Dhansak ("Dhan" is Persian/Urdu for "seed"- referring to grains or legumes; "Sak" (derived from Gujarati "shaak" meaning vegetable greens or cooked vegetables). The Gujarati element of the recipe is the liberal use of a variety of Indian spices and condiments, in contrast to the more mellow Iranian recipes. In Parsi homes, dhansak is traditionally made on Sundays owing to the long preparation time required to cook the lentils and vegetables into a mush (in the days before pressure cooking was employed). Dhansak is also always had on the fourth day after the death of a near one. There is no meat
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.