Dhansak them the tradition of cooking meat with lentils and/or vegetables. However, tomatoes, chilies, pumpkin and potatoes are native to the Americas and were unknown in India until some time after the Portuguese (who in turn got them through trade with Spain) brought them to India in the 16th century CE. The dhansak is flavoured with a spice mixture called "dhansak masala", which is similar to "garam masala" except that the spices chosen are more aromatic and sweet rather than pungent. Cinnamon, cardamom, cloves, nutmeg, dried ginger, coriander seed and cumin seed, as well as a pinch of asafetida, are among
Pulse tube refrigerator developed for cooling of astronomical detectors where liquid cryogens are typically used, such as the Atacama Cosmology Telescope or the Qubic experiment (an interferometer for cosmology studies). PTRs are used as precoolers of dilution refrigerators. Pulse tubes will be particularly useful in space-based telescopes such as the James Webb Space Telescope where it is not possible to replenish the cryogens as they are depleted. It has also been suggested that pulse tubes could be used to liquefy oxygen on Mars. Here the so-called Stirling-type single-orifice pulse-tube refrigerator will be treated operating with an ideal gas (helium) as the working fluid.