A set S of edge-disjoint hamilton cycles in a graph G is said to be maximal if the edges in the hamilton cycles in S induce a subgraph H of G such that G À EðHÞ contains no hamilton cycles. In this context, the spectrum SðGÞ of a graph G is the set of integers m such that G contains a maximal set of m edge-disjoint hamilton cycles. This spectrum has ------------------C. A. Rodger on leave from:

SEPT. 23, 1961 MEDICAL MEMORANDA MEDIBRrrO=UNAL 809 adrenals was therefore followed by a reduction of pituitary activity as a first effect. It is possible, however, that the phase of depigmentation was only coincidentally related to the adrenalectomy, and represented a natural remission of pituitary hyperfunction. In Bagshawe's personal case a deep-brown pigmentation of the exposed skin appeared first and then faded, to be followed later by Cushing's syndrome and carcinoma of the lung. Remissions occurred in the cases of Cushing's syndrome associated with thymic neoplasms described by Sprague et al. (1950) and Anderson and Haymaker (1944). A remarkable case of cyclical remissions in Cushing's syndrome has recently been described by Aber and Cheetham (1961). During the attacks there was a high level of excretion of urinary steroids and severe hypokalaemia. The patient died during an attack, but, surprisingly in view of the hypokalaemia, no tumour was found at necropsy.It seems very likely that carcinoma did not develop in our patient until the second period of pituitary hyperactivity, and some long time after adrenalectomy. We had read Thorne's paper at an early stage in our investigations and were aware of the further sinister associations of Cushing's syndrome with hypokalaemia. Repeated clinical and radiological examinations were made, seeking evidence of tumour formation; also a careful search when the abdomen was opened to carry out adrenalectomy. Nothing, however, was found until the last year of the patient's life. If we accept a causal relationship between Cushing's syndrome and the development of carcinoma of the breast, the sequence of events strongly suggests that the pituitary was exercising a direct carcinogenic action.Our thanks are due to Professor F. T. G. Prunty and his colleagues for help with this case and for permission to use the notes taken at

The time and stoichiometric ratio dependence on dissolution of Cu from Cu(I)O and Cu(II)O and metallic Cu was investigated for a series of known Cu chelators. This was monitored by ICP-OES and UV-VIS. A notable difference in the rate of reaction for Cu(I)O vs Cu(II)O was observed and the impact of a copper adduct precipitating from solution discussed as this may present a redeposition issue for Cu surface cleaning. Additionally these chelators were found to selectively favour Cu0 and typically showed higher solution levels of Cu when exposed to the oxides.

No abstract