Clay mineral data have been obtained on 348 soil profiles representing 117 different soil series from 28 of Pennsylvania’s 67 counties. The surface rock from which the soils were formed ranged from Pre-Cambrian to Tertiary-Pliocene and includes igneous, metamorphic and various types of sedimentary rocks. Major attention was focused on the subsoil mineralogy. Mica was found to be the most predominant clay mineral in terms of amounts and frequency of occurrence. It is dominant or co-dominant in 82 per cent of the profiles. In shale derived soils it is important in 95 per cent of the cases and in 68 per cent of the limestone soils. Kaolinite is a prominent component of soils derived from sandstone and metamorphic rocks. Montmorillonite was detected in over half of the soils but is very infrequently a prominent component and is more frequently found in the poorly drained soils. A mica-kaolinite suite is characteristic of soils from Pennsylvanian age rock whereas soils derived from Devonian, Mississippian, and Ordovician age rock had a mica-chlorite suite. The chlorite is frequently found weathered to chlorite-vermiculite in a 1:1 ratio. Gibbsite, talc, and pyrophyllite have been identified but only rarely occur. A difference in clay mineral types is frequently found among different profiles of the same soil series. Soils derived from limestone and highly calcareous rock may have rather unusual clay suites such as the dominance of a well-crystallized triocta-hedral chlorite, well crystallized mica, and soils approaching a monominerallic character in mica.

An X-ray spectrochemical method is compared with the flame photometer determination of potassium in a series of sixty-five soil clay fractions. Two methods of preparing the clay samples for the X-ray determination were used. In one case a 20 mg sample of clay in suspension was dried onto a plastic disc as a thin film. Potassium was determined by comparing the fluorescence intensity of the unknown with a sample of known composition which was prepared for analysis by the same technique. For the second method a 100 mg sample of dried clay was pressed into a pellet using methyl cellulose as a backing. In this case a National Bureau of Standards sample (NBS-98) was prepared in an identical manner and used as a standard for determining the potassium in the unknown. The results for both techniques were highly significantly correlated with the values as determined by flame photometric analysis. The pellet technique gave a more accurate measure of the potassium content. With the thin films the same sample may be used for X-ray diffraction analysis. In either case the X-ray spectrochemical technique provides a fairly rapid and simple procedure that can be useful for handling large numbers of samples.

The particle size distribution, total and exchangeable Mg, and mineralogical compositions were determined on eight well-drained, noncultivated subsoils from Pennsylvania. No correlation was found between the clay content and total Mg (r =.29), or between the clay content and exchangeable Mg (r =.35). Serpentine, talc, and hypersthene were found in the very fine sand and silt fractions of soils having relatively high exchangeable Mg. Mica and 14-Å clay minerals were the only Mg-bearing minerals noted in the same fractions of soils having relatively low exchangeable Mg. Of the Mg-bearing clay minerals found in the clay fractions (smectite, vermiculite, chlorite, illite, and interstratified chlorite/vermiculite), only smectite decreased as the exchangeable Mg in the soils decreased. Two distinctly different distribution patterns of Mg were found for soils having relatively high and low exchangeable Mg. The former soils showed a decreasing Mg content as the particle size decreased, and the latter soils showed the opposite. Exchangeable Mg correlated significantly with the amount of Mg in whole soil, sand, and silt, but not with the amount of Mg in the clay, an indication that sand and silt but not clay were the important sources of exchangeable Mg in these soils.

One of the largest remnants of tropical dry forest is the South American Gran Chaco. A quarter of this biome is in Paraguay, but there have been few studies in the Paraguayan Chaco. The Gran Chaco flora is diverse in structure, function, composition and phenology. Fundamental ecological questions remain in this biome, such as what bioclimatic factors shape the Chaco’s composition, structure and phenology. In this study, we integrated forest inventories from permanent plots with monthly high-resolution NDVI from PlanetScope and historical climate data from WorldClim to identify bioclimatic predictors of forest structure, composition and phenology. We found that bioclimatic variables related to precipitation were correlated with stem density and Pielou evenness index, while temperature-related variables correlated with basal area. The best predictor of forest phenology (NDVI variation) was precipitation lagged by 1 month followed by temperature lagged by 2 months. In the period with most water stress, the phenological response correlates with diversity, height and basal area, showing links with dominance and tree size. Our results indicate that even if the ecology and function of Dry Chaco Forest is characterised by water limitation, temperature has a moderating effect by limiting growth and influencing leaf flush and deciduousness.

Performances and performative instantiations respond to the urgencies of “pressure” and its effects. What is the work of performance when wrung by such pressures as financial constraint, racial subordination, misogyny, and sexism?

Field experiments were conducted across the north-central United States to determine the benefits of various weed control strategies in corn. Weed control, corn yield, and economic return increased when a preemergence (PRE) broad-spectrum herbicide was followed by (fb) postemergence (POST) herbicides. Weed control decisions based on field scouting after a PRE broad-spectrum herbicide application increased weed control and economic return. Application of a PRE grass herbicide fb a POST herbicide based on field scouting resulted in less control of velvetleaf and morningglory species, corn yield, and economic return compared with a PRE broad-spectrum herbicide application fb scouting. Cultivation after a PRE broad-spectrum herbicide application increased weed control and corn yield compared with the herbicide applied alone, but economic return was not increased. An early-postemergence herbicide application fb cultivation resulted in the highest level of broadleaf weed control, the highest corn yield, and the greatest economic return compared with all other strategies. Weed control based on scouting proved to be useful in reducing the effect of weed escapes on corn yield and increased economic return compared with PRE herbicide application alone. However, economic return was not greater than the PRE fb planned POST or total POST strategies.

Our survey of 112 Australian aged-care facilities demonstrated the prevalence of healthcare-associated infections to be 2.9%. Urinary tract infections (UTIs) defined by McGeer criteria comprised 35% of all clinically defined UTIs. To estimate the infection burden in these facilities where microbiologic testing is not routine, modified surveillance criteria for UTIs are necessary.

Infect Control Hosp Epidemiol 2016;37:610–612