4,096 research outputs found
Nitrous oxide emissions from irrigated cotton soils of northern Australia
An automated gas sampling methodology has been used to estimate nitrous oxide (N2O) emissions from heavy black clay soil in northern Australia where split applications of urea were applied to furrow irrigated cotton. Nitrous oxide emissions from the beds were 643 g N/ha over the 188 day measurement period (after planting), whilst the N2O emissions from the furrows were significantly higher at 967 g N/ha. The DNDC model was used to develop a full season simulation of N2O and N2 emissions. Seasonal N2O emissions were equivalent to 0.83% of applied N, with total gaseous N losses (excluding NH3) estimated to be 16% of the applied N
Developing a panarchy model of landscape conservation and management of alpine-mountain grassland in Northern Italy.
This paper explores methods of applying resilience theory to a case study of natural resource management and the cultural landscape of upland and alpine pasture in northern Italy. We identify that the close interaction between alpine pastures and its managers offers a strong fit with the concept of a social-ecological system that maintains the cultural landscape. We first considered a descriptive approach looking historically at socio-economic development in the study area. We explored whether this can be related to resilience phenomena such as regime shifts, thresholds and/or regime stability through adaptive processes. However, we found it difficult at this overarching level to conceptually combine natural and social capital of alpine pastures and their managers in any quantitative way. We also interpreted our data through considering economic, social and ecological information as acting within separate but interacting domains. This led us to construct conceptual models of adaptive cycles to describe the alpine mountain grassland ecosystem of our study site and to conclude that a panarchy model can offer a powerful metaphor for its ecological dynamics. This has practical implications both for the management of Natura 2000 interest and the maintenance of the cultural landscape in which this Alpine interest occurs. We suggest that Resilience theory through its dynamic approach of interacting scales of adaptive cycles offers useful insights into the resource management (of valued cultural and natural attributes) but that care is needed in distinguishing between descriptive metaphor and predictive model or "real" system.natural resource management, natural and social capital
Microarrays in ecological research: A case study of a cDNA microarray for plant-herbivore interactions
BACKGROUND: Microarray technology allows researchers to simultaneously monitor changes in the expression ratios (ERs) of hundreds of genes and has thereby revolutionized most of biology. Although this technique has the potential of elucidating early stages in an organism's phenotypic response to complex ecological interactions, to date, it has not been fully incorporated into ecological research. This is partially due to a lack of simple procedures of handling and analyzing the expression ratio (ER) data produced from microarrays. RESULTS: We describe an analysis of the sources of variation in ERs from 73 hybridized cDNA microarrays, each with 234 herbivory-elicited genes from the model ecological expression system, Nicotiana attenuata, using procedures that are commonly used in ecologic research. Each gene is represented by two independently labeled PCR products and each product was arrayed in quadruplicate. We present a robust method of normalizing and analyzing ERs based on arbitrary thresholds and statistical criteria, and characterize a "norm of reaction" of ERs for 6 genes (4 of known function, 2 of unknown) with different ERs as determined across all analyzed arrays to provide a biologically-informed alternative to the use of arbitrary expression ratios in determining significance of expression. These gene-specific ERs and their variance (gene CV) were used to calculate array-based variances (array CV), which, in turn, were used to study the effects of array age, probe cDNA quantity and quality, and quality of spotted PCR products as estimates of technical variation. Cluster analysis and a Principal Component Analysis (PCA) were used to reveal associations among the transcriptional "imprints" of arrays hybridized with cDNA probes derived from mRNA from N. attenuata plants variously elicited and attacked by different herbivore species and from three congeners: N. quadrivalis, N. longiflora and N. clevelandii. Additionally, the PCA revealed the contribution of individual gene ERs to the associations among arrays. CONCLUSIONS: While the costs of 'boutique' array fabrication are rapidly declining, familiar methods for the analysis of the data they create are still missing. The case history illustrated here demonstrates the ease with which this powerful technology can be adapted to ecological research
Two-fold differences are the detection limit for determining transgene copy numbers in plants by real-time PCR
BACKGROUND: After transformation, plants that are homozygous and contain one copy of the transgene are typically selected for further study. If real-time PCR is to be used to determine copy number and zygosity, it must be able to distinguish hemizygous from homozygous and one-copy from two-copy plants. That is, it must be able to detect two-fold differences. RESULTS: When transgenic Nicotiana attenuata plants which had been previously determined by Southern analysis to contain one or two copies of the transgene, were analyzed by real-time PCR (2(-ÎÎCt )method), the method failed to confirm the results from the Southern analysis. In a second data set we analyzed offspring of a hemizygous one-copy plant, which were expected to segregate into three groups of offspring in a 1:2:1 ratio: no transgene, hemizygous, homozygous. Because it was not possible to distinguish homozygous from hemizygous plants with real-time PCR, we could not verify this segregation ratio. CONCLUSIONS: Detection of two-fold differences by real-time PCR is essential if this procedure is to be used for the characterization of transgenic plants. However, given the high variability between replicates, a detection of two-fold differences is in many cases not possible; in such cases Southern analysis is the more reliable procedure
Predicting Audio Advertisement Quality
Online audio advertising is a particular form of advertising used abundantly
in online music streaming services. In these platforms, which tend to host tens
of thousands of unique audio advertisements (ads), providing high quality ads
ensures a better user experience and results in longer user engagement.
Therefore, the automatic assessment of these ads is an important step toward
audio ads ranking and better audio ads creation. In this paper we propose one
way to measure the quality of the audio ads using a proxy metric called Long
Click Rate (LCR), which is defined by the amount of time a user engages with
the follow-up display ad (that is shown while the audio ad is playing) divided
by the impressions. We later focus on predicting the audio ad quality using
only acoustic features such as harmony, rhythm, and timbre of the audio,
extracted from the raw waveform. We discuss how the characteristics of the
sound can be connected to concepts such as the clarity of the audio ad message,
its trustworthiness, etc. Finally, we propose a new deep learning model for
audio ad quality prediction, which outperforms the other discussed models
trained on hand-crafted features. To the best of our knowledge, this is the
first large-scale audio ad quality prediction study.Comment: WSDM '18 Proceedings of the Eleventh ACM International Conference on
Web Search and Data Mining, 9 page
06391 Abstracts Collection -- Algorithms and Complexity for Continuous Problems
From 24.09.06 to 29.09.06, the Dagstuhl Seminar 06391 ``Algorithms and Complexity for Continuous Problems\u27\u27 was held
in the International Conference and Research Center (IBFI),
Schloss Dagstuhl.
During the seminar, participants presented their current
research, and ongoing work and open problems were discussed. Abstracts of
the presentations given during the seminar
are put together in this paper. The first section
describes the seminar topics and goals in general.
Links to extended abstracts or full papers are provided, if available
Do face masks introduce bias in speech technologies? The case of automated scoring of speaking proficiency
The COVID-19 pandemic has led to a dramatic increase in the use of face masks
worldwide. Face coverings can affect both acoustic properties of the signal as
well as speech patterns and have unintended effects if the person wearing the
mask attempts to use speech processing technologies. In this paper we explore
the impact of wearing face masks on the automated assessment of English
language proficiency. We use a dataset from a large-scale speaking test for
which test-takers were required to wear face masks during the test
administration, and we compare it to a matched control sample of test-takers
who took the same test before the mask requirements were put in place. We find
that the two samples differ across a range of acoustic measures and also show a
small but significant difference in speech patterns. However, these differences
do not lead to differences in human or automated scores of English language
proficiency. Several measures of bias showed no differences in scores between
the two groups
Incoherently pumped continuous wave optical parametric oscillator broadened by non-collinear phasematching
In this paper, we report on a singly resonant optical parametric oscillator
(OPO) pumped by an amplified spontaneous emission (ASE) source. The pump
focusing conditions allow non-collinear phasematching, which resulted in a 230
nm (190 cm) spectral bandwidth. Calculations indicate that such
phasematching schemes may be used to further broaden OPO spectral bandwidths.Comment: 7 pages 4 figure
Recovering a lost seismic disaster. The destruction of El Castillejo and the discovery of the earliest historic earthquake affecting the Granada region (Spain)
This paper discusses recent archaeological fieldwork conducted at El Castillejo, a medieval Islamic settlement in Los GuĂĄjares, Granada, southern Spain. Results from combined archaeological excavation and archaeoseismological assessment of standing structures suggest that the site was affected by a destructive earthquake during its occupation. Radiocarbon samples and OSL analysis point to a seismic event in the period CE 1224â1266. The earthquake occurred within an area marked by a âseismological gapâ in terms of historic seismicity and the causative fault has been tentatively identified in the NigĂŒelas-Padul Fault System which lies north of the settlement. This event is not recorded by national or European seismic catalogues and represents the oldest historic earthquake in the Granada area. Our work stresses the significant impact that targeted archaeological investigations can generate in our understanding of the local historic seismicity, thus providing clear implications for seismic disaster prevention and reduction
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