Relationship between body temperature and air temperature in stridulating male crickets, Gryllus bimaculatus (Orthoptera: Gryllidae)

Body temperatures of singing male Gryllus bimaculatus were measured for the first time. Body temperatures were strongly correlated with ambient temperature. This indicates that, unlike some other orthopterans, larger crickets are not dependent on an elevated body temperature for efficient calling. Our results confirm that it is reasonable to use ambient temperature as an approximation of body temperature in behavioural and bio- acoustic studies

Site-specific management of pH-induced iron chlorosis of maize

A study was conducted over nine site/years in Nebraska, USA between 2004 and 2005 to evaluate the potential to predict chlorosis-prone areas within fields which are relatively stable in space and time. The study also investigated the potential benefits of site-specific cultivar management according to chlorosis pressure. Sites were mapped for soil apparent electrical conductivity (ECa) at two depths (0-30 cm and 0-90 cm), and soil pH at a depth of 10 cm. Sites were also sampled by hand on a regular grid to a depth of 20 cm and analyzed for a range of soil properties. Sites were evaluated in-season with natural color and near-infrared imagery, and at the end of the season by yield mapping. In all or a portion of each field, replicated paired strips of two maize cultivars were planted, one considered susceptible to iron chlorosis (P34N42), another with similar characteristics but tolerant to iron chlorosis (P34B99). Detailed evaluation of the ability to predict iron chlorosisprone areas was conducted over 3 site/years. Management zones were delineated using combinations of yield data, biCa and vegetation indices derived from aerial imagery. Across all locations, grid sampled pH ranged from 6.1 to 9.1; on-the-go pH ranged from 4.9 to 9.2; shallow ECa ranged from 0.1 to 39 InSini: deep ECa ranged From 0.2 to 152 mS/rn. For one field, planted to maize one year and soybean the next, two chlorosis management zones were consistently delineated both years, with similar spatial relationships. For another field, soil water holding capacity was a larger yield limiting factor than iron chlorosis and management zones for iron chlorosis could riot be delineated. For 8 site/years where paired strips of chlorosis-prone or tolerant cultivars were planted, no distinct advantage of site-specific maize cultivar management was found based on yield response of the two cultivars evaluated. Generally P34B99 yields were superior to P34N42 regardless of the level of chlorosis pressure. This study found spatial information on factors conducive to iron chlorosis can be useful in delineating chlorosis-prone areas within fields_ However, other yield limiting [-actors may confound delineation of zones strictly for chlorosis management. Successful spatial cultivar selection for iron chlorosis management will require the use of cultivars with response characteristics which differ more than those used in this study

Meeting Report: Application of Genotyping Methods to Assess Risks from Cryptosporidium in Watersheds

A workshop titled "Application of Genotyping Methods to Assess Pathogen Risks from Cryptosporidium in Drinking Water Catchments" was held at the International Water Association biennial conference, Marrakech, Morocco, 23 September 2004. The workshop presented and discussed the findings of an interlaboratory trial that compared methods for genotyping Cryptosporidium oocysts isolated from feces. The primary goal of the trial and workshop was to assess the utility of current Cryptosporidium genotyping methods for determining the public health significance of oocysts isolated from feces in potable-water-supply watersheds. An expert panel of 16 watershed managers, public health practitioners, and molecular parasitologists was assembled for the workshop. A subordinate goal of the workshop was to educate watershed management and public health practitioners. An open invitation was extended to all conference delegates to attend the workshop, which drew approximately 50 interested delegates. In this report we summarize the peer consensus emerging from the workshop. Recommendations on the use of current methods by watershed managers and public health practitioners were proposed. Importantly, all the methods that were reported in the trial were mutually supporting and found to be valuable and worthy of further utility and development. Where there were choices as to which method to apply, the small-subunit ribosomal RNA gene was considered to be the optimum genetic locus to target. The single-strand conformational polymorphism method was considered potentially the most valuable for discriminating to the subtype level and where a large number of samples were to be analyzed. A research agenda for protozoan geneticists was proposed to improve the utility of methods into the future. Standardization of methods and nomenclature was promoted

Delinearing site-specific management zones for pH-induced iron chlorosis

Iron chlorosis can limit crop yield, especially on calcareous soil. Typical management for iron chlorosis includes the use of iron fertilizers or chlorosis tolerant cultivars. Calcareous and non-calcareous soil can be interspersed within fields. If chlorosis-prone areas within fields can be predicted accurately, site-specific use of iron fertilizers and chlorosis-tolerant cultivars might be more profitable than uniform management. In this study, the use of vegetation indices (VI) derived from aerial imagery, on-the-go measurement of soil pH and apparent soil electrical conductivity (ECa) were evaluated for their potential to delineate chlorosis management zones. The study was conducted at six sites in 2004 and 2005. There was a significant statistical relationship between grain yield and selected properties at two sites (sites 1 (2005) and 3), moderate relationships at sites 2 and 4, and weak relationships at site 5. For sites 1 (2005) and 3, and generally across all sites, yield was predicted best with the combination of NDVI and deep ECa. These two properties were used to delineate chlorosis management zones for all sites. Sites 1 and 3 showed a good relationship between delineated zones and the selected properties, and would be good candidates for site-specific chlorosis management. For site 5, differences in the properties between mapped zones were small, and the zones had weak relationships to yield. This site would be a poor candidate for site-specific chlorosis management. Based on this study, the delineation of chlorosis management zones from aerial imagery combined with soil ECa appears to be a useful tool for the site-specific management of iron chlorosis

Nitrogen Response and Economics for Irrigated Corn in Nebraska

Nitrogen management recommendations may change as yield levels and efficiency of crop production increase. The mean yield with adequate nutrient availability in 32 irrigated corn (Zea mays L.) trials conducted across Nebraska to evaluate crop response to split-applied N was 14.8 Mg per ha. The mean economically optimal N rates (EONR) for irrigated corn varied with the fertilizer N to grain price ratio. At a fertilizer N:corn price ratio of 7, the EONR was 171, 122, and 93 kg per hectare, respectively, for cropping systems with corn following corn (CC), soybean (Glycine max L.) (CS), and drybean (Phaseolus vulgaris L.) (CD). At this price ratio the present University of Nebraska (UNL) recommendation procedure gave mean N recommendations that were 17.2, 0.3, and 68.1 kg per hectare higher than the mean EONR determined in this study for CC, CS, and CD, respectively. The UNL algorithm, adjusted for mean cropping system EONR gave more accurate prediction of site-year EONR than alternative N rate predictions for CC and CD with returns to applied N (RTN) of -$22 and -$13 per hectare compared with measured site-year EONR. Prediction of site-year EONR using mean EONR adjusted for soil organic matter was more accurate for CS than other methods with an RTN of -$6 per hectare compared with measured site-year EONR. Further research is needed to extend the results to: lower yield situations, alternatives to split application of N, and adjustment of EONR to protect against inadequate N in atypical seasons or for environmental protection

High-yielding corn response to applied phosphorus, potassium, and sulfur in Nebraska

Nutrient management recommendations may change as yield levels and efficiency of crop production increase. Recommendations for P, K, and S were evaluated using results from 34 irrigated corn (Zea mays L.) trials conducted in diverse situations across Nebraska. The mean yield was 14.7 Mg ha–1 with adequate fertilizer applied. The median harvest index values were 0.52, 0.89, 0.15, and 0.56 for biomass, P, K, and S, respectively. Median grain yields were 372, 49, and 613 kg kg–1 of aboveground plant uptake of P, K, and S, respectively. The estimated critical Bray-1 P level for corn response to 20 kg P ha–1 was 20 mg kg–1 when the previous crop was corn compared with 10 mg kg–1 when corn followed soybean [Glycine max (L.) Merr.]. Soil test K was generally high with only three site-years <125 mg kg–1. Over all trials, application of 40 kg K ha–1 resulted in a 0.2 Mg ha–1 mean grain yield decrease. Application of 22 kg S ha–1 did not result in significant yield increase in any trial. Soil test results accounted for twice as much variation in nutrient uptake when soil organic matter (SOM) and pH were considered in addition to the soil test nutrient values. The results indicate a need to revise the current recommendation for P, to maintain the current K and S recommendations, and to use SOM and pH in addition to soil test nutrient values in estimating applied nutrient requirements for irrigated high yield corn production

Nitrogen Use Efficiency of Irrigated Corn for Three Cropping Systems in Nebraska

Nitrogen use efficiency (NUE) is of economic and environmental importance. Components of NUE were evaluated in 32 irrigated corn (Zea mays L.) trials conducted across Nebraska with different N rates and where the previous crop was either corn (CC), drybean (Phaseolus vulgaris L.) (CD), or soybean (Glycine max L.) (CS). The mean grain yield with adequate nutrient availability was 14.7 Mg ha–1 . When no N was applied, measured soil properties and irrigation water N accounted for <20% of the variation in plant N uptake (UN). Mean fertilizer N recovery in above-ground biomass was 74% at the lowest N rate compared with 40% at the highest N rate, a mean of 64% at the economically optimal N rate (EONR), and least with CD. Agronomic efficiency of fertilizer N averaged 29 kg grain kg-1 N at EONR and was also least with CD. Partial factor productivity of N averaged 100 kg grain kg-1 N at EONR, and was greater with CS compared with CC and CD. After harvest, residual soil nitrate-N (RSN) in the 0 to 1.2 m depth ranged from 21 to 121 kg ha-1 and increased with N rate. Mean RSN was 88, 59, and 59 kg ha-1 for CD, CC, and CS, respectively. High corn yields can be achieved with high NUE and low RSN by management to maximize profitability in consideration of yield potential, and by applying N at the right amount and time

YREC: The Yale Rotating Stellar Evolution Code

The stellar evolution code YREC is outlined with emphasis on its applications to helio- and asteroseismology. The procedure for calculating calibrated solar and stellar models is described. Other features of the code such as a non-local treatment of convective core overshoot, and the implementation of a parametrized description of turbulence in stellar models, are considered in some detail. The code has been extensively used for other astrophysical applications, some of which are briefly mentioned at the end of the paper.Comment: 10 pages, 2 figures, ApSS accepte

Habitable Zones and UV Habitable Zones around Host Stars

Ultraviolet radiation is a double-edged sword to life. If it is too strong, the terrestrial biological systems will be damaged. And if it is too weak, the synthesis of many biochemical compounds can not go along. We try to obtain the continuous ultraviolet habitable zones, and compare the ultraviolet habitable zones with the habitable zones of host stars. Using the boundary ultraviolet radiation of ultraviolet habitable zone, we calculate the ultraviolet habitable zones of host stars with masses from 0.08 to 4.00 \mo. For the host stars with effective temperatures lower than 4,600 K, the ultraviolet habitable zones are closer than the habitable zones. For the host stars with effective temperatures higher than 7,137 K, the ultraviolet habitable zones are farther than the habitable zones. For hot subdwarf as a host star, the distance of the ultraviolet habitable zone is about ten times more than that of the habitable zone, which is not suitable for life existence.Comment: 5 pages, 3 figure

The History of Galaxy Formation in Groups: An Observational Perspective

We present a pedagogical review on the formation and evolution of galaxies in groups, utilizing observational information from the Local Group to galaxies at z~6. The majority of galaxies in the nearby universe are found in groups, and galaxies at all redshifts up to z~6 tend to cluster on the scale of nearby groups (~1 Mpc). This suggests that the group environment may play a role in the formation of most galaxies. The Local Group, and other nearby groups, display a diversity in star formation and morphological properties that puts limits on how, and when, galaxies in groups formed. Effects that depend on an intragroup medium, such as ram-pressure and strangulation, are likely not major mechanisms driving group galaxy evolution. Simple dynamical friction arguments however show that galaxy mergers should be common, and a dominant process for driving evolution. While mergers between L_* galaxies are observed to be rare at z < 1, they are much more common at earlier times. This is due to the increased density of the universe, and to the fact that high mass galaxies are highly clustered on the scale of groups. We furthermore discus why the local number density environment of galaxies strongly correlates with galaxy properties, and why the group environment may be the preferred method for establishing the relationship between properties of galaxies and their local density.Comment: Invited review, 16 pages, to be published in ESO Astrophysics Symposia: "Groups of Galaxies in the Nearby Universe", eds. I. Saviane, V. Ivanov, J. Borissov