity, biogeochemical modeling, and an inverse analysis of atmospheric CO anomalies. During the 1997 to 1998 El Ni?o, the fire emissions anomaly was 2.1 +/- 0.8 petagrams of carbon, or 66 +/- 24% of the CO2 growth rate anomaly. The main contributors were Southeast Asia (60%), Central and South America (30%), and boreal regions of Eurasia and North America (10%).     

Quantum-enhanced measurements: beating the standard quantum limit

Quantum mechanics, through the Heisenberg uncertainty principle, imposes limits on the precision of measurement. Conventional measurement techniques typically fail to reach these limits. Conventional bounds to the precision of measurements such as the shot noise limit or the standard quantum limit are not as fundamental as the Heisenberg limits and can be beaten using quantum strategies that employ "quantum tricks" such as squeezing and entanglement.     

A mutation in the TRPC6 cation channel causes familial focal segmental glomerulosclerosis

Focal and segmental glomerulosclerosis (FSGS) is a kidney disorder of unknown etiology, and up to 20% of patients on dialysis have been diagnosed with it. Here we show that a large family with hereditary FSGS carries a missense mutation in the TRPC6 gene on chromosome 11q, encoding the ion-channel protein transient receptor potential cation channel 6 (TRPC6). The proline-to-glutamine substitution at position 112, which occurs in a highly conserved region of the protein, enhances TRPC6-mediated calcium signals in response to agonists such as angiotensin II and appears to alter the intracellular distribution of TRPC6 protein. Previous work has emphasized the importance of cytoskeletal and structural proteins in proteinuric kidney diseases. Our findings suggest an alternative mechanism for the pathogenesis of glomerular disease.     

Spin disorder on a triangular lattice

As liquids crystallize into solids on cooling, spins in magnets generally form periodic order. However, three decades ago, it was theoretically proposed that spins on a triangular lattice form a liquidlike disordered state at low temperatures. Whether or not a spin liquid is stabilized by geometrical frustration has remained an active point of inquiry ever since. Our thermodynamic and neutron measurements on NiGa2S4, a rare example of a two-dimensional triangular lattice antiferromagnet, demonstrate that geometrical frustration stabilizes a low-temperature spin-disordered state with coherence beyond the two-spin correlation length. Spin liquid formation may be an origin of such behavior.     

Quantum information matters

This Perspective discusses the role that quantum information plays in determining the quantum-mechanical aspects of matter. Beginning with the entwined concepts of information and entropy, the article discusses how quantum information theory can supply us with novel concepts and techniques for understanding how matter behaves at the most microscopic of levels.