881 research outputs found
Hierarchical Bin Buffering: Online Local Moments for Dynamic External Memory Arrays
Local moments are used for local regression, to compute statistical measures
such as sums, averages, and standard deviations, and to approximate probability
distributions. We consider the case where the data source is a very large I/O
array of size n and we want to compute the first N local moments, for some
constant N. Without precomputation, this requires O(n) time. We develop a
sequence of algorithms of increasing sophistication that use precomputation and
additional buffer space to speed up queries. The simpler algorithms partition
the I/O array into consecutive ranges called bins, and they are applicable not
only to local-moment queries, but also to algebraic queries (MAX, AVERAGE, SUM,
etc.). With N buffers of size sqrt{n}, time complexity drops to O(sqrt n). A
more sophisticated approach uses hierarchical buffering and has a logarithmic
time complexity (O(b log_b n)), when using N hierarchical buffers of size n/b.
Using Overlapped Bin Buffering, we show that only a single buffer is needed, as
with wavelet-based algorithms, but using much less storage. Applications exist
in multidimensional and statistical databases over massive data sets,
interactive image processing, and visualization
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Determination of the thermal diffusivity of pyrotechnic materials
Thermal diffusivity studies have been initiated to better characterize developmental pyrotechnic materials. Thermal diffusivity, along with density and specific heat, can be used to calculate another important thermophysical property, namely, thermal conductivity. A literature search revealed the relatively simple method commonly known as the flash-diffusivity method. This method, with appropriate modification to accent pyrotechnic materials at elevated temperatures, was selected for these studies
Potential tumour doubling time: determination of Tpot for various canine and feline tumours
Spontaneous tumours in dogs and cats are an excellent model for clinical human research, such as in developing proton conformation radiotherapy for humans. The kinetics of tumour cells can be used effectively to predict prognosis and response to therapy in patients with tumours. Knowledge of the kinetic parameters in these tumours is therefore important. In the present study the kinetic parameters evaluated included the labelling index (LI), relative movement (RM), mitotic index (MI), and potential doubling time (Tpot). These parameters were determined using in vivo labelling with bromodeoxyuridine, flow cytometry and histological preparation. Samples were obtained and evaluated from 72 dogs and 20 cats, presenting as patients in our clinic. Within the groups of epithelial and mesenchymal tumours from dogs and cats, the kinetic parameters LI, RM and MI were compared with Tpot. Significant correlations were observed for the comparison Tpot and LI. No correlation was found between Tpot and R
A Mark in Time Saves Nein
A method for predicting political interactions and policy outcomes based on two political theorems is presented and illustrated with an examination of the decision to merge the two German currencies. Political perceptions and actions are anticipated by combining the substantive knowledge of area experts with the theoretical insights embedded in the median voter theorem and a monotonicity theorem that links expectations to probabilistic statements of action. The proposed model has proven accurate about 90 percent of the time. The proposed forecasting method identifies a sequential strategy that may have been followed by Chancellor Kohl in forging the coalition needed to merge successfully the two German currencies. Using comparative statics, the analysis suggests how subtle and sophisticated Chancellor Kohl had to be to succeed in getting the policy outcome he desired despite stiff opposition.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66924/2/10.1177_019251219201300106.pd
Using the surface profiles of modern ice masses to inform palaeo-glacier reconstructions
Morphometric study of modern ice masses is useful because many reconstructions of glaciers traditionally draw on their shape for guidance Here we analyse data derived from the surface profiles of 200 modern ice masses-valley glaciers icefields ice caps and ice sheets with length scales from 10(0) to 10(3) km-from different parts of the world Four profile attributes are investigated relief span and two parameters C* and C that result from using Nye s (1952) theoretical parabola as a profile descriptor C* and C respectively measure each profile s aspect ratio and steepness and are found to decrease in size and variability with span This dependence quantifies the competing influences of unconstrained spreading behaviour of ice flow and bed topography on the profile shape of ice masses which becomes more parabolic as span Increases (with C* and C tending to low values of 2 5-3 3 m(1/2)) The same data reveal coherent minimum bounds in C* and C for modern ice masses that we develop into two new methods of palaeo glacier reconstruction In the first method glacial limits are known from moraines and the bounds are used to constrain the lowest palaeo ice surface consistent with modern profiles We give an example of applying this method over a three-dimensional glacial landscape in Kamchatka In the second method we test the plausibility of existing reconstructions by comparing their C* and C against the modern minimum bounds Of the 86 published palaeo ice masses that we put to this test 88% are found to be plausible The search for other morphometric constraints will help us formalise glacier reconstructions and reduce their uncertainty and subjectiveness (C) 2010 Elsevier Ltd All rights reserve
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Sources and characteristics of summertime organic aerosol in the Colorado Front Range: perspective from measurements and WRF-Chem modeling
Abstract. The evolution of organic aerosols (OAs) and their precursors in the boundary layer (BL) of the Colorado Front Range during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ, July–August 2014) was analyzed by in situ measurements and chemical transport modeling. Measurements indicated significant production of secondary OA (SOA), with enhancement ratio of OA with respect to carbon monoxide (CO) reaching 0.085±0.003 µg m−3 ppbv−1. At background mixing ratios of CO, up to ∼ 1.8 µg m−3 background OA was observed, suggesting significant non-combustion contribution to OA in the Front Range. The mean concentration of OA in plumes with a high influence of oil and natural gas (O&G) emissions was ∼ 40 % higher than in urban-influenced plumes. Positive matrix factorization (PMF) confirmed a dominant contribution of secondary, oxygenated OA (OOA) in the boundary layer instead of fresh, hydrocarbon-like OA (HOA). Combinations of primary OA (POA) volatility assumptions, aging of semi-volatile species, and different emission estimates from the O&G sector were used in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) simulation scenarios. The assumption of semi-volatile POA resulted in greater than a factor of 10 lower POA concentrations compared to PMF-resolved HOA. Including top-down modified O&G emissions resulted in substantially better agreements in modeled ethane, toluene, hydroxyl radical, and ozone compared to measurements in the high-O&G-influenced plumes. By including emissions from the O&G sector using the top-down approach, it was estimated that the O&G sector contributed to < 5 % of total OA, but up to 38 % of anthropogenic SOA (aSOA) in the region. The best agreement between the measured and simulated median OA was achieved by limiting the extent of biogenic hydrocarbon aging and consequently biogenic SOA (bSOA) production. Despite a lower production of bSOA in this scenario, contribution of bSOA to total SOA remained high at 40–54 %. Future studies aiming at a better emissions characterization of POA and intermediate-volatility organic compounds (IVOCs) from the O&G sector are valuable
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FAMIN is a multifunctional purine enzyme enabling the purine nucleotide cycle
Mutations in FAMIN cause arthritis and inflammatory bowel disease in early childhood, and a common genetic variant increases risk for Crohn’s disease and leprosy. We developed an unbiased liquid chromatography mass spectrometry screen for enzymatic activity of this orphan protein. We report that FAMIN phosphorolytically cleaves adenosine into adenine and ribose-1-phosphate. Such activity was considered absent from eukaryotic metabolism. FAMIN and its prokaryotic paralogues additionally have adenosine deaminase, purine nucleoside phosphorylase, and S-methyl-5'-thioadenosine phosphorylase activity, hence combine activities of the namesake enzymes of central purine metabolism. FAMIN enables in macrophages a purine nucleotide cycle (PNC) between adenosine and inosine monophosphate and adenylosuccinate, which consumes aspartate and releases fumarate in a manner involving fatty acid oxidation and ATP-citrate lyase activity. This macrophage PNC synchronises mitochondrial activity with glycolysis by balancing electron transfer to mitochondria, thereby supporting glycolytic activity and promoting oxidative phosphorylation and mitochondrial H+ and phosphate recycling.Includes ERC. Wellcome Trust and MRC
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Speciated measurements of semivolatile and intermediate volatility organic compounds (S/IVOCs) in a pine forest during BEACHON-RoMBAS 2011
Understanding organic composition of gases and particles is essential to identifying sources and atmospheric processing leading to organic aerosols (OA), but atmospheric chemical complexity and the analytical techniques available often limit such analysis. Here we present speciated measurements of semivolatile and intermediate volatility organic compounds (S/IVOCs) using a novel dual-use instrument (SV-TAG-AMS) deployed at Manitou Forest, CO, during the Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H_2O, Organics & Nitrogen – Rocky Mountain Biogenic Aerosol Study (BEACHON-RoMBAS) 2011 campaign. This instrument provides on-line speciation of ambient organic compounds with 2 h time resolution. The species in this volatility range are complex in composition, but their chemical identities reveal potential sources. Observed compounds of biogenic origin include sesquiterpenes with molecular formula C_(15)H_(24) (e.g., β-caryophyllene and longifolene), which were most abundant at night. A variety of other biogenic compounds were observed, including sesquiterpenoids with molecular formula C_(15)H_(22), abietatriene and other terpenoid compounds. Many of these compounds have been identified in essential oils and branch enclosure studies but were observed in ambient air for the first time in our study. Semivolatile polycyclic aromatic hydrocarbons (PAHs) and alkanes were observed with highest concentrations during the day and the dependence on temperature suggests the role of an evaporative source. Using statistical analysis by positive matrix factorization (PMF), we classify observed S/IVOCs by their likely sources and processes, and characterize them based on chemical composition. The total mass concentration of elutable S/IVOCs was estimated to be on the order of 0.7 µg m^(−3) and their volatility distributions are estimated for modeling aerosol formation chemistry
Author Correction: A HIF independent oxygen-sensitive pathway for controlling cholesterol synthesis (Nature Communications, (2023), 14, 1, (4816), 10.1038/s41467-023-40541-1)
\ua9 The Author(s) 2024.The original version of this Article contained errors in Figs. 2, 3, and 5. In the original Fig. 2e, the flow cytometry panel on the right (labelled “StD (24 hr) followed by 1% O2 (~16 hr)”), was inadvertently duplicated from the panel on the left (labelled “Concurrent StD and 1% O2 (~24 hr)”). In the original Fig. 3a, the flow cytometry panel on the right (labelled “Roxadustat”), was inadvertently duplicated from the panel on the left (labelled “DMOG”). In the original Fig. 5c, the labels did not properly communicate that both panels come from the same experiment and have the same controls. The following sentence has been added to the end of the legend for Fig. 5c: “The data depicted in the left and right panels originated from the same experiment and as such the control plots are the same in both.” Figures 2, 3, and 5 have been corrected in both the PDF and HTML versions of the Article. The original version of the Supplementary Information associated with this Article contained an error in Supplementary Fig. 5. In the original Supplementary Fig. 5a, the labels did not properly communicate that all three panels come from the same experiment and have the same control. The following sentence has been added to the end of the legend for Supplementary Fig. 5a: “The data depicted in the three panels originated from the same experiment and as such the control plot is the same in all panels”. The HTML has been updated to include a corrected version of the Supplementary Information
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