Characterizing colon cancer stages through optical polarimetry-assisted digital staining

Tissue polarimetry has been gaining importance in extracting useful diagnostic information from the structural attributes of tissues, which vary in response to the tissue health status and hence find great potential in cancer diagnosis. However, the complexities associated with cancer make it challenging to isolate the characteristic changes as the tumor progresses using polarimetry. This study attempts to experimentally characterize the polarimetric behavior in colon cancer associated with various stages of development. Bulk and unstained sections of normal and tumor colon tissue were imaged in the reflection and transmission polarimetry configurations at low and high imaging resolutions using an in-house developed Mueller polarimeter. Through this study, we observed that the information about the major contributors of scattering in colon tissue, manifesting in depolarization and retardance, can be obtained from the bulk tissue and unstained sections. These parameters aid in characterizing the polarimetric changes as the colon tumor progresses. While the unstained colon section best indicated the depolarization contrast between normal and tumor, the contrast through the retardance parameter was more pronounced in the bulk colon tissue. The results suggest that the polarimetric "digitally stained" images obtained by Mueller polarimetry are comparable with the bulk tissue counterparts, making it useful for characterizing colon cancer tissues across different stages of development.

Seasonal variability and long-term trends of the surface and subsurface circulation features in the Equatorial Indian Ocean

Herein, we have examined the seasonal variability and long-term trends in the recent 35 years (1980-2014) of the wind stresses and circulation features in the Equatorial Indian Ocean (EIO) using reanalysis and observed data. Annual mean flow of the EIO is eastward along the equator, with the strong current in the upper 80 m and weak below that. The prominent surface currents in the EIO are the eastward Wyrtki Jets (WJs) occurring during spring (April-May) and fall (October-November), with active flows within 2° of the equator between 60° E and 90° E. The fall WJs are stronger than the spring WJs. The Equatorial Undercurrent (EUC), the prominent subsurface eastward flow with core within 70-150 m, occurs twice annually-February-April and August-October-with the well-developed flow in March-April. Long-term trends reveal that during 1980-2014, the annual mean eastward surface current in the upper 75 m has increased, primarily due to the rise of WJs forced by the westerly wind stresses during November-December. But the subsurface eastward current (below 75 m) has decreased due to the weakening of winter North Equatorial Current (NEC) and EUC during February-April. Consolidation of the westerly wind stresses during November-April results in the strengthening of the wind-driven surface WJs and weakening of the pressure-driven EUCs during 1980-2014. Intensification of WJs are the direct effects of wind forcing. However, strengthening of westerly stresses also results in weakening of the surface westward NEC and thereby restricts the strong eastward gradient of SSH which is required to build up the essential eastward pressure gradient for the EUC. Since WJs and EUCs modulate the hydrographic structure of the eastern part of the EIO, any change in the strength of these flows, in turn, will influence mostly this oceanic region and thereby the local as well as global climate.

Degeneracy in the diffraction of orbital angular momentum carrying beams

Symmetry constraints on the far-field diffraction of Laguerre-Gauss vortex beams by planar aperture arrays with N-fold rotational symmetry are considered. The experiments reveal a simple structure for the diffraction pattern and high degree of degeneracy in its dependence on the orbital angular momentum index of the incident beam in agreement with analytical and numerical results.

Water quality assessment of open wells in and around Chavara industrial area, Quilon, Kerala

Water quality of four open wells representing four localities around the Kerala Minerals and Metals Ltd industrial area, Chavara, Quilon district was studied fora period of six months from December, 2006 to May 2007 to assess the suitability of the well waters for domestic purposes. The well waters exhibited high BOD (average values from 12.87-15.96 mg l(-1)), COD (666.67-796.67 mg l(-1)), TDS (500-1466.67mg l(-1)), total hardness (110-835 mg l(-1)), nitrate (1.12-4.97 mg l(-1)), calcium (30.59-271.22 mg l(-1)), phosphate (0.19-0.48 mg l(-1)) and free CO2 (49.13-102.47 mg l(-1)) and low dissolved oxygen (2.63-3.13 mg l(-1)). Heavy metal analysis revealed that the third and fourth wells are free from heavy metal pollution. Coliform test showed bacterial contamination in all the wells. The values of BOD, COD, TDS and phosphate exceeded the maximum permissible limits and the dissolved oxygen was much lower than the desirable limit in all the well waters. Hence all the four well waters are found unsuitable for domestic purposes as it is confirmed by water quality index. The use of waters of open wells in and around the industrial area may cause health hazards to nearby inhabitants.