43,576 research outputs found
New Limits for Neutrinoless Tau Decays
No full textNeutrinoless 3-prong tau lepton decays into a charged lepton and either two charged particles or one neutral meson have been searched for using 4.79 fb \Gamma1 of data collected with the CLEO II detector at CESR. This analysis represents an update of a previous study and the addition of six decay channels. In all channels the numbers of events found are compatible with background estimates and branching fraction upper limits are set for 28 different decay modes. These limits are either more stringent than those set previously or represent the first attempt to find these decays. PACS numbers: 13.35.Dx, 14.60.Fg Typeset using REVT E X D. W. Bliss, 1 G. Masek, 1 H. P. Paar, 1 S. Prell, 1 V. Sharma, 1 D. M. Asner, 2 J. Gronberg, 2 T. S. Hill, 2 D. J. Lange, 2 R. J. Morrison, 2 H. N. Nelson, 2 T. K. Nelson, 2 D. Roberts, 2 A. Ryd, 2 R. Balest, 3 B. H. Behrens, 3 W. T. Ford, 3 H. Park, 3 J. Roy, 3 J. G. Smith, 3 J. P. Alexander, 4 R. Baker, 4 C..
Options for monitoring and estimating historical carbon emissions from forest degradation in the context of REDD+
No full textAbstract Measuring forest degradation and related forest carbon stock changes is more challenging than measuring deforestation since degradation implies changes in the structure of the forest and does not entail a change in land use, making it less easily detectable through remote sensing. Although we anticipate the use of the IPCC guidance under the United Framework Convention on Climate Change (UNFCCC), there is no one single method for monitoring forest degradation for the case of REDD+ policy. In this review paper we highlight that the choice depends upon a number of factors including the type of degradation, available historical data, capacities and resources, and the potentials and limitations of various measurement and monitoring approaches. Current degradation rates can be measured through field data (i.e. multi-date national forest inventories and permanent sample plot data, commercial forestry data sets, proxy data from domestic markets) and/or remote sensing data (i.e. direct mapping of canopy and forest structural changes or indirect mapping through modelling approaches), with the combination of techniques providing the best options. Developing countries frequently lack consistent historical field data for assessing past forest degradation, and so must rely more on remote sensing approaches mixed with current field assessments of carbon stock changes. Historical degradation estimates will have larger uncertainties as it will be difficult to determine their accuracy. However improving monitoring capacities for systematic forest degradation estimates today will help reduce uncertainties even for historical estimates.</p
Osa Peninsula, Costa Rica foliar nitrogen (%)
No full textField collected foliar nitrogen (%) from mature canopy leaves see Balzotti et al. (2016) Environmental Controls on Canopy Foliar N Distributions in a Neotropical Lowland Forest. Ecological Applications and Asner, G. P., & Martin, R. E. (2016). Convergent elevation trends in canopy chemical traits of tropical forests. Global Change Biology. 22, 2216-2227, doi: 10.1111/gcb.1316
P Values and Statistical Significance
No full textThis resource, created by author Will G. Hopkins, defines what a p-value is, why .05 is significant, and when to use it. It also covers related topics such as one-tailed/two-tailed tests and hypothesis testing. Overall, this is a wonderful resource for students wanting to learn more about statistics, and more specially, significant testing
Area-based vs tree-centric approaches to mapping forest carbon in Southeast Asian forests from airborne laser scanning data
No full textTropical forests are a key component of the global carbon cycle, and mapping their carbon density is essential for understanding human influences on climate and for ecosystem-service-based payments for forest protection. Discrete-return airborne laser scanning (ALS) is increasingly recognised as a high-quality technology for mapping tropical forest carbon, because it generates 3D point clouds of forest structure from which aboveground carbon density (ACD) can be estimated. Area-based models are state of the art when it comes to estimating ACD from ALS data, but discard tree-level information contained within the ALS point cloud. This paper compares area-based and tree-centric models for estimating ACD in lowland old-growth forests in Sabah, Malaysia. These forests are challenging to map because of their immense height. We compare the performance of (a) an area-based model developed by Asner and Mascaro (2014), and used primarily in the neotropics hitherto, with (b) a tree-centric approach that uses a new algorithm (itcSegment) to locate trees within the ALS canopy height model, measures their heights and crown widths, and calculates biomass from these dimensions. We find that Asner and Mascaro’s model needed regional calibration, reflecting the distinctive structure of Southeast Asian forests. We also discover that forest basal area is closely related to canopy gap fraction measured by ALS, and use this finding to refine Asner and Mascaro’s model. Finally, we show that our tree-centric approach is less accurate at estimating ACD than the best-performing area-based model (RMSE 18% vs 13%). Tree-centric modelling is appealing because it is based on summing the biomass of individual trees, but until algorithms can detect understory trees reliably and estimate biomass from crown dimensions precisely, areas-based modelling will remain the method of choice
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Measurement of the branching fraction
No full textThe B
0
s
→ J/ψK
0
S
branching fraction is measured in a data sample corresponding to 0.41 fb−1
of integrated luminosity collected with the LHCb detector at the LHC. This channel is sensitive to
the penguin contributions affecting the sin 2β measurement from B
0
→ J/ψK
0
S
. The time-integrated
branching fraction is measured to be B(B
0
s
→ J/ψK
0
S
) = (1.83±0.28)×10−5
. This is the most precise
measurement to date
Linguaggio, simbolo, memoria. Pico e l’ircocervo
No full textThis article examines the role of language, symbols, and memory in the thought of Giovanni Pico della Mirandola, focusing on a particular passage in his Apologia where he mentions the "hircocervus". The author explores the meaning of this symbol, linking it to medieval philosophical debates on intelligibility and truth, as well as to the Kabbalistic tradition. By analyzing Pico’s sources a connection emerges between the "hircocervus" and Flavius Mithridates’ translation of the Song of Songs, highlighting the complex interplay between philosophy, Kabbalah, and the art of memory in Renaissance thought. At the same time, this symbol provides a crucial clue for investigating Pico’s mnemonic structures
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