233 research outputs found
Economic Impact of Energy on Food Production
This study is concerned with the evaluation of the effect energy prices and availability have on food production. For a predicted price and availability of variable inputs, the study optimally allocates these inputs to maximize the growers' profits and simulates the effect of this allocation on food prices, demand, and energy consumption. The study investigates possible future energy situations and their effect as well as investigating alternate methods and policies for food production in an energy and food conscious world
ICE-SHEET DYNAMICS OF WARTA GLACIATION (SAALE) IN THE MARGINAL ZONE OF KNYSZEWICZE AREA, NORTHEASTERN POLAND
The paper presents a research on a marginal zone near Knyszewicze in the southern part of Sokółka Hills (northeastern Poland). Terminal moraine hills arearranged amphitheatrically in a lobal pattern. Dynamics of the Knyszewicze frontal ice-sheet lobe during the Saale Glaciation and successive stages of the marginal zone near the village of Knyszewicze were reconstructed based on sedimentary and geomorphological analysis, using a digital elevation model and morpholineaments. Three main phases of the Knyszewicze glacial-lobe activity were identified including accumulation of glaciofluvial deposits, advances of the ice margin and ice-lobe retreat. Moraine hills developed at a stable ice-lobe terminus, initially as short end-moraine fans with the fol low ing se quence of lithofacies Gh-SGh-Sh or Gm-Gh-Sh. Such a sequence indicates cyclic sheet-floods. During a small but dynamic advance of the ice sheet terminus, these depos its were moved for ward and monoclinally folded, then furrowed with sloping faults due to horizontal pressure. Typ i cal thrust-block push moraines developed in this way. Ice sheet advance took place when permafrost was present in the substratum and very high water pressure occurred at glacial terminus. Inside a lobal configuration of
moraines, there is a rich inventory of glacial forms with a classic terminal depression in the central part. Based on this landform pattern, their shape, rhythm and glaciotectonic disturbances, the land relief may be referred to as a hill-hole pair. The structure of Horczaki Knoll, deposited on the sub-Quaternary tectonic structure, significantly contributed to a development of this marginal zone
Effects of loosening combined with straw incorporation into the upper subsoil on soil properties and crop yield in a three-year field experiment
Subsoil management needs to be integrated into the current tillage regimes in order to access additional resources of water and nutrients and sustain crop production. However, arable subsoil is often deficient in nutrients and carbon, and it is compacted, affecting root growth and yield. In this study, crop yield and soil responses to loosening of the upper subsoil, without and with straw injection below the plough layer (25-34 cm), were studied during three crop cycles (2016-2018) in a field experiment near Uppsala, Sweden. Responses to straw injection after loosening were studied after single and triple consecutive applications of 24-30 Mg ha-1 during 2015-2017 to spring-sown barley and oats. Subsoil loosening combined with one-time or repeated straw addition (LS treatments) significantly reduced soil bulk density (BD) and increased porosity, soil organic carbon (SOC) and total nitrogen (N) compared with loosening (L) alone (one-time or repeated annually) and the control. In treatment L, the soil re-compacted over time to a similar level as in the control. Field inspections indicated higher abundance of earthworms and biopores in and close to straw incorporation strips. Aggregates readily crumbled/fragmented by hand and casts (fine crumbs) were frequently observed in earthworm burrows. The treatment LS improved soil properties (SOC and porosity) and water holding capacity, but had no significant influence on crop yield compared with the control. Crop yield in all treatments was 6.5-6.8 Mg ha-1 in 2017 and 3.8-4.0 Mg ha-1 in 2018, and differences were non-significant. Absence of yield effect due to treatments could be possibly due to other confounding factors buffering expression of treatment effects on yield. Lower relative chlorophyll content in leaves in the loosening with straw treatment during early growth stages, did not affect final crop yield. Subsoil loosening performed three times gave no further improvement in soil properties and grain yield compared with one-time loosening. There was no difference in yield between repeated subsoil loosening + straw and one-time treatment. It will be interesting to study the long-term effects of deep straw injection and evaluate its impact under other soil and weather conditions
Lysimeter deep N fertilizer placement reduced leaching and improved N use efficiency
Deep fertilization has been tested widely for nitrogen (N) use efficiency but there is little evidence of its impact on N leaching and the interplay between climate factors and crop N use. In this study, we tested the effect of three fertilizer N placements on leaching, crop growth, and greenhouse gas (GHG) emissions in a lysimeter experiment over three consecutive years with spring-sown cereals (S1, S2, and S3). Leaching was additionally monitored in an 11-month fallow period (F1) preceding S1 and a 15-month fallow period (F2) following S3. In addition to a control with no N fertilizer (Control), 100 kg N ha(-1) year(-1) of ammonium nitrate was placed at 0.2 m (Deep), 0.07 m (Shallow), or halved between 0.07 m and 0.2 m (Mixed). Deep reduced leachate amount in each cropping period, with significant reductions (p < 0.05) in the drought year (S2) and cumulatively for S1-S3. Overall, Deep reduced leaching by 22, 25 and 34% compared to Shallow, Mixed and Control, respectively. Deep and Mixed reduced N leaching across S1-S3 compared with Shallow, but Deep further reduced N loads by 15% compared to Mixed and was significantly lowest (p < 0.05) among the fertilized treatments in S1 and S2. In S3, Deep increased grain yields by 28 and 22% compared to Shallow and Mixed, respectively, while nearly doubling the agronomic efficiency of N (AE(N)) and the recovery efficiency of N (REN). Deep N placement is a promising mitigation practice that should be further investigated
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The hallmarks of a tradeoff in transcriptomes that balances stress and growth functions.
Fast growth phenotypes are achieved through optimal transcriptomic allocation, in which cells must balance tradeoffs in resource allocation between diverse functions. One such balance between stress readiness and unbridled growth in E. coli has been termed the fear versus greed (f/g) tradeoff. Two specific RNA polymerase (RNAP) mutations observed in adaptation to fast growth have been previously shown to affect the f/g tradeoff, suggesting that genetic adaptations may be primed to control f/g resource allocation. Here, we conduct a greatly expanded study of the genetic control of the f/g tradeoff across diverse conditions. We introduced 12 RNA polymerase (RNAP) mutations commonly acquired during adaptive laboratory evolution (ALE) and obtained expression profiles of each. We found that these single RNAP mutation strains resulted in large shifts in the f/g tradeoff primarily in the RpoS regulon and ribosomal genes, likely through modifying RNAP-DNA interactions. Two of these mutations additionally caused condition-specific transcriptional adaptations. While this tradeoff was previously characterized by the RpoS regulon and ribosomal expression, we find that the GAD regulon plays an important role in stress readiness and ppGpp in translation activity, expanding the scope of the tradeoff. A phylogenetic analysis found the greed-related genes of the tradeoff present in numerous bacterial species. The results suggest that the f/g tradeoff represents a general principle of transcriptome allocation in bacteria where small genetic changes can result in large phenotypic adaptations to growth conditions.IMPORTANCETo increase growth, E. coli must raise ribosomal content at the expense of non-growth functions. Previous studies have linked RNAP mutations to this transcriptional shift and increased growth but were focused on only two mutations found in the proteins central region. RNAP mutations, however, commonly occur over a large structural range. To explore RNAP mutations impact, we have introduced 12 RNAP mutations found in laboratory evolution experiments and obtained expression profiles of each. The mutations nearly universally increased growth rates by adjusting said tradeoff away from non-growth functions. In addition to this shift, a few caused condition-specific adaptations. We explored the prevalence of this tradeoff across phylogeny and found it to be a widespread and conserved trend among bacteria
Insights from Amphioxus into the Evolution of Vertebrate Cartilage
Central to the story of vertebrate evolution is the origin of the vertebrate head, a problem difficult to approach using paleontology and comparative morphology due to a lack of unambiguous intermediate forms. Embryologically, much of the vertebrate head is derived from two ectodermal tissues, the neural crest and cranial placodes. Recent work in protochordates suggests the first chordates possessed migratory neural tube cells with some features of neural crest cells. However, it is unclear how and when these cells acquired the ability to form cellular cartilage, a cell type unique to vertebrates. It has been variously proposed that the neural crest acquired chondrogenic ability by recruiting proto-chondrogenic gene programs deployed in the neural tube, pharynx, and notochord. To test these hypotheses we examined the expression of 11 amphioxus orthologs of genes involved in neural crest chondrogenesis. Consistent with cellular cartilage as a vertebrate novelty, we find that no single amphioxus tissue co-expresses all or most of these genes. However, most are variously co-expressed in mesodermal derivatives. Our results suggest that neural crest-derived cartilage evolved by serial cooption of genes which functioned primitively in mesoderm
Molar form, enamel growth, and durophagy in Cercocebus and Lophocebus
Objectives: To test the hypothesis that differences in crown structure, enamel
growth, and crown geometry in Cercocebus and Lophocebus molars covary with differences
in the feeding strategies (habitual vs. fallback durophagy, respectively) of these
two genera. Relative to Lophocebus molars, Cercocebus molars are predicted to possess
features associated with greater fracture resistance and to differ in enamel
growth parameters related to these features.
Materials and Methods: Sample proveniences are as follows: Cercocebus atys molars
are from the Taï Forest, Ivory Coast; Lophocebus albigena molars are from a site north
of Makoua, Republic of Congo; and a Lophocebus atterimus molar is from the Lomako
Forest, Democratic Republic of Congo. For μCT scans on which aspects of molar
form were measured, sample sizes ranged from 5 to 35 for Cercocebus and 3 to
12 for Lophocebus. A subsample of upper molars was physically sectioned to measure
enamel growth variables.
Results: Partly as a function of their larger size, Cercocebus molars had significantly
greater absolute crown strength (ACS) than Lophocebus molars, supporting the
hypothesis. Greater crown heights in Cercocebus are achieved through faster enamel
extension rates. Also supporting the hypothesis, molar flare and proportional occlusal
basin enamel thickness were significantly greater in Cercocebus. Relative enamel
thickness (RET), however, was significantly greater in Lophocebus.
Discussion: If ACS is a better predictor of fracture resistance than RET, then Cercocebus
molars may be more fracture resistant than those of Lophocebus. Greater molar
flare and proportional occlusal basin thickness might also afford Cercocebus molars
greater fracture resistance
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