Notes on the Forests of Southern Iowa

In the southernmost tier of counties in Iowa, particularly in Jefferson, Van Buren, Wapello, Davis, Monroe, Appanoose, Lucas and Wayne counties there exist rather extensive natural forests of oak and other hardwood species. These counties lie within an area of considerable loessal soils. This part of the state has been designated in agricultural parlance as the southern Iowa pasture section. The relief of the land in these parts consists of a rather distinct upland plain lying generally about 1000 feet above sea-level. Dissection of this plain by drainage has resulted in numerous fingering and tortuous headwaters creating slopes or terraces, and flat to narrow ridges and bottoms of variable widths and patterns. The plain is composed of a number of soil types in; the Clinton silt loam, the Lindley silt loam, the Edina, the Marion and Grundy silt loams, etc. The Clinton silt loam is one of the most prevalent upland loess soils; it has a light gray yellow and buff color and a loose texture. It over-lies much of the loose and erosive Lindley drift soil which comprises a goodly proportion of the slope land. Some upland sections contain small quantities of the whitish Edina and powdery Marion soils. In the bottoms we find generally deep accumulations of the dark and fertile Wabash silt loam

Determination of Soil Moisture Content at Permanent Wilting for Us in Field Studies

In ecological investigations of interactions between plants and soil moisture, whether the aim is to determine fundamental plant-environment relationships or primarily to solve immediate plant production problems, the soil moisture content at permanent wilting, expressed as a percentage of the dry weight, is a basic determination. Although there is evidence that this soil moisture value may not represent the exact non-available moisture content of the soil (4, 8) it is generally agreed that it represents the limit of favorable plant growth conditions and will be considered here as non-available soil moisture

Selection of Australian Root Nodule Bacteria for Broad-Scale Inoculation of Native Legumes

The unique and diverse native Australian perennial legumes are under current investigation for use as pastures in Australian agriculture. Identification of root nodule bacteria (RNB) that can fix nitrogen effectively for the plant is a critical factor for the success of a legume species in agriculture (Howieson et al., 2000). Some legumes under investigation are relatively promiscuous (Lange, 1961). This trait may allow the development of a single, broad-scale inoculant that could allow inoculation of multiple species of agricultural importance, whilst more effective, specific RNB are developed in time. Aimed to identify strains that can form effective symbioses with several native legume species of potential interest to agriculture, this experiment screened putative indigenous RNB on 5 native legumes

(2-Hydroxy­phenyl­imido-κN)(methano­lato-κO)[2-(2-oxidobenzyl­ideneamino)phenolato-κ2 O,N,O′](triphenyl­phosphine-κP)rhenium(V)

In the neutral title compound, [Re(C6H5NO)(C13H9NO2)(CH3O)(C18H15P)], an 18-valence-electron complex, the ReV ion lies in an octa­hedral coordination geometry with the tridentate dianionic Schiff base 2-(2-oxidobenzyl­idene­amino)phenolate ligand occupying three equatorial coordination sites, and with the triphenyl­phosphine ligand situated trans to the imine N atom. The ReV coordination is completed with a methano­late ligand and a 2-hydroxy­phenyl­imido(2-) ligand. There are two molecules in the asymmetric unit. The crystal structure involves O—H⋯O and C—H⋯O hydrogen bonds. One N and one C atom are disordered over two positions; the site occupancy factors are ca 0.7 and 0.3

A polynomial bound for untangling geometric planar graphs

To untangle a geometric graph means to move some of the vertices so that the resulting geometric graph has no crossings. Pach and Tardos [Discrete Comput. Geom., 2002] asked if every n-vertex geometric planar graph can be untangled while keeping at least n^\epsilon vertices fixed. We answer this question in the affirmative with \epsilon=1/4. The previous best known bound was \Omega((\log n / \log\log n)^{1/2}). We also consider untangling geometric trees. It is known that every n-vertex geometric tree can be untangled while keeping at least (n/3)^{1/2} vertices fixed, while the best upper bound was O(n\log n)^{2/3}. We answer a question of Spillner and Wolff [arXiv:0709.0170 2007] by closing this gap for untangling trees. In particular, we show that for infinitely many values of n, there is an n-vertex geometric tree that cannot be untangled while keeping more than 3(n^{1/2}-1) vertices fixed. Moreover, we improve the lower bound to (n/2)^{1/2}.Comment: 14 pages, 7 figure

The atrial natriuretic peptide (ANP) knockout mouse does not exhibit the phenotypic features of pre-eclampsia or demonstrate fetal growth restriction

The ANP knockout mouse is reported to exhibit pregnancy-associated hypertension, proteinuria and impaired placental trophoblast invasion and spiral artery remodeling, key features of pre-eclampsia (PE). We hypothesized that these mice may provide a relevant model of human PE with associated fetal growth restriction (FGR). Here, we investigated pregnancies of ANP wild type (ANP+/+), heterozygous (ANP+/-) and knockout (ANP−/-) mice. Maternal blood pressure did not differ between genotypes (E12.5, E17.5), and fetal weight (E18.5) was unaffected. Placental weight was greater in ANP−/− versus ANP+/+ mice. Therefore, in our hands, the ANP model does not express phenotypic features of PE with FGR