Polish Society of Nephrology improvements in continuous professional development as well as research activities among young doctors and other professionals in the fields of nephrology, dialysis therapy and renal transplantation. PSN Congresses are organized every three years. As yet twelve Congresses were held in the following locations in Poland: 1st Congress - Bydgoszcz (1983) 2nd Congress - Kraków (1986) 3rd Congress - Gdańsk (1989) 4th Congress - Katowice (1992) 5th Congress - Lublin (1995) 6th Congress - Poznań (1998) 7th Congress - Kraków (2001) 8th Congress - Białystok (2004) 9th Congress – Katowice/Wisła (2007) 10th Congress - Bydgoszcz (2010) 11th Congress - Wrocław (2013)
Four Treasures of the Study ceramic stones (澄泥硯) which are manufactured by a process which is said to have been developed in Luoyang in Henan. Classical scholars had more than just the Four treasures in their studies. The other "Treasures" include the brush-holder (笔架), brush-hanger (笔挂), paperweights (镇纸), the brush-rinsing pot (笔洗), and the seal (圖章) and seal-ink (印泥). For painting, Chinese pigments are also used. Four Treasures of the Study Four Treasures of the Study, Four Jewels of the Study or Four Friends of the Study is an expression used to denote the brush, ink, paper and ink stone used in Chinese and other