Malignant histiocytosis of the brain in three dogs.

Three dogs (two Rottweilers and a Flat-coated retriever) showed various neurological signs, including apathy, depression, circling, a partial decrease in functions associated with cranial nerves, seizures, hyperaesthesia, proprioceptive deficits, and increased spinal reflexes. In all three cases, necropsy revealed a solid, distinct, white mass in the brain and multiple, poorly demarcated, firm nodular proliferations in the lung; in one case the liver was also affected. Histopathological examination showed loosely aggregated, pleomorphic cells, with abundant eosinophilic cytoplasm. The neoplastic cells sometimes contained vacuoles or phagocytized cells. Binucleated and multinucleated giant cells, and mitotic figures, were common. Immunohistochemically, the tumour cells reacted strongly for lysozyme and vimentin, but there was no reaction for S-100 protein, cytokeratin, CD3 or CD79a. The histological and immunohistochemical examinations indicated a histiocytic origin of the tumour cells and malignant histiocytosis was therefore diagnosed.

[Case report: tenesmus in a cow with a liver abscess and nephritis]. / Fallbericht. Tenesmus bei einer Kuh mit Leberabszess und Nephritis.

A two-year-old Swiss Braunvieh cow was referred to our clinic because of tenesmus and weight loss. Clinical examination revealed a moderately abnormal general behaviour and condition, thin body condition and a rectal temperature of 40.1 degrees C. Tenesmus was evident, and rumen and intestinal motility were markedly reduced. All tests for a reticular foreign body were positive. On rectal examination, a round, smooth, firm, non-painful mass with a diameter of approximately 15 cm was palpated far cranially on the right side. Abnormal haematological and biochemical findings included marked anaemia, neutrophilic leucocytosis, markedly elevated concentration of fibrinogen and mildly elevated gamma-glutamyl-transferase activity. The clotting time of the glutaraldehyde test was one minute. Ultrasonographic examination revealed abscesses involving the liver and extending caudally into the right flank region. The liver parenchyma had diffuse changes. Because of a grave prognosis, the cow was euthanized. Postmortem findings substantiated ultrasonographic results; there were abscesses, caused by Fasciola hepatica infestation, originating in the liver and extending into the right flank. As well, there was severe, bilateral, multifocal, suppurative nephritis due to thromboembolism. Based on all the findings, a diagnosis of liver abscess caused by fascioliasis and bilateral suppurative nephritis was made.

Theory of extraordinary optical transmission through subwavelength hole arrays.

We present a fully three-dimensional theoretical study of the extraordinary transmission of light through subwavelength hole arrays in optically thick metal films. Good agreement is obtained with experimental data. An analytical minimal model is also developed, which conclusively shows that the enhancement of transmission is due to tunneling through surface plasmons formed on each metal-dielectric interface. Different regimes of tunneling (resonant through a "surface plasmon molecule," or sequential through two isolated surface plasmons) are found depending on the geometrical parameters defining the system.

Delay in light transmission through small apertures.

We demonstrate a technique for measuring pulse propagation time delays with 0.5-fs resolution by use of a widely available 100-fs pulsed laser. Using this technique, we measured the time delay of a light pulse transiting through subwavelength apertures placed on a 0.3-mum metallic film. We measured a 7-fs total transit time, corresponding to an effective group velocity of c/7 . The experimental result yielded additional evidence that light interacts resonantly with oscillators formed by the surface modes near the small apertures.

Enhanced light transmission through a single subwavelength aperture.

The optical transmission through a subwavelength aperture in a metal film is strongly enhanced when the incident light is resonant with surface plasmons at the corrugated metal surface surrounding the aperture. Conversely, the aperture acts as a novel probe of the surface plasmons, yielding useful insights for optimizing the transmission enhancement. For the optimal corrugation geometry, a set of concentric circular grooves, three times more light is transmitted through the central subwavelength aperture than directly impinges upon it. This effect is useful in the fabrication of near-field optical devices with extremely high optical throughput.

Enhanced Room-Temperature Geometric Magnetoresistance in Inhomogeneous Narrow-Gap Semiconductors.

A symmetric van der Pauw disk of homogeneous nonmagnetic indium antimonide with an embedded concentric gold inhomogeneity is found to exhibit room-temperature geometric magnetoresistance as high as 100, 9100, and 750,000 percent at magnetic fields of 0.05, 0.25, and 4.0 teslas, respectively. For inhomogeneities of sufficiently large diameter relative to that of the surrounding disk, the resistance is field-independent up to an onset field above which it increases rapidly. These results can be understood in terms of the field-dependent deflection of current around the inhomogeneity.

Control of optical transmission through metals perforated with subwavelength hole arrays.

The transmission spectrum of a metal that is perforated with a periodic array of subwavelength holes exhibits well-defined maxima and minima resulting from, respectively, a transmission enhancement by surface plasmons and Wood's anomaly, a diffraction effect. These features occur at wavelengths determined by the geometry of the hole arrays, the refractive index of the adjacent medium, and the angle of incidence. We demonstrate control of the transmission through variation of these parameters and show that perforated metal films may form a novel basis for electro-optic devices such as flat-panel displays, spatial light modulators, and tunable optical filters.

Thick plasma gratings using a local photorefractive effect in CdZnTe:In.

Diffraction gratings have been encoded in bulk Cd(0.8)Zn(0.2)Te:In samples by near-band-gap excitation. The photoinduced index change is associated with persistent photoconductivity resulting from ionization of DX centers. The gratings have a thickness of 1.7 mm, as evinced by Bragg selectivity during the readout process. Encoded grating are shown to be persistent for sufficiently low temperatures and are not erased by subsequent writing of more gratings.