Electromagnetic metamaterials to approach superconductive-like electrical conductivity

This paper explores the possibility of using electromagnetic metamaterials to synthesize an equivalent structure that approaches superconductive-like properties, i.e. extremely high electrical conductivity. The underlying electromagnetic model is formalized analytically using transmission line theory and supported by experimental measurements. This particular use of metamaterials could bring to the ground-breaking scenario of developing superconductive-like cavities and lossless guiding structures at ambient temperature.

A video densitometric analysis of viral burden and follicular dendritic cell damage in lymph nodes in the latency phase of HIV infection

BACKGROUND

The aim of this study was to collect quantitative data on damage to follicular dendritic cells (FDC) and on the structure of germinal centers (GC) in the early phase of HIV infection.

METHODS

Lymph node sections from 10 HIV(+) subjects and from 5 HIV(-) control subjects were stained by immunohistochemistry for CD21, an FDC marker; gp24, to assess the HIV load; and IgM, to measure antibodies within the GC.

RESULTS

The volume fraction (V(area)) and the logarithm of the inverse gray value (ArLIGV) of CD21 areas showed a highly significant decrease in HIV(+) specimens. The mean ArLIGV values ranged between 0.0916 +/- 0.01 and 0.3826 +/- 0.11 versus 0.6856 +/- 0.19 on average in controls (P < 0.001 for both). Six of 10 HIV(+) specimens were positive for gp24. Staining was limited to GC and showed a distribution pattern similar to that of CD21.

CONCLUSIONS

FDC already undergo considerable damage during the latency phase of HIV infection. The pattern of CD21 indicates that, although FDC decrease in number, the staining intensity of positive cells is basically preserved. Video densitometric analysis, an approach requiring a strict standardized protocol, may help monitor disease course and evaluate response to therapy by quantifying viral burden and lymph node damage.

Cell counting and three-dimensional reconstruction to identify a cellular wave in human spermatogenesis

OBJECTIVE

To collect quantitative and stereologic data on the main cell types represented in the seminiferous tubule in order to produce a three-dimensional representation of the morphologic events of normal cell production and maturation.

STUDY DESIGN

Three-dimensional reconstruction and differential cell counting were performed on serial sections of normal testicular tissue from normal young men through image analysis and computer-based rendering.

RESULTS

Peculiar periodicity in the total number of tubular cells considered along the sequence of serial sections was recognized. Also, consensual periodicity pertaining to each cell type was recognized. Adjacent high cellularity and low cellularity segments included a fairly constant mixture of cell types considered.

CONCLUSION

A newly defined cellular wave, composed of regular alternations of high and low cellularity segments, was identified in the normal human seminiferous tubule.