2,104 research outputs found

    Mesoscale modeling of smoke transport from equatorial Southeast Asian Maritime Continent to the Philippines: First comparison of ensemble analysis with in situ observations

    Full text link
    Atmospheric transport of smoke from equatorial Southeast Asian Maritime Continent (Indonesia, Singapore, and Malaysia) to the Philippines was recently verified by the first‐ever measurement of aerosol composition in the region of the Sulu Sea from a research vessel named Vasco. However, numerical modeling of such transport can have large uncertainties due to the lack of observations for parameterization schemes and for describing fire emission and meteorology in this region. These uncertainties are analyzed here, for the first time, with an ensemble of 24 Weather Research and Forecasting model with Chemistry (WRF‐Chem) simulations. The ensemble reproduces the time series of observed surface nonsea‐salt PM2.5 concentrations observed from the Vasco vessel during 17–30 September 2011 and overall agrees with satellite (Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and Moderate Resolution Imaging Spectroradiometer (MODIS)) and Aerosol Robotic Network (AERONET) data. The difference of meteorology between National Centers for Environmental Prediction (NCEP’s) Final (FNL) and European Center for Medium range Weather Forecasting (ECMWF’s) ERA renders the biggest spread in the ensemble (up to 20 μg m−3 or 200% in surface PM2.5), with FNL showing systematically superior results. The second biggest uncertainty is from fire emissions; the 2 day maximum Fire Locating and Modelling of Burning Emissions (FLAMBE) emission is superior than the instantaneous one. While Grell‐Devenyi (G3) and Betts‐Miller‐Janjić cumulus schemes only produce a difference of 3 μg m−3 of surface PM2.5 over the Sulu Sea, the ensemble mean agrees best with Climate Prediction Center (CPC) MORPHing (CMORPH)’s spatial distribution of precipitation. Simulation with FNL‐G3, 2 day maximum FLAMBE, and 800 m injection height outperforms other ensemble members. Finally, the global transport model (Navy Aerosol Analysis and Prediction System (NAAPS)) outperforms all WRF‐Chem simulations in describing smoke transport on 20 September 2011, suggesting the challenges to model tropical meteorology at mesoscale and finer scale.Plain Language SummaryIt is well known that smoke particles from fires in Indonesia, Singapore, and Malaysia can affect each other’s air quality. Less known and surely not well documented is the transport of smoke particles from these countries to the Philippines. Here we use the first‐ever measurements took nearby the coastal of the Philippines to analyze an ensemble of 24 WRF‐Chem simulations of smoke transport. Because of persistent cloud cover and the complexity of meteorology, mesoscale modeling of smoke transport in these regions normally has large uncertainties. We show these uncertainties are caused first by meteorology and then by fire emissions. We further show that models with finer resolution not necessarily produce better results.Key PointsFirst mesoscale modeling of smoke transport from equatorial Southeast Asian Maritime Continent to the PhilippinesEnsemble analysis of modeling uncertainties with first‐ever measurement of aerosol composition data in the region of the Sulu SeaMeteorological initial and boundary conditions, not cumulus parametrization and fire emission, have the largest uncertainty in the simulationPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137624/1/jgrd53809_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137624/2/jgrd53809.pd

    Kinship Index Variations among Populations and Thresholds for Familial Searching

    Get PDF
    Current familial searching strategies are developed primarily based on autosomal STR loci, since most of the offender profiles in the forensic DNA databases do not contain Y-STR or mitochondrial DNA data. There are generally two familial searching methods, Identity-by-State (IBS) based methods or kinship index (KI) based methods. The KI based method is an analytically superior method because the allele frequency information is considered as opposed to solely allele counting. However, multiple KIs should be calculated if the unknown forensic profile may be attributed to multiple possible relevant populations. An important practical issue is the KI threshold to select for limiting the list of candidates from a search. There are generally three strategies of setting the KI threshold for familial searching: (1) SWGDAM recommendation 6; (2) minimum KI≥KI threshold; and (3) maximum KI≥KI threshold. These strategies were evaluated and compared by using both simulation data and empirical data. The minimum KI will tend to be closer to the KI appropriate for the population of which the forensic profile belongs. The minimum KI≥KI threshold performs better than the maximum KI≥KI threshold. The SWGDAM strategy may be too stringent for familial searching with large databases (e.g., 1 million or more profiles), because its KI thresholds depend on the database size and the KI thresholds of large databases have a higher probability to exclude true relatives than smaller databases. Minimum KI≥KI threshold strategy is a better option, as it provides the flexibility to adjust the KI threshold according to a pre-determined number of candidates or false positive/negative rates. Joint use of both IBS and KI does not significantly reduce the chance of including true relatives in a candidate list, but does provide a higher efficiency of familial searching

    The Mass Function of Newly Formed Stars (Review)

    Full text link
    The topic of the stellar "original mass function" has a nearly 50 year history,dating to the publication in 1955 of Salpeter's seminal paper. In this review I discuss the many more recent results that have emerged on the initial mass function (IMF), as it is now called, from studies over the last decade of resolved populations in star forming regions and young open clusters.Comment: 9 pages, 1 figure; to appear in "The Dense Instellar Medium in Galaxies -- 4'th Cologne-Bonn-Zermatt-Symposium" editted by S. Pfalzner, C. Kramer, C. Straubmeier and A. Heithausen, Springer-Verlag (2004

    Circular Stochastic Fluctuations in SIS Epidemics with Heterogeneous Contacts Among Sub-populations

    Full text link
    The conceptual difference between equilibrium and non-equilibrium steady state (NESS) is well established in physics and chemistry. This distinction, however, is not widely appreciated in dynamical descriptions of biological populations in terms of differential equations in which fixed point, steady state, and equilibrium are all synonymous. We study NESS in a stochastic SIS (susceptible-infectious-susceptible) system with heterogeneous individuals in their contact behavior represented in terms of subgroups. In the infinite population limit, the stochastic dynamics yields a system of deterministic evolution equations for population densities; and for very large but finite system a diffusion process is obtained. We report the emergence of a circular dynamics in the diffusion process, with an intrinsic frequency, near the endemic steady state. The endemic steady state is represented by a stable node in the deterministic dynamics; As a NESS phenomenon, the circular motion is caused by the intrinsic heterogeneity within the subgroups, leading to a broken symmetry and time irreversibility.Comment: 29 pages, 5 figure

    Orchiectomy as a result of ischemic orchitis after laparoscopic inguinal hernia repair: case report of a rare complication

    Get PDF
    which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background: Ischemic orchitis is an established complication after open inguinal hernia repair, but ischemic orchitis resulting in orchiectomy after the laparoscopic approach has not been reported. Case presentation: The patient was a thirty-three year-old man who presented with bilateral direct inguinal hernias, right larger than left. He was a thin, muscular male with a narrow pelvis who underwent bilateral extraperitoneal mesh laparoscopic inguinal hernia repair. The case was complicated by pneumoperitoneum which limited the visibility of the pelvic anatomy; however, the mesh was successfully deployed bilaterally. Cautery was used to resect the direct sac on the right. The patient was discharged the same day and doing well with minimal pain and swelling until the fourth day after surgery. That night he presented with sudden-onset pain and swelling of his right testicle and denied both trauma to the area and any sexual activity. Ultrasound of the testicle revealed no blood flow to the testicle which required exploration and subsequent orchiectomy. Conclusion: Ischemic orchitis typically presents 2–3 days after inguinal hernia surgery and can progress to infarction. This ischemic injury is likely due to thrombosis of the venous plexus, rathe

    Isospin-Violating Meson-Nucleon Vertices as an Alternate Mechanism of Charge-Symmetry Breaking

    Get PDF
    We compute isospin-violating meson-nucleon coupling constants and their consequent charge-symmetry-breaking nucleon-nucleon potentials. The couplings result from evaluating matrix elements of quark currents between nucleon states in a nonrelativistic constituent quark model; the isospin violations arise from the difference in the up and down constituent quark masses. We find, in particular, that isospin violation in the omega-meson--nucleon vertex dominates the class IV CSB potential obtained from these considerations. We evaluate the resulting spin-singlet--triplet mixing angles, the quantities germane to the difference of neutron and proton analyzing powers measured in elastic np\vec{n}-\vec{p} scattering, and find them commensurate to those computed originally using the on-shell value of the ρ\rho-ω\omega mixing amplitude. The use of the on-shell ρ\rho-ω\omega mixing amplitude at q2=0q^2=0 has been called into question; rather, the amplitude is zero in a wide class of models. Our model possesses no contribution from ρ\rho-ω\omega mixing at q2=0q^2=0, and we find that omega-meson exchange suffices to explain the measured npn-p analyzing power difference~at~183 MeV.Comment: 20 pages, revtex, 3 uuencoded PostScript figure

    A magnetically collimated jet from an evolved star

    Full text link
    Planetary nebulae often have asymmetric shapes, which could arise due to collimated jets from evolved stars before evolution to the planetary nebula phase. The source of jet collimation in these stars is unknown. Magnetic fields are thought to collimate outflows that are observed in many other astrophysical sources, such as active galactic nuclei and proto-stars, although hitherto there are no direct observations of both the magnetic field direction and strength in any collimated jet. Theoretical models have shown that magnetic fields could also be the dominant source of collimation of jet in evolved stars. Here we report measurements of the polarization of water vapour masers that trace the precessing jet emanating from the asymptotic giant branch star W43A at 2.6 kpc from the Sun, which is undergoing rapid evolution into a planetary nebula. The masers occur in two clusters at opposing tips of the jets, ~1,000 AU from the star. We find direct evidence that the magnetic field is collimating the jet.Comment: Published in Nature 440 (March 2nd 2006). High-res figures can be found at http://www.jb.man.ac.uk/~wouter/papers/w43a/w43a.htm

    Exploiting temporal information for DCNN-based fine-grained object classification

    Get PDF
    Fine-grained classification is a relatively new field that has concentrated on using information from a single image, while ignoring the enormous potential of using video data to improve classification. In this work we present the novel task of video-based fine-grained object classification, propose a corresponding new video dataset, and perform a systematic study of several recent deep convolutional neural network (DCNN) based approaches, which we specifically adapt to the task. We evaluate three-dimensional DCNNs, two-stream DCNNs, and bilinear DCNNs. Two forms of the two-stream approach are used, where spatial and temporal data from two independent DCNNs are fused either via early fusion (combination of the fully-connected layers) and late fusion (concatenation of the softmax outputs of the DCNNs). For bilinear DCNNs, information from the convolutional layers of the spatial and temporal DCNNs is combined via local co-occurrences. We then fuse the bilinear DCNN and early fusion of the two-stream approach to combine the spatial and temporal information at the local and global level (Spatio-Temporal Co-occurrence). Using the new and challenging video dataset of birds, classification performance is improved from 23.1% (using single images) to 41.1% when using the Spatio-Temporal Co-occurrence system. Incorporating automatically detected bounding box location further improves the classification accuracy to 53.6%

    The Competition of Charge Remote and Charge Directed Fragmentation Mechanisms in Quaternary Ammonium Salt Derivatized Peptides—An Isotopic Exchange Study

    Get PDF
    Derivatization of peptides as quaternary ammonium salts (QAS) is a promising method for sensitive detection by electrospray ionization tandem mass spectrometry (Cydzik et al. J. Pept. Sci.2011, 17, 445–453). The peptides derivatized by QAS at their N-termini undergo fragmentation according to the two competing mechanisms – charge remote (ChR) and charge directed (ChD). The absence of mobile proton in the quaternary salt ion results in ChR dissociation of a peptide bond. However, Hofmann elimination of quaternary salt creates an ion with one mobile proton leading to the ChD fragmentation. The experiments on the quaternary ammonium salts with deuterated N-alkyl groups or amide NH bonds revealed that QAS derivatized peptides dissociate according to the mixed ChR-ChD mechanism. The isotopic labeling allows differentiation of fragments formed according to ChR and ChD mechanisms

    Reconstructing the three-dimensional GABAergic microcircuit of the striatum

    Get PDF
    A system's wiring constrains its dynamics, yet modelling of neural structures often overlooks the specific networks formed by their neurons. We developed an approach for constructing anatomically realistic networks and reconstructed the GABAergic microcircuit formed by the medium spiny neurons (MSNs) and fast-spiking interneurons (FSIs) of the adult rat striatum. We grew dendrite and axon models for these neurons and extracted probabilities for the presence of these neurites as a function of distance from the soma. From these, we found the probabilities of intersection between the neurites of two neurons given their inter-somatic distance, and used these to construct three-dimensional striatal networks. The MSN dendrite models predicted that half of all dendritic spines are within 100 mu m of the soma. The constructed networks predict distributions of gap junctions between FSI dendrites, synaptic contacts between MSNs, and synaptic inputs from FSIs to MSNs that are consistent with current estimates. The models predict that to achieve this, FSIs should be at most 1% of the striatal population. They also show that the striatum is sparsely connected: FSI-MSN and MSN-MSN contacts respectively form 7% and 1.7% of all possible connections. The models predict two striking network properties: the dominant GABAergic input to a MSN arises from neurons with somas at the edge of its dendritic field; and FSIs are interconnected on two different spatial scales: locally by gap junctions and distally by synapses. We show that both properties influence striatal dynamics: the most potent inhibition of a MSN arises from a region of striatum at the edge of its dendritic field; and the combination of local gap junction and distal synaptic networks between FSIs sets a robust input-output regime for the MSN population. Our models thus intimately link striatal micro-anatomy to its dynamics, providing a biologically grounded platform for further study
    corecore