Sappho and Anacreon in Plato’s Phaedrus

Plato’s praise of the poets Sappho and Anacreon at Phaedrus 235c is a sincere tribute to their vivid presentations of the shock of love. Allusions to the lyric poets in the prologue and Socrates’ narrative of soul support Plato’s exploration of the relationship between mania and self-control. Plato analyses the power-dynamic within a soul experiencing erotic desire and in response to the poets creates an intricate picture of how the force and energy of eros is absorbed, transferred and redirected

Neurological signs in inflammatory demyelination

Vass and colleagues recently reported that interferon-gamma potentiates antibody-mediated demyelination in the spinal cord in the rat. The rats developed prolongation of the latencies of somatosensory evoked potentials but no neurological signs. The authors stated that in this model there was more extended demyelination than is usually found in acute experimental allergic encephalomyelitis (EAE), and they concluded that their results contradicted the opinion that neurological dysfunction in rats with either actively induced or passively transferred EAE can be explained by demyelination alone. I wish to challenge their statement that there was more demyelination than usually present in acute EAE. In myelin basic protein-induced acute EAE (MBP-EAE) in the Lewis rat, there is substantial demyelination in the peripheral nervous system (PNS) randomly distributed along the lengths of the ventral and dorsal spinal roots. Significant demyelination is also present in the PNS in whole spinal cord-induced acute EAE in the rat. The lack of neurological signs in the model of Vass and colleagues is most likely explained by too few fibers in critical functional pathways undergoing demyelination simultaneously

Land Lease Markets and Agricultural Efficiency: Theory and Evidence from Ethiopia

In this paper, we develop a theoretical model of land leasing that includes transaction costs, risk pooling motives and non-tradable productive inputs, and investigate the empirical implications of land contracts using data collected from four villages in Ethiopia. We show that sharecropping is the dominant contract if transaction costs are negligible, but that a rental contract may arise if transaction costs decrease with increasing the tenant’s share of output. When this is the case, the theory predicts that area operated by tenants will be an increasing function of their land endowment and that fixed rental contracts will be more likely in situations where transaction costs are higher. We find empirical support for these predictions in the villages studied. We also find that input of labor per hectare is about 25% lower on sharecropped than on other land tenure types, but that the differences in total value of inputs, outputs and profits per hectare are statistically insignificant and relatively small in magnitude. These results support the Marshallian argument that sharecropping reduces labor effort, but also support the “New School” perspective since the magnitude of the inefficiency is relatively small. A bigger source of inefficiency (and inequity) in the study villages appears to be the limited lease market for oxen services, together with credit constraints that limit the ability of land and oxen poor households to purchase oxen.land lease markets, land tenure, sharecropping, agricultural efficiency

Land Lease Markets and Agricultural Efficiency: Theory and Evidence from Ethiopia

In this paper, we develop a theoretical model of land leasing that includes transaction costs, risk pooling motives and non-tradable productive inputs, and investigate the empirical implications of land contracts using data collected from four villages in Ethiopia. We show that sharecropping is the dominant contract if transaction costs are negligible, but that a rental contract may arise if transaction costs decrease with increasing the tenant’s share of output. When this is the case, the theory predicts that area operated by tenants will be an increasing function of their land endowment and that fixed rental contracts will be more likely in situations where transaction costs are higher. We find empirical support for these predictions in the villages studied. We also find that input of labor per hectare is about 25% lower on sharecropped than on other land tenure types, but that the differences in total value of inputs, outputs and profits per hectare are statistically insignificant and relatively small in magnitude. These results support the Marshallian argument that sharecropping reduces labor effort, but also support the “New School” perspective since the magnitude of the inefficiency is relatively small. A bigger source of inefficiency (and inequity) in the study villages appears to be the limited lease market for oxen services, together with credit constraints that limit the ability of land and oxen poor households to purchase oxen.land lease markets, land tenure, sharecropping, agricultural efficiency

LAND LEASE MARKETS AND AGRICULTURAL EFFICIENCY: THEORY AND EVIDENCE FROM ETHIOPIA

This paper develops a theoretical model of land leasing that includes transaction costs of enforcing labor effort, risk pooling motives and non-tradable capital inputs. We test the implications of this model compared to those of the "Marshallian" (unenforceable labor effort) and "New School" (costlessly enforceable effort) perspectives using data collected from four villages in Ethiopia. We find that land lease markets operate relatively efficiently in the villages studied, supporting the New School perspective. Land contract choice is found to depend upon the social relationships between landlords and tenants, but differences in contracts are not associated with significant differences in input use or output value per hectare. We find that other household and village characteristics do affect input use and output value, suggesting imperfections in other factor markets.Land Economics/Use,

Demyelination and Early Remyelination in Experimental Allergic Encephalomyelitis Passively Transferred With Myelin Basic Protein-Sensitized Lymphocytes in the Lewis Rat

Histological studies were performed on Lewis rats with experimental allergic encephalomyelitis (EAE) passively transferred by myelin basic protein (MBP)-sensitized syngeneic spleen cells in order to determine the relationship between demyelination and neurological signs. Neither inflammation nor demyelination was present on the day prior to the onset of neurological signs but both were present in the spinal roots and spinal cord on the day of onset of tail weakness (4 days after passive transfer). Demyelination and the neurological signs both increased over the next 48 h. There was evidence that the caudal roots were more severely affected than the rostral roots. The peripheral nerves were spared. Demyelination in the spinal cord was concentrated in the dorsal root entry and ventral root exit zones. The initial stages of repair of demyelinated spinal root fibres by Schwann cells were observed on the earliest day that clinical recovery commenced (day 7). At this time some demyelinated fibres were closely associated with debris-free Schwann cells, and occasional fibres were completely invested by 1-2 layers of Schwann cell cytoplasm. Remyelination (compact myelin lamellae formation) by Schwann cells was first observed in the spinal roots on day 9. By the time of complete clinical recovery (day 11) the majority of affected spinal root fibres had thin new myelin sheaths. Repair of central nervous system myelin by oligodendrocytes was slower than peripheral nervous system myelin repair. Investment of demyelinated spinal cord axons by oligodendrocytes was observed on day 9, and remyelination by these cells was seen on day 10. We conclude that the neurological signs of passively induced MBP-EAE can be accounted for by demyelination of the lumbar, sacral and coccygeal spinal roots and spinal cord root entry and exit zones, and that the subsequent clinical recovery can be explained by investment and remyelination of demyelinated peripheral and central nervous system fibres by Schwann cells and oligodendrocytes respectively