Moving towards a more mechanistic approach in the determination of soil heat flux from remote measurements - I. A universal approach to calculate thermal inertia

In this paper we pledge that physically based equations should be combined with remote sensing techniques to enable a more theoretically rigorous estimation of area-average soil heat flux, G. A standard physical equation (i.e. the analytical or exact method) for the estimation of G, in combination with a simple, but theoretically derived, equation for soil thermal inertia (F), provides the basis for a more transparent and readily interpretable method for the estimation of G; without the requirement for in situ instrumentation. Moreover, such an approach ensures a more universally applicable method than those derived from purely empirical studies (employing vegetation indices and albedo, for example). Hence, a new equation for the estimation of Gamma(for homogeneous soils) is discussed in this paper which only requires knowledge of soil type, which is readily obtainable from extant soil databases and surveys, in combination with a coarse estimate of moisture status. This approach can be used to obtain area-averaged estimates of Gamma(and thus G, as explained in paper II) which is important for large-scale energy balance studies that employ aircraft or satellite data. Furthermore, this method also relaxes the instrumental demand for studies at the plot and field scale (no requirement for in situ soil temperature sensors, soil heat flux plates and/or thermal conductivity sensors). In addition, this equation can be incorporated in soil-vegetation-atmosphere-transfer models that use the force restore method to update surface temperatures (such as the well-known ISBA model), to replace the thermal inertia coefficient.

The release of silicon from amorphous silica and rice straw in Sri Lankan soils

Silicon release from rice straw and amorphous silica when shaken in solution with five Sri Lankan soils was studied indirectly using sorption isotherms and changes in concentration and directly using straw in dialysis bags examined using electron microscopy. The aim was to further our understanding of the processes and factors affecting the release of straw-Si in soils and its availability to rice. The soils (alfisols and ultisols) shaken with 0.1 M NaCl (5 g per 125 mL for 250 days) produced concentrations of 1 - 4 mg L-1 of monosilicic acid-Si. Amorphous silica added to these suspensions (36.5 mg, containing 17 mg Si) raised the concentrations to 20 - 40 mg L-1, and added rice straw (0.5 g, containing 17 mg Si) gave 10 - 25 mg L-1. Sorption isotherms (7 days equilibrations) were used to calculate from the concentrations the amounts of Si released ( 24 - 38% and 8 - 21%, respectively). Both materials gave about 40 mg L-1 of monosilicic acid-Si plus 30 mg L-1 of disilicic acid-Si when shaken in solution alone (5 g per 125 mL). Straw in dialysis bags ( 0.5 g per 25 mL in 0.1 M NaCl) was shaken in soil suspension ( 5 g per 100 mL) for 60 days. Similar concentrations and releases were measured to those obtained above. About one fifth of the mass of straw was lost by decomposition in the first 15 days. A chloroform treatment prevented decomposition, but Si release was unaffected. Disintegration continued throughout the experiments, with phytoliths being exposed and dissolved. Compared to the rate of release from straw into solution without soil, the release of Si into soil suspensions was increased during the first 20 days by adsorption on the soil, but was then reduced probably through the effect of Fe and Al on the phytolith surfaces. The extent of this blocking effect varied between soils and was not simply related to soil pH.

Efficient operator pipelining in a bit serial genetic algorithm engine

The authors propose a bit serial pipeline used to perform the genetic operators in a hardware genetic algorithm. The bit-serial nature of the dataflow allows the operators to be pipelined, resulting in an architecture which is area efficient, easily scaled and is independent of the lengths of the chromosomes. An FPGA implementation of the device achieves a throughput of >25 million genes per second

Stereo and motion parallax cues in human 3D vision: can they vanish without a trace?

In an immersive virtual reality environment, subjects fail to notice when a scene expands or contracts around them, despite correct and consistent information from binocular stereopsis and motion parallax, resulting in gross failures of size constancy (A. Glennerster, L. Tcheang, S. J. Gilson, A. W. Fitzgibbon, & A. J. Parker, 2006). We determined whether the integration of stereopsis/motion parallax cues with texture-based cues could be modified through feedback. Subjects compared the size of two objects, each visible when the room was of a different size. As the subject walked, the room expanded or contracted, although subjects failed to notice any change. Subjects were given feedback about the accuracy of their size judgments, where the “correct��� size setting was defined either by texture-based cues or (in a separate experiment) by stereo/motion parallax cues. Because of feedback, observers were able to adjust responses such that fewer errors were made. For texture-based feedback, the pattern of responses was consistent with observers weighting texture cues more heavily. However, for stereo/motion parallax feedback, performance in many conditions became worse such that, paradoxically, biases moved away from the point reinforced by the feedback. This can be explained by assuming that subjects remap the relationship between stereo/motion parallax cues and perceived size or that they develop strategies to change their criterion for a size match on different trials. In either case, subjects appear not to have direct access to stereo/motion parallax cues.

Indirect population dynamic benefits of altered life-history trade-offs in response to egg harvesting

Variations in demographic rates due to differential resource allocation between individuals are important considerations in the development of accurate population dynamic models. Systematic harvesting can alter age structure and/or reduce population density, conferring indirect positive benefits on the source population as a result of a consequent redistribution of resources between the remaining individuals. Independently of effects mediated through changes in density and competition, demographic rates can also be influenced by within-individual competition for resources. Harvesting dependent life stages can reduce an individual's current reproductive costs, allowing increased investment in its future fecundity and survival. Although such changes in demographic rates are well known, there has been little exploration of the potential impact on population dynamics. We use empirical data collected from a successfully reintroduced population of the Mauritius kestrel Falco punctatus to explore the population consequences of manipulating reproductive effort through harvesting. Consequent increases in an individual's future fecundity and survival allow source populations to withstand longer and more intensive harvesting regimes without being exposed to an increase in extinction risk, increasing maximum sustainable yields. These effects may also buffer populations against the impacts of stochastic events, but directional shifts in environmental conditions that increase reproductive costs may have detrimental population-level effects.

Effect of energy and protein supplementation on phosphorus utilization in lactating dairy cows

Two experiments were undertaken in which grass silage was used in conjunction with a series of different concentrate types designed to examine the effect of carbohydrate source, protein level and degradability on total dietary phosphorus (P) utilization with emphasis on P pollution. Twelve Holstein-Friesian dairy cows in early to mid-lactation were used in an incomplete changeover design with four periods consisting of 4 weeks each. Phosphorus intake ranged from 54 to 80 g/day and faecal P represented the principal route by which ingested P was disposed of by cows, with insignificant amounts being voided in urine. A positive linear relationship between faecal P and P intake was established. In Experiment 1, P utilization was affected by dietary carbohydrate type, with an associated output of 3.3 g faecal P/g milk P produced for all treatments except those utilizing low degradable starch and low protein supplements, where a mean value of 2.8 g faecal P/g milk P was observed. In Experiment 2, where two protein levels and three protein degradabilities were examined, the efficiency of P utilization for milk P production was not affected by either level or degradability of crude protein (CP) but a significant reduction in faecal P excretion due to lower protein and P intake was observed. In general, P utilization in Experiment 2 was substantially improved compared to the Experiment 1, with an associated output of 1.8 g faecal P/g milk P produced. The improved utilization of P in Experiment 2 could be due to lower P content of the diets offered and higher dry matter (DM) intake. For dairy cows weighing 600 kg, consuming 17-18 kg DM/day and producing about 25 kg milk, P excretion in faeces and hence P pollution to the environment might be minimized without compromising lactational performance by formulating diets to supply about 68 g P/day, which is close to recent published recommended requirements for P.

Effects of forage source and soybean and marine algal oil supplementation on milk fatty acid composition in ewes

The objective of the present studies was to determine effects of basal dietary forage source on the response of milk fatty acid composition to an oil supplement based (2:1, respectively, w/w) on soybean oil and marine algae biomass oil high in cis-9, cis-12 C18:2n − 3 and C22:6n − 3, respectively. In Study 1, Hampshire × Dorset ewes (48) were randomly assigned to one of four treatments and 12 pens in a completely randomized design blocked on the basis of lambing date and number of lambs suckled. Control rations (60:40 forage:concentrate, dry matter (DM) basis) based on alfalfa pellets (AP) or corn silage (CS) were fed from lambing. Beginning at 22 days postpartum, three pens of ewes fed AP and three pens of ewes fed CS were supplemented with oil (30 g/kg of ration DM) in place of corn meal. Average ewe DM intake (DMI) and average daily gain (ADG) were measured weekly. Milk yield and composition were measured at 42 days postpartum. DMI was lower (P<0.02) for CS and for oil, but milk yield was not affected by forage source or oil supplementation. Milk fat content was higher for oil (P<0.10) and milk protein content was higher for AP (P<0.04). Total CLA concentration (g/100 g fatty acids) increased (P<0.01) with CS and oil, and the response to oil was greater for AP (P<0.04). Similarly, total trans-C18:1 and C22:6ω−3 concentrations were higher for CS and oil, but the response to oil was greater for CS (P<0.06 and P<0.01, respectively). In Study 2, the experiment was repeated using alfalfa haylage (AH) instead of AP. The DMI decreased (P<0.05) with oil feeding, but was not affected by forage source. Milk yield was decreased by feeding oil with AH, but not by feeding oil with CS (P<0.03). Milk fat content tended to be increased by feeding oil with AH, but tended to be decreased by feeding oil with CS (P<0.08). Total CLA concentration was increased (P<0.01) for AH versus CS and by oil, and the response to oil supplementation was greater for AH (P<0.01). In contrast, total trans-C18:1 concentration was higher for CS versus AH, with a greater response to oil for CS (P<0.05). Feeding marine oil increased the C22:6ω−3 (P<0.01) concentration, and the response was greater for AH (P<0.04). To further characterize the response of milk fat composition to dietary oil in ewes, a third study used six pens of three ewes each assigned to either the control CS diet used for Study 2 or the same diet supplemented with 45 g/kg (DM basis) of the oil mixture. Feeding oil had no effect on DMI, milk yield or milk fat concentration, but again increased (P<0.001) total trans-C18:1 and C22:6ω−3 concentrations and numerically increased (114%) total CLA concentration. Milk fatty acid composition responses to supplemental vegetable and marine oils were affected by forage source. Milk trans-C18:1 concentration was higher when CS was fed in Studies 1 and 2, but the effect of forage species on CLA concentration differed between studies, which may reflect differences in diet PUFA content and consumption, as well as amounts of dietary starch and fiber consumed. Despite large increases in trans-C18:1 concentration, milk fat content was not decreased by feeding unsaturated oils to ewes, even at diet levels of 45 g/kg of ration DM.

Plasmodiophora brassicae in its Environment

Plasmodiophora brassicae Wor. is viewed in this article from the standpoint of a highly evolved and successful organism, well fitted for the ecological niche that it occupies. Physical, chemical, and biological components of the soil environment are discussed in relation to their effects on the survival, growth, and reproduction of this microbe. It is evident that P. brassicae is well equipped by virtue of its robust resting spores for survival through many seasonal cycles. Germination is probably triggered as a result of signals initiated by root exudates. The resultant motile zoospore moves rapidly to the root hair surface and penetration and colonization follow. The short period between germination and penetration is one of greatest vulnerability for P. brassicae. In this phase survival is affected at the very least by soil texture and structure; its moisture; pH; calcium, boron, and nitrogen content; and the presence of active microbial antagonists. These factors influence the inoculum potential (sensu Garrett, 1956) and its viability and invasive capacity. There is evidence that these effects may also influence differentially the survival of some physiologic races of P. brassicae. Considering the interaction of P. brassicae with the soil environment from the perspective of its biological fitness is an unusual approach; most authors consider only the opportunities to destroy this organism. The approach adopted here is borne of several decades spent studying P. brassicae and the respect that has been engendered for it as a biological entity. This review stops at the point of penetration, although some of the implications of the environment for successful colonization are included because they form a continuum. Interactions with the molecular and biochemical cellular environment are considered in other sections in this special edition.

Evaluation of film forming polymers to control apple scab (Venturia inaequalis (Cooke) G. Wint.) under laboratory and field conditions

A detached leaf bioassay was used to determine the influence of several film forming polymers and a conventional triazole fungicide on apple scab (Venturia inaequalis (Cooke) G. Wint.) development under laboratory in vitro conditions, supported by two field trials using established apple cv. Golden Delicious to further assess the efficacy of foliar applied film forming polymers as scab protectant compounds. All film forming polymers used in this investigation (Bond, Designer, Nu-Film P, Spray Gard, Moisturin, Companion PCT12) inhibited germination of conidia, subsequent formation of appressoria and reduced leaf scab severity using a detached leaf bioassay. Regardless of treatment, there were no obvious trends in the percentage of conidia with one to four appressoria 5 days after inoculation. The synthetic fungicide penconazole resulted in the greatest levels of germination inhibition, appressorium development and least leaf scab severity. Under field conditions, scab severity on leaves and fruit of apple cv. Golden Delicious treated with a film forming polymer (Bond, Spray Gard, Moisturin) was less than on untreated controls. However, greatest protection in both field trials was provided by the synthetic fungicide penconazole. Higher chlorophyll fluorescence Fv/Fm emissions in polymer and penconazole treated trees indicated less damage to the leaf photosynthetic system as a result of fungal invasion. In addition, higher SPAD values as measures of leaf chlorophyll content were recorded in polymer and penconazole treated trees. Application of a film forming polymer or penconazole resulted in a higher apple yield per tree at harvest in both the 2005 and 2006 field trials compared to untreated controls. Results suggest application of an appropriate film forming polymer may provide a useful addition to existing methods of apple scab management. (C) 2008 Elsevier Ltd. All rights reserved.

Investigation of cooperativity in the binding of ligands to the D-2 dopamine receptor

The D 2 dopamine receptor exists as dimers or as higher-order oligomers, as determined from data from physical experiments. In this study, we sought evidence that this oligomerization leads to cooperativity by examining the binding of three radioligands ([H-3] nemonapride, [H-3] raclopride, and [H-3] spiperone) to D 2 dopamine receptors expressed in membranes of Sf9 cells. In saturation binding experiments, the three radioligands exhibited different B-max values, and the B-max values could be altered by the addition of sodium ions to assays. Despite labeling different numbers of sites, the different ligands were able to achieve full inhibition in competition experiments. Some ligand pairs also exhibited complex inhibition curves in these experiments. In radioligand dissociation experiments, the rate of dissociation of [H-3] nemonapride or [H-3] spiperone depended on the sodium ion concentration but was independent of the competing ligand. Although some of the data in this study are consistent with the behavior of a cooperative oligomeric receptor, not all of the data are in agreement with this model. It may, therefore, be necessary to consider more complex models for the behavior of this receptor.

The genetic basis of resistance to anticoagulants in rodents

Anticoagulant compounds, i.e., derivatives of either 4-hydroxycoumarin (e.g., warfarin, bromadiolone) or indane-1,3-dione (e.g., diphacinone, chlorophacinone), have been in worldwide use as rodenticides for > 50 years. These compounds inhibit blood coagulation by repression of the vitamin K reductase reaction (VKOR). Anticoagulant-resistant rodent populations have been reported from many countries and pose a considerable problem for pest control. Resistance is transmitted as an autosomal dominant trait although, until recently, the basic genetic mutation was unknown. Here, we report on the identification of eight different mutations in the VKORC1 gene in resistant laboratory strains of brown rats and house mice and in wild-caught brown rats from various locations in Europe with five of these mutations affecting only two amino acids (Tyr139Cys, Tyr139Ser, Tyr139Phe and Leu128Gln, Leu128Ser). By recombinant expression of VKORC1 constructs in HEK293 cells we demonstrate that mutations at Tyr139 confer resistance to warlarin at variable degrees while the other mutations, in addition, dramatically reduce VKOR activity. Our data strongly argue for at least seven independent mutation events in brown rats and two in mice. They suggest that mutations in VKORC1 are the genetic basis of anticoagulant resistance in wild populations of rodents, although the mutations alone do not explain all aspects of resistance that have been reported. We hypothesize that these mutations, apart from generating structural changes in the VKORC1 protein, may induce compensatory mechanisms to maintain blood clotting. Our findings provide the basis for a DNA-based field monitoring of anticoagulant resistance in rodents.