Can we predict which species win when new habitat becomes available?

Land cover change is a key component of anthropogenic global environmental change, contributing to changes in environmental conditions of habitats. Deforestation is globally the most widespread and anthropogenically driven land cover change leading to conversion from closed forest to open non-forest habitat. This study investigates the relative roles of geographic features, characteristics of species climatic niche and species traits in determining the ability of open-habitat plant species to take advantage of recently opened habitats. We use current occurrence records of 18 herbaceous, predominantly open-habitat species of the genus Acaena (Rosaceae) to determine their prevalence in recently opened habitat. We tested correlation of species prevalence in anthropogenically opened habitat with (i) geographic features of the spatial distribution of open habitat, (ii) characteristics of species climatic niche, and (iii) species traits related to dispersal. While primary open habitat (naturally open) was characterised by cold climates, secondary open habitat (naturally closed but anthropogenically opened) is characterised by warmer and wetter conditions. We found high levels of variation in the species prevalence in secondary open habitat indicating species differences in their ability to colonise newly opened habitat. For the species investigated, geographical features of habitat and climatic niche factors showed generally stronger relationships with species prevalence in secondary open habitat than functional traits. Therefore, for small herbaceous species, geographical features of habitat and environmental factors appear to be more important than species functional traits for facilitating expansion into secondary open habitats. Our results suggested that the land cover change might have triggered the shifts of factors controlling open-habitat plant distributions from the competition with forest trees to current environmental constraints.

Kyrle's disease. Effectively treated with isotretinoin

Kyrle's disease is an uncommon dermatologic entity with characteristic clinical and histopathologic features. A case is recorded in a 63-year-old man undergoing hemodialysis for chronic renal failure. Systemic isotretinoin treatment for 13 weeks resulted in a complete clearance of the cutaneous lesions. Systemic treatment is effective and could be considered preferred therapy.

Marriage markets and nonmarital fertility in the United States

We merge census microdata with vital statistics data to examine the effect of women's marriage opportunities on nonmarital fertility rates and ratios across 75 U.S. metropolitan areas. Measures of the quantity and "quality" of marriageable men simultaneously specific for women's age, race, education, and place of residence reveal especially poor marriage prospects for highly educated black women. The effect of mate availability on nonmarital fertility is generally modest. Among white women, marriage opportunities are associated inversely with the nonmarital fertility rate, perhaps reflecting an increased likelihood that a premarital conception will be legitimated. Marriage opportunities also reduce nonmarital fertility ratios for young black and white women. The nonmarital fertility rate is lower among women whose marriage pool includes a large percentage of nonemployed males. Only a small proportion of the racial difference in nonmarital fertility appears attributable to differences in the marriage markets of black and of white women.

Malignant transformation in a solitary dermal cylindroma

We describe a case of a solitary dermal cylindroma with focal malignant transformation. The scalp tumor measured 3 cm in greatest dimension and was successfully surgically excised. The patient has been followed up for the last two years with no recurrences. Changes of malignant transformation included loss of peripheral palisading, destruction of the hyaline sheath, areas of necrosis, and pleomorphism of nuclei with frequent mitosis. We reviewed data on 12 other reported cases of dermal cylindromas with malignant transformation. Morphologic features of both benign cylindromas and their malignant counterparts are described. The literature was reviewed regarding the controversy of the cell of origin.

Chloracne from manufacture of a new herbicide

Forty-one chemical company workers had chloracne as a result of exposure to 3,4,3',4'-tetrachloroazoxybenzene (TCAB), an extraneous intermediate produced during the manufacture of a new herbicide. There was no laboratory evidence of significant hepatotoxicity or porphyria during the short time the herbicide was produced. An acnegenic when applied to the rabbit ear, TCAB is also a potent inducer of the microsomal enzyme aryl hydrocarbon hydroxylase. Prevention of chlorance is a difficult industrial engineering task and treatment of the disease is even more perplexing.