The antiquity and decline of the Bronze Age Harappan civilization in the Indus-Ghaggar-Hakra river valleys is an enigma in archaeology. Weakening of the monsoon after ~5 ka BP (and droughts throughout the Asia) is a strong contender for the Harappan collapse, although controversy exists about the synchroneity of climate change and collapse of civilization. One reason for this controversy is lack of a continuous record of cultural levels and palaeomonsoon change in close proximity. We report a high resolution oxygen isotope (δ18O) record of animal teeth-bone phosphates from an archaeological trench itself at Bhirrana, NW India, preserving all cultural levels of this civilization. Bhirrana was part of a high concentration of settlements along the dried up mythical Vedic river valley ‘Saraswati’, an extension of Ghaggar river in the Thar desert. Isotope and archaeological data suggest that the pre-Harappans started inhabiting this area along the mighty Ghaggar-Hakra rivers fed by intensified monsoon from 9 to 7 ka BP. The monsoon monotonically declined after 7 ka yet the settlements continued to survive from early to mature Harappan time. Our study suggests that other cause like change in subsistence strategy by shifting crop patterns rather than climate change was responsible for Harappan collapse.

A thermally fixed photorefractive Bragg grating is written in a single-mode Ti:Fe:Er:LiNbO3 channel waveguide and used to develop a distributed feedback-distributed Bragg reflector coupled cavity laser with a second broadband dielectric cavity mirror. The optically pumped (lambda(p) = 1480 nm, P = 130 mW) laser emits in single-frequency operation as much as 8 mW at lambda = 1557.2 nm with a slope efficiency of approximately 22%. The laser wavelength can be thermo-optically and electro-optically tuned over 100 pm.

We report the discovery of coherent radio emission from the young, rapidly-rotating magnetic Bp star HD 133880 at a frequency of 610 MHz with the Giant Metrewave Radio Telescope (GMRT). This is only the second magnetic star in which coherent radio emission has been detected. In our observations of HD 133880 covering the full rotational cycle of the star (except for a phase window 0.17 − 0.24), we witness an abrupt order-of-magnitude flux enhancement along with ≈ 100 percent right circular polarization. We attribute this phenomenon to coherent Electron Cyclotron MASER Emission. We attribute the lack of left circularly polarised emission to the asymmetric topology of the star's magnetic field. The phase of enhancement, 0.73, differs from the previously reported phase of enhancement, 0.16, (at 610 MHz Chandra et al. 2015) by one-half cycle. However, no flux enhancement is found at phase 0.16 in our data, which could be due to an unstable or drifting emission region, or a consequence of the reported changes of the star's rotational period. Either of these factors could have shifted the enhancement to the above-mentioned phase window not sampled by our observations.

A distributed feedback ͑DFB͒ laser in LiNbO 3 is demonstrated using a Ti:Fe:Er:LiNbO 3 waveguide with a holographically written photorefractive grating. The DFB laser was combined with a waveguide amplifier on the same substrate. Up to 1.12 mW of output power at ϭ1531.35 nm was emitted by the laser/amplifier combination at a pump power level of 240 mW (P ϭ1480 nm). The emission spectrum consists of the two lowest-order DFB modes of about 3.9 GHz frequency spacing. Whereas the measured threshold gain of ϳ3.3 dB/cm approximately agreed with the modeling results, the observed mode spacing was clearly smaller than calculated.