Even circuits of prescribed clockwise parity

We show that a graph has an orientation under which every circuit of even length is clockwise odd if and only if the graph contains no subgraph which is, after the contraction of at most one circuit of odd length, an even subdivision of K_{2,3}. In fact we give a more general characterisation of graphs that have an orientation under which every even circuit has a prescribed clockwise parity. This problem was motivated by the study of Pfaffian graphs, which are the graphs that have an orientation under which every alternating circuit is clockwise odd. Their significance is that they are precisely the graphs to which Kasteleyn's powerful method for enumerating perfect matchings may be applied

Size at Maturity of Female American Lobsters from an Estuarine and Coastal Population

The size at which female lobsters reach sexual maturity was determined for two populations that inhabit waters along the coast of New Hampshire. One group was captured in the Great Bay estuary, where water temperatures in the summer typically average between 17 C and 20 C. The other gorup of lobsters resided in coastal waters, near the Isles of Shoals, where the water temperature was much colder during the summer (11-15 C). Maturity was assessed using criteria that included the following: ovarian classification; abdominal width/carapce length (CL) ratio; and the size frequency distribution of berried females. All the techniques yielded similar results and consistently demonstrated that female lobsters in the estuary matured at a smaller size than those in colder coastal waters. The smallest mature females from Great Bay were 72 mm in CL, with 50% reaching sexual maturity by 83 mm CL and all becoming mature by 89 mm CL. The difference in the proportion of mature lobsters in the estuarine versus coastal populations was much greater in the smaler size classes than in the larger size claases, suggesting a mixing of the two populations, most likely due to females from Great Bay migrating into coastal waters

Third Party Originators and Mortgage Prepayment Risk: An Agency Problem?

We focus on an agency problem encountered by mortgage lenders and investors in mortgage-backed securities when the underlying collateral is originated by third parties. Third parties, such as mortgage brokers, have economic incentives to encourage borrowers to refinance and, accordingly, their actions may affect asset values. We sketch the principal-agent problem and examine two sets of data. Results support the argument: loans originated by third parties are significantly more likely to prepay after controlling for other known determinants of termination risk. Moreover, third party loans are about three times as sensitive to refinancing incentives, compared to retail loans.

AN ANALYSIS OF OKLAHOMA'S ECONOMY BY DISTRICTS USING INPUT-OUTPUT TECHNIQUES

Community/Rural/Urban Development,

Letter from J[ohn] Wesley Little to John Muir, 1913 Feb 25 .

Picture Rocks, Pa. Feb 25 1913My dear John MuirThis little letter from an eleven year old school girl written on her own impulse explains itself. If you feel like putting your autograph on the enclosed sheet I am quite sure it would be an incentive for her to continue her interest in John Muir and his Sierras. She does not know I am actually taking the liberty to mail this to you so she will not be disappointed if the autograph does not appear but I know she will be overjoyed if it doesVery sincerely and respectfully J Wesley Little05383 Picture Rocks, Pa.Feb 27, 1913Dear Mr Muir:I have heard and read about you. And would like to know you. So would my father J. Wesley Little. He is an artist. He said he would rather take a walk with you than any other person in the world. I live in a beautiful little town that lies between three beautiful hills One looks like the work of a glacier Father found a rock there that was made up of a different kind of stone than what is around here and fossils. I would like to live in the Sierra Nevada mountains among the birds, animals, flowers and trees although I love my home.Yours trulyEleanor R. Little0538