Hybrid spread spectrum radio system

DOEpatents

Smith, Stephen F [London, TN; Dress, William B [Camas, WA

2010-02-09

Systems and methods are described for hybrid spread spectrum radio systems. A method, includes receiving a hybrid spread spectrum signal including: fast frequency hopping demodulating and direct sequence demodulating a direct sequence spread spectrum signal, wherein multiple frequency hops occur within a single data-bit time and each bit is represented by chip transmissions at multiple frequencies.

Interacting epidemics on overlay networks

NASA Astrophysics Data System (ADS)

Funk, Sebastian; Jansen, Vincent A. A.

2010-03-01

The interaction between multiple pathogens spreading on networks connecting a given set of nodes presents an ongoing theoretical challenge. Here, we aim to understand such interactions by studying bond percolation of two different processes on overlay networks of arbitrary joint degree distribution. We find that an outbreak of a first pathogen providing immunity to another one spreading subsequently on a second network connecting the same set of nodes does so most effectively if the degrees on the two networks are positively correlated. In that case, the protection is stronger the more heterogeneous the degree distributions of the two networks are. If, on the other hand, the degrees are uncorrelated or negatively correlated, increasing heterogeneity reduces the potential of the first process to prevent the second one from reaching epidemic proportions. We generalize these results to cases where the edges of the two networks overlap to arbitrary amount, or where the immunity granted is only partial. If both processes grant immunity to each other, we find a wide range of possible situations of coexistence or mutual exclusion, depending on the joint degree distribution of the underlying networks and the amount of immunity granted mutually. These results generalize the concept of a coexistence threshold and illustrate the impact of large-scale network structure on the interaction between multiple spreading agents.

Asynchronous, Decentralized DS-CDMA Using Feedback-Controlled Spreading Sequences for Time-Dispersive Channels

NASA Astrophysics Data System (ADS)

Miyatake, Teruhiko; Chiba, Kazuki; Hamamura, Masanori; Tachikawa, Shin'ichi

We propose a novel asynchronous direct-sequence codedivision multiple access (DS-CDMA) using feedback-controlled spreading sequences (FCSSs) (FCSS/DS-CDMA). At the receiver of FCSS/DS-CDMA, the code-orthogonalizing filter (COF) produces a spreading sequence, and the receiver returns the spreading sequence to the transmitter. Then the transmitter uses the spreading sequence as its updated version. The performance of FCSS/DS-CDMA is evaluated over time-dispersive channels. The results indicate that FCSS/DS-CDMA greatly suppresses both the intersymbol interference (ISI) and multiple access interference (MAI) over time-invariant channels. FCSS/DS-CDMA is applicable to the decentralized multiple access.

FIR Filter of DS-CDMA UWB Modem Transmitter

NASA Astrophysics Data System (ADS)

Kang, Kyu-Min; Cho, Sang-In; Won, Hui-Chul; Choi, Sang-Sung

This letter presents low-complexity digital pulse shaping filter structures of a direct sequence code division multiple access (DS-CDMA) ultra wide-band (UWB) modem transmitter with a ternary spreading code. The proposed finite impulse response (FIR) filter structures using a look-up table (LUT) have the effect of saving the amount of memory by about 50% to 80% in comparison to the conventional FIR filter structures, and consequently are suitable for a high-speed parallel data process.

Analysis of the Yule-Nielsen effect with the multiple-path point spread function in a frequency-modulated halftone.

PubMed

Rogers, Geoffrey

2018-06-01

The Yule-Nielsen effect is an influence on halftone color caused by the diffusion of light within the paper upon which the halftone ink is printed. The diffusion can be characterized by a point spread function. In this paper, a point spread function for paper is derived using the multiple-path model of reflection. This model treats the interaction of light with turbid media as a random walk. Using the multiple-path point spread function, a general expression is derived for the average reflectance of light from a frequency-modulated halftone, in which dot size is constant and the number of dots is varied, with the arrangement of dots random. It is also shown that the line spread function derived from the multiple-path model has the form of a Lorentzian function.

Study of spread spectrum multiple access systems for satellite communications with overlay on current services

NASA Technical Reports Server (NTRS)

Ha, Tri T.; Pratt, Timothy

1989-01-01

The feasibility of using spread spectrum techniques to provide a low-cost multiple access system for a very large number of low data terminals was investigated. Two applications of spread spectrum technology to very small aperture terminal (VSAT) satellite communication networks are presented. Two spread spectrum multiple access systems which use a form of noncoherent M-ary FSK (MFSK) as the primary modulation are described and the throughput analyzed. The analysis considers such factors as satellite power constraints and adjacent satellite interference. Also considered is the effect of on-board processing on the multiple access efficiency and the feasibility of overlaying low data rate spread spectrum signals on existing satellite traffic as a form of frequency reuse is investigated. The use of chirp is examined for spread spectrum communications. In a chirp communication system, each data bit is converted into one or more up or down sweeps of frequency, which spread the RF energy across a broad range of frequencies. Several different forms of chirp communication systems are considered, and a multiple-chirp coded system is proposed for overlay service. The mutual interference problem is examined in detail and a performance analysis undertaken for the case of a chirp data channel overlaid on a video channel.

Rapid localized spread and immunologic containment define Herpes simplex virus-2 reactivation in the human genital tract.

PubMed

Schiffer, Joshua T; Swan, David; Al Sallaq, Ramzi; Magaret, Amalia; Johnston, Christine; Mark, Karen E; Selke, Stacy; Ocbamichael, Negusse; Kuntz, Steve; Zhu, Jia; Robinson, Barry; Huang, Meei-Li; Jerome, Keith R; Wald, Anna; Corey, Lawrence

2013-04-16

Herpes simplex virus-2 (HSV-2) is shed episodically, leading to occasional genital ulcers and efficient transmission. The biology explaining highly variable shedding patterns, in an infected person over time, is poorly understood. We sampled the genital tract for HSV DNA at several time intervals and concurrently at multiple sites, and derived a spatial mathematical model to characterize dynamics of HSV-2 reactivation. The model reproduced heterogeneity in shedding episode duration and viral production, and predicted rapid early viral expansion, rapid late decay, and wide spatial dispersion of HSV replication during episodes. In simulations, HSV-2 spread locally within single ulcers to thousands of epithelial cells in <12 hr, but host immune responses eliminated infected cells in <24 hr; secondary ulcers formed following spatial propagation of cell-free HSV-2, allowing for episode prolongation. We conclude that HSV-2 infection is characterized by extremely rapid virological growth and containment at multiple contemporaneous sites within genital epithelium. DOI:http://dx.doi.org/10.7554/eLife.00288.001.

Rapid localized spread and immunologic containment define Herpes simplex virus-2 reactivation in the human genital tract

PubMed Central

Schiffer, Joshua T; Swan, David; Al Sallaq, Ramzi; Magaret, Amalia; Johnston, Christine; Mark, Karen E; Selke, Stacy; Ocbamichael, Negusse; Kuntz, Steve; Zhu, Jia; Robinson, Barry; Huang, Meei-Li; Jerome, Keith R; Wald, Anna; Corey, Lawrence

2013-01-01

Herpes simplex virus-2 (HSV-2) is shed episodically, leading to occasional genital ulcers and efficient transmission. The biology explaining highly variable shedding patterns, in an infected person over time, is poorly understood. We sampled the genital tract for HSV DNA at several time intervals and concurrently at multiple sites, and derived a spatial mathematical model to characterize dynamics of HSV-2 reactivation. The model reproduced heterogeneity in shedding episode duration and viral production, and predicted rapid early viral expansion, rapid late decay, and wide spatial dispersion of HSV replication during episodes. In simulations, HSV-2 spread locally within single ulcers to thousands of epithelial cells in <12 hr, but host immune responses eliminated infected cells in <24 hr; secondary ulcers formed following spatial propagation of cell-free HSV-2, allowing for episode prolongation. We conclude that HSV-2 infection is characterized by extremely rapid virological growth and containment at multiple contemporaneous sites within genital epithelium. DOI: http://dx.doi.org/10.7554/eLife.00288.001 PMID:23606943

Microwave Comb Generator

NASA Technical Reports Server (NTRS)

Sigman, E. H.

1989-01-01

Stable reference tones aid testing and calibration of microwave receivers. Signal generator puts out stable tones in frequency range of 2 to 10 GHz at all multiples of reference input frequency, at any frequency up to 1 MHz. Called "comb generator" because spectral plot resembles comb. DC reverse-bias current switched on and off at 1 MHz to generate sharp pulses in step-recovery diode. Microwave components mounted on back of special connector containing built-in attenuator. Used in testing microwave and spread-spectrum wide-band receivers.

Jungle Computing: Distributed Supercomputing Beyond Clusters, Grids, and Clouds

NASA Astrophysics Data System (ADS)

Seinstra, Frank J.; Maassen, Jason; van Nieuwpoort, Rob V.; Drost, Niels; van Kessel, Timo; van Werkhoven, Ben; Urbani, Jacopo; Jacobs, Ceriel; Kielmann, Thilo; Bal, Henri E.

In recent years, the application of high-performance and distributed computing in scientific practice has become increasingly wide spread. Among the most widely available platforms to scientists are clusters, grids, and cloud systems. Such infrastructures currently are undergoing revolutionary change due to the integration of many-core technologies, providing orders-of-magnitude speed improvements for selected compute kernels. With high-performance and distributed computing systems thus becoming more heterogeneous and hierarchical, programming complexity is vastly increased. Further complexities arise because urgent desire for scalability and issues including data distribution, software heterogeneity, and ad hoc hardware availability commonly force scientists into simultaneous use of multiple platforms (e.g., clusters, grids, and clouds used concurrently). A true computing jungle.

Evaluation of High Dynamic Range Photography as a Luminance Mapping Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inanici, Mehlika; Galvin, Jim

2004-12-30

The potential, limitations, and applicability of the High Dynamic Range (HDR) photography technique is evaluated as a luminance mapping tool. Multiple exposure photographs of static scenes are taken with a Nikon 5400 digital camera to capture the wide luminance variation within the scenes. The camera response function is computationally derived using the Photosphere software, and is used to fuse the multiple photographs into HDR images. The vignetting effect and point spread function of the camera and lens system is determined. Laboratory and field studies have shown that the pixel values in the HDR photographs can correspond to the physical quantitymore » of luminance with reasonable precision and repeatability.« less

Identifying multiple influential spreaders based on generalized closeness centrality

NASA Astrophysics Data System (ADS)

Liu, Huan-Li; Ma, Chuang; Xiang, Bing-Bing; Tang, Ming; Zhang, Hai-Feng

2018-02-01

To maximize the spreading influence of multiple spreaders in complex networks, one important fact cannot be ignored: the multiple spreaders should be dispersively distributed in networks, which can effectively reduce the redundance of information spreading. For this purpose, we define a generalized closeness centrality (GCC) index by generalizing the closeness centrality index to a set of nodes. The problem converts to how to identify multiple spreaders such that an objective function has the minimal value. By comparing with the K-means clustering algorithm, we find that the optimization problem is very similar to the problem of minimizing the objective function in the K-means method. Therefore, how to find multiple nodes with the highest GCC value can be approximately solved by the K-means method. Two typical transmission dynamics-epidemic spreading process and rumor spreading process are implemented in real networks to verify the good performance of our proposed method.

Effects of the distance among multiple spreaders on the spreading

NASA Astrophysics Data System (ADS)

Hu, Z.-L.; Liu, J.-G.; Yang, G.-Y.; Ren, Z.-M.

2014-04-01

It is very important to investigate the multiple spreaders' effects since the spreading phenomenon is ubiquitous in many complex systems. In this letter, we investigate the effects of the distance among the initial multiple spreaders for regular networks and WS (Watts-Strogatz) small-world networks based on the SIR (Susceptible-Infected-Recovered) model. Assuming the epidemics can spread over the network, the theoretical and experimental results show that for regular networks the larger the distance between spreaders is, the more effective the spreading is. For WS networks, the spreading efficiency will decrease when the distance exceeds a certain value, and a larger connection probability and average degree will result in a smaller distance of the most effective spreading. A better spreading strategy using n spreaders is to choose either the highest k or ks nodes with the condition that there are not any pairs of the n spreaders linked directly (Kitsak M. et al., Nat. Phys., 6 (2010) 888). However, we find that the spreading will be more effective when the distances among the largest-degree spreaders increase. All these results are independent of the network size for the two initial spreaders case. This work may give new insights to explore more effective methods to inhibit the epidemic spreading or increase the information diffusion.

Is Vector Control Sufficient to Limit Pathogen Spread in Vineyards?

PubMed

Daugherty, M P; O'Neill, S; Byrne, F; Zeilinger, A

2015-06-01

Vector control is widely viewed as an integral part of disease management. Yet epidemiological theory suggests that the effectiveness of control programs at limiting pathogen spread depends on a variety of intrinsic and extrinsic aspects of a pathosystem. Moreover, control programs rarely evaluate whether reductions in vector density or activity translate into reduced disease prevalence. In areas of California invaded by the glassy-winged sharpshooter (Homalodisca vitripennis Germar), Pierce's disease management relies heavily on chemical control of this vector, primarily via systemic conventional insecticides (i.e., imidacloprid). But, data are lacking that attribute reduced vector pressure and pathogen spread to sharpshooter control. We surveyed 34 vineyards over successive years to assess the epidemiological value of within-vineyard chemical control. The results showed that imidacloprid reduced vector pressure without clear nontarget effects or secondary pest outbreaks. Effects on disease prevalence were more nuanced. Treatment history over the preceding 5 yr affected disease prevalence, with significantly more diseased vines in untreated compared with regularly or intermittently treated vineyards. Yet, the change in disease prevalence between years was low, with no significant effects of insecticide treatment or vector abundance. Collectively, the results suggest that within-vineyard applications of imidacloprid can reduce pathogen spread, but with benefits that may take multiple seasons to become apparent. The relatively modest effect of vector control on disease prevalence in this system may be attributable in part to the currently low regional sharpshooter population densities stemming from area-wide control, without which the need for within-vineyard vector control would be more pronounced. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Impact of treatment heterogeneity on drug resistance and supply chain costs☆

PubMed Central

Spiliotopoulou, Eirini; Boni, Maciej F.; Yadav, Prashant

2013-01-01

The efficacy of scarce drugs for many infectious diseases is threatened by the emergence and spread of resistance. Multiple studies show that available drugs should be used in a socially optimal way to contain drug resistance. This paper studies the tradeoff between risk of drug resistance and operational costs when using multiple drugs for a specific disease. Using a model for disease transmission and resistance spread, we show that treatment with multiple drugs, on a population level, results in better resistance-related health outcomes, but more interestingly, the marginal benefit decreases as the number of drugs used increases. We compare this benefit with the corresponding change in procurement and safety stock holding costs that result from higher drug variety in the supply chain. Using a large-scale simulation based on malaria transmission dynamics, we show that disease prevalence seems to be a less important factor when deciding the optimal width of drug assortment, compared to the duration of one episode of the disease and the price of the drug(s) used. Our analysis shows that under a wide variety of scenarios for disease prevalence and drug cost, it is optimal to simultaneously deploy multiple drugs in the population. If the drug price is high, large volume purchasing discounts are available, and disease prevalence is high, it may be optimal to use only one drug. Our model lends insights to policy makers into the socially optimal size of drug assortment for a given context. PMID:25843982

Impact of treatment heterogeneity on drug resistance and supply chain costs.

PubMed

Spiliotopoulou, Eirini; Boni, Maciej F; Yadav, Prashant

2013-09-01

The efficacy of scarce drugs for many infectious diseases is threatened by the emergence and spread of resistance. Multiple studies show that available drugs should be used in a socially optimal way to contain drug resistance. This paper studies the tradeoff between risk of drug resistance and operational costs when using multiple drugs for a specific disease. Using a model for disease transmission and resistance spread, we show that treatment with multiple drugs, on a population level, results in better resistance-related health outcomes, but more interestingly, the marginal benefit decreases as the number of drugs used increases. We compare this benefit with the corresponding change in procurement and safety stock holding costs that result from higher drug variety in the supply chain. Using a large-scale simulation based on malaria transmission dynamics, we show that disease prevalence seems to be a less important factor when deciding the optimal width of drug assortment, compared to the duration of one episode of the disease and the price of the drug(s) used. Our analysis shows that under a wide variety of scenarios for disease prevalence and drug cost, it is optimal to simultaneously deploy multiple drugs in the population. If the drug price is high, large volume purchasing discounts are available, and disease prevalence is high, it may be optimal to use only one drug. Our model lends insights to policy makers into the socially optimal size of drug assortment for a given context.

Statistical survey of widely spread out solar electron events observed with STEREO and ACE with special attention to anisotropies

NASA Astrophysics Data System (ADS)

Dresing, N.; Gómez-Herrero, R.; Heber, B.; Klassen, A.; Malandraki, O.; Dröge, W.; Kartavykh, Y.

2014-07-01

Context. In February 2011, the two STEREO spacecrafts reached a separation of 180 degrees in longitude, offering a complete view of the Sun for the first time ever. When the full Sun surface is visible, source active regions of solar energetic particle (SEP) events can be identified unambiguously. STEREO, in combination with near-Earth observatories such as ACE or SOHO, provides three well separated viewpoints, which build an unprecedented platform from which to investigate the longitudinal variations of SEP events. Aims: We show an ensemble of SEP events that were observed between 2009 and mid-2013 by at least two spacecrafts and show a remarkably wide particle spread in longitude (wide-spread events). The main selection criterion for these events was a longitudinal separation of at least 80 degrees between active region and spacecraft magnetic footpoint for the widest separated spacecraft. We investigate the events statistically in terms of peak intensities, onset delays, and rise times, and determine the spread of the longitudinal events, which is the range filled by SEPs during the events. Energetic electron anisotropies are investigated to distinguish the source and transport mechanisms that lead to the observed wide particle spreads. Methods: According to the anisotropy distributions, we divided the events into three classes depending on different source and transport scenarios. One potential mechanism for wide-spread events is efficient perpendicular transport in the interplanetary medium that competes with another scenario, which is a wide particle spread that occurs close to the Sun. In the latter case, the observations at 1 AU during the early phase of the events are expected to show significant anisotropies because of the wide injection range at the Sun and particle-focusing during the outward propagation, while in the first case only low anisotropies are anticipated. Results: We find events for both of these scenarios in our sample that match the expected observations and even different events that do not agree with the scenarios. We conclude that probably both an extended source region at the Sun and perpendicular transport in the interplanetary medium are involved for most of these wide-spread events. Appendix A is available in electronic form at http://www.aanda.org

Multiple dispersal vectors drive range expansion in an invasive marine species.

PubMed

Richardson, Mark F; Sherman, Craig D H; Lee, Randall S; Bott, Nathan J; Hirst, Alastair J

2016-10-01

The establishment and subsequent spread of invasive species is widely recognized as one of the most threatening processes contributing to global biodiversity loss. This is especially true for marine and estuarine ecosystems, which have experienced significant increases in the number of invasive species with the increase in global maritime trade. Understanding the rate and mechanisms of range expansion is therefore of significant interest to ecologists and conservation managers alike. Using a combination of population genetic surveys, environmental DNA (eDNA) plankton sampling and hydrodynamic modelling, we examined the patterns of introduction of the predatory Northern Pacific seastar (Asterias amurensis) and pathways of secondary spread within southeast Australia. Genetic surveys across the invasive range reveal some genetic divergence between the two main invasive regions and no evidence of ongoing gene flow, a pattern that is consistent with the establishment of the second invasive region via a human-mediated translocation event. In contrast, hydrodynamic modelling combined with eDNA plankton sampling demonstrated that the establishment of range expansion populations within a region is consistent with natural larval dispersal and recruitment. Our results suggest that both anthropogenic and natural dispersal vectors have played an important role in the range expansion of this species in Australia. The multiple modes of spread combined with high levels of fecundity and a long larval duration in A. amurensis suggests it is likely to continue its range expansion and significantly impact Australian marine ecosystems. © 2016 John Wiley & Sons Ltd.

Avian Paramyxovirus Serotype-1: A Review of Disease Distribution, Clinical Symptoms, and Laboratory Diagnostics

PubMed Central

Hines, Nichole L.; Miller, Cathy L.

2012-01-01

Avian paramyxovirus serotype-1 (APMV-1) is capable of infecting a wide range of avian species leading to a broad range of clinical symptoms. Ease of transmission has allowed the virus to spread worldwide with varying degrees of virulence depending on the virus strain and host species. Classification systems have been designed to group isolates based on their genetic composition. The genetic composition of the fusion gene cleavage site plays an important role in virulence. Presence of multiple basic amino acids at the cleavage site allows enzymatic cleavage of the fusion protein enabling virulent viruses to spread systemically. Diagnostic tests, including virus isolation, real-time reverse-transcription PCR, and sequencing, are used to characterize the virus and identify virulent strains. Genetic diversity within APMV-1 demonstrates the need for continual monitoring for changes that may arise requiring modifications to the molecular assays to maintain their usefulness for diagnostic testing. PMID:22577610

Spread-spectrum multiple access using wideband noncoherent MFSK

NASA Technical Reports Server (NTRS)

Ha, Tri T.; Pratt, Timothy; Maggenti, Mark A.

1987-01-01

Two spread-spectrum multiple access systems which use wideband M-ary frequency shift keying (FSK) (MFSK) as the primary modulation are presented. A bit error rate performance analysis is presented and system throughput is calculated for sample C band and Ku band satellite systems. Sample link analyses are included to illustrate power and adjacent satellite interference considerations in practical multiple access systems.

Atmospheric Spread of Foot-and-mouth Disease During The Early Phase of The Uk Epidemic 2001

NASA Astrophysics Data System (ADS)

Sørensen, J. H.; Mikkelsen, T.; Astrup, P.; Alexandersen, S.; Donaldson, A. I.

Foot-and-mouth disease (FMD) is a highly contagious viral disease in cloven-hoofed domesticated and wild animals. The highly contagious nature of FMD is a reflection of the wide range of species which are susceptible, the enormous quantities of virus liberated by infected animals, the range of excretions and secretions which can be infectious, the stability of the virus in the environment, the multiplicity of routes of infection and the very small doses of virus that can initiate infection in susceptible hosts. One of the routes for the spread of the disease is the atmospheric dispersion of virus exhaled by infected animals. Such spread can be rapid and extensive, and it is known in certain circumstances to have occurred over a distance of several hundred kilometres. For the FMD epidemic in UK in 2001, atmospheric dispersion models were applied in real time in order to describe the atmospheric dispersion of virus for the larger outbreaks of the disease. The operational value of such modelling is first of all to identify risk zones, which is helpful to the emergency management. The paper addresses the modelling techniques and presents results related with the epidemic in UK in 2001.

Adaptive Digital Signature Design and Short-Data-Record Adaptive Filtering

DTIC Science & Technology

2008-04-01

rate BPSK binary phase shift keying CA − CFAR cell averaging− constant false alarm rate CDMA code − division multiple − access CFAR constant false...Cotae, “Spreading sequence design for multiple cell synchronous DS-CDMA systems under total weighted squared correlation criterion,” EURASIP Journal...415-428, Mar. 2002. [6] P. Cotae, “Spreading sequence design for multiple cell synchronous DS-CDMA systems under total weighted squared correlation

Relentless spread and adaptation of non-typeable vanA vancomycin-resistant Enterococcus faecium: a genome-wide investigation.

PubMed

van Hal, Sebastiaan J; Beukers, Alicia G; Timms, Verlaine J; Ellem, Justin A; Taylor, Peter; Maley, Michael W; Newton, Peter J; Ferguson, John K; Lee, Andie; Chen, Sharon C-A; Sintchenko, Vitali

2018-03-16

VRE are prevalent among patients in ICUs. Non-typeable vanA VRE, due to loss of one of the genes used for MLST (pstS), have increased in Australia, suggestive of a new, hospital-acquired lineage. To understand the significance of this lineage and its transmission using WGS of strains isolated from patients in ICUs across New South Wales, Australia. A total of 240 Enterococcus faecium isolates collected between February and May 2016, and identified by conventional PCR as vanA positive, were sequenced. Isolates originated from 12 ICUs in New South Wales, grouped according to six local health districts, and represented both rectal screening swab (n = 229) and clinical (n = 11) isolates. ST analysis revealed the absence of the pstS gene in 84.2% (202 of 240) of vanA isolates. Two different non-typeable STs were present based on different allelic backbone patterns. Loss of the pstS gene appeared to be the result of multiple recombination events across this region. Evidence for pstS-negative lineage spread across all six local health districts was observed suggestive of inter-hospital transmission. In addition, multiple outbreaks were detected, some of which were protracted and lasted for the duration of the study. These findings confirmed the evolution, emergence and dissemination of non-typeable vanA E. faecium. This study has highlighted the utility of WGS when attempting to describe accurately the hospital-based pathogen epidemiology, which in turn will continue to inform optimal infection control measures necessary to halt the spread of this important nosocomial organism.

A novel information cascade model in online social networks

NASA Astrophysics Data System (ADS)

Tong, Chao; He, Wenbo; Niu, Jianwei; Xie, Zhongyu

2016-02-01

The spread and diffusion of information has become one of the hot issues in today's social network analysis. To analyze the spread of online social network information and the attribute of cascade, in this paper, we discuss the spread of two kinds of users' decisions for city-wide activities, namely the "want to take part in the activity" and "be interested in the activity", based on the users' attention in "DouBan" and the data of the city-wide activities. We analyze the characteristics of the activity-decision's spread in these aspects: the scale and scope of the cascade subgraph, the structure characteristic of the cascade subgraph, the topological attribute of spread tree, and the occurrence frequency of cascade subgraph. On this basis, we propose a new information spread model. Based on the classical independent diffusion model, we introduce three mechanisms, equal probability, similarity of nodes, and popularity of nodes, which can generate and affect the spread of information. Besides, by conducting the experiments in six different kinds of network data set, we compare the effects of three mechanisms above mentioned, totally six specific factors, on the spread of information, and put forward that the node's popularity plays an important role in the information spread.

Measuring landscape-scale spread and persistence of an invaded submerged plant community from airborne remote sensing.

PubMed

Santos, Maria J; Khanna, Shruti; Hestir, Erin L; Greenberg, Jonathan A; Ustin, Susan L

2016-09-01

Processes of spread and patterns of persistence of invasive species affect species and communities in the new environment. Predicting future rates of spread is of great interest for timely management decisions, but this depends on models that rely on understanding the processes of invasion and historic observations of spread and persistence. Unfortunately, the rates of spread and patterns of persistence are difficult to model or directly observe, especially when multiple rates of spread and diverse persistence patterns may be co-occurring over the geographic distribution of the invaded ecosystem. Remote sensing systematically acquires data over large areas at fine spatial and spectral resolutions over multiple time periods that can be used to quantify spread processes and persistence patterns. We used airborne imaging spectroscopy data acquired once a year for 5 years from 2004 to 2008 to map an invaded submerged aquatic vegetation (SAV) community across 2220 km 2 of waterways in the Sacramento-San Joaquin River Delta, California, USA, and measured its spread rate and its persistence. Submerged aquatic vegetation covered 13-23 km 2 of the waterways (6-11%) every year. Yearly new growth accounted for 40-60% of the SAV area, ~50% of which survived to following year. Spread rates were overall negative and persistence decreased with time. From this dataset, we were able to identify both radial and saltatorial spread of the invaded SAV in the entire extent of the Delta over time. With both decreasing spread rate and persistence, it is possible that over time the invasion of this SAV community could decrease its ecological impact. A landscape-scale approach allows measurements of all invasion fronts and the spatial anisotropies associated with spread processes and persistence patterns, without spatial interpolation, at locations both proximate and distant to the focus of invasion at multiple points in time. © 2016 by the Ecological Society of America.

Enrichment of short interspersed transposable elements to embryonic stem cell-specific hypomethylated gene regions.

PubMed

Muramoto, Hiroki; Yagi, Shintaro; Hirabayashi, Keiji; Sato, Shinya; Ohgane, Jun; Tanaka, Satoshi; Shiota, Kunio

2010-08-01

Embryonic stem cells (ESCs) have a distinctive epigenome, which includes their genome-wide DNA methylation modification status, as represented by the ESC-specific hypomethylation of tissue-dependent and differentially methylated regions (T-DMRs) of Pou5f1 and Nanog. Here, we conducted a genome-wide investigation of sequence characteristics associated with T-DMRs that were differentially methylated between ESCs and somatic cells, by focusing on transposable elements including short interspersed elements (SINEs), long interspersed elements (LINEs) and long terminal repeats (LTRs). We found that hypomethylated T-DMRs were predominantly present in SINE-rich/LINE-poor genomic loci. The enrichment for SINEs spread over 300 kb in cis and there existed SINE-rich genomic domains spreading continuously over 1 Mb, which contained multiple hypomethylated T-DMRs. The characterization of sequence information showed that the enriched SINEs were relatively CpG rich and belonged to specific subfamilies. A subset of the enriched SINEs were hypomethylated T-DMRs in ESCs at Dppa3 gene locus, although SINEs are overall methylated in both ESCs and the liver. In conclusion, we propose that SINE enrichment is the genomic property of regions harboring hypomethylated T-DMRs in ESCs, which is a novel aspect of the ESC-specific epigenomic information.

Focus expansion and stability of the spread parameter estimate of the power law model for dispersal gradients

PubMed Central

Gent, David H.; Mehra, Lucky K.; Christie, David; Magarey, Roger

2017-01-01

Empirical and mechanistic modeling indicate that pathogens transmitted via aerially dispersed inoculum follow a power law, resulting in dispersive epidemic waves. The spread parameter (b) of the power law model, which is an indicator of the distance of the epidemic wave front from an initial focus per unit time, has been found to be approximately 2 for several animal and plant diseases over a wide range of spatial scales under conditions favorable for disease spread. Although disease spread and epidemic expansion can be influenced by several factors, the stability of the parameter b over multiple epidemic years has not been determined. Additionally, the size of the initial epidemic area is expected to be strongly related to the final epidemic extent for epidemics, but the stability of this relationship is also not well established. Here, empirical data of cucurbit downy mildew epidemics collected from 2008 to 2014 were analyzed using a spatio-temporal model of disease spread that incorporates logistic growth in time with a power law function for dispersal. Final epidemic extent ranged from 4.16 ×108 km2 in 2012 to 6.44 ×108 km2 in 2009. Current epidemic extent became significantly associated (P < 0.0332; 0.56 < R2 < 0.99) with final epidemic area beginning near the end of April, with the association increasing monotonically to 1.0 by the end of the epidemic season in July. The position of the epidemic wave-front became exponentially more distant with time, and epidemic velocity increased linearly with distance. Slopes from the temporal and spatial regression models varied with about a 2.5-fold range across epidemic years. Estimates of b varied substantially ranging from 1.51 to 4.16 across epidemic years. We observed a significant b ×time (or distance) interaction (P < 0.05) for epidemic years where data were well described by the power law model. These results suggest that the spread parameter b may not be stable over multiple epidemic years. However, b ≈ 2 may be considered the lower limit of the distance traveled by epidemic wave-fronts for aerially transmitted pathogens that follow a power law dispersal function. PMID:28649473

Use of bacterial co-cultures for the efficient production of chemicals.

PubMed

Jones, J Andrew; Wang, Xin

2017-12-02

The microbial production of chemicals has traditionally relied on a single engineered microbe to enable the complete bioconversion of substrate to final product. Recently, a growing fraction of research has transitioned towards employing a modular co-culture engineering strategy using multiple microbes growing together to facilitate a divide-and-conquer approach for chemical biosynthesis. Here, we review key success stories that leverage the unique advantages of co-culture engineering, while also addressing the critical concerns that will limit the wide-spread implementation of this technology. Future studies that address the need to monitor and control the population dynamics of each strain module, while maintaining robust flux routes towards a wide range of desired products will lead the efforts to realize the true potential of co-culture engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.

Abdominal girth, vertebral column length, and spread of spinal anesthesia in 30 minutes after plain bupivacaine 5 mg/mL.

PubMed

Zhou, Qing-he; Xiao, Wang-pin; Shen, Ying-yan

2014-07-01

The spread of spinal anesthesia is highly unpredictable. In patients with increased abdominal girth and short stature, a greater cephalad spread after a fixed amount of subarachnoidally administered plain bupivacaine is often observed. We hypothesized that there is a strong correlation between abdominal girth/vertebral column length and cephalad spread. Age, weight, height, body mass index, abdominal girth, and vertebral column length were recorded for 114 patients. The L3-L4 interspace was entered, and 3 mL of 0.5% plain bupivacaine was injected into the subarachnoid space. The cephalad spread (loss of temperature sensation and loss of pinprick discrimination) was assessed 30 minutes after intrathecal injection. Linear regression analysis was performed for age, weight, height, body mass index, abdominal girth, vertebral column length, and the spread of spinal anesthesia, and the combined linear contribution of age up to 55 years, weight, height, abdominal girth, and vertebral column length was tested by multiple regression analysis. Linear regression analysis showed that there was a significant univariate correlation among all 6 patient characteristics evaluated and the spread of spinal anesthesia (all P < 0.039) except for age and loss of temperature sensation (P > 0.068). Multiple regression analysis showed that abdominal girth and the vertebral column length were the key determinants for spinal anesthesia spread (both P < 0.0001), whereas age, weight, and height could be omitted without changing the results (all P > 0.059, all 95% confidence limits < 0.372). Multiple regression analysis revealed that the combination of a patient's 5 general characteristics, especially abdominal girth and vertebral column length, had a high predictive value for the spread of spinal anesthesia after a given dose of plain bupivacaine.

Widely distributed SEP events and pseudostreamers

NASA Astrophysics Data System (ADS)

Panasenco, O.; Panasenco, A.; Velli, M.

2017-12-01

Our analysis of the pseudostreamer magnetic topology reveals new interesting implications for understanding SEP acceleration in CMEs. The possible reasons for the wide distribution of some SEP events can be the presence of pseudostreamers in the vicinity of the SEP source region which creates conditions for the existence of strong longitudinal spread of energetic particles as well as an anomalous longitudinal solar wind magnetic field component. We reconstructed the 3D magnetic configurations of pseudostreamers with a potential field source surface (PFSS) model, which uses as a lower boundary condition the magnetic field derived from an evolving surface-flux transport model. In order to estimate the possible magnetic connections between the spacecraft and the SEP source region, we used the Parker spiral, ENLIL and PFSS models. We found that in cases of the wide SEP distributions a specific configuration of magnetic field appears to exist at low solar latitudes all the way around the sun, we named this phenomenon a pseudostreamers belt. It appears that the presence of the well developed pseudostreamer or, rather multiple pseudostreamers, organized into the pseudostreamer belt can be considered as a very favorable condition for wide SEP events.

Wetting-induced formation of controllable monodisperse multiple emulsions in microfluidics.

PubMed

Deng, Nan-Nan; Wang, Wei; Ju, Xiao-Jie; Xie, Rui; Weitz, David A; Chu, Liang-Yin

2013-10-21

Multiple emulsions, which are widely applied in a myriad of fields because of their unique ability to encapsulate and protect active ingredients, are typically produced by sequential drop-formations and drop-encapsulations using shear-induced emulsification. Here we report a qualitatively novel method of creating highly controlled multiple emulsions from lower-order emulsions. By carefully controlling the interfacial energies, we adjust the spreading coefficients between different phases to cause drops of one fluid to completely engulf other drops of immiscible fluids; as a result multiple emulsions are directly formed by simply putting preformed lower-order emulsion drops together. Our approach has highly controllable flexibility. We demonstrate this in preparation of both double and triple emulsions with a controlled number of inner drops and precisely adjusted shell thicknesses including ultra-thin shells. Moreover, this controllable drop-engulfing-drop approach has a high potential in further investigations and applications of microfluidics. Importantly, this innovative approach opens a window to exploit new phenomena occurring in fluids at the microscale level, which is of great significance for developing novel microfluidics.

Two Distinct Patterns of Clostridium Difficile Diversity Across Europe Indicates Contrasting Routes of Spread.

PubMed

Eyre, David W; Davies, Kerrie A; Davis, Georgina; Fawley, Warren N; Dingle, Kate E; De Maio, Nicola; Karas, Andreas; Crook, Derrick W; Peto, Tim E A; Walker, A Sarah; Wilcox, Mark H

2018-04-06

Rates of Clostridium difficile infection vary widely across Europe, as do prevalent ribotypes. The extent of Europe-wide diversity within each ribotype is however unknown. Inpatient diarrhoeal faecal samples submitted on one day in summer and winter (2012-2013) to laboratories in 482 European hospitals were cultured for C. difficile, and isolates ribotyped; those from the 10 most prevalent ribotypes were Illumina whole-genome sequenced. Pairwise single nucleotide differences (SNPs) were obtained from recombination-corrected maximum-likelihood phylogenies. Within each ribotype, country-based sequence clustering was assessed using the ratio of the median SNPs between isolates within versus across different countries using permutation tests. Time-scaled Bayesian phylogenies where used to reconstruct the historic location of each lineage. Sequenced isolates (n=624) were from 19 countries. Five ribotypes had within-country clustering: ribotype-356, only in Italy; ribotype-018, predominantly in Italy; ribotype-176, with distinct Czech and German clades; ribotype-001/072, including distinct German, Slovakian, and Spanish clades; and ribotype-027, with multiple predominantly country-specific clades including in Hungary, Italy, Germany, Romania and Poland. By contrast, we found no within-country clustering for ribotypes 078, 015, 002, 014, and 020, consistent with a Europe-wide distribution. Fluoroquinolone-resistance was significantly more common in within-country clustered ribotypes (p=0.009). Fluoroquinolone-resistant isolates were also more tightly geographically clustered, median (IQR) 43 (0-213) miles between each isolate and the most closely genetically-related isolate vs. 421 (204-680) in non-resistant pairs (p<0.001). Two distinct patterns of C. difficile ribotype spread were observed, consistent with either predominantly healthcare-associated acquisition or Europe-wide dissemination via other routes/sources, e.g. the food chain.

Ecological multiplex interactions determine the role of species for parasite spread amplification

PubMed Central

Stella, Massimo; Selakovic, Sanja; Antonioni, Alberto

2018-01-01

Despite their potential interplay, multiple routes of many disease transmissions are often investigated separately. As a unifying framework for understanding parasite spread through interdependent transmission paths, we present the ‘ecomultiplex’ model, where the multiple transmission paths among a diverse community of interacting hosts are represented as a spatially explicit multiplex network. We adopt this framework for designing and testing potential control strategies for Trypanosoma cruzi spread in two empirical host communities. We show that the ecomultiplex model is an efficient and low data-demanding method to identify which species enhances parasite spread and should thus be a target for control strategies. We also find that the interplay between predator-prey and host-parasite interactions leads to a phenomenon of parasite amplification, in which top predators facilitate T. cruzi spread, offering a mechanistic interpretation of previous empirical findings. Our approach can provide novel insights in understanding and controlling parasite spreading in real-world complex systems. PMID:29683427

Effects of green tea extract and α-tocopherol on the lipid oxidation rate of omega-3 oils, incorporated into table spreads, prepared using multiple emulsion technology.

PubMed

Dwyer, Sandra P O'; O'Beirne, David; Ní Eidhin, Deirdre; O'Kennedy, Brendan T

2012-12-01

This study examined the effectiveness of fat and water soluble antioxidants on the oxidative stability of omega (ω)-3 rich table spreads, produced using novel multiple emulsion technology. Table spreads were produced by dispersing an oil-in-water (O/W) emulsion (500 g/kg 85 camelina/15 fish oil blend) in a hardstock/rapeseed oil blend, using sodium caseinate and polyglycerol polyricinoleate as emulsifiers. The O/W and oil-in-water-in-oil (O/W/O) emulsions contained either a water soluble antioxidant (green tea extract [GTE]), an oil soluble antioxidant (α-Tocopherol), or both. Spreads containing α-Tocopherol had the highest lipid hydroperoxide values, whereas spreads containing GTE had the lowest (P < 0.05), during storage at 5°C, while p-Anisidine values did not differ significantly. Particle size was generally unaffected by antioxidant type (P < 0.05). Double emulsion (O/W/O) structures were clearly seen in confocal images of the spreads. By the end of storage, none of the spreads had significantly different G' values. Firmness (Newtons) of all spreads generally increased during storage (P < 0.05). © 2012 Institute of Food Technologists®

Fluid Management of and Flame Spread Across Liquid Pools

NASA Technical Reports Server (NTRS)

Ross, H. D.; Miller, F. J.

2001-01-01

The goal of our research on flame spread across pools of liquid fuel remains the quantitative identification of the mechanisms that control the rate and nature of flame spread when the initial temperature of the liquid pool is below the fuel's flash point temperature. As described in, four microgravity (mu-g) sounding rocket flights examined the effect of forced opposed airflow over a 2.5 cm deep x 2 cm wide x 30 cm long pool of 1-butanol. Among many unexpected findings, it was observed that the flame spread is much slower and steadier than in 1g where flame spread has a pulsating character. Our numerical model, restricted to two dimensions, had predicted faster, pulsating flame spread in mu-g. In a test designed to achieve a more 2-D experiment, our investigation of a shallow, wide pool (2 mm deep x 78 mm wide x 30 cm long) was unsuccessful in mu-g, due to an unexpectedly long time required to fill the tray. As such, the most recent Spread Across Liquids (SAL) sounding rocket experiment had two principal objectives: 1) determine if pulsating flame spread in deep fuel trays would occur under the conditions that a state-of-the-art computational combustion code and short-duration drop tower tests predict; and 2) determine if a long, rectangular, shallow fuel tray could achieve a visibly flat liquid surface across the whole tray without spillage in the mu-g time allotted. If the second objective was met, the shallow tray was to be ignited to determine the nature of flame spread in mu-g for this geometry. For the first time in the experiment series, two fuel trays - one deep (30 cm long x 2 cm wide x 25 mm deep) and one shallow (same length and width, but 2 mm deep)-- were flown. By doing two independent experiments in a single flight, a significant cost savings was realized. In parallel, the computational objective was to modify the code to improve agreement with earlier results. This last objective was achieved by modifying the fuel mass diffusivity and adding a parameter to correct for radiative and lateral heat loss.

Heterogeneity in multiple transmission pathways: modelling the spread of cholera and other waterborne disease in networks with a common water source.

PubMed

Robertson, Suzanne L; Eisenberg, Marisa C; Tien, Joseph H

2013-01-01

Many factors influencing disease transmission vary throughout and across populations. For diseases spread through multiple transmission pathways, sources of variation may affect each transmission pathway differently. In this paper we consider a disease that can be spread via direct and indirect transmission, such as the waterborne disease cholera. Specifically, we consider a system of multiple patches with direct transmission occurring entirely within patch and indirect transmission via a single shared water source. We investigate the effect of heterogeneity in dual transmission pathways on the spread of the disease. We first present a 2-patch model for which we examine the effect of variation in each pathway separately and propose a measure of heterogeneity that incorporates both transmission mechanisms and is predictive of R(0). We also explore how heterogeneity affects the final outbreak size and the efficacy of intervention measures. We conclude by extending several results to a more general n-patch setting.

Unified tensor model for space-frequency spreading-multiplexing (SFSM) MIMO communication systems

NASA Astrophysics Data System (ADS)

de Almeida, André LF; Favier, Gérard

2013-12-01

This paper presents a unified tensor model for space-frequency spreading-multiplexing (SFSM) multiple-input multiple-output (MIMO) wireless communication systems that combine space- and frequency-domain spreadings, followed by a space-frequency multiplexing. Spreading across space (transmit antennas) and frequency (subcarriers) adds resilience against deep channel fades and provides space and frequency diversities, while orthogonal space-frequency multiplexing enables multi-stream transmission. We adopt a tensor-based formulation for the proposed SFSM MIMO system that incorporates space, frequency, time, and code dimensions by means of the parallel factor model. The developed SFSM tensor model unifies the tensorial formulation of some existing multiple-access/multicarrier MIMO signaling schemes as special cases, while revealing interesting tradeoffs due to combined space, frequency, and time diversities which are of practical relevance for joint symbol-channel-code estimation. The performance of the proposed SFSM MIMO system using either a zero forcing receiver or a semi-blind tensor-based receiver is illustrated by means of computer simulation results under realistic channel and system parameters.

Community engagement research and dual diagnosis anonymous.

PubMed

Roush, Sean; Monica, Corbett; Pavlovich, Danny; Drake, Robert E

2015-01-01

Community engagement research is widely discussed but rarely implemented. This article describes the implementation of a community engagement research project on Dual Diagnosis Anonymous, a rapidly spreading peer support program in Oregon for people with co-occurring mental illness and substance use disorders. After three years of discussions, overcoming barriers, and involving several institutions, this grassroots research project has been implemented and is expanding. Active participants in Dual Diagnosis Anonymous inspired and instructed policy makers, professionals, and students. Community engagement research requires frontline participants, community members, and professional collaborators to overcome multiple barriers with persistence and steadfastness. Building trust, collaboration, and structures for community engagement research takes time and a community effort.

Mechanisms of developmental neurite pruning.

PubMed

Schuldiner, Oren; Yaron, Avraham

2015-01-01

The precise wiring of the nervous system is a combined outcome of progressive and regressive events during development. Axon guidance and synapse formation intertwined with cell death and neurite pruning sculpt the mature circuitry. It is now well recognized that pruning of dendrites and axons as means to refine neuronal networks, is a wide spread phenomena required for the normal development of vertebrate and invertebrate nervous systems. Here we will review the arising principles of cellular and molecular mechanisms of neurite pruning. We will discuss these principles in light of studies in multiple neuronal systems, and speculate on potential explanations for the emergence of neurite pruning as a mechanism to sculpt the nervous system.

Lithospheric "corner flow" via extensional faulting and tectonic rotation at non-volcanic, slow-spreading ridges

NASA Astrophysics Data System (ADS)

Schroeder, T.; Cheadle, M. J.; Dick, H. J.; Faul, U.

2005-12-01

Large degrees (up to 90°) of tectonic rotation may be the norm at slow-spreading, non-volcanic ridges. Vertically upwelling mantle beneath all mid-ocean ridges must undergo corner flow to move horizontally with the spreading plate. Because little or no volcanic crust is produced at some slow-spreading ridges, the uppermost lithospheric mantle must undergo this rotation in the regime of localized, rather than distributed deformation. Anomalous paleomagnetic inclinations in peridotite and gabbro cores drilled near the 15-20 Fracture Zone (Mid-Atlantic Ridge, ODP Leg 209) support such large rotations, with sub-Curie-temperature rotations up to 90° (Garces et al., 2004). Here, we present two end-member tectonic mechanisms, with supporting data from Leg 209 cores and bathymetry, to show how rotation is accomplished via extensional faults and shear zones: 1) long-lived detachment faults, and 2) multiple generations of high-angle normal faults. Detachment faults accommodate rotation by having a moderate to steep dip at depth, and rotating to horizontal through a rolling hinge as the footwall is tectonically denuded. Multiple generations of high-angle normal faults accommodate large rotations in a domino fashion; early faults become inactive when rotated to inopportune slip angles, and are cut by younger high-angle faults. Thus, each generation of high-angle faults accommodates part of the total rotation. There is likely a gradation between the domino and detachment mechanisms; transition from domino to detachment faulting occurs when a single domino fault remains active at inopportune slip angles and evolves into a detachment that accommodates all corner flow for that region. In both cases, the original attitude of layering within mantle-emplaced gabbro bodies must be significantly different than present day observed attitudes; sub-horizontal bodies may have been formed sub-vertically and vice-versa. Leg 209 cores record an average major brittle fault spacing of approximately 100 m, suggesting that the width of individual rotating fault blocks may be on the order of 100-200 m. Numerous fault bounded domino slices could therefore be formed within a 10km wide axial valley, with large rotations (and commensurate extension) leading to the exposure of 1km wide shallow-dipping fault surfaces, as are seen in the 15-20 FZ region bathymetry. The region's bathymetry is dominated by irregular, low-relief ridges that were likely formed by domino faulting of lithosphere with a small elastic thickness. The region contains relatively few corrugated detachment fault domes, suggesting that domino faulting may be the normal mode of lithospheric corner flow at non-volcanic ridges.

Proposals to reject the names Spermacoce stigosa and S. hyssopifolia Sm. and conserve the names S. hyssopifolia Wild. Es oem. & Schult. (Rubiaceae)

USDA-ARS?s Scientific Manuscript database

The genus Spermacoce is a wide spread, common weed that frequently occurs in agricultural situations, and is a member of the family Rubiaceae. Diodella apiculata is a wide spread weedy species found in Central America, the Caribbean, and South America, all the way to Argentina. Two earlier names, S....

HCMV Reprogramming of Infected Monocyte Survival and Differentiation: A Goldilocks Phenomenon

PubMed Central

Stevenson, Emily V.; Collins-McMillen, Donna; Kim, Jung Heon; Cieply, Stephen J.; Bentz, Gretchen L.; Yurochko, Andrew D.

2014-01-01

The wide range of disease pathologies seen in multiple organ sites associated with human cytomegalovirus (HCMV) infection results from the systemic hematogenous dissemination of the virus, which is mediated predominately by infected monocytes. In addition to their role in viral spread, infected monocytes are also known to play a key role in viral latency and life-long persistence. However, in order to utilize infected monocytes for viral spread and persistence, HCMV must overcome a number of monocyte biological hurdles, including their naturally short lifespan and their inability to support viral gene expression and replication. Our laboratory has shown that HCMV is able to manipulate the biology of infected monocytes in order to overcome these biological hurdles by inducing the survival and differentiation of infected monocytes into long-lived macrophages capable of supporting viral gene expression and replication. In this current review, we describe the unique aspects of how HCMV promotes monocyte survival and differentiation by inducing a “finely-tuned” macrophage cell type following infection. Specifically, we describe the induction of a uniquely polarized macrophage subset from infected monocytes, which we argue is the ideal cellular environment for the initiation of viral gene expression and replication and, ultimately, viral spread and persistence within the infected host. PMID:24531335

Episodic normal faulting and magmatism during the syn-spreading stage of the Baiyun sag in Pearl River Mouth Basin: response to the multi-phase seafloor spreading of the South China Sea

NASA Astrophysics Data System (ADS)

Deng, Peng; Mei, Lianfu; Liu, Jun; Zheng, Jinyun; Liu, Minghui; Cheng, Zijie; Guo, Fengtai

2018-03-01

Considerable post-breakup extensional deformation is recorded in the continental margins of the South China Sea (SCS). To recognize the nature and origin of the significant deformation during the syn-spreading stage (32-15.5 Ma) in the SCS, we comprehensively analyzed the geometry and kinematics of the faults and contemporaneous magmas in the Baiyun sag, northern margin of the SCS, using high-resolution regional three-dimensional seismic data. The kinematic analyses indicate that the faults in the Baiyun sag are recently formed following the onset of seafloor spreading in the SCS. The faults exhibit multiple episodes of growth history, with three active episodes, 32-29, 23.8-21 and 18.5-16.5 Ma, separated by periods of inactivity. Four volcanic groups comprising 98 volcanic mounds have been identified and described, located separately in the northwestern, the central, the southeastern and the northern slope areas. The occurrence of multiple palaeo-seafloors, complemented by the biostratigraphic and K-Ar dating data, reveals multiple extrusive events of the syn-spreading magmas in the Baiyun sag, with three active periods of 23.8-21, 18.5-17.5 and 17.5-16.5 Ma. This study confirms that the normal faulting has a shared genetic origin with the contemporaneous magmatism during the syn-spreading stage in the deep-offshore Baiyun sag, northern margin of the SCS. The episodic fault growth and magmatic extrusive events reveal that the Baiyun sag has undergone at least three episodic tectonic events during the syn-spreading stage, which evolved in response to the multi-stage seafloor spreading of the SCS.

Lens and Camera Arrays for Sky Surveys and Space Surveillance

NASA Astrophysics Data System (ADS)

Ackermann, M.; Cox, D.; McGraw, J.; Zimmer, P.

2016-09-01

In recent years, a number of sky survey projects have chosen to use arrays of commercial cameras coupled with commercial photographic lenses to enable low-cost, wide-area observation. Projects such as SuperWASP, FAVOR, RAPTOR, Lotis, PANOPTES, and DragonFly rely on multiple cameras with commercial lenses to image wide areas of the sky each night. The sensors are usually commercial astronomical charge coupled devices (CCDs) or digital single reflex (DSLR) cameras, while the lenses are large-aperture, highend consumer items intended for general photography. While much of this equipment is very capable and relatively inexpensive, this approach comes with a number of significant limitations that reduce sensitivity and overall utility of the image data. The most frequently encountered limitations include lens vignetting, narrow spectral bandpass, and a relatively large point spread function. Understanding these limits helps to assess the utility of the data, and identify areas where advanced optical designs could significantly improve survey performance.

The interconnected and cross-border nature of risks posed by infectious diseases

PubMed Central

Suk, Jonathan E.; Van Cangh, Thomas; Beauté, Julien; Bartels, Cornelius; Tsolova, Svetla; Pharris, Anastasia; Ciotti, Massimo; Semenza, Jan C.

2014-01-01

Infectious diseases can constitute public health emergencies of international concern when a pathogen arises, acquires new characteristics, or is deliberately released, leading to the potential for loss of human lives as well as societal disruption. A wide range of risk drivers are now known to lead to and/or exacerbate the emergence and spread of infectious disease, including global trade and travel, the overuse of antibiotics, intensive agriculture, climate change, high population densities, and inadequate infrastructures, such as water treatment facilities. Where multiple risk drivers interact, the potential impact of a disease outbreak is amplified. The varying temporal and geographic frequency with which infectious disease events occur adds yet another layer of complexity to the issue. Mitigating the emergence and spread of infectious disease necessitates mapping and prioritising the interdependencies between public health and other sectors. Conversely, during an international public health emergency, significant disruption occurs not only to healthcare systems but also to a potentially wide range of sectors, including trade, tourism, energy, civil protection, transport, agriculture, and so on. At the same time, dealing with a disease outbreak may require a range of critical sectors for support. There is a need to move beyond narrow models of risk to better account for the interdependencies between health and other sectors so as to be able to better mitigate and respond to the risks posed by emerging infectious disease. PMID:25308818

High-mobility group box 1 is an important mediator of microglial activation induced by cortical spreading depression.

PubMed

Takizawa, Tsubasa; Shibata, Mamoru; Kayama, Yohei; Shimizu, Toshihiko; Toriumi, Haruki; Ebine, Taeko; Unekawa, Miyuki; Koh, Anri; Yoshimura, Akihiko; Suzuki, Norihiro

2017-03-01

Single episodes of cortical spreading depression (CSD) are believed to cause typical migraine aura, whereas clusters of spreading depolarizations have been observed in cerebral ischemia and subarachnoid hemorrhage. We recently demonstrated that the release of high-mobility group box 1 (HMGB1) from cortical neurons after CSD in a rodent model is dependent on the number of CSD episodes, such that only multiple CSD episodes can induce significant HMGB1 release. Here, we report that only multiple CSD inductions caused microglial hypertrophy (activation) accompanied by a greater impact on the transcription activity of the HMGB1 receptor genes, TLR2 and TLR4, while the total number of cortical microglia was not affected. Both an HMGB1-neurtalizing antibody and the HMGB1 inhibitor glycyrrhizin abrogated multiple CSD-induced microglial hypertrophy. Moreover, multiple CSD inductions failed to induce microglial hypertrophy in TLR2/4 double knockout mice. These results strongly implicate the HMGB1-TLR2/4 axis in the activation of microglia following multiple CSD inductions. Increased expression of the lysosomal acid hydrolase cathepsin D was detected in activated microglia by immunostaining, suggesting that lysosomal phagocytic activity may be enhanced in multiple CSD-activated microglia.

Evaluation of electrosurgical interference to low-power spread-spectrum local area net transceivers.

PubMed

Gibby, G L; Schwab, W K; Miller, W C

1997-11-01

To study whether an electrosurgery device interferes with the operation of a low-power spread-spectrum wireless network adapter. Nonrandomized, unblinded trials with controls, conducted in the corridor of our institution's operating suite using two portable computers equipped with RoamAbout omnidirectional 250 mW spread-spectrum 928 MHz wireless network adapters. To simulate high power electrosurgery interference, a 100-watt continuous electrocoagulation arc was maintained five feet from the receiving adapter, while device reported signal to noise values were measured at 150 feet and 400 feet distance between the wireless-networked computers. At 150 feet range, and with continuous 100-watt electrocoagulation arc five feet from one computer, error-corrected local area net throughput was measured by sending and receiving a large file multiple times. The reported signal to noise (N = 50) decreased with electrocoagulation from 36.42+/-3.47 (control) to 31.85+/-3.64 (electrocoagulation) (p < 0.001) at 400 feet inter-adapter distance, and from 64.53+/-1.43 (control) to 60.12+/-3.77 (electrocoagulation) (p < 0.001) at 150 feet inter-adapter distance. There was no statistically significant change in network throughput (average 93 kbyte/second) at 150 feet inter-adapter distance, either transmitting or receiving during continuous 100 Watt electrocoagulation arc. The manufacturer indicates "acceptable" performance will be obtained with signal to noise values as low as 20. In view of this, while electrocoagulation affects this spread spectrum network adapter, the effects are small even at 400 feet. At a distance of 150 feet, no discernible effect on network communications was found, suggesting that if other obstructions are minimal, within a wide range on one floor of an operating suite, network communications may be maintained using the technology of this wireless spread spectrum network adapter. The impact of such adapters on cardiac pacemakers should be studied. Wireless spread spectrum network adapters are an attractive technology for mobile computer communications in the operating room.

Local variations in spatial synchrony of influenza epidemics.

PubMed

Stark, James H; Cummings, Derek A T; Ermentrout, Bard; Ostroff, Stephen; Sharma, Ravi; Stebbins, Samuel; Burke, Donald S; Wisniewski, Stephen R

2012-01-01

Understanding the mechanism of influenza spread across multiple geographic scales is not complete. While the mechanism of dissemination across regions and states of the United States has been described, understanding the determinants of dissemination between counties has not been elucidated. The paucity of high resolution spatial-temporal influenza incidence data to evaluate disease structure is often not available. We report on the underlying relationship between the spread of influenza and human movement between counties of one state. Significant synchrony in the timing of epidemics exists across the entire state and decay with distance (regional correlation=62%). Synchrony as a function of population size display evidence of hierarchical spread with more synchronized epidemics occurring among the most populated counties. A gravity model describing movement between two populations is a stronger predictor of influenza spread than adult movement to and from workplaces suggesting that non-routine and leisure travel drive local epidemics. These findings highlight the complex nature of influenza spread across multiple geographic scales.

Local Variations in Spatial Synchrony of Influenza Epidemics

PubMed Central

Stark, James H.; Cummings, Derek A. T.; Ermentrout, Bard; Ostroff, Stephen; Sharma, Ravi; Stebbins, Samuel; Burke, Donald S.; Wisniewski, Stephen R.

2012-01-01

Background Understanding the mechanism of influenza spread across multiple geographic scales is not complete. While the mechanism of dissemination across regions and states of the United States has been described, understanding the determinants of dissemination between counties has not been elucidated. The paucity of high resolution spatial-temporal influenza incidence data to evaluate disease structure is often not available. Methodology and Findings We report on the underlying relationship between the spread of influenza and human movement between counties of one state. Significant synchrony in the timing of epidemics exists across the entire state and decay with distance (regional correlation = 62%). Synchrony as a function of population size display evidence of hierarchical spread with more synchronized epidemics occurring among the most populated counties. A gravity model describing movement between two populations is a stronger predictor of influenza spread than adult movement to and from workplaces suggesting that non-routine and leisure travel drive local epidemics. Conclusions These findings highlight the complex nature of influenza spread across multiple geographic scales. PMID:22916274

Code-Time Diversity for Direct Sequence Spread Spectrum Systems

PubMed Central

Hassan, A. Y.

2014-01-01

Time diversity is achieved in direct sequence spread spectrum by receiving different faded delayed copies of the transmitted symbols from different uncorrelated channel paths when the transmission signal bandwidth is greater than the coherence bandwidth of the channel. In this paper, a new time diversity scheme is proposed for spread spectrum systems. It is called code-time diversity. In this new scheme, N spreading codes are used to transmit one data symbol over N successive symbols interval. The diversity order in the proposed scheme equals to the number of the used spreading codes N multiplied by the number of the uncorrelated paths of the channel L. The paper represents the transmitted signal model. Two demodulators structures will be proposed based on the received signal models from Rayleigh flat and frequency selective fading channels. Probability of error in the proposed diversity scheme is also calculated for the same two fading channels. Finally, simulation results are represented and compared with that of maximal ration combiner (MRC) and multiple-input and multiple-output (MIMO) systems. PMID:24982925

The role of China in the global spread of the current cholera pandemic.

PubMed

Didelot, Xavier; Pang, Bo; Zhou, Zhemin; McCann, Angela; Ni, Peixiang; Li, Dongfang; Achtman, Mark; Kan, Biao

2015-03-01

Epidemics and pandemics of cholera, a severe diarrheal disease, have occurred since the early 19th century and waves of epidemic disease continue today. Cholera epidemics are caused by individual, genetically monomorphic lineages of Vibrio cholerae: the ongoing seventh pandemic, which has spread globally since 1961, is associated with lineage L2 of biotype El Tor. Previous genomic studies of the epidemiology of the seventh pandemic identified three successive sub-lineages within L2, designated waves 1 to 3, which spread globally from the Bay of Bengal on multiple occasions. However, these studies did not include samples from China, which also experienced multiple epidemics of cholera in recent decades. We sequenced the genomes of 71 strains isolated in China between 1961 and 2010, as well as eight from other sources, and compared them with 181 published genomes. The results indicated that outbreaks in China between 1960 and 1990 were associated with wave 1 whereas later outbreaks were associated with wave 2. However, the previously defined waves overlapped temporally, and are an inadequate representation of the shape of the global genealogy. We therefore suggest replacing them by a series of tightly delineated clades. Between 1960 and 1990 multiple such clades were imported into China, underwent further microevolution there and then spread to other countries. China was thus both a sink and source during the pandemic spread of V. cholerae, and needs to be included in reconstructions of the global patterns of spread of cholera.

Mechanisms of developmental neurite pruning

PubMed Central

Schuldiner, Oren; Yaron, Avraham

2016-01-01

The precise wiring of the nervous system is a combined outcome of progressive and regressive events during development. Axon guidance and synapse formation intertwined with cell death and neurite pruning sculpt the mature circuitry. It is now well recognized that pruning of dendrites and axons as means to refine neuronal networks, is a wide spread phenomena required for the normal development of vertebrate and invertebrate nervous systems. Here we will review the arising principles of cellular and molecular mechanisms of neurite pruning. We will discuss these principles in light of studies in multiple neuronal systems, and speculate on potential explanations for the emergence of neurite pruning as a mechanism to sculpt the nervous system. PMID:25213356

Analysis of Initial Cell Spreading Using Mechanistic Contact Formulations for a Deformable Cell Model

PubMed Central

Odenthal, Tim; Smeets, Bart; Van Liedekerke, Paul; Tijskens, Engelbert; Van Oosterwyck, Hans; Ramon, Herman

2013-01-01

Adhesion governs to a large extent the mechanical interaction between a cell and its microenvironment. As initial cell spreading is purely adhesion driven, understanding this phenomenon leads to profound insight in both cell adhesion and cell-substrate interaction. It has been found that across a wide variety of cell types, initial spreading behavior universally follows the same power laws. The simplest cell type providing this scaling of the radius of the spreading area with time are modified red blood cells (RBCs), whose elastic responses are well characterized. Using a mechanistic description of the contact interaction between a cell and its substrate in combination with a deformable RBC model, we are now able to investigate in detail the mechanisms behind this universal power law. The presented model suggests that the initial slope of the spreading curve with time results from a purely geometrical effect facilitated mainly by dissipation upon contact. Later on, the spreading rate decreases due to increasing tension and dissipation in the cell's cortex as the cell spreads more and more. To reproduce this observed initial spreading, no irreversible deformations are required. Since the model created in this effort is extensible to more complex cell types and can cope with arbitrarily shaped, smooth mechanical microenvironments of the cells, it can be useful for a wide range of investigations where forces at the cell boundary play a decisive role. PMID:24146605

Distributed reservation-based code division multiple access

NASA Astrophysics Data System (ADS)

Wieselthier, J. E.; Ephremides, A.

1984-11-01

The use of spread spectrum signaling, motivated primarily by its antijamming capabilities in military applications, leads naturally to the use of Code Division Multiple Access (CDMA) techniques that permit the successful simultaneous transmission by a number of users over a wideband channel. In this paper we address some of the major issues that are associated with the design of multiple access protocols for spread spectrum networks. We then propose, analyze, and evaluate a distributed reservation-based multiple access protocol that does in fact exploit CDMA properties. Especially significant is the fact that no acknowledgment or feedback information from the destination is required (thus facilitating communication with a radio-silent mode), nor is any form of coordination among the users necessary.

Site-wide seismic risk model for Savannah River Site nuclear facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eide, S.A.; Shay, R.S.; Durant, W.S.

1993-09-01

The 200,000 acre Savannah River Site (SRS) has nearly 30 nuclear facilities spread throughout the site. The safety of each facility has been established in facility-specific safety analysis reports (SARs). Each SAR contains an analysis of risk from seismic events to both on-site workers and the off-site population. Both radiological and chemical releases are considered, and air and water pathways are modeled. Risks to the general public are generally characterized by evaluating exposure to the maximally exposed individual located at the SRS boundary and to the off-site population located within 50 miles. Although the SARs are appropriate methods for studyingmore » individual facility risks, there is a class of accident initiators that can simultaneously affect several of all of the facilities, Examples include seismic events, strong winds or tornados, floods, and loss of off-site electrical power. Overall risk to the off-site population from such initiators is not covered by the individual SARs. In such cases multiple facility radionuclide or chemical releases could occur, and off-site exposure would be greater than that indicated in a single facility SAR. As a step towards an overall site-wide risk model that adequately addresses multiple facility releases, a site-wide seismic model for determining off-site risk has been developed for nuclear facilities at the SRS. Risk from seismic events up to the design basis earthquake (DBE) of 0.2 g (frequency of 2.0E-4/yr) is covered by the model. Present plans include expanding the scope of the model to include other types of initiators that can simultaneously affect multiple facilities.« less

Cooperative behavior cascades in human social networks.

PubMed

Fowler, James H; Christakis, Nicholas A

2010-03-23

Theoretical models suggest that social networks influence the evolution of cooperation, but to date there have been few experimental studies. Observational data suggest that a wide variety of behaviors may spread in human social networks, but subjects in such studies can choose to befriend people with similar behaviors, posing difficulty for causal inference. Here, we exploit a seminal set of laboratory experiments that originally showed that voluntary costly punishment can help sustain cooperation. In these experiments, subjects were randomly assigned to a sequence of different groups to play a series of single-shot public goods games with strangers; this feature allowed us to draw networks of interactions to explore how cooperative and uncooperative behaviors spread from person to person to person. We show that, in both an ordinary public goods game and in a public goods game with punishment, focal individuals are influenced by fellow group members' contribution behavior in future interactions with other individuals who were not a party to the initial interaction. Furthermore, this influence persists for multiple periods and spreads up to three degrees of separation (from person to person to person to person). The results suggest that each additional contribution a subject makes to the public good in the first period is tripled over the course of the experiment by other subjects who are directly or indirectly influenced to contribute more as a consequence. These results show experimentally that cooperative behavior cascades in human social networks.

Propagation dynamics for a spatially periodic integrodifference competition model

NASA Astrophysics Data System (ADS)

Wu, Ruiwen; Zhao, Xiao-Qiang

2018-05-01

In this paper, we study the propagation dynamics for a class of integrodifference competition models in a periodic habitat. An interesting feature of such a system is that multiple spreading speeds can be observed, which biologically means different species may have different spreading speeds. We show that the model system admits a single spreading speed, and it coincides with the minimal wave speed of the spatially periodic traveling waves. A set of sufficient conditions for linear determinacy of the spreading speed is also given.

Pulsations, interpulsations, and sea-floor spreading.

NASA Technical Reports Server (NTRS)

Pessagno, E. A., Jr.

1973-01-01

It is postulated that worldwide transgressions (pulsations) and regressions (interpulsations) through the course of geologic time are related to the elevation and subsidence of oceanic ridge systems and to sea-floor spreading. Two multiple working hypotheses are advanced to explain major transgressions and regressions and the elevation and subsidence of oceanic ridge systems. One hypothesis interrelates the sea-floor spreading hypothesis to the hypothesis of sub-Mohorovicic serpentinization. The second hypothesis relates the sea-floor spreading hypothesis to a hypothesis involving thermal expansion and contraction.

Priority setting for invasive species management: risk assessment of Ponto-Caspian invasive species into Great Britain.

PubMed

Gallardo, Belinda; Aldridge, David C

2013-03-01

Invasive species drive important ecological and economic losses across wide geographies, with some regions supporting especially large numbers of nonnative species and consequently suffering relatively high impacts. For this reason, integrated risk assessments able to screen a suite of multiple invaders over large geographic areas are needed for prioritizing the allocation of limited resources. A total of 16 Ponto-Caspian aquatic species (10 gammarids, one isopod, two mysids, and three fishes) have been short-listed as recent or potential future invaders of British waters, whose introduction and spread is of high concern. In this study, we use multiple modeling techniques to assess their risk of establishment and spread into Great Britain. Climate suitability maps for these 16 species differed depending on the eastern and western distribution of species in continental Europe, which was related to their respective migration corridor: southern (Danube-Rhine rivers), and northern (Don and Volga rivers and Baltic lakes). Species whose suitability was high across large parts of Great Britain included four gammarids (Cheliorophium robustum, Dikerogammarus bispinosus, D. villosus, and Echinogammarus trichiatus) and a mysid (Hemimysis anomala). A climatic "heat map" combining the results of all 16 species together pointed to the southeast of England as the area most vulnerable to multiple invasions, particularly the Thames, Anglian, Severn, and Humber river basin districts. Regression models further suggested that alkalinity concentration > 120 mg/L in southeast England may favor the establishment of Ponto-Caspian invaders. The production of integrated risk maps for future invaders provides a means for the scientifically informed prioritization of resources toward particular species and geographic regions. Such tools have great utility in helping environmental managers focus efforts on the most effective prevention, management, and monitoring programs.

The Emergence of Resistance to the Benzimidazole Anthlemintics in Parasitic Nematodes of Livestock Is Characterised by Multiple Independent Hard and Soft Selective Sweeps

PubMed Central

Redman, Elizabeth; Whitelaw, Fiona; Tait, Andrew; Burgess, Charlotte; Bartley, Yvonne; Skuce, Philip John; Jackson, Frank; Gilleard, John Stuart

2015-01-01

Anthelmintic resistance is a major problem for the control of parasitic nematodes of livestock and of growing concern for human parasite control. However, there is little understanding of how resistance arises and spreads or of the “genetic signature” of selection for this group of important pathogens. We have investigated these questions in the system for which anthelmintic resistance is most advanced; benzimidazole resistance in the sheep parasites Haemonchus contortus and Teladorsagia circumcincta. Population genetic analysis with neutral microsatellite markers reveals that T. circumcincta has higher genetic diversity but lower genetic differentiation between farms than H. contortus in the UK. We propose that this is due to epidemiological differences between the two parasites resulting in greater seasonal bottlenecking of H. contortus. There is a remarkably high level of resistance haplotype diversity in both parasites compared with drug resistance studies in other eukaryotic systems. Our analysis suggests a minimum of four independent origins of resistance mutations on just seven farms for H. contortus, and even more for T. circumincta. Both hard and soft selective sweeps have occurred with striking differences between individual farms. The sweeps are generally softer for T. circumcincta than H. contortus, consistent with its higher level of genetic diversity and consequent greater availability of new mutations. We propose a model in which multiple independent resistance mutations recurrently arise and spread by migration to explain the widespread occurrence of resistance in these parasites. Finally, in spite of the complex haplotypic diversity, we show that selection can be detected at the target locus using simple measures of genetic diversity and departures from neutrality. This work has important implications for the application of genome-wide approaches to identify new anthelmintic resistance loci and the likelihood of anthelmintic resistance emerging as selection pressure is increased in human soil-transmitted nematodes by community wide treatment programs. PMID:25658086

Similitude assessment method for comparing PMHS response data from impact loading across multiple test devices.

PubMed

Dooley, Christopher J; Tenore, Francesco V; Gayzik, F Scott; Merkle, Andrew C

2018-04-27

Biological tissue testing is inherently susceptible to the wide range of variability specimen to specimen. A primary resource for encapsulating this range of variability is the biofidelity response corridor or BRC. In the field of injury biomechanics, BRCs are often used for development and validation of both physical, such as anthropomorphic test devices, and computational models. For the purpose of generating corridors, post-mortem human surrogates were tested across a range of loading conditions relevant to under-body blast events. To sufficiently cover the wide range of input conditions, a relatively small number of tests were performed across a large spread of conditions. The high volume of required testing called for leveraging the capabilities of multiple impact test facilities, all with slight variations in test devices. A method for assessing similitude of responses between test devices was created as a metric for inclusion of a response in the resulting BRC. The goal of this method was to supply a statistically sound, objective method to assess the similitude of an individual response against a set of responses to ensure that the BRC created from the set was affected primarily by biological variability, not anomalies or differences stemming from test devices. Copyright © 2018 Elsevier Ltd. All rights reserved.

A wide diversity of bacteria from the human gut produces and degrades biogenic amines.

PubMed

Pugin, Benoit; Barcik, Weronika; Westermann, Patrick; Heider, Anja; Wawrzyniak, Marcin; Hellings, Peter; Akdis, Cezmi A; O'Mahony, Liam

2017-01-01

Background : Biogenic amines (BAs) are metabolites produced by the decarboxylation of amino acids with significant physiological functions in eukaryotic and prokaryotic cells. BAs can be produced by bacteria in fermented foods, but little is known concerning the potential for microbes within the human gut microbiota to produce or degrade BAs. Objective : To isolate and identify BA-producing and BA-degrading microbes from the human gastrointestinal tract. Design : Fecal samples from human volunteers were screened on multiple growth media, under multiple growth conditions. Bacterial species were identified using 16S rRNA sequencing and BA production or degradation was assessed using ultra-performance liquid chromatography. Results : In total, 74 BA-producing or BA-degrading strains were isolated from the human gut. These isolates belong to the genera Bifidobacterium , Clostridium , Enterococcus , Lactobacillus , Pediococcus , Streptococcus , Enterobacter , Escherichia , Klebsiella , Morganella and Proteus . While differences in production or degradation of specific BAs were observed at the strain level, our results suggest that these metabolic activities are widely spread across different taxa present within the human gut microbiota. Conclusions : The isolation and identification of microbes from the human gut with BA-producing and BA-degrading metabolic activity is an important first step in developing a better understanding of how these metabolites influence health and disease.

Analysis, optimization, and implementation of a hybrid DS/FFH spread-spectrum technique for smart grid communications

DOE PAGES

Olama, Mohammed M.; Ma, Xiao; Killough, Stephen M.; ...

2015-03-12

In recent years, there has been great interest in using hybrid spread-spectrum (HSS) techniques for commercial applications, particularly in the Smart Grid, in addition to their inherent uses in military communications. This is because HSS can accommodate high data rates with high link integrity, even in the presence of significant multipath effects and interfering signals. A highly useful form of this transmission technique for many types of command, control, and sensing applications is the specific code-related combination of standard direct sequence modulation with fast frequency hopping, denoted hybrid DS/FFH, wherein multiple frequency hops occur within a single data-bit time. Inmore » this paper, error-probability analyses are performed for a hybrid DS/FFH system over standard Gaussian and fading-type channels, progressively including the effects from wide- and partial-band jamming, multi-user interference, and varying degrees of Rayleigh and Rician fading. In addition, an optimization approach is formulated that minimizes the bit-error performance of a hybrid DS/FFH communication system and solves for the resulting system design parameters. The optimization objective function is non-convex and can be solved by applying the Karush-Kuhn-Tucker conditions. We also present our efforts toward exploring the design, implementation, and evaluation of a hybrid DS/FFH radio transceiver using a single FPGA. Numerical and experimental results are presented under widely varying design parameters to demonstrate the adaptability of the waveform for varied harsh smart grid RF signal environments.« less

Clustering of two genes putatively involved in cyanate detoxification evolved recently and independently in multiple fungal lineages.

PubMed

Elmore, M Holly; McGary, Kriston L; Wisecaver, Jennifer H; Slot, Jason C; Geiser, David M; Sink, Stacy; O'Donnell, Kerry; Rokas, Antonis

2015-02-06

Fungi that have the enzymes cyanase and carbonic anhydrase show a limited capacity to detoxify cyanate, a fungicide employed by both plants and humans. Here, we describe a novel two-gene cluster that comprises duplicated cyanase and carbonic anhydrase copies, which we name the CCA gene cluster, trace its evolution across Ascomycetes, and examine the evolutionary dynamics of its spread among lineages of the Fusarium oxysporum species complex (hereafter referred to as the FOSC), a cosmopolitan clade of purportedly clonal vascular wilt plant pathogens. Phylogenetic analysis of fungal cyanase and carbonic anhydrase genes reveals that the CCA gene cluster arose independently at least twice and is now present in three lineages, namely Cochliobolus lunatus, Oidiodendron maius, and the FOSC. Genome-wide surveys within the FOSC indicate that the CCA gene cluster varies in copy number across isolates, is always located on accessory chromosomes, and is absent in FOSC's closest relatives. Phylogenetic reconstruction of the CCA gene cluster in 163 FOSC strains from a wide variety of hosts suggests a recent history of rampant transfers between isolates. We hypothesize that the independent formation of the CCA gene cluster in different fungal lineages and its spread across FOSC strains may be associated with resistance to plant-produced cyanates or to use of cyanate fungicides in agriculture. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Quantitative Infrared Image Analysis Of Simultaneous Upstream and Downstream Microgravity Flame Spread over Thermally-Thin Cellulose in Low Speed Forced Flow

NASA Technical Reports Server (NTRS)

Olson, S. L.; Lee, J. R.; Fujita, O.; Kikuchi, M.; Kashiwagi, T.

2013-01-01

The effect of low velocity forced flow on microgravity flame spread is examined using quantitative analysis of infrared video imaging. The objective of the quantitative analysis is to provide insight into the mechanisms of flame spread in microgravity where the flame is able to spread from a central location on the fuel surface, rather than from an edge. Surface view calibrated infrared images of ignition and flame spread over a thin cellulose fuel were obtained along with a color video of the surface view and color images of the edge view using 35 mm color film at 2 Hz. The cellulose fuel samples were mounted in the center of a 12 cm wide by 16 cm tall flow duct and were ignited in microgravity using a straight hot wire across the center of the 7.5 cm wide by 14 cm long samples. Four cases, at 1 atm. 35%O2 in N2, at forced flows from 2 cm/s to 20 cm/s are presented here. This flow range captures flame spread from strictly upstream spread at low flows, to predominantly downstream spread at high flow. Surface temperature profiles are evaluated as a function of time, and temperature gradients for upstream and downstream flame spread are measured. Flame spread rates from IR image data are compared to visible image spread rate data. IR blackbody temperatures are compared to surface thermocouple readings to evaluate the effective emissivity of the pyrolyzing surface. Preheat lengths and pyrolysis lengths are evaluated both upstream and downstream of the central ignition point. A surface energy balance estimates the net heat flux from the flame to the fuel surface along the length of the fuel. Surface radiative loss and gas-phase radiation from soot are measured relative to the net heat feedback from the flame. At high surface heat loss relative to heat feedback, the downstream flame spread does not occur.

Predicting the evolution of spreading on complex networks

PubMed Central

Chen, Duan-Bing; Xiao, Rui; Zeng, An

2014-01-01

Due to the wide applications, spreading processes on complex networks have been intensively studied. However, one of the most fundamental problems has not yet been well addressed: predicting the evolution of spreading based on a given snapshot of the propagation on networks. With this problem solved, one can accelerate or slow down the spreading in advance if the predicted propagation result is narrower or wider than expected. In this paper, we propose an iterative algorithm to estimate the infection probability of the spreading process and then apply it to a mean-field approach to predict the spreading coverage. The validation of the method is performed in both artificial and real networks. The results show that our method is accurate in both infection probability estimation and spreading coverage prediction. PMID:25130862

Epidemic Spreading in a Multi-compartment System

NASA Astrophysics Data System (ADS)

Gao, Zong-Mao; Gu, Jiao; Li, Wei

2012-02-01

We introduce the variant rate and white noise into the susceptible-infected-removed (SIR) model for epidemics, discuss the epidemic dynamics of a multiple-compartment system, and describe this system by using master equations. For both the local epidemic spreading system and the whole multiple-compartment system, we find that a threshold could be useful in forecasting when the epidemic vanishes. Furthermore, numerical simulations show that a model with the variant infection rate and white noise can improve fitting with real SARS data.

Measures of model performance based on the log accuracy ratio

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morley, Steven Karl; Brito, Thiago Vasconcelos; Welling, Daniel T.

Quantitative assessment of modeling and forecasting of continuous quantities uses a variety of approaches. We review existing literature describing metrics for forecast accuracy and bias, concentrating on those based on relative errors and percentage errors. Of these accuracy metrics, the mean absolute percentage error (MAPE) is one of the most common across many fields and has been widely applied in recent space science literature and we highlight the benefits and drawbacks of MAPE and proposed alternatives. We then introduce the log accuracy ratio, and derive from it two metrics: the median symmetric accuracy; and the symmetric signed percentage bias. Robustmore » methods for estimating the spread of a multiplicative linear model using the log accuracy ratio are also presented. The developed metrics are shown to be easy to interpret, robust, and to mitigate the key drawbacks of their more widely-used counterparts based on relative errors and percentage errors. Their use is illustrated with radiation belt electron flux modeling examples.« less

Measures of model performance based on the log accuracy ratio

DOE PAGES

Morley, Steven Karl; Brito, Thiago Vasconcelos; Welling, Daniel T.

2018-01-03

Quantitative assessment of modeling and forecasting of continuous quantities uses a variety of approaches. We review existing literature describing metrics for forecast accuracy and bias, concentrating on those based on relative errors and percentage errors. Of these accuracy metrics, the mean absolute percentage error (MAPE) is one of the most common across many fields and has been widely applied in recent space science literature and we highlight the benefits and drawbacks of MAPE and proposed alternatives. We then introduce the log accuracy ratio, and derive from it two metrics: the median symmetric accuracy; and the symmetric signed percentage bias. Robustmore » methods for estimating the spread of a multiplicative linear model using the log accuracy ratio are also presented. The developed metrics are shown to be easy to interpret, robust, and to mitigate the key drawbacks of their more widely-used counterparts based on relative errors and percentage errors. Their use is illustrated with radiation belt electron flux modeling examples.« less

The Unified Medical Language System

PubMed Central

Humphreys, Betsy L.; Lindberg, Donald A. B.; Schoolman, Harold M.; Barnett, G. Octo

1998-01-01

In 1986, the National Library of Medicine (NLM) assembled a large multidisciplinary, multisite team to work on the Unified Medical Language System (UMLS), a collaborative research project aimed at reducing fundamental barriers to the application of computers to medicine. Beyond its tangible products, the UMLS Knowledge Sources, and its influence on the field of informatics, the UMLS project is an interesting case study in collaborative research and development. It illustrates the strengths and challenges of substantive collaboration among widely distributed research groups. Over the past decade, advances in computing and communications have minimized the technical difficulties associated with UMLS collaboration and also facilitated the development, dissemination, and use of the UMLS Knowledge Sources. The spread of the World Wide Web has increased the visibility of the information access problems caused by multiple vocabularies and many information sources which are the focus of UMLS work. The time is propitious for building on UMLS accomplishments and making more progress on the informatics research issues first highlighted by the UMLS project more than 10 years ago. PMID:9452981

The Unified Medical Language System: an informatics research collaboration.

PubMed

Humphreys, B L; Lindberg, D A; Schoolman, H M; Barnett, G O

1998-01-01

In 1986, the National Library of Medicine (NLM) assembled a large multidisciplinary, multisite team to work on the Unified Medical Language System (UMLS), a collaborative research project aimed at reducing fundamental barriers to the application of computers to medicine. Beyond its tangible products, the UMLS Knowledge Sources, and its influence on the field of informatics, the UMLS project is an interesting case study in collaborative research and development. It illustrates the strengths and challenges of substantive collaboration among widely distributed research groups. Over the past decade, advances in computing and communications have minimized the technical difficulties associated with UMLS collaboration and also facilitated the development, dissemination, and use of the UMLS Knowledge Sources. The spread of the World Wide Web has increased the visibility of the information access problems caused by multiple vocabularies and many information sources which are the focus of UMLS work. The time is propitious for building on UMLS accomplishments and making more progress on the informatics research issues first highlighted by the UMLS project more than 10 years ago.

Spontaneous cortical activity alternates between motifs defined by regional axonal projections

PubMed Central

Mohajerani, Majid H.; Chan, Allen W.; Mohsenvand, Mostafa; LeDue, Jeffrey; Liu, Rui; McVea, David A.; Boyd, Jamie D.; Wang, Yu Tian; Reimers, Mark; Murphy, Timothy H.

2014-01-01

In lightly anaesthetized or awake adult mice using millisecond timescale voltage sensitive dye imaging, we show that a palette of sensory-evoked and hemisphere-wide activity motifs are represented in spontaneous activity. These motifs can reflect multiple modes of sensory processing including vision, audition, and touch. Similar cortical networks were found with direct cortical activation using channelrhodopsin-2. Regional analysis of activity spread indicated modality specific sources such as primary sensory areas, and a common posterior-medial cortical sink where sensory activity was extinguished within the parietal association area, and a secondary anterior medial sink within the cingulate/secondary motor cortices for visual stimuli. Correlation analysis between functional circuits and intracortical axonal projections indicated a common framework corresponding to long-range mono-synaptic connections between cortical regions. Maps of intracortical mono-synaptic structural connections predicted hemisphere-wide patterns of spontaneous and sensory-evoked depolarization. We suggest that an intracortical monosynaptic connectome shapes the ebb and flow of spontaneous cortical activity. PMID:23974708

Parsing learning in networks using brain-machine interfaces.

PubMed

Orsborn, Amy L; Pesaran, Bijan

2017-10-01

Brain-machine interfaces (BMIs) define new ways to interact with our environment and hold great promise for clinical therapies. Motor BMIs, for instance, re-route neural activity to control movements of a new effector and could restore movement to people with paralysis. Increasing experience shows that interfacing with the brain inevitably changes the brain. BMIs engage and depend on a wide array of innate learning mechanisms to produce meaningful behavior. BMIs precisely define the information streams into and out of the brain, but engage wide-spread learning. We take a network perspective and review existing observations of learning in motor BMIs to show that BMIs engage multiple learning mechanisms distributed across neural networks. Recent studies demonstrate the advantages of BMI for parsing this learning and its underlying neural mechanisms. BMIs therefore provide a powerful tool for studying the neural mechanisms of learning that highlights the critical role of learning in engineered neural therapies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Design Sketches For Optical Crossbar Switches Intended For Large-Scale Parallel Processing Applications

NASA Astrophysics Data System (ADS)

Hartmann, Alfred; Redfield, Steve

1989-04-01

This paper discusses design of large-scale (1000x 1000) optical crossbar switching networks for use in parallel processing supercom-puters. Alternative design sketches for an optical crossbar switching network are presented using free-space optical transmission with either a beam spreading/masking model or a beam steering model for internodal communications. The performances of alternative multiple access channel communications protocol-unslotted and slotted ALOHA and carrier sense multiple access (CSMA)-are compared with the performance of the classic arbitrated bus crossbar of conventional electronic parallel computing. These comparisons indicate an almost inverse relationship between ease of implementation and speed of operation. Practical issues of optical system design are addressed, and an optically addressed, composite spatial light modulator design is presented for fabrication to arbitrarily large scale. The wide range of switch architecture, communications protocol, optical systems design, device fabrication, and system performance problems presented by these design sketches poses a serious challenge to practical exploitation of highly parallel optical interconnects in advanced computer designs.

Mid-latitude spread-F structure

NASA Astrophysics Data System (ADS)

Meehan, D. H.; From, W. R.

1988-07-01

Observations of spread-F at frequencies of 1.98, 3.84, and 5.80 MHz and multiple angles of arrival have been obtained with an HF radar near Brisbane. It is suggested that the spreading of the ionogram trace is due to a spread in the arrival angles of echoes, and that the reflection process may involve total specular reflection rather than scattering. The results indicate that the structure cannot be purely frontal with purely linear movement. The velocities are found to be much less than for coexisting traveling ionospheric disturbances.

Effects of multiple spreaders in community networks

NASA Astrophysics Data System (ADS)

Hu, Zhao-Long; Ren, Zhuo-Ming; Yang, Guang-Yong; Liu, Jian-Guo

2014-12-01

Human contact networks exhibit the community structure. Understanding how such community structure affects the epidemic spreading could provide insights for preventing the spreading of epidemics between communities. In this paper, we explore the spreading of multiple spreaders in community networks. A network based on the clustering preferential mechanism is evolved, whose communities are detected by the Girvan-Newman (GN) algorithm. We investigate the spreading effectiveness by selecting the nodes as spreaders in the following ways: nodes with the largest degree in each community (community hubs), the same number of nodes with the largest degree from the global network (global large-degree) and randomly selected one node within each community (community random). The experimental results on the SIR model show that the spreading effectiveness based on the global large-degree and community hubs methods is the same in the early stage of the infection and the method of community random is the worst. However, when the infection rate exceeds the critical value, the global large-degree method embodies the worst spreading effectiveness. Furthermore, the discrepancy of effectiveness for the three methods will decrease as the infection rate increases. Therefore, we should immunize the hubs in each community rather than those hubs in the global network to prevent the outbreak of epidemics.

Demography and Intercontinental Spread of the USA300 Community-Acquired Methicillin-Resistant Staphylococcus aureus Lineage

PubMed Central

Glaser, Philippe; Martins-Simões, Patrícia; Villain, Adrien; Barbier, Maxime; Tristan, Anne; Bouchier, Christiane; Ma, Laurence; Bes, Michele; Laurent, Frederic; Guillemot, Didier; Wirth, Thierry

2016-01-01

ABSTRACT Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was recognized worldwide during the 1990s; in less than a decade, several genetically distinct CA-MRSA lineages carrying Panton-Valentine leukocidin genes have emerged on every continent. Most notably, in the United States, the sequence type 18-IV (ST8-IV) clone known as USA300 has become highly prevalent, outcompeting methicillin-susceptible S. aureus (MSSA) and other MRSA strains in both community and hospital settings. CA-MRSA bacteria are much less prevalent in Europe, where the European ST80-IV European CA-MRSA clone, USA300 CA-MRSA strains, and other lineages, such as ST22-IV, coexist. The question that arises is whether the USA300 CA-MRSA present in Europe (i) was imported once or on very few occasions, followed by a broad geographic spread, anticipating an increased prevalence in the future, or (ii) derived from multiple importations with limited spreading success. In the present study, we applied whole-genome sequencing to a collection of French USA300 CA-MRSA strains responsible for sporadic cases and micro-outbreaks over the past decade and United States ST8 MSSA and MRSA isolates. Genome-wide phylogenetic analysis demonstrated that the population structure of the French isolates is the product of multiple introductions dating back to the onset of the USA300 CA-MRSA clone in North America. Coalescent-based demography of the USA300 lineage shows that a strong expansion occurred during the 1990s concomitant with the acquisition of the arginine catabolic mobile element and antibiotic resistance, followed by a sharp decline initiated around 2008, reminiscent of the rise-and-fall pattern previously observed in the ST80 lineage. A future expansion of the USA300 lineage in Europe is therefore very unlikely. PMID:26884428

Multiple alignment analysis on phylogenetic tree of the spread of SARS epidemic using distance method

NASA Astrophysics Data System (ADS)

Amiroch, S.; Pradana, M. S.; Irawan, M. I.; Mukhlash, I.

2017-09-01

Multiple Alignment (MA) is a particularly important tool for studying the viral genome and determine the evolutionary process of the specific virus. Application of MA in the case of the spread of the Severe acute respiratory syndrome (SARS) epidemic is an interesting thing because this virus epidemic a few years ago spread so quickly that medical attention in many countries. Although there has been a lot of software to process multiple sequences, but the use of pairwise alignment to process MA is very important to consider. In previous research, the alignment between the sequences to process MA algorithm, Super Pairwise Alignment, but in this study used a dynamic programming algorithm Needleman wunchs simulated in Matlab. From the analysis of MA obtained and stable region and unstable which indicates the position where the mutation occurs, the system network topology that produced the phylogenetic tree of the SARS epidemic distance method, and system area networks mutation.

Distribution and establishment of the alien Australian redclaw crayfish, Cherax quadricarinatus, in South Africa and Swaziland

PubMed Central

Zengeya, Tsungai A.; Hoffman, Andries C.; Measey, G. John; Weyl, Olaf L.F.

2017-01-01

Background The Australian redclaw crayfish (Cherax quadricarinatus, von Martens), is native to Australasia, but has been widely translocated around the world due to aquaculture and aquarium trade. Mostly as a result of escape from aquaculture facilities, this species has established extralimital populations in Australia and alien populations in Europe, Asia, Central America and Africa. In South Africa, C. quadricarinatus was first sampled from the wild in 2002 in the Komati River, following its escape from an aquaculture facility in Swaziland, but data on the current status of its populations are not available. Methods To establish a better understanding of its distribution, rate of spread and population status, we surveyed a total of 46 sites in various river systems in South Africa and Swaziland. Surveys were performed between September 2015 and August 2016 and involved visual observations and the use of collapsible crayfish traps. Results Cherax quadricarinatus is now present in the Komati, Lomati, Mbuluzi, Mlawula and Usutu rivers, and it was also detected in several off-channel irrigation impoundments. Where present, it was generally abundant, with populations having multiple size cohorts and containing ovigerous females. In the Komati River, it has spread more than 112 km downstream of the initial introduction point and 33 km upstream of a tributary, resulting in a mean spread rate of 8 km year−1 downstream and 4.7 km year−1 upstream. In Swaziland, estimated downstream spread rate might reach 14.6 km year−1. Individuals were generally larger and heavier closer to the introduction site, which might be linked to juvenile dispersal. Discussion These findings demonstrate that C. quadricarinatus is established in South Africa and Swaziland and that the species has spread, not only within the river where it was first introduced, but also between rivers. Considering the strong impacts that alien crayfish usually have on invaded ecosystems, assessments of its potential impacts on native freshwater biota and an evaluation of possible control measures are, therefore, urgent requirements. PMID:28439454

Genome-wide selective sweeps and gene-specific sweeps in natural bacterial populations

DOE PAGES

Bendall, Matthew L.; Stevens, Sarah L.R.; Chan, Leong-Keat; ...

2016-01-08

Multiple models describe the formation and evolution of distinct microbial phylogenetic groups. These evolutionary models make different predictions regarding how adaptive alleles spread through populations and how genetic diversity is maintained. Processes predicted by competing evolutionary models, for example, genome-wide selective sweeps vs gene-specific sweeps, could be captured in natural populations using time-series metagenomics if the approach were applied over a sufficiently long time frame. Direct observations of either process would help resolve how distinct microbial groups evolve. Using a 9-year metagenomic study of a freshwater lake (2005–2013), we explore changes in single-nucleotide polymorphism (SNP) frequencies and patterns of genemore » gain and loss in 30 bacterial populations. SNP analyses revealed substantial genetic heterogeneity within these populations, although the degree of heterogeneity varied by >1000-fold among populations. SNP allele frequencies also changed dramatically over time within some populations. Interestingly, nearly all SNP variants were slowly purged over several years from one population of green sulfur bacteria, while at the same time multiple genes either swept through or were lost from this population. Furthermore, these patterns were consistent with a genome-wide selective sweep in progress, a process predicted by the ‘ecotype model’ of speciation but not previously observed in nature. In contrast, other populations contained large, SNP-free genomic regions that appear to have swept independently through the populations prior to the study without purging diversity elsewhere in the genome. Finally, evidence for both genome-wide and gene-specific sweeps suggests that different models of bacterial speciation may apply to different populations coexisting in the same environment.« less

Environmental Spread of New Delhi Metallo-β-Lactamase-1-Producing Multidrug-Resistant Bacteria in Dhaka, Bangladesh

PubMed Central

Islam, Moydul; Hasan, Rashedul; Hossain, M. Iqbal; Nabi, Ashikun; Rahman, Mahdia; Goessens, Wil H. F.; Endtz, Hubert P.; Faruque, Shah M.

2017-01-01

ABSTRACT Resistance to carbapenem antibiotics through the production of New Delhi metallo-β-lactamase-1 (NDM-1) constitutes an emerging challenge in the treatment of bacterial infections. To monitor the possible source of the spread of these organisms in Dhaka, Bangladesh, we conducted a comparative analysis of wastewater samples from hospital-adjacent areas (HAR) and from community areas (COM), as well as public tap water samples, for the occurrence and characteristics of NDM-1-producing bacteria. Of 72 HAR samples tested, 51 (71%) samples were positive for NDM-1-producing bacteria, as evidenced by phenotypic tests and the presence of the blaNDM-1 gene, compared to 5 of 41 (12.1%) samples from COM samples (P < 0.001). All tap water samples were negative for NDM-1-producing bacteria. Klebsiella pneumoniae (44%) was the predominant bacterial species among blaNDM-1-positive isolates, followed by Escherichia coli (29%), Acinetobacter spp. (15%), and Enterobacter spp. (9%). These bacteria were also positive for one or more other antibiotic resistance genes, including blaCTX-M-1 (80%), blaCTX-M-15 (63%), blaTEM (76%), blaSHV (33%), blaCMY-2 (16%), blaOXA-48-like (2%), blaOXA-1 (53%), and blaOXA-47-like (60%) genes. Around 40% of the isolates contained a qnr gene, while 50% had 16S rRNA methylase genes. The majority of isolates hosted multiple plasmids, and plasmids of 30 to 50 MDa carrying blaNDM-1 were self-transmissible. Our results highlight a number of issues related to the characteristics and source of spread of multidrug-resistant bacteria as a potential public health threat. In view of the existing practice of discharging untreated liquid waste into the environment, hospitals in Dhaka city contribute to the potential dissemination of NDM-1-producing bacteria into the community. IMPORTANCE Infections caused by carbapenemase-producing Enterobacteriaceae are extremely difficult to manage due to their marked resistance to a wide range of antibiotics. NDM-1 is the most recently described carbapenemase, and the blaNDM-1 gene, which encodes NDM-1, is located on self-transmissible plasmids that also carry a considerable number of other antibiotic resistance genes. The present study shows a high prevalence of NDM-1-producing organisms in the wastewater samples from hospital-adjacent areas as a potential source for the spread of these organisms to community areas in Dhaka, Bangladesh. The study also examines the characteristics of the isolates and their potential to horizontally transmit the resistance determinants. The significance of our research is in identifying the mode of spread of multiple-antibiotic-resistant organisms, which will allow the development of containment measures, leading to broader impacts in reducing their spread to the community. PMID:28526792

Aerial dispersal and multiple-scale spread of epidemics

USDA-ARS?s Scientific Manuscript database

Disease spread has traditionally been described as a traveling wave of constant velocity. However, aerially dispersed pathogens capable of long distance dispersal (LDD) often have dispersal gradients with extended tails that could result in acceleration of the epidemic front over time and space. W...

HF band filter bank multi-carrier spread spectrum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laraway, Stephen Andrew; Moradi, Hussein; Farhang-Boroujeny, Behrouz

Abstract—This paper describes modifications to the filter bank multicarrier spread spectrum (FB-MC-SS) system, that was presented in [1] and [2], to enable transmission of this waveform in the HF skywave channel. FB-MC-SS is well suited for the HF channel because it performs well in channels with frequency selective fading and interference. This paper describes new algorithms for packet detection, timing recovery and equalization that are suitable for the HF channel. Also, an algorithm for optimizing the peak to average power ratio (PAPR) of the FBMC- SS waveform is presented. Application of this algorithm results in a waveform with low PAPR.more » Simulation results using a wide band HF channel model demonstrate the robustness of this system over a wide range of delay and Doppler spreads.« less

Cooperative behavior cascades in human social networks

PubMed Central

Fowler, James H.; Christakis, Nicholas A.

2010-01-01

Theoretical models suggest that social networks influence the evolution of cooperation, but to date there have been few experimental studies. Observational data suggest that a wide variety of behaviors may spread in human social networks, but subjects in such studies can choose to befriend people with similar behaviors, posing difficulty for causal inference. Here, we exploit a seminal set of laboratory experiments that originally showed that voluntary costly punishment can help sustain cooperation. In these experiments, subjects were randomly assigned to a sequence of different groups to play a series of single-shot public goods games with strangers; this feature allowed us to draw networks of interactions to explore how cooperative and uncooperative behaviors spread from person to person to person. We show that, in both an ordinary public goods game and in a public goods game with punishment, focal individuals are influenced by fellow group members’ contribution behavior in future interactions with other individuals who were not a party to the initial interaction. Furthermore, this influence persists for multiple periods and spreads up to three degrees of separation (from person to person to person to person). The results suggest that each additional contribution a subject makes to the public good in the first period is tripled over the course of the experiment by other subjects who are directly or indirectly influenced to contribute more as a consequence. These results show experimentally that cooperative behavior cascades in human social networks. PMID:20212120

Pharmacological targeting of spreading depression in migraine

PubMed Central

Eikermann-Haerter, Katharina; Can, Anil; Ayata, Cenk

2012-01-01

Migraine, particularly with aura, is a genetically heterogeneous disorder of ion channels, pumps or transporters associated with increased cortical excitability. Spreading depression, as one reflection of hyperexcitability, is the electrophysiological event underlying aura symptoms and a trigger for headache. Endogenous (e.g., genes and hormones) and exogenous factors (e.g., drugs) modulating migraine susceptibility have also been shown to modulate spreading depression susceptibility concordantly, suggesting that spreading depression can be a relevant therapeutic target in migraine. In support of this, several migraine prophylactic drugs used in clinical practice have been shown to suppress spreading depression susceptibility as a probable mechanism of action, despite belonging to widely different pharmacological classes. Hence, susceptibility to spreading depression can be a useful preclinical model with good positive and negative predictive value for drug screening. PMID:22364328

Development and application of a novel genome-wide SNP array reveals domestication history in soybean

PubMed Central

Wang, Jiao; Chu, Shanshan; Zhang, Huairen; Zhu, Ying; Cheng, Hao; Yu, Deyue

2016-01-01

Domestication of soybeans occurred under the intense human-directed selections aimed at developing high-yielding lines. Tracing the domestication history and identifying the genes underlying soybean domestication require further exploration. Here, we developed a high-throughput NJAU 355 K SoySNP array and used this array to study the genetic variation patterns in 367 soybean accessions, including 105 wild soybeans and 262 cultivated soybeans. The population genetic analysis suggests that cultivated soybeans have tended to originate from northern and central China, from where they spread to other regions, accompanied with a gradual increase in seed weight. Genome-wide scanning for evidence of artificial selection revealed signs of selective sweeps involving genes controlling domestication-related agronomic traits including seed weight. To further identify genomic regions related to seed weight, a genome-wide association study (GWAS) was conducted across multiple environments in wild and cultivated soybeans. As a result, a strong linkage disequilibrium region on chromosome 20 was found to be significantly correlated with seed weight in cultivated soybeans. Collectively, these findings should provide an important basis for genomic-enabled breeding and advance the study of functional genomics in soybean. PMID:26856884

Development and application of a novel genome-wide SNP array reveals domestication history in soybean.

PubMed

Wang, Jiao; Chu, Shanshan; Zhang, Huairen; Zhu, Ying; Cheng, Hao; Yu, Deyue

2016-02-09

Domestication of soybeans occurred under the intense human-directed selections aimed at developing high-yielding lines. Tracing the domestication history and identifying the genes underlying soybean domestication require further exploration. Here, we developed a high-throughput NJAU 355 K SoySNP array and used this array to study the genetic variation patterns in 367 soybean accessions, including 105 wild soybeans and 262 cultivated soybeans. The population genetic analysis suggests that cultivated soybeans have tended to originate from northern and central China, from where they spread to other regions, accompanied with a gradual increase in seed weight. Genome-wide scanning for evidence of artificial selection revealed signs of selective sweeps involving genes controlling domestication-related agronomic traits including seed weight. To further identify genomic regions related to seed weight, a genome-wide association study (GWAS) was conducted across multiple environments in wild and cultivated soybeans. As a result, a strong linkage disequilibrium region on chromosome 20 was found to be significantly correlated with seed weight in cultivated soybeans. Collectively, these findings should provide an important basis for genomic-enabled breeding and advance the study of functional genomics in soybean.

Why is CDMA the solution for mobile satellite communication

NASA Technical Reports Server (NTRS)

Gilhousen, Klein S.; Jacobs, Irwin M.; Padovani, Roberto; Weaver, Lindsay A.

1989-01-01

It is demonstrated that spread spectrum Code Division Multiple Access (CDMA) systems provide an economically superior solution to satellite mobile communications by increasing the system maximum capacity with respect to single channel per carrier Frequency Division Multiple Access (FDMA) systems. Following the comparative analysis of CDMA and FDMA systems, the design of a model that was developed to test the feasibility of the approach and the performance of a spread spectrum system in a mobile environment. Results of extensive computer simulations as well as laboratory and field tests results are presented.

Shock-induced bubble jetting into a viscous fluid with application to tissue injury in shock-wave lithotripsy.

PubMed

Freund, J B; Shukla, R K; Evan, A P

2009-11-01

Shock waves in liquids are known to cause spherical gas bubbles to rapidly collapse and form strong re-entrant jets in the direction of the propagating shock. The interaction of these jets with an adjacent viscous liquid is investigated using finite-volume simulation methods. This configuration serves as a model for tissue injury during shock-wave lithotripsy, a medical procedure to remove kidney stones. In this case, the viscous fluid provides a crude model for the tissue. It is found that for viscosities comparable to what might be expected in tissue, the jet that forms upon collapse of a small bubble fails to penetrate deeply into the viscous fluid "tissue." A simple model reproduces the penetration distance versus viscosity observed in the simulations and leads to a phenomenological model for the spreading of injury with multiple shocks. For a reasonable selection of a single efficiency parameter, this model is able to reproduce in vivo observations of an apparent 1000-shock threshold before wide-spread tissue injury occurs in targeted kidneys and the approximate extent of this injury after a typical clinical dose of 2000 shock waves.

Shock-induced bubble jetting into a viscous fluid with application to tissue injury in shock-wave lithotripsy

PubMed Central

Freund, J. B.; Shukla, R. K.; Evan, A. P.

2009-01-01

Shock waves in liquids are known to cause spherical gas bubbles to rapidly collapse and form strong re-entrant jets in the direction of the propagating shock. The interaction of these jets with an adjacent viscous liquid is investigated using finite-volume simulation methods. This configuration serves as a model for tissue injury during shock-wave lithotripsy, a medical procedure to remove kidney stones. In this case, the viscous fluid provides a crude model for the tissue. It is found that for viscosities comparable to what might be expected in tissue, the jet that forms upon collapse of a small bubble fails to penetrate deeply into the viscous fluid “tissue.” A simple model reproduces the penetration distance versus viscosity observed in the simulations and leads to a phenomenological model for the spreading of injury with multiple shocks. For a reasonable selection of a single efficiency parameter, this model is able to reproduce in vivo observations of an apparent 1000-shock threshold before wide-spread tissue injury occurs in targeted kidneys and the approximate extent of this injury after a typical clinical dose of 2000 shock waves. PMID:19894850

Enclaves of genetic diversity resisted Inca impacts on population history.

PubMed

Barbieri, Chiara; Sandoval, José R; Valqui, Jairo; Shimelman, Aviva; Ziemendorff, Stefan; Schröder, Roland; Geppert, Maria; Roewer, Lutz; Gray, Russell; Stoneking, Mark; Fujita, Ricardo; Heggarty, Paul

2017-12-12

The Inca Empire is claimed to have driven massive population movements in western South America, and to have spread Quechua, the most widely-spoken language family of the indigenous Americas. A test-case is the Chachapoyas region of northern Peru, reported as a focal point of Inca population displacements. Chachapoyas also spans the environmental, cultural and demographic divides between Amazonia and the Andes, and stands along the lowest-altitude corridor from the rainforest to the Pacific coast. Following a sampling strategy informed by linguistic data, we collected 119 samples, analysed for full mtDNA genomes and Y-chromosome STRs. We report a high indigenous component, which stands apart from the network of intense genetic exchange in the core central zone of Andean civilization, and is also distinct from neighbouring populations. This unique genetic profile challenges the routine assumption of large-scale population relocations by the Incas. Furthermore, speakers of Chachapoyas Quechua are found to share no particular genetic similarity or gene-flow with Quechua speakers elsewhere, suggesting that here the language spread primarily by cultural diffusion, not migration. Our results demonstrate how population genetics, when fully guided by the archaeological, historical and linguistic records, can inform multiple disciplines within anthropology.

Comparison of Direct Sequence Spread Spectrum Rake Receiver with a Maximum Ratio Combining Multicarrier Spread Spectrum Receiver

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daryl Leon Wasden; Hussein Moradi; Behrouz Farhang-Broujeny

2014-06-01

This paper presents a theoretical analysis of the performance of a filter bank-based multicarrier spread spectrum (FB-MC-SS) system. We consider an FB-MC-SS setup where each data symbol is spread across multiple subcarriers, but there is no spreading in time. The results are then compared with those of the well-known direct sequence spread spectrum (DS-SS) system with a rake receiver for its best performance. We compare the two systems when the channel noise is white. We prove that as the processing gains of the two systems tend to infinity both approach the same performance. However, numerical simulations show that, in practice,more » where processing gain is limited, FB-MC-SS outperforms DS-SS.« less

Consequences of Rift Propagation for Spreading in Thick Oceanic Crust in Iceland

NASA Astrophysics Data System (ADS)

Karson, J. A.

2015-12-01

Iceland has long been considered a natural laboratory for processes related to seafloor spreading, including propagating rifts, migrating transforms and rotating microplates. The thick, hot, weak crust and subaerial processes of Iceland result in variations on the themes developed along more typical parts of the global MOR system. Compared to most other parts of the MOR, Icelandic rift zones and transform faults are wider and more complex. Rift zones are defined by overlapping arrays of volcanic/tectonic spreading segments as much as 50 km wide. The most active rift zones propagate N and S away from the Iceland hot spot causing migration of transform faults. A trail of crust deformed by bookshelf faulting forms in their wakes. Dead or dying transform strands are truncated along pseudofaults that define propagation rates close to the full spreading rate of ~20 mm/yr. Pseudofaults are blurred by spreading across wide rift zones and laterally extensive subaerial lava flows. Propagation, with decreasing spreading toward the propagator tips causes rotation of crustal blocks on both sides of the active rift zones. The blocks deform internally by the widespread reactivation of spreading-related faults and zones of weakness along dike margins. The sense of slip on these rift-parallel strike-slip faults is inconsistent with transform-fault deformation. These various deformation features as well as subaxial subsidence that accommodate the thickening of the volcanic upper crustal units are probably confined to the brittle, seismogenic, upper 10 km of the crust. At least beneath the active rift zones, the upper crust is probably decoupled from hot, mechanically weak middle and lower gabbroic crust resulting in a broad plate boundary zone between the diverging lithosphere plates. Similar processes may occur at other types of propagating spreading centers and magmatic rifts.

Disentangling invasion processes in a dynamic shipping-boating network.

PubMed

Lacoursière-Roussel, Anaïs; Bock, Dan G; Cristescu, Melania E; Guichard, Frédéric; Girard, Philippe; Legendre, Pierre; McKindsey, Christopher W

2012-09-01

The relative importance of multiple vectors to the initial establishment, spread and population dynamics of invasive species remains poorly understood. This study used molecular methods to clarify the roles of commercial shipping and recreational boating in the invasion by the cosmopolitan tunicate, Botryllus schlosseri. We evaluated (i) single vs. multiple introduction scenarios, (ii) the relative importance of shipping and boating to primary introductions, (iii) the interaction between these vectors for spread (i.e. the presence of a shipping-boating network) and (iv) the role of boating in determining population similarity. Tunicates were sampled from 26 populations along the Nova Scotia, Canada, coast that were exposed to either shipping (i.e. ports) or boating (i.e. marinas) activities. A total of 874 individuals (c. 30 per population) from five ports and 21 marinas was collected and analysed using both mitochondrial cytochrome c oxidase subunit I gene (COI) and 10 nuclear microsatellite markers. The geographical location of multiple hotspot populations indicates that multiple invasions have occurred in Nova Scotia. A loss of genetic diversity from port to marina populations suggests a stronger influence of ships than recreational boats on primary coastal introductions. Population genetic similarity analysis reveals a dependence of marina populations on those that had been previously established in ports. Empirical data on marina connectivity because of boating better explains patterns in population similarities than does natural spread. We conclude that frequent primary introductions arise by ships and that secondary spread occurs gradually thereafter around individual ports, facilitated by recreational boating. © 2012 Blackwell Publishing Ltd.

The search for multiple populations in Magellanic Cloud Clusters IV: Coeval multiple stellar populations in the young star cluster NGC 1978

NASA Astrophysics Data System (ADS)

Martocchia, S.; Niederhofer, F.; Dalessandro, E.; Bastian, N.; Kacharov, N.; Usher, C.; Cabrera-Ziri, I.; Lardo, C.; Cassisi, S.; Geisler, D.; Hilker, M.; Hollyhead, K.; Kozhurina-Platais, V.; Larsen, S.; Mackey, D.; Mucciarelli, A.; Platais, I.; Salaris, M.

2018-04-01

We have recently shown that the ˜2 Gyr old Large Magellanic Cloud star cluster NGC 1978 hosts multiple populations in terms of star-to-star abundance variations in [N/Fe]. These can be seen as a splitting or spread in the sub-giant and red giant branches (SGB and RGB) when certain photometric filter combinations are used. Due to its relative youth, NGC 1978 can be used to place stringent limits on whether multiple bursts of star-formation have taken place within the cluster, as predicted by some models for the origin of multiple populations. We carry out two distinct analyses to test whether multiple star-formation epochs have occurred within NGC 1978. First, we use UV CMDs to select stars from the first and second population along the SGB, and then compare their positions in optical CMDs, where the morphology is dominantly controlled by age as opposed to multiple population effects. We find that the two populations are indistinguishable, with age differences of 1 ± 20 Myr between them. This is in tension with predictions from the AGB scenario for the origin of multiple populations. Second, we estimate the broadness of the main sequence turnoff (MSTO) of NGC 1978 and we report that it is consistent with the observational errors. We find an upper limit of ˜65 Myr on the age spread in the MSTO of NGC 1978. This finding is in conflict with the age spread scenario as origin of the extendend MSTO in intermediate age clusters, while it fully supports predictions from the stellar rotation model.

The search for multiple populations in Magellanic Cloud clusters - IV. Coeval multiple stellar populations in the young star cluster NGC 1978

NASA Astrophysics Data System (ADS)

Martocchia, S.; Niederhofer, F.; Dalessandro, E.; Bastian, N.; Kacharov, N.; Usher, C.; Cabrera-Ziri, I.; Lardo, C.; Cassisi, S.; Geisler, D.; Hilker, M.; Hollyhead, K.; Kozhurina-Platais, V.; Larsen, S.; Mackey, D.; Mucciarelli, A.; Platais, I.; Salaris, M.

2018-07-01

We have recently shown that the ˜2 Gyr old Large Magellanic Cloud star cluster NGC 1978 hosts multiple populations in terms of star-to-star abundance variations in [N/Fe]. These can be seen as a splitting or spread in the subgiant and red giant branches (SGB and RGB) when certain photometric filter combinations are used. Because of its relative youth, NGC 1978 can be used to place stringent limits on whether multiple bursts of star formation have taken place within the cluster, as predicted by some models for the origin of multiple populations. We carry out two distinct analyses to test whether multiple star formation epochs have occurred within NGC 1978. First, we use ultraviolet colour-magnitude diagrams (CMDs) to select stars from the first and second population along the SGB, and then compare their positions in optical CMDs, where the morphology is dominantly controlled by age as opposed to multiple population effects. We find that the two populations are indistinguishable, with age differences of 1 ± 20 Myr between them. This is in tension with predictions from the asymptotic giant branch scenario for the origin of multiple populations. Second, we estimate the broadness of the main-sequence turn-off (MSTO) of NGC 1978 and we report that it is consistent with the observational errors. We find an upper limit of ˜65 Myr on the age spread in the MSTO of NGC 1978. This finding is in conflict with the age spread scenario as origin of the extended MSTO in intermediate-age clusters, while it fully supports predictions from the stellar rotation model.

Strain Partitioning and Accumulation across Overlapping Spreading Centers: Geodetic GPS Measurements in South Iceland

NASA Astrophysics Data System (ADS)

La Femina, P. C.; Dixon, T. H.; Malservisi, R.; Árnadóttir, T.; Sigmundsson, F.; Sturkell, E.

2004-12-01

Overlapping spreading centers (OSCs) and propagating ridges are important classes of mid-ocean ridges. Kinematic models of OSCs predict along strike variability in spreading rate associated with the propagation of one center and deactivation of the other. Iceland offers a unique opportunity to investigate strain accumulation and partitioning across slow, overlapping spreading centers, and the influence of a ridge centered hotspot on ridge kinematics and morphology. We present results of detailed GPS observations across the Eastern and Western Volcanic Zones, south Iceland, spanning a seven to nine year inter-rifting period, and compare our observations with two-dimensional elastic half-space models that simulate the long-term spreading process. We then compare the elastic half-space models with simple viscoelastic coupling models. We model three velocity profiles across the EVZ-WVZ system, solving for the spreading rate, locking depth and horizontal location of each spreading center. Our spreading rate estimates indicate along strike variations as expected in an OSC system and total spreading rates consistent with geodetic and geologic plate motion models. Spreading rates in the WVZ increase from northeast (3 ±1 mm/yr) to southwest (7 ±1 mm/yr). Spreading rates in the southwest propagating EVZ decrease from northeast (17 ±1 mm/yr) to southwest (12 ±1 mm/yr). These results are consistent with a model whereby the WVZ is deactivating in the direction of EVZ propagation. The morphology of the two spreading centers reflects the spreading rate differences and their location relative to the Iceland hotspot. The predicted locations of the spreading axis for each zone are consistent with mapped Holocene fissure swarms. The neovolcanic zone of the slower WVZ consists of a narrow (10-20 km wide) axial graben and has had few Holocene eruptions. The faster EVZ consists of two parallel neovolcanic zones separated by a 20 km gap of inactivity, little normal faulting, higher topography and five historical fissure eruptions, reflecting its proximity to the hotspot. The maximum velocity gradient in the EVZ is located on the Veidivotn fissure swarm, which had a small volume eruption in 1864. The last major fissure eruption in the EVZ was the 1783 Lakagigar, located 20 km to the east. This pattern of current and past strain accumulation and release suggests intra-ridge jumping of activity and crustal accretion across a 60 km wide area.

Spreading Activation in an Attractor Network with Latching Dynamics: Automatic Semantic Priming Revisited

ERIC Educational Resources Information Center

Lerner, Itamar; Bentin, Shlomo; Shriki, Oren

2012-01-01

Localist models of spreading activation (SA) and models assuming distributed representations offer very different takes on semantic priming, a widely investigated paradigm in word recognition and semantic memory research. In this study, we implemented SA in an attractor neural network model with distributed representations and created a unified…

Reformulation of Rothermel's wildland fire behaviour model for heterogeneous fuelbeds.

Treesearch

David V. Sandberg; Cynthia L. Riccardi; Mark D. Schaaf

2007-01-01

Abstract: The Fuel Characteristic Classification System (FCCS) includes equations that calculate energy release and one-dimensional spread rate in quasi-steady-state fires in heterogeneous but spatially uniform wildland fuelbeds, using a reformulation of the widely used Rothermel fire spread model. This reformulation provides an automated means to predict fire behavior...

Simulating the epidemiological and economic effects of an African swine fever epidemic in industrialized swine populations.

PubMed

Halasa, Tariq; Bøtner, Anette; Mortensen, Sten; Christensen, Hanne; Toft, Nils; Boklund, Anette

2016-09-25

African swine fever (ASF) is a notifiable infectious disease with a considerable impact on animal health and is currently one of the most important emerging diseases of domestic pigs. ASF was introduced into Georgia in 2007 and subsequently spread to the Russian Federation and several Eastern European countries. Consequently, there is a non-negligible risk of ASF spread towards Western Europe. Therefore it is important to develop tools to improve our understanding of the spread and control of ASF for contingency planning. A stochastic and dynamic spatial spread model (DTU-DADS) was adjusted to simulate the spread of ASF virus between domestic swine herds exemplified by the Danish swine population. ASF was simulated to spread via animal movement, low- or medium-risk contacts and local spread. Each epidemic was initiated in a randomly selected herd - either in a nucleus herd, a sow herd, a randomly selected herd or in multiple herds simultaneously. A sensitivity analysis was conducted on input parameters. Given the inputs and assumptions of the model, epidemics of ASF in Denmark are predicted to be small, affecting about 14 herds in the worst-case scenario. The duration of an epidemic is predicted to vary from 1 to 76days. Substantial economic damages are predicted, with median direct costs and export losses of €12 and €349 million, respectively, when epidemics were initiated in multiple herds. Each infectious herd resulted in 0 to 2 new infected herds varying from 0 to 5 new infected herds, depending on the index herd type. Copyright © 2016 Elsevier B.V. All rights reserved.

RNA silencing in the life cycle of soybean: multiple restriction systems and spatiotemporal variation associated with plant architecture.

PubMed

Mori, Ayumi; Sato, Hiroshi; Kasai, Megumi; Yamada, Tetsuya; Kanazawa, Akira

2017-06-01

The expression of transgenes introduced into a plant genome is sometimes suppressed by RNA silencing. Although local and systemic spread of RNA silencing have been studied, little is known about the mechanisms underlying spatial and temporal variation in transgene silencing between individual plants or between plants of different generations, which occurs seemingly stochastically. Here, we analyzed the occurrence, spread, and transmission of RNA silencing of the green fluorescent protein (GFP) gene over multiple generations of the progeny of a single soybean transformant. Observation of GFP fluorescence in entire plants of the T 3 -T 5 generations indicated that the initiation and subsequent spread of GFP silencing varied between individuals, although this GFP silencing most frequently began in the primary leaves. In addition, GFP silencing could spread into the outer layer of seed coat tissues but was hardly detectable in the embryos. These results are consistent with the notion that transgene silencing involves its reset during reproductive phase, initiation after germination, and systemic spread in each generation. GFP silencing was absent in the pulvinus, suggesting that its cortical cells inhibit cell-to-cell spread or induction of RNA silencing. The extent of GFP silencing could differ between the stem and a petiole or between petiolules, which have limited vascular bundles connecting them and thus deter long-distant movement of silencing. Taken together, these observations indicate that the initiation and/or spread of RNA silencing depend on specific features of the architecture of the plant in addition to the mechanisms that can be conserved in higher plants.

Spreading to localized targets in complex networks

NASA Astrophysics Data System (ADS)

Sun, Ye; Ma, Long; Zeng, An; Wang, Wen-Xu

2016-12-01

As an important type of dynamics on complex networks, spreading is widely used to model many real processes such as the epidemic contagion and information propagation. One of the most significant research questions in spreading is to rank the spreading ability of nodes in the network. To this end, substantial effort has been made and a variety of effective methods have been proposed. These methods usually define the spreading ability of a node as the number of finally infected nodes given that the spreading is initialized from the node. However, in many real cases such as advertising and news propagation, the spreading only aims to cover a specific group of nodes. Therefore, it is necessary to study the spreading ability of nodes towards localized targets in complex networks. In this paper, we propose a reversed local path algorithm for this problem. Simulation results show that our method outperforms the existing methods in identifying the influential nodes with respect to these localized targets. Moreover, the influential spreaders identified by our method can effectively avoid infecting the non-target nodes in the spreading process.

Epidemic dynamics and endemic states in complex networks

NASA Astrophysics Data System (ADS)

Pastor-Satorras, Romualdo; Vespignani, Alessandro

2001-06-01

We study by analytical methods and large scale simulations a dynamical model for the spreading of epidemics in complex networks. In networks with exponentially bounded connectivity we recover the usual epidemic behavior with a threshold defining a critical point below that the infection prevalence is null. On the contrary, on a wide range of scale-free networks we observe the absence of an epidemic threshold and its associated critical behavior. This implies that scale-free networks are prone to the spreading and the persistence of infections whatever spreading rate the epidemic agents might possess. These results can help understanding computer virus epidemics and other spreading phenomena on communication and social networks.

Recording, analysis, and interpretation of spreading depolarizations in neurointensive care: Review and recommendations of the COSBID research group.

PubMed

Dreier, Jens P; Fabricius, Martin; Ayata, Cenk; Sakowitz, Oliver W; William Shuttleworth, C; Dohmen, Christian; Graf, Rudolf; Vajkoczy, Peter; Helbok, Raimund; Suzuki, Michiyasu; Schiefecker, Alois J; Major, Sebastian; Winkler, Maren Kl; Kang, Eun-Jeung; Milakara, Denny; Oliveira-Ferreira, Ana I; Reiffurth, Clemens; Revankar, Gajanan S; Sugimoto, Kazutaka; Dengler, Nora F; Hecht, Nils; Foreman, Brandon; Feyen, Bart; Kondziella, Daniel; Friberg, Christian K; Piilgaard, Henning; Rosenthal, Eric S; Westover, M Brandon; Maslarova, Anna; Santos, Edgar; Hertle, Daniel; Sánchez-Porras, Renán; Jewell, Sharon L; Balança, Baptiste; Platz, Johannes; Hinzman, Jason M; Lückl, Janos; Schoknecht, Karl; Schöll, Michael; Drenckhahn, Christoph; Feuerstein, Delphine; Eriksen, Nina; Horst, Viktor; Bretz, Julia S; Jahnke, Paul; Scheel, Michael; Bohner, Georg; Rostrup, Egill; Pakkenberg, Bente; Heinemann, Uwe; Claassen, Jan; Carlson, Andrew P; Kowoll, Christina M; Lublinsky, Svetlana; Chassidim, Yoash; Shelef, Ilan; Friedman, Alon; Brinker, Gerrit; Reiner, Michael; Kirov, Sergei A; Andrew, R David; Farkas, Eszter; Güresir, Erdem; Vatter, Hartmut; Chung, Lee S; Brennan, K C; Lieutaud, Thomas; Marinesco, Stephane; Maas, Andrew Ir; Sahuquillo, Juan; Dahlem, Markus A; Richter, Frank; Herreras, Oscar; Boutelle, Martyn G; Okonkwo, David O; Bullock, M Ross; Witte, Otto W; Martus, Peter; van den Maagdenberg, Arn Mjm; Ferrari, Michel D; Dijkhuizen, Rick M; Shutter, Lori A; Andaluz, Norberto; Schulte, André P; MacVicar, Brian; Watanabe, Tomas; Woitzik, Johannes; Lauritzen, Martin; Strong, Anthony J; Hartings, Jed A

2017-05-01

Spreading depolarizations (SD) are waves of abrupt, near-complete breakdown of neuronal transmembrane ion gradients, are the largest possible pathophysiologic disruption of viable cerebral gray matter, and are a crucial mechanism of lesion development. Spreading depolarizations are increasingly recorded during multimodal neuromonitoring in neurocritical care as a causal biomarker providing a diagnostic summary measure of metabolic failure and excitotoxic injury. Focal ischemia causes spreading depolarization within minutes. Further spreading depolarizations arise for hours to days due to energy supply-demand mismatch in viable tissue. Spreading depolarizations exacerbate neuronal injury through prolonged ionic breakdown and spreading depolarization-related hypoperfusion (spreading ischemia). Local duration of the depolarization indicates local tissue energy status and risk of injury. Regional electrocorticographic monitoring affords even remote detection of injury because spreading depolarizations propagate widely from ischemic or metabolically stressed zones; characteristic patterns, including temporal clusters of spreading depolarizations and persistent depression of spontaneous cortical activity, can be recognized and quantified. Here, we describe the experimental basis for interpreting these patterns and illustrate their translation to human disease. We further provide consensus recommendations for electrocorticographic methods to record, classify, and score spreading depolarizations and associated spreading depressions. These methods offer distinct advantages over other neuromonitoring modalities and allow for future refinement through less invasive and more automated approaches.

Recording, analysis, and interpretation of spreading depolarizations in neurointensive care: Review and recommendations of the COSBID research group

PubMed Central

Fabricius, Martin; Ayata, Cenk; Sakowitz, Oliver W; William Shuttleworth, C; Dohmen, Christian; Graf, Rudolf; Vajkoczy, Peter; Helbok, Raimund; Suzuki, Michiyasu; Schiefecker, Alois J; Major, Sebastian; Winkler, Maren KL; Kang, Eun-Jeung; Milakara, Denny; Oliveira-Ferreira, Ana I; Reiffurth, Clemens; Revankar, Gajanan S; Sugimoto, Kazutaka; Dengler, Nora F; Hecht, Nils; Foreman, Brandon; Feyen, Bart; Kondziella, Daniel; Friberg, Christian K; Piilgaard, Henning; Rosenthal, Eric S; Westover, M Brandon; Maslarova, Anna; Santos, Edgar; Hertle, Daniel; Sánchez-Porras, Renán; Jewell, Sharon L; Balança, Baptiste; Platz, Johannes; Hinzman, Jason M; Lückl, Janos; Schoknecht, Karl; Schöll, Michael; Drenckhahn, Christoph; Feuerstein, Delphine; Eriksen, Nina; Horst, Viktor; Bretz, Julia S; Jahnke, Paul; Scheel, Michael; Bohner, Georg; Rostrup, Egill; Pakkenberg, Bente; Heinemann, Uwe; Claassen, Jan; Carlson, Andrew P; Kowoll, Christina M; Lublinsky, Svetlana; Chassidim, Yoash; Shelef, Ilan; Friedman, Alon; Brinker, Gerrit; Reiner, Michael; Kirov, Sergei A; Andrew, R David; Farkas, Eszter; Güresir, Erdem; Vatter, Hartmut; Chung, Lee S; Brennan, KC; Lieutaud, Thomas; Marinesco, Stephane; Maas, Andrew IR; Sahuquillo, Juan; Dahlem, Markus A; Richter, Frank; Herreras, Oscar; Boutelle, Martyn G; Okonkwo, David O; Bullock, M Ross; Witte, Otto W; Martus, Peter; van den Maagdenberg, Arn MJM; Ferrari, Michel D; Dijkhuizen, Rick M; Shutter, Lori A; Andaluz, Norberto; Schulte, André P; MacVicar, Brian; Watanabe, Tomas; Woitzik, Johannes; Lauritzen, Martin; Strong, Anthony J; Hartings, Jed A

2016-01-01

Spreading depolarizations (SD) are waves of abrupt, near-complete breakdown of neuronal transmembrane ion gradients, are the largest possible pathophysiologic disruption of viable cerebral gray matter, and are a crucial mechanism of lesion development. Spreading depolarizations are increasingly recorded during multimodal neuromonitoring in neurocritical care as a causal biomarker providing a diagnostic summary measure of metabolic failure and excitotoxic injury. Focal ischemia causes spreading depolarization within minutes. Further spreading depolarizations arise for hours to days due to energy supply-demand mismatch in viable tissue. Spreading depolarizations exacerbate neuronal injury through prolonged ionic breakdown and spreading depolarization-related hypoperfusion (spreading ischemia). Local duration of the depolarization indicates local tissue energy status and risk of injury. Regional electrocorticographic monitoring affords even remote detection of injury because spreading depolarizations propagate widely from ischemic or metabolically stressed zones; characteristic patterns, including temporal clusters of spreading depolarizations and persistent depression of spontaneous cortical activity, can be recognized and quantified. Here, we describe the experimental basis for interpreting these patterns and illustrate their translation to human disease. We further provide consensus recommendations for electrocorticographic methods to record, classify, and score spreading depolarizations and associated spreading depressions. These methods offer distinct advantages over other neuromonitoring modalities and allow for future refinement through less invasive and more automated approaches. PMID:27317657

Aldosterone mediates metastatic spread of renal cancer via the G protein-coupled estrogen receptor (GPER).

PubMed

Feldman, Ross D; Ding, Qingming; Hussain, Yasin; Limbird, Lee E; Pickering, J Geoffrey; Gros, Robert

2016-06-01

Although aldosterone is a known regulator of renal and cardiovascular function, its role as a regulator of cancer growth and spread has not been widely considered. This study tested the hypothesis that aldosterone regulates cancer cell growth/spread via G protein-coupled estrogen receptor (GPER) activation. In vitro in murine renal cortical adenocarcinoma (RENCA) cells, a widely used murine in vitro model for the study of renal cell adenocarcinoma, aldosterone increased RENCA cell proliferation to a maximum of 125 ± 3% of control at a concentration of 10 nM, an effect blocked by the GPER antagonist G15 or by GPER knockdown using short interfering (sh) RNA techniques. Further, aldosterone increased RENCA cell migration to a maximum of 170 ± 20% of control at a concentration of 100 nM, an effect also blocked by G15 or by GPER down-regulation. In vivo, after orthotopic RENCA cell renal transplantation, pulmonary tumor spread was inhibited by pharmacologic blockade of aldosterone effects with spironolactone (percentage of lung occupied by metastasis: control = 68 ± 13, spironolactone = 26 ± 8, P < 0.05) or inhibition of aldosterone synthesis with a high dietary salt diet (percentage of lung: control = 44 ± 6, high salt = 12 ± 3, P < 0.05), without reducing primary tumor size. Additionally, adrenalectomy significantly reduced the extent of pulmonary tumor spread, whereas aldosterone infusion recovered pulmonary metastatic spread toward baseline levels. Finally, inhibition of GPER either with the GPER antagonist G15 or by GPER knockdown comparably inhibited RENCA cell pulmonary metastatic cancer spread. Taken together, these findings provide strong evidence for aldosterone serving a causal role in renal cell cancer regulation via its GPER receptor; thus, antagonism of GPER represents a potential new target for treatment to reduce metastatic spread.-Feldman, R. D., Ding, Q., Hussain, Y., Limbird, L. E., Pickering, J. G., Gros, R. Aldosterone mediates metastatic spread of renal cancer via the G protein-coupled estrogen receptor (GPER). © FASEB.

Coastal river plumes: Collisions and coalescence

USGS Publications Warehouse

Warrick, Jonathan; Farnsworth, Katherine L

2017-01-01

Plumes of buoyant river water spread in the ocean from river mouths, and these plumes influence water quality, sediment dispersal, primary productivity, and circulation along the world’s coasts. Most investigations of river plumes have focused on large rivers in a coastal region, for which the physical spreading of the plume is assumed to be independent from the influence of other buoyant plumes. Here we provide new understanding of the spreading patterns of multiple plumes interacting along simplified coastal settings by investigating: (i) the relative likelihood of plume-to-plume interactions at different settings using geophysical scaling, (ii) the diversity of plume frontal collision types and the effects of these collisions on spreading patterns of plume waters using a two-dimensional hydrodynamic model, and (iii) the fundamental differences in plume spreading patterns between coasts with single and multiple rivers using a three-dimensional hydrodynamic model. Geophysical scaling suggests that coastal margins with numerous small rivers (watershed areas < 10,000 km2), such as found along most active geologic coastal margins, were much more likely to have river plumes that collide and interact than coastal settings with large rivers (watershed areas > 100,000 km2). When two plume fronts meet, several types of collision attributes were found, including refection, subduction and occlusion. We found that the relative differences in pre-collision plume densities and thicknesses strongly influenced the resulting collision types. The three-dimensional spreading of buoyant plumes was found to be influenced by the presence of additional rivers for all modeled scenarios, including those with and without Coriolis and wind. Combined, these results suggest that plume-to-plume interactions are common phenomena for coastal regions offshore of the world’s smaller rivers and for coastal settings with multiple river mouths in close proximity, and that the spreading and fate of river waters in these settings will be strongly influenced by these interactions. We conclude that new investigations are needed to characterize how plumes interact offshore of river mouths to better understand the transport and fate of terrestrial sources of pollution, nutrients and other materials in the ocean.

Oxygen availability and spreading depolarizations provide complementary prognostic information in neuromonitoring of aneurysmal subarachnoid hemorrhage patients.

PubMed

Winkler, Maren Kl; Dengler, Nora; Hecht, Nils; Hartings, Jed A; Kang, Eun J; Major, Sebastian; Martus, Peter; Vajkoczy, Peter; Woitzik, Johannes; Dreier, Jens P

2017-05-01

Multimodal neuromonitoring in neurocritical care increasingly includes electrocorticography to measure epileptic events and spreading depolarizations. Spreading depolarization causes spreading depression of activity (=isoelectricity) in electrically active tissue. If the depression is long-lasting, further spreading depolarizations occur in still isoelectric tissue where no activity can be suppressed. Such spreading depolarizations are termed isoelectric and are assumed to indicate energy compromise. However, experimental and clinical recordings suggest that long-lasting spreading depolarization-induced depression and isoelectric spreading depolarizations are often recorded outside of the actual ischemic zones, allowing the remote diagnosis of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage. Here, we analyzed simultaneous electrocorticography and tissue partial pressure of oxygen recording in 33 aneurysmal subarachnoid hemorrhage patients. Multiple regression showed that both peak total depression duration per recording day and mean baseline tissue partial pressure of oxygen were independent predictors of outcome. Moreover, tissue partial pressure of oxygen preceding spreading depolarization was similar and differences in tissue partial pressure of oxygen responses to spreading depolarization were only subtle between isoelectric spreading depolarizations and spreading depressions. This further supports that, similar to clustering of spreading depolarizations, long spreading depolarization-induced periods of isoelectricity are useful to detect energy compromise remotely, which is valuable because the exact location of future developing pathology is unknown at the time when the neurosurgeon implants recording devices.

Effect of multiple circular holes Fraunhofer diffraction for the infrared optical imaging

NASA Astrophysics Data System (ADS)

Lu, Chunlian; Lv, He; Cao, Yang; Cai, Zhisong; Tan, Xiaojun

2014-11-01

With the development of infrared optics, infrared optical imaging systems play an increasingly important role in modern optical imaging systems. Infrared optical imaging is used in industry, agriculture, medical, military and transportation. But in terms of infrared optical imaging systems which are exposed for a long time, some contaminations will affect the infrared optical imaging. When the contamination contaminate on the lens surface of the optical system, it would affect diffraction. The lens can be seen as complementary multiple circular holes screen happen Fraunhofer diffraction. According to Babinet principle, you can get the diffraction of the imaging system. Therefore, by studying the multiple circular holes Fraunhofer diffraction, conclusions can be drawn about the effect of infrared imaging. This paper mainly studies the effect of multiple circular holes Fraunhofer diffraction for the optical imaging. Firstly, we introduce the theory of Fraunhofer diffraction and Point Spread Function. Point Spread Function is a basic tool to evaluate the image quality of the optical system. Fraunhofer diffraction will affect Point Spread Function. Then, the results of multiple circular holes Fraunhofer diffraction are given for different hole size and hole spacing. We choose the hole size from 0.1mm to 1mm and hole spacing from 0.3mm to 0.8mm. The infrared wavebands of optical imaging are chosen from 1μm to 5μm. We use the MATLAB to simulate light intensity distribution of multiple circular holes Fraunhofer diffraction. Finally, three-dimensional diffraction maps of light intensity are given to contrast.

Complex social contagion makes networks more vulnerable to disease outbreaks.

PubMed

Campbell, Ellsworth; Salathé, Marcel

2013-01-01

Social network analysis is now widely used to investigate the dynamics of infectious disease spread. Vaccination dramatically disrupts disease transmission on a contact network, and indeed, high vaccination rates can potentially halt disease transmission altogether. Here, we build on mounting evidence that health behaviors - such as vaccination, and refusal thereof - can spread across social networks through a process of complex contagion that requires social reinforcement. Using network simulations that model health behavior and infectious disease spread, we find that under otherwise identical conditions, the process by which the health behavior spreads has a very strong effect on disease outbreak dynamics. This dynamic variability results from differences in the topology within susceptible communities that arise during the health behavior spreading process, which in turn depends on the topology of the overall social network. Our findings point to the importance of health behavior spread in predicting and controlling disease outbreaks.

Emergence and Spread of New Races of Wheat Stem Rust Fungus: Continued Threat to Food Security and Prospects of Genetic Control.

PubMed

Singh, Ravi P; Hodson, David P; Jin, Yue; Lagudah, Evans S; Ayliffe, Michael A; Bhavani, Sridhar; Rouse, Matthew N; Pretorius, Zacharias A; Szabo, Les J; Huerta-Espino, Julio; Basnet, Bhoja R; Lan, Caixia; Hovmøller, Mogens S

2015-07-01

Race Ug99 (TTKSK) of Puccinia graminis f. sp. tritici, detected in Uganda in 1998, has been recognized as a serious threat to food security because it possesses combined virulence to a large number of resistance genes found in current widely grown wheat (Triticum aestivum) varieties and germplasm, leading to its potential for rapid spread and evolution. Since its initial detection, variants of the Ug99 lineage of stem rust have been discovered in Eastern and Southern African countries, Yemen, Iran, and Egypt. To date, eight races belonging to the Ug99 lineage are known. Increased pathogen monitoring activities have led to the identification of other races in Africa and Asia with additional virulence to commercially important resistance genes. This has led to localized but severe stem rust epidemics becoming common once again in East Africa due to the breakdown of race-specific resistance gene SrTmp, which was deployed recently in the 'Digalu' and 'Robin' varieties in Ethiopia and Kenya, respectively. Enhanced research in the last decade under the umbrella of the Borlaug Global Rust Initiative has identified various race-specific resistance genes that can be utilized, preferably in combinations, to develop resistant varieties. Research and development of improved wheat germplasm with complex adult plant resistance (APR) based on multiple slow-rusting genes has also progressed. Once only the Sr2 gene was known to confer slow rusting APR; now, four more genes-Sr55, Sr56, Sr57, and Sr58-have been characterized and additional quantitative trait loci identified. Cloning of some rust resistance genes opens new perspectives on rust control in the future through the development of multiple resistance gene cassettes. However, at present, disease-surveillance-based chemical control, large-scale deployment of new varieties with multiple race-specific genes or adequate levels of APR, and reducing the cultivation of susceptible varieties in rust hot-spot areas remains the best stem rust management strategy.

Multiple Signal Classification for Determining Direction of Arrival of Frequency Hopping Spread Spectrum Signals

DTIC Science & Technology

2014-03-27

42 4.2.3 Number of Hops Hs . . . . . . . . . . . . . . . . . . . . . . . . . 45 4.2.4 Number of Sensors M... 45 4.5 Standard deviation vs. Ns. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 4.6 Bias...laboratory MTM multiple taper method MUSIC multiple signal classification MVDR minimum variance distortionless reposnse PSK phase shift keying QAM

Effect of Heterogeneous Interest Similarity on the Spread of Information in Mobile Social Networks

NASA Astrophysics Data System (ADS)

Zhao, Narisa; Sui, Guoqin; Yang, Fan

2018-06-01

Mobile social networks (MSNs) are important platforms for spreading news. The fact that individuals usually forward information aligned with their own interests inevitably changes the dynamics of information spread. Thereby, first we present a theoretical model based on the discrete Markov chain and mean field theory to evaluate the effect of interest similarity on the information spread in MSNs. Meanwhile, individuals' interests are heterogeneous and vary with time. These two features result in interest shift behavior, and both features are considered in our model. A leveraging simulation demonstrates the accuracy of our model. Moreover, the basic reproduction number R0 is determined. Further extensive numerical analyses based on the model indicate that interest similarity has a critical impact on information spread at the early spreading stage. Specifically, the information always spreads more quickly and widely if the interest similarity between an individual and the information is higher. Finally, five actual data sets from Sina Weibo illustrate the validity of the model.

Development of an Inverse Algorithm for Resonance Inspection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lai, Canhai; Xu, Wei; Sun, Xin

2012-10-01

Resonance inspection (RI), which employs the natural frequency spectra shift between the good and the anomalous part populations to detect defects, is a non-destructive evaluation (NDE) technique with many advantages such as low inspection cost, high testing speed, and broad applicability to structures with complex geometry compared to other contemporary NDE methods. It has already been widely used in the automobile industry for quality inspections of safety critical parts. Unlike some conventionally used NDE methods, the current RI technology is unable to provide details, i.e. location, dimension, or types, of the flaws for the discrepant parts. Such limitation severely hindersmore » its wide spread applications and further development. In this study, an inverse RI algorithm based on maximum correlation function is proposed to quantify the location and size of flaws for a discrepant part. A dog-bone shaped stainless steel sample with and without controlled flaws are used for algorithm development and validation. The results show that multiple flaws can be accurately pinpointed back using the algorithms developed, and the prediction accuracy decreases with increasing flaw numbers and decreasing distance between flaws.« less

[Second opinion clinic: is the Web Babel Syndrome treatable?].

PubMed

Palmieri, B; Iannitti, T; Capone, S; Fistetto, G; Arisi, E

2011-01-01

The term "second opinion" has been widely used, since the 70's in the American hospitals with the aim of reducing the skyrocketing costs of the patients' healthcare, improving their diagnosis, the patient's care and his healing process at the same time. In this paper, after a short review of the "second opinion" impact on different medical fields, we give the reasons why, nowadays, patients are strongly addressed towards a second opinion seeking behaviour. In fact, due to the spreading of the world wide web, the patient can obtain any kind of medical information, even if it is an unqualified one. This fact leads the patient to carry out an obsessive search that can result in confusion and disorientation. We have defined this psychological distress the "Web Babel Syndrome". Building upon these foundations, we strongly support a "second opinion medical clinic" that can face the patient's needs and help those patients with impending single or multiple unresolved illnesses. They need a multispecialty diagnostic or therapeutic medical or surgical approach in order to heal properly or achieve a better quality of life.

A mathematical model for predicting fire spread in wildland fuels

Treesearch

Richard C. Rothermel

1972-01-01

A mathematical fire model for predicting rate of spread and intensity that is applicable to a wide range of wildland fuels and environment is presented. Methods of incorporating mixtures of fuel sizes are introduced by weighting input parameters by surface area. The input parameters do not require a prior knowledge of the burning characteristics of the fuel.

Multiple data sets and modelling choices in a comparative LCA of disposable beverage cups.

PubMed

van der Harst, Eugenie; Potting, José; Kroeze, Carolien

2014-10-01

This study used multiple data sets and modelling choices in an environmental life cycle assessment (LCA) to compare typical disposable beverage cups made from polystyrene (PS), polylactic acid (PLA; bioplastic) and paper lined with bioplastic (biopaper). Incineration and recycling were considered as waste processing options, and for the PLA and biopaper cup also composting and anaerobic digestion. Multiple data sets and modelling choices were systematically used to calculate average results and the spread in results for each disposable cup in eleven impact categories. The LCA results of all combinations of data sets and modelling choices consistently identify three processes that dominate the environmental impact: (1) production of the cup's basic material (PS, PLA, biopaper), (2) cup manufacturing, and (3) waste processing. The large spread in results for impact categories strongly overlaps among the cups, however, and therefore does not allow a preference for one type of cup material. Comparison of the individual waste treatment options suggests some cautious preferences. The average waste treatment results indicate that recycling is the preferred option for PLA cups, followed by anaerobic digestion and incineration. Recycling is slightly preferred over incineration for the biopaper cups. There is no preferred waste treatment option for the PS cups. Taking into account the spread in waste treatment results for all cups, however, none of these preferences for waste processing options can be justified. The only exception is composting, which is least preferred for both PLA and biopaper cups. Our study illustrates that using multiple data sets and modelling choices can lead to considerable spread in LCA results. This makes comparing products more complex, but the outcomes more robust. Copyright © 2014 Elsevier B.V. All rights reserved.

Ultrasonic Multiple-Access Ranging System Using Spread Spectrum and MEMS Technology for Indoor Localization

PubMed Central

Segers, Laurent; Tiete, Jelmer; Braeken, An; Touhafi, Abdellah

2014-01-01

Indoor localization of persons and objects poses a great engineering challenge. Previously developed localization systems demonstrate the use of wideband techniques in ultrasound ranging systems. Direct sequence and frequency hopping spread spectrum ultrasound signals have been proven to achieve a high level of accuracy. A novel ranging method using the frequency hopping spread spectrum with finite impulse response filtering will be investigated and compared against the direct sequence spread spectrum. In the first setup, distances are estimated in a single-access environment, while in the second setup, two senders and one receiver are used. During the experiments, the micro-electromechanical systems are used as ultrasonic sensors, while the senders were implemented using field programmable gate arrays. Results show that in a single-access environment, the direct sequence spread spectrum method offers slightly better accuracy and precision performance compared to the frequency hopping spread spectrum. When two senders are used, measurements point out that the frequency hopping spread spectrum is more robust to near-far effects than the direct sequence spread spectrum. PMID:24553084

Flame Spread Along Free Edges of Thermally Thin Samples in Microgravity

NASA Technical Reports Server (NTRS)

Mell, W. E.; Olson, S. L.; Kashiwagi, T.

2000-01-01

The effects of imposed flow velocity on flame spread along open edges of a thermally thin cellulosic sample in microgravity are studied experimentally and theoretically. In this study, the sample is ignited locally at the middle of the 4 cm wide sample and subsequent flame spread reaches both open edges of the sample. The following flame behaviors are observed in the experiments and predicted by the numerical calculation; in order of increased imposed flow velocity: (1) ignition but subsequent flame spread is not attained, (2) flame spreads upstream (opposed mode) without any downstream flame, and (3) the upstream flame and two separate downstream flames traveling along the two open edges (concurrent mode). Generally, the upstream and downstream edge flame spread rates are faster than the central flame spread rate for an imposed flow velocity of up to 5 cm/s. This is due to greater oxygen supply from the outer free stream to the edge flames than the central flames, For the upstream edge flame, the greater oxygen supply results in a flame spread rate that is nearly independent of, or decreases gradually, with the imposed flow velocity. The spread rate of the downstream edge, however, increases significantly with the imposed flow velocity.

Roles of the spreading scope and effectiveness in spreading dynamics on multiplex networks

NASA Astrophysics Data System (ADS)

Li, Ming; Liu, Run-Ran; Peng, Dan; Jia, Chun-Xiao; Wang, Bing-Hong

2018-02-01

Comparing with single networks, the multiplex networks bring two main effects on the spreading process among individuals. First, the pathogen or information can be transmitted to more individuals through different layers at one time, which enlarges the spreading scope. Second, through different layers, an individual can also transmit the pathogen or information to the same individuals more than once at one time, which makes the spreading more effective. To understand the different roles of the spreading scope and effectiveness, we propose an epidemic model on multiplex networks with link overlapping, where the spreading effectiveness of each interaction as well as the variety of channels (spreading scope) can be controlled by the number of overlapping links. We find that for Poisson degree distribution, increasing the epidemic scope (the first effect) is more efficient than enhancing epidemic probability (the second effect) to facilitate the spreading process. However, for power-law degree distribution, the effects of the two factors on the spreading dynamics become complicated. Enhancing epidemic probability makes pathogen or rumor easier to outbreak in a finite system. But after that increasing epidemic scopes is still more effective for a wide spreading. Theoretical results along with reasonable explanation for these phenomena are all given in this paper, which indicates that the epidemic scope could play an important role in the spreading dynamics.

Payment for multiple forest benefits alters the effect of tree disease on optimal forest rotation length.

PubMed

Macpherson, Morag F; Kleczkowski, Adam; Healey, John R; Hanley, Nick

2017-04-01

Forests deliver multiple benefits both to their owners and to wider society. However, a wave of forest pests and pathogens is threatening this worldwide. In this paper we examine the effect of disease on the optimal rotation length of a single-aged, single rotation forest when a payment for non-timber benefits, which is offered to private forest owners to partly internalise the social values of forest management, is included. Using a generalisable bioeconomic framework we show how this payment counteracts the negative economic effect of disease by increasing the optimal rotation length, and under some restrictive conditions, even makes it optimal to never harvest the forest. The analysis shows a range of complex interactions between factors including the rate of spread of infection and the impact of disease on the value of harvested timber and non-timber benefits. A key result is that the effect of disease on the optimal rotation length is dependent on whether the disease affects the timber benefit only compared to when it affects both timber and non-timber benefits. Our framework can be extended to incorporate multiple ecosystem services delivered by forests and details of how disease can affect their production, thus facilitating a wide range of applications.

Computational Study of Droplet Trains Impacting a Smooth Solid Surface

NASA Astrophysics Data System (ADS)

Markt, David, Jr.; Pathak, Ashish; Raessi, Mehdi; Lee, Seong-Young; Zhao, Emma

2017-11-01

The study of droplet impingement is vital to understanding the fluid dynamics of fuel injection in modern internal combustion engines. One widely accepted model was proposed by Yarin and Weiss (JFM, 1995), developed from experiments of single trains of ethanol droplets impacting a substrate. The model predicts the onset of splashing and the mass ejected upon splashing. In this study, using an in-house 3D multiphase flow solver, the experiments of Yarin and Weiss were computationally simulated. The experimentally observed splashing threshold was captured by the simulations, thus validating the solver's ability to accurately simulate the splashing dynamics. Then, we performed simulations of cases with multiple droplet trains, which have high relevance to dense fuel sprays, where droplets impact within the spreading diameters of their neighboring droplets, leading to changes in splashing dynamics due to interactions of spreading films. For both single and multi-train simulations the amount of splashed mass was calculated as a function of time, allowing a quantitative comparison between the two cases. Furthermore, using a passive scalar the amount of splashed mass per impinging droplet was also calculated. This work is supported by the Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) and the Department of Defense, Tank and Automotive Research, Development, and Engineering Center (TARDEC), under Award Number DE-EE0007292.

Influence of solidification on the impact of supercooled water drops onto cold surfaces

NASA Astrophysics Data System (ADS)

Li, Hai; Roisman, Ilia V.; Tropea, Cameron

2015-06-01

This study presents an experimental investigation of the impact of a supercooled drop onto hydrophilic and superhydrophobic substrates. The aim is to better understand the process of airframe icing caused by supercooled large droplets, which has been recently identified as a severe hazard in aviation. The Weber number and Reynolds number of the impinging drop ranged from 200 to 300 and from 2600 to 5800, respectively. Drop impact, spreading, and rebound were observed using a high-speed video system. The maximum spreading diameter of an impacting drop on hydrophilic surfaces was measured. The temperature effect on this parameter was only minor for a wide range of the drop and substrate temperatures. However, ice/water mixtures emerged when both the drop and substrate temperatures were below 0 °C. Similarly, drop rebound on superhydrophobic substrates was significantly hindered by solidification when supercooled drop impacted onto substrates below the freezing point. The minimum receding diameter and the speed of ice accretion on the substrate were measured for various wall temperatures. Both parameters increased almost linearly with decreasing wall temperature, but eventually leveled off beyond a certain substrate temperature. The rate of ice formation on the substrate was significantly higher than the growth rate of free ice dendrites, implying that multiple nucleation sites were present.

An epidemiological model of internet worms with hierarchical dispersal and spatial clustering of hosts.

PubMed

Hiebeler, David E; Audibert, Andrew; Strubell, Emma; Michaud, Isaac J

2017-04-07

Beginning in 2001, many instances of malicious software known as Internet worms have been using biological strategies such as hierarchical dispersal to seek out and spread to new susceptible hosts more efficiently. We measured the distribution of potentially susceptible hosts in the space of Internet addresses to determine their clustering. We have used the results to construct a full-size simulated Internet with 2 32 hosts with mean and variance of susceptible hosts chosen to match our measurements at multiple spatial scales. Epidemiological simulations of outbreaks among the roughly 2.8×10 6 susceptible hosts on this full-sized network show that local preference scanning greatly increases the chances for an infected host to locate and infect other susceptible hosts by a factor of as much as several hundred. However, once deploying this strategy, the overall success of a worm is relatively insensitive to the details of its dispersal strategy over a wide range of parameters. In addition, although using localized interactions may allow malicious software to spread more rapidly or to more hosts on average, it can also lead to increased variability in infection levels among replicate simulations. Using such dispersal strategies may therefore be a high risk, high reward strategy for the authors of such software. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dynamic Neurovascular Coupling and Uncoupling during Ictal Onset, Propagation, and Termination Revealed by Simultaneous In Vivo Optical Imaging of Neural Activity and Local Blood Volume

PubMed Central

Zhao, Mingrui; Schwartz, Theodore H.

2013-01-01

Traditional models of ictal propagation involve the concept of an initiation site and a progressive outward march of activation. The process of neurovascular coupling, whereby the brain supplies oxygenated blood to metabolically active neurons presumably results in a similar outward cascade of hyperemia. However, ictal neurovascular coupling has never been assessed in vivo using simultaneous measurements of membrane potential change and hyperemia with wide spatial sampling. In an acute rat ictal model, using simultaneous intrinsic optical signal (IOS) and voltage-sensitive dye (VSD) imaging of cerebral blood volume and membrane potential changes, we demonstrate that seizures consist of multiple dynamic multidirectional waves of membrane potential change with variable onset sites that spread through a widespread network. Local blood volume evolves on a much slower spatiotemporal scale. At seizure onset, the VSD waves extend beyond the IOS signal. During evolution, spatial correlation with hemodynamic signal only exists briefly at the maximal spread of the VSD signal. At termination, the IOS signal extends spatially and temporally beyond the VSD waves. Hence, vascular reactivity evolves in a separate but parallel fashion to membrane potential changes resulting in a mechanism of neurovascular coupling and uncoupling, which is as dynamic as the seizure itself. PMID:22499798

Multiple origins of resistance-conferring mutations in Plasmodium vivax dihydrofolate reductase

PubMed Central

Hawkins, Vivian N; Auliff, Alyson; Prajapati, Surendra Kumar; Rungsihirunrat, Kanchana; Hapuarachchi, Hapuarachchige C; Maestre, Amanda; O'Neil, Michael T; Cheng, Qin; Joshi, Hema; Na-Bangchang, Kesara; Sibley, Carol Hopkins

2008-01-01

Background In order to maximize the useful therapeutic life of antimalarial drugs, it is crucial to understand the mechanisms by which parasites resistant to antimalarial drugs are selected and spread in natural populations. Recent work has demonstrated that pyrimethamine-resistance conferring mutations in Plasmodium falciparum dihydrofolate reductase (dhfr) have arisen rarely de novo, but spread widely in Asia and Africa. The origin and spread of mutations in Plasmodium vivax dhfr were assessed by constructing haplotypes based on sequencing dhfr and its flanking regions. Methods The P. vivax dhfr coding region, 792 bp upstream and 683 bp downstream were amplified and sequenced from 137 contemporary patient isolates from Colombia, India, Indonesia, Papua New Guinea, Sri Lanka, Thailand, and Vanuatu. A repeat motif located 2.6 kb upstream of dhfr was also sequenced from 75 of 137 patient isolates, and mutational relationships among the haplotypes were visualized using the programme Network. Results Synonymous and non-synonymous single nucleotide polymorphisms (SNPs) within the dhfr coding region were identified, as was the well-documented in-frame insertion/deletion (indel). SNPs were also identified upstream and downstream of dhfr, with an indel and a highly polymorphic repeat region identified upstream of dhfr. The regions flanking dhfr were highly variable. The double mutant (58R/117N) dhfr allele has evolved from several origins, because the 58R is encoded by at least 3 different codons. The triple (58R/61M/117T) and quadruple (57L/61M/117T/173F, 57I/58R/61M/117T and 57L/58R/61M/117T) mutant alleles had at least three independent origins in Thailand, Indonesia, and Papua New Guinea/Vanuatu. Conclusion It was found that the P. vivax dhfr coding region and its flanking intergenic regions are highly polymorphic and that mutations in P. vivax dhfr that confer antifolate resistance have arisen several times in the Asian region. This contrasts sharply with the selective sweep of rare antifolate resistant alleles observed in the P. falciparum populations in Asia and Africa. The finding of multiple origins of resistance-conferring mutations has important implications for drug policy. PMID:18442404

Multiple origins of resistance-conferring mutations in Plasmodium vivax dihydrofolate reductase.

PubMed

Hawkins, Vivian N; Auliff, Alyson; Prajapati, Surendra Kumar; Rungsihirunrat, Kanchana; Hapuarachchi, Hapuarachchige C; Maestre, Amanda; O'Neil, Michael T; Cheng, Qin; Joshi, Hema; Na-Bangchang, Kesara; Sibley, Carol Hopkins

2008-04-28

In order to maximize the useful therapeutic life of antimalarial drugs, it is crucial to understand the mechanisms by which parasites resistant to antimalarial drugs are selected and spread in natural populations. Recent work has demonstrated that pyrimethamine-resistance conferring mutations in Plasmodium falciparum dihydrofolate reductase (dhfr) have arisen rarely de novo, but spread widely in Asia and Africa. The origin and spread of mutations in Plasmodium vivax dhfr were assessed by constructing haplotypes based on sequencing dhfr and its flanking regions. The P. vivax dhfr coding region, 792 bp upstream and 683 bp downstream were amplified and sequenced from 137 contemporary patient isolates from Colombia, India, Indonesia, Papua New Guinea, Sri Lanka, Thailand, and Vanuatu. A repeat motif located 2.6 kb upstream of dhfr was also sequenced from 75 of 137 patient isolates, and mutational relationships among the haplotypes were visualized using the programme Network. Synonymous and non-synonymous single nucleotide polymorphisms (SNPs) within the dhfr coding region were identified, as was the well-documented in-frame insertion/deletion (indel). SNPs were also identified upstream and downstream of dhfr, with an indel and a highly polymorphic repeat region identified upstream of dhfr. The regions flanking dhfr were highly variable. The double mutant (58R/117N) dhfr allele has evolved from several origins, because the 58R is encoded by at least 3 different codons. The triple (58R/61M/117T) and quadruple (57L/61M/117T/173F, 57I/58R/61M/117T and 57L/58R/61M/117T) mutant alleles had at least three independent origins in Thailand, Indonesia, and Papua New Guinea/Vanuatu. It was found that the P. vivax dhfr coding region and its flanking intergenic regions are highly polymorphic and that mutations in P. vivax dhfr that confer antifolate resistance have arisen several times in the Asian region. This contrasts sharply with the selective sweep of rare antifolate resistant alleles observed in the P. falciparum populations in Asia and Africa. The finding of multiple origins of resistance-conferring mutations has important implications for drug policy.

Fast Image Restoration for Spatially Varying Defocus Blur of Imaging Sensor

PubMed Central

Cheong, Hejin; Chae, Eunjung; Lee, Eunsung; Jo, Gwanghyun; Paik, Joonki

2015-01-01

This paper presents a fast adaptive image restoration method for removing spatially varying out-of-focus blur of a general imaging sensor. After estimating the parameters of space-variant point-spread-function (PSF) using the derivative in each uniformly blurred region, the proposed method performs spatially adaptive image restoration by selecting the optimal restoration filter according to the estimated blur parameters. Each restoration filter is implemented in the form of a combination of multiple FIR filters, which guarantees the fast image restoration without the need of iterative or recursive processing. Experimental results show that the proposed method outperforms existing space-invariant restoration methods in the sense of both objective and subjective performance measures. The proposed algorithm can be employed to a wide area of image restoration applications, such as mobile imaging devices, robot vision, and satellite image processing. PMID:25569760

Ancient genomes document multiple waves of migration in Southeast Asian prehistory.

PubMed

Lipson, Mark; Cheronet, Olivia; Mallick, Swapan; Rohland, Nadin; Oxenham, Marc; Pietrusewsky, Michael; Pryce, Thomas Oliver; Willis, Anna; Matsumura, Hirofumi; Buckley, Hallie; Domett, Kate; Hai, Nguyen Giang; Hiep, Trinh Hoang; Kyaw, Aung Aung; Win, Tin Tin; Pradier, Baptiste; Broomandkhoshbacht, Nasreen; Candilio, Francesca; Changmai, Piya; Fernandes, Daniel; Ferry, Matthew; Gamarra, Beatriz; Harney, Eadaoin; Kampuansai, Jatupol; Kutanan, Wibhu; Michel, Megan; Novak, Mario; Oppenheimer, Jonas; Sirak, Kendra; Stewardson, Kristin; Zhang, Zhao; Flegontov, Pavel; Pinhasi, Ron; Reich, David

2018-05-17

Southeast Asia is home to rich human genetic and linguistic diversity, but the details of past population movements in the region are not well known. Here, we report genome-wide ancient DNA data from eighteen Southeast Asian individuals spanning from the Neolithic period through the Iron Age (4100-1700 years ago). Early farmers from Man Bac in Vietnam exhibit a mixture of East Asian (southern Chinese agriculturalist) and deeply diverged eastern Eurasian (hunter-gatherer) ancestry characteristic of Austroasiatic speakers, with similar ancestry as far south as Indonesia providing evidence for an expansive initial spread of Austroasiatic languages. By the Bronze Age, in a parallel pattern to Europe, sites in Vietnam and Myanmar show close connections to present-day majority groups, reflecting substantial additional influxes of migrants. Copyright © 2018, American Association for the Advancement of Science.

Uncertainty quantification in Rothermel's Model using an efficient sampling method

Treesearch

Edwin Jimenez; M. Yousuff Hussaini; Scott L. Goodrick

2007-01-01

The purpose of the present work is to quantify parametric uncertainty in Rothermel’s wildland fire spread model (implemented in software such as BehavePlus3 and FARSITE), which is undoubtedly among the most widely used fire spread models in the United States. This model consists of a nonlinear system of equations that relates environmental variables (input parameter...

Evaluation of English as a Foreign Language and Its Curriculum in Indonesia: A Review

ERIC Educational Resources Information Center

Mappiasse, Sitti Syamsinar; Sihes, Ahmad Johari Bin

2014-01-01

The most widely used language in research, business, politics and other areas of life in our contemporary world is the English language. The exploration of the world by the British people through colonization and their conquest of North America contribute immensely to the spreading of the language. This paper traces the historical spread of…

As Aussie as Vegemite: Building the Capacity of Sustainability Educators in Australia

ERIC Educational Resources Information Center

Smith, Phil; Collier, Grahame; Storey, Hazel

2011-01-01

Vegemite, a thick, rich and salty product made from yeast extract, is a paste commonly spread on bread or toast in Australian households. This iconic product mirrors some of the unique aspects of this country. For example, Vegemite thinly spread is best. The population of this country is sparse across the wide lands, and the Australian environment…

ULTRA-WIDE-FIELD FUNDUS AUTOFLUORESCENCE FINDINGS IN PATIENTS WITH ACUTE ZONAL OCCULT OUTER RETINOPATHY.

PubMed

Shifera, Amde Selassie; Pennesi, Mark E; Yang, Paul; Lin, Phoebe

2017-06-01

To determine whether ultra-wide-field fundus autofluorescence (UWFFAF) findings in acute zonal occult outer retinopathy correlated well with perimetry, optical coherence tomography, and electroretinography findings. Retrospective observational study on 16 eyes of 10 subjects with AZOOR seen at a single referral center from October 2012 to March 2015 who had UWFFAF performed. Chi-square analysis was performed to compare categorical variables, and Mann-Whitney U test used for comparisons of nonparametric continuous variables. All eyes examined within 3 months of symptom onset (five of the five eyes) had diffusely hyperautofluorescent areas on UWFFAF. The remaining eyes contained hypoautofluorescent lesions with hyperautofluorescent borders. In 11/16 (68.8%) eyes, UWFFAF showed the full extent of lesions that would not have been possible with standard fundus autofluorescence centered on the fovea. There were 3 patterns of spread: centrifugal spread (7/16, 43.8%), centripetal spread (5/16, 31.3%), and centrifugal + centripetal spread (4/16, 25.0%). The UWFFAF lesions corresponded well with perimetric, optical coherence tomography, and electroretinography abnormalities. The UWFFAF along with optical coherence tomography can be useful in the evaluation and monitoring of acute zonal occult outer retinopathy patients.

ULTRA-WIDE-FIELD FUNDUS AUTOFLUORESCENCE FINDINGS IN PATIENTS WITH ACUTE ZONAL OCCULT OUTER RETINOPATHY

PubMed Central

Shifera, Amde Selassie; Pennesi, Mark E.; Yang, Paul; Lin, Phoebe

2016-01-01

Purpose To determine if ultra-wide-field fundus autofluorescence (UWFFAF) findings in acute zonal occult outer retinopathy (AZOOR) correlated well with perimetry, optical coherence tomography (OCT), and electroretinography (ERG) findings. Methods Retrospective observational study on 16 eyes of 10 subjects with AZOOR seen at a single referral center from October 2012 to March 2015 who had UWFFAF performed. Chi-square analysis was performed to compare categorical variables and Mann-Whitney U-test used for comparisons of non-parametric continuous variables. Results All eyes examined within 3 months of symptom onset (5 of 5 eyes) had diffusely hyperautofluorescent areas on UWFFAF. The remaining eyes contained hypoautofluorescent lesions with hyperautofluorescent borders. In 11/16 (68.8%) eyes, UWFFAF showed the full extent of lesions that would not have been possible with standard FAF centered on the fovea. There were 3 patterns of spread: centrifugal spread (7/16, 43.8%), centripetal spread (5/16, 31.3%), and centrifugal + centripetal spread (4/16, 25.0%). UWFFAF lesions corresponded well with perimetric, OCT, and ERG abnormalities. Conclusions UWFFAF along with OCT can be useful in the evaluation and monitoring of AZOOR patients. PMID:27755372

Effects of rewiring strategies on information spreading in complex dynamic networks

NASA Astrophysics Data System (ADS)

Ally, Abdulla F.; Zhang, Ning

2018-04-01

Recent advances in networks and communication services have attracted much interest to understand information spreading in social networks. Consequently, numerous studies have been devoted to provide effective and accurate models for mimicking information spreading. However, knowledge on how to spread information faster and more widely remains a contentious issue. Yet, most existing works are based on static networks which limit the reality of dynamism of entities that participate in information spreading. Using the SIR epidemic model, this study explores and compares effects of two rewiring models (Fermi-Dirac and Linear functions) on information spreading in scale free and small world networks. Our results show that for all the rewiring strategies, the spreading influence replenishes with time but stabilizes in a steady state at later time-steps. This means that information spreading takes-off during the initial spreading steps, after which the spreading prevalence settles toward its equilibrium, with majority of the population having recovered and thus, no longer affecting the spreading. Meanwhile, rewiring strategy based on Fermi-Dirac distribution function in one way or another impedes the spreading process, however, the structure of the networks mimic the spreading, even with a low spreading rate. The worst case can be when the spreading rate is extremely small. The results emphasize that despite a big role of such networks in mimicking the spreading, the role of the parameters cannot be simply ignored. Apparently, the probability of giant degree neighbors being informed grows much faster with the rewiring strategy of linear function compared to that of Fermi-Dirac distribution function. Clearly, rewiring model based on linear function generates the fastest spreading across the networks. Therefore, if we are interested in speeding up the spreading process in stochastic modeling, linear function may play a pivotal role.

Disease spread across multiple scales in a spatial hierarchy: effect of host spatial structure and of inoculum quantity and distribution.

PubMed

Gosme, Marie; Lucas, Philippe

2009-07-01

Spatial patterns of both the host and the disease influence disease spread and crop losses. Therefore, the manipulation of these patterns might help improve control strategies. Considering disease spread across multiple scales in a spatial hierarchy allows one to capture important features of epidemics developing in space without using explicitly spatialized variables. Thus, if the system under study is composed of roots, plants, and planting hills, the effect of host spatial pattern can be studied by varying the number of plants per planting hill. A simulation model based on hierarchy theory was used to simulate the effects of large versus small planting hills, low versus high level of initial infections, and aggregated versus uniform distribution of initial infections. The results showed that aggregating the initially infected plants always resulted in slower epidemics than spreading out the initial infections uniformly. Simulation results also showed that, in most cases, disease epidemics were slower in the case of large host aggregates (100 plants/hill) than with smaller aggregates (25 plants/hill), except when the initially infected plants were both numerous and spread out uniformly. The optimal strategy for disease control depends on several factors, including initial conditions. More importantly, the model offers a framework to account for the interplay between the spatial characteristics of the system, rates of infection, and aggregation of the disease.

Investigation of airborne foot-and-mouth disease virus transmission during low-wind conditions in the early phase of the UK 2001 epidemic

NASA Astrophysics Data System (ADS)

Mikkelsen, T.; Alexandersen, S.; Astrup, P.; Champion, H. J.; Donaldson, A. I.; Dunkerley, F. N.; Gloster, J.; Sørensen, J. H.; Thykier-Nielsen, S.

2003-11-01

Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed domesticated and wild animals. The highly contagious nature of FMD is a reflection of the wide range of host species, the enormous quantities of virus liberated by infected animals, the range of excretions and secretions which can be infectious, the stability of the virus in the environment, the multiplicity of routes of infection and the very small doses of the virus that can initiate infection. One of the mechanisms of spread is the carriage of droplets and droplet nuclei exhaled in the breath of infected animals. Such spread can be rapid and extensive, and it is known in certain circumstances to have transmitted disease over a distance of several hundred kilometres. During the 2001 FMD epidemic in the United Kingdom (UK), atmospheric dispersion models were applied in real time in order to assess the potential for atmospheric dispersion of the disease. The operational value of such modelling is primarily to identify premises which may have been exposed so that the human resources for surveillance and disease control purposes are employed most effectively.

The paper describes the combined modelling techniques and presents the results obtained of detailed analyses performed during the early stages of the UK 2001 epidemic. This paper investigates the potential for disease spread in relation to two outbreaks (Burnside Farm, Heddon-on-the-Wall and Prestwick Hall Farm, Ponteland, Northumberland). A separate paper (Gloster et al., 2002) provides a more detailed analysis of the airborne disease transmission in the vicinity of Burnside Farm.

The combined results are consistent with airborne transmission of disease to livestock in the Heddon-on-the-Wall area. Local topography may have played a significant role in influencing the pattern of disease spread.

Investigation of airborne foot-and-mouth disease virus transmission during low-wind conditions in the early phase of the UK 2001 epidemic

NASA Astrophysics Data System (ADS)

Mikkelsen, T.; Alexandersen, S.; Astrup, P.; Champion, H. J.; Donaldson, A. I.; Dunkerley, F. N.; Gloster, J.; Sørensen, J. H.; Thykier-Nielsen, S.

2003-02-01

Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed domesticated and wild animals. The highly contagious nature of FMD is a reflection of the wide range of host species, the enormous quantities of virus liberated by infected animals, the range of excretions and secretions which can be infectious, the stability of the virus in the environment, the multiplicity of routes of infection and the very small doses of the virus that can initiate infection. One of the mechanisms of spread is the carriage of droplets and droplet nuclei exhaled in the breath of infected animals. Such spread can be rapid and extensive, and it is known in certain circumstances to have transmitted disease over a distance of several hundred kilometres. During the 2001 FMD epidemic in the United Kingdom (UK), atmospheric dispersion models were applied in real time in order to assess the potential for atmospheric dispersion of the disease. The operational value of such modelling is primarily to identify premises which may have been exposed so that the human resources for surveillance and disease control purposes are employed most effectively. The paper describes the combined modelling techniques and presents the results obtained of detailed analyses performed during the early stages of the UK 2001 epidemic. This paper investigates the potential for disease spread in relation to two outbreaks (Burnside Farm, Heddon-on-the-Wall and Prestwick Hall Farm, Ponteland, Northumberland). A separate paper (Gloster et al., 2002) provides a more detailed analysis of the airborne disease transmission in the vicinity of Burnside Farm. The combined results are consistent with airborne transmission of disease to livestock in the Heddon-on-the Wall area. Local topography may have played a significant role in influencing the pattern of disease spread.

The Impact of Heterogeneous Thresholds on Social Contagion with Multiple Initiators

PubMed Central

Karampourniotis, Panagiotis D.; Sreenivasan, Sameet; Szymanski, Boleslaw K.; Korniss, Gyorgy

2015-01-01

The threshold model is a simple but classic model of contagion spreading in complex social systems. To capture the complex nature of social influencing we investigate numerically and analytically the transition in the behavior of threshold-limited cascades in the presence of multiple initiators as the distribution of thresholds is varied between the two extreme cases of identical thresholds and a uniform distribution. We accomplish this by employing a truncated normal distribution of the nodes’ thresholds and observe a non-monotonic change in the cascade size as we vary the standard deviation. Further, for a sufficiently large spread in the threshold distribution, the tipping-point behavior of the social influencing process disappears and is replaced by a smooth crossover governed by the size of initiator set. We demonstrate that for a given size of the initiator set, there is a specific variance of the threshold distribution for which an opinion spreads optimally. Furthermore, in the case of synthetic graphs we show that the spread asymptotically becomes independent of the system size, and that global cascades can arise just by the addition of a single node to the initiator set. PMID:26571486

Collective Influence of Multiple Spreaders Evaluated by Tracing Real Information Flow in Large-Scale Social Networks.

PubMed

Teng, Xian; Pei, Sen; Morone, Flaviano; Makse, Hernán A

2016-10-26

Identifying the most influential spreaders that maximize information flow is a central question in network theory. Recently, a scalable method called "Collective Influence (CI)" has been put forward through collective influence maximization. In contrast to heuristic methods evaluating nodes' significance separately, CI method inspects the collective influence of multiple spreaders. Despite that CI applies to the influence maximization problem in percolation model, it is still important to examine its efficacy in realistic information spreading. Here, we examine real-world information flow in various social and scientific platforms including American Physical Society, Facebook, Twitter and LiveJournal. Since empirical data cannot be directly mapped to ideal multi-source spreading, we leverage the behavioral patterns of users extracted from data to construct "virtual" information spreading processes. Our results demonstrate that the set of spreaders selected by CI can induce larger scale of information propagation. Moreover, local measures as the number of connections or citations are not necessarily the deterministic factors of nodes' importance in realistic information spreading. This result has significance for rankings scientists in scientific networks like the APS, where the commonly used number of citations can be a poor indicator of the collective influence of authors in the community.

Gene Therapy for Neurologic Manifestations of Mucopolysaccharidoses

PubMed Central

Wolf, Daniel A.; Banerjee, Sharbani; Hackett, Perry B.; Whitley, Chester B.; McIvor, R. Scott; Low, Walter C.

2015-01-01

Introduction Mucopolysaccharidoses are a family of lysosomal disorders caused by mutations in genes that encode enzymes involved in the catabolism of glycoaminoglycans. These mutations affect multiple organ systems and can be particularly deleterious to the nervous system. At the present time, enzyme replacement therapy and hematopoietic stem-cell therapy are used to treat patients with different forms of these disorders. However, to a great extent the nervous system is not adequately responsive to current therapeutic approaches. Areas Covered Recent advances in gene therapy show great promise for treating mucopolysaccharidoses. This article reviews the current state of the art for routes of delivery in developing genetic therapies for treating the neurologic manifestations of mucopolysaccharidoses. Expert Opinion Gene therapy for treating neurological manifestations of mucopolysaccharidoses can be achieved by intraventricular, intrathecal, intranasal, and systemic administration. The intraventricular route of administration appears to provide the most wide-spread distribution of gene therapy vectors to the brain. The intrathecal route of delivery results in predominant distribution to the caudal areas of the brain while the intranasal route of delivery results in good distribution to the rostral areas of brain. The systemic route of delivery via intravenous delivery can also achieve wide spread delivery to the CNS, however, the distribution to the brain is greatly dependent on the vector system. Intravenous delivery using lentiviral vectors appear to be less effective than adeno-associated viral (AAV) vectors. Moreover, some subtypes of AAV vectors are more effective than others in crossing the blood-brain-barrier. In summary, the recent advances in gene vector technology and routes of delivery to the CNS will facilitate the clinical translation of gene therapy for the treatment of the neurological manifestations of mucopolysaccharidoses. PMID:25510418

Full Duplex, Spread Spectrum Radio System

NASA Technical Reports Server (NTRS)

Harvey, Bruce A.

2000-01-01

The goal of this project was to support the development of a full duplex, spread spectrum voice communications system. The assembly and testing of a prototype system consisting of a Harris PRISM spread spectrum radio, a TMS320C54x signal processing development board and a Zilog Z80180 microprocessor was underway at the start of this project. The efforts under this project were the development of multiple access schemes, analysis of full duplex voice feedback delays, and the development and analysis of forward error correction (FEC) algorithms. The multiple access analysis involved the selection between code division multiple access (CDMA), frequency division multiple access (FDMA) and time division multiple access (TDMA). Full duplex voice feedback analysis involved the analysis of packet size and delays associated with full loop voice feedback for confirmation of radio system performance. FEC analysis included studies of the performance under the expected burst error scenario with the relatively short packet lengths, and analysis of implementation in the TMS320C54x digital signal processor. When the capabilities and the limitations of the components used were considered, the multiple access scheme chosen was a combination TDMA/FDMA scheme that will provide up to eight users on each of three separate frequencies. Packets to and from each user will consist of 16 samples at a rate of 8,000 samples per second for a total of 2 ms of voice information. The resulting voice feedback delay will therefore be 4 - 6 ms. The most practical FEC algorithm for implementation was a convolutional code with a Viterbi decoder. Interleaving of the bits of each packet will be required to offset the effects of burst errors.

The potential and realized spread of wildfires across Canada.

PubMed

Wang, Xianli; Parisien, Marc-André; Flannigan, Mike D; Parks, Sean A; Anderson, Kerry R; Little, John M; Taylor, Steve W

2014-08-01

Given that they can burn for weeks or months, wildfires in temperate and boreal forests may become immense (eg., 10(0) - 10(4) km(2) ). However, during the period within which a large fire is 'active', not all days experience weather that is conducive to fire spread; indeed most of the spread occurs on a small proportion (e.g., 1 - 15 days) of not necessarily consecutive days during the active period. This study examines and compares the Canada-wide patterns in fire-conducive weather ('potential' spread) and the spread that occurs on the ground ('realized' spread). Results show substantial variability in distributions of potential and realized spread days across Canada. Both potential and realized spread are higher in western than in eastern Canada; however, whereas potential spread generally decreases from south to north, there is no such pattern with realized spread. The realized-to-potential fire-spread ratio is considerably higher in northern Canada than in the south, indicating that proportionally more fire-conducive days translate into fire progression. An exploration of environmental correlates to spread show that there may be a few factors compensating for the lower potential spread in northern Canada: a greater proportion of coniferous (i.e., more flammable) vegetation, lesser human impacts (i.e., less fragmented landscapes), sufficient fire ignitions, and intense droughts. Because a linear relationship exists between the frequency distributions of potential spread days and realized spread days in a fire zone, it is possible to obtain one from the other using a simple conversion factor. Our methodology thus provides a means to estimate realized fire spread from weather-based data in regions where fire databases are poor, which may improve our ability to predict future fire activity. © 2014 John Wiley & Sons Ltd.

Improved spatial regression analysis of diffusion tensor imaging for lesion detection during longitudinal progression of multiple sclerosis in individual subjects

NASA Astrophysics Data System (ADS)

Liu, Bilan; Qiu, Xing; Zhu, Tong; Tian, Wei; Hu, Rui; Ekholm, Sven; Schifitto, Giovanni; Zhong, Jianhui

2016-03-01

Subject-specific longitudinal DTI study is vital for investigation of pathological changes of lesions and disease evolution. Spatial Regression Analysis of Diffusion tensor imaging (SPREAD) is a non-parametric permutation-based statistical framework that combines spatial regression and resampling techniques to achieve effective detection of localized longitudinal diffusion changes within the whole brain at individual level without a priori hypotheses. However, boundary blurring and dislocation limit its sensitivity, especially towards detecting lesions of irregular shapes. In the present study, we propose an improved SPREAD (dubbed improved SPREAD, or iSPREAD) method by incorporating a three-dimensional (3D) nonlinear anisotropic diffusion filtering method, which provides edge-preserving image smoothing through a nonlinear scale space approach. The statistical inference based on iSPREAD was evaluated and compared with the original SPREAD method using both simulated and in vivo human brain data. Results demonstrated that the sensitivity and accuracy of the SPREAD method has been improved substantially by adapting nonlinear anisotropic filtering. iSPREAD identifies subject-specific longitudinal changes in the brain with improved sensitivity, accuracy, and enhanced statistical power, especially when the spatial correlation is heterogeneous among neighboring image pixels in DTI.

Virality Prediction and Community Structure in Social Networks

NASA Astrophysics Data System (ADS)

Weng, Lilian; Menczer, Filippo; Ahn, Yong-Yeol

2013-08-01

How does network structure affect diffusion? Recent studies suggest that the answer depends on the type of contagion. Complex contagions, unlike infectious diseases (simple contagions), are affected by social reinforcement and homophily. Hence, the spread within highly clustered communities is enhanced, while diffusion across communities is hampered. A common hypothesis is that memes and behaviors are complex contagions. We show that, while most memes indeed spread like complex contagions, a few viral memes spread across many communities, like diseases. We demonstrate that the future popularity of a meme can be predicted by quantifying its early spreading pattern in terms of community concentration. The more communities a meme permeates, the more viral it is. We present a practical method to translate data about community structure into predictive knowledge about what information will spread widely. This connection contributes to our understanding in computational social science, social media analytics, and marketing applications.

Virality Prediction and Community Structure in Social Networks

PubMed Central

Weng, Lilian; Menczer, Filippo; Ahn, Yong-Yeol

2013-01-01

How does network structure affect diffusion? Recent studies suggest that the answer depends on the type of contagion. Complex contagions, unlike infectious diseases (simple contagions), are affected by social reinforcement and homophily. Hence, the spread within highly clustered communities is enhanced, while diffusion across communities is hampered. A common hypothesis is that memes and behaviors are complex contagions. We show that, while most memes indeed spread like complex contagions, a few viral memes spread across many communities, like diseases. We demonstrate that the future popularity of a meme can be predicted by quantifying its early spreading pattern in terms of community concentration. The more communities a meme permeates, the more viral it is. We present a practical method to translate data about community structure into predictive knowledge about what information will spread widely. This connection contributes to our understanding in computational social science, social media analytics, and marketing applications. PMID:23982106

Virality prediction and community structure in social networks.

PubMed

Weng, Lilian; Menczer, Filippo; Ahn, Yong-Yeol

2013-01-01

How does network structure affect diffusion? Recent studies suggest that the answer depends on the type of contagion. Complex contagions, unlike infectious diseases (simple contagions), are affected by social reinforcement and homophily. Hence, the spread within highly clustered communities is enhanced, while diffusion across communities is hampered. A common hypothesis is that memes and behaviors are complex contagions. We show that, while most memes indeed spread like complex contagions, a few viral memes spread across many communities, like diseases. We demonstrate that the future popularity of a meme can be predicted by quantifying its early spreading pattern in terms of community concentration. The more communities a meme permeates, the more viral it is. We present a practical method to translate data about community structure into predictive knowledge about what information will spread widely. This connection contributes to our understanding in computational social science, social media analytics, and marketing applications.

Experimental assessment and analysis of super-resolution in fluorescence microscopy based on multiple-point spread function fitting of spectrally demultiplexed images

NASA Astrophysics Data System (ADS)

Nishimura, Takahiro; Kimura, Hitoshi; Ogura, Yusuke; Tanida, Jun

2018-06-01

This paper presents an experimental assessment and analysis of super-resolution microscopy based on multiple-point spread function fitting of spectrally demultiplexed images using a designed DNA structure as a test target. For the purpose, a DNA structure was designed to have binding sites at a certain interval that is smaller than the diffraction limit. The structure was labeled with several types of quantum dots (QDs) to acquire their spatial information as spectrally encoded images. The obtained images are analyzed with a point spread function multifitting algorithm to determine the QD locations that indicate the binding site positions. The experimental results show that the labeled locations can be observed beyond the diffraction-limited resolution using three-colored fluorescence images that were obtained with a confocal fluorescence microscope. Numerical simulations show that labeling with eight types of QDs enables the positions aligned at 27.2-nm pitches on the DNA structure to be resolved with high accuracy.

Russian isolates of Potato spindle tuber viroid exhibit low population diversity

USDA-ARS?s Scientific Manuscript database

Potato spindle tuber viroid (PSTVd) is currently wide-spread in seed potatoes grown in Russia. Characterization of 39 PSTVd isolates collected from widely separated areas in Russia over a 15-year period revealed the presence of 17 different sequence variants, all but one of which were previously unk...

Amagmatic Accretionary Segments, Ultraslow Spreading and Non-Volcanic Rifted Margins (Invited)

NASA Astrophysics Data System (ADS)

Dick, H. J.; Snow, J. E.

2009-12-01

The evolution of non-volcanic rifted margins is key to understanding continental breakup and the early evolution of some of the world’s most productive hydrocarbon basins. However, the early stages of such rifting are constrained by limited observations on ancient heavily sedimented margins such as Newfoundland and Iberia. Ultraslow spreading ridges, however, provide a modern analogue for early continental rifting. Ultraslow spreading ridges (<20 mm/yr) comprise ~30% of the global ridge system (e.g. Gakkel, Southwest Indian, Terceira, and Knipovitch Ridges). They have unique tectonics with widely spaced volcanic segments and amagmatic accretionary ridge segments. The volcanic segments, though far from hot spots, include some of the largest axial volcanoes on the global ridge system, and have, unusual magma chemistry, often showing local isotopic and incompatible element enrichment unrelated to mantle hot spots. The transition from slow to ultraslow tectonics and spreading is not uniquely defined by spreading rate, and may also be moderated by magma supply and mantle temperature. Amagmatic accretionary segments are the 4th class of plate boundary structure, and, we believe, the defining tectonic feature of early continental breakup. They form at effective spreading rates <12 mm/yr, assume any orientation to spreading, and replace transform faults and magmatic segments. At amagmatic segments the earth splits apart with the mantle emplaced directly to the seafloor, and great slabs of peridotite are uplifted to form the rift mountains. A thick conductive lid suppresses mantle melting, and magmatic segments form only at widely spaced intervals, with only scattered volcanics in between. Amagmatic segments link with the magmatic segments forming curvilinear plate boundaries, rather than the step-like morphology found at faster spreading ridges. These are all key features of non-volcanic rifted margins; explaining, for example, the presence of mantle peridotites emplaced simultaneously on both the Newfoundland and Iberian Margins in the Jurassic and Cretaceous. Miocene Lena Trough is a new mid-ocean rift plate boundary and the final event in the separation of the North American and Eurasian continents. Mapping and sampling of Lena Trough confirms that it is both oblique and amagmatic, showing that initiation of seafloor spreading at a non-volcanic rifted continental margin follows the same pattern as ultraslow spreading ridges.

Quantitative Infrared Image Analysis Of Thermally-Thin Cellulose Surface Temperatures During Upstream and Downstream Microgravity Flame Spread from A Central Ignition Line

NASA Technical Reports Server (NTRS)

Olson, Sandra L.; Lee, J. R.; Fujita, O.; Kikuchi, M.; Kashiwagi, T.

2012-01-01

Surface view calibrated infrared images of ignition and flame spread over a thin cellulose fuel were obtained at 30 Hz during microgravity flame spread tests in the 10 second Japan Microgravity Center (JAMIC). The tests also used a color video of the surface view and color images of the edge view using 35 millimeter 1600 Kodak Ektapress film at 2 Hz. The cellulose fuel samples (50% long fibers from lumi pine and 50% short fibers from birch) were made with an area density of 60 grams per square meters. The samples were mounted in the center of a 12 centimeter wide by 16 centimeter tall flow duct that uses a downstream fan to draw the air through the flow duct. Samples were ignited after the experiment package was released using a straight hot wire across the center of the 7.5 centimeter wide by 14 centimeter long samples. One case, at 1 atmosphere 35%O2 in N2, at a forced flow of 10 centimeters per second, is presented here. In this case, as the test progresses, the single flame begins to separate into simultaneous upstream and downstream flames. Surface temperature profiles are evaluated as a function of time, and temperature gradients for upstream and downstream flame spread are measured. Flame spread rates from IR image data are compared to visible image spread rate data. IR blackbody temperatures are compared to surface thermocouple readings to evaluate the effective emissivity of the pyrolyzing surface. Preheat lengths are evaluated both upstream and downstream of the central ignition point. A surface energy balance estimates the net heat flux from the flame to the fuel surface along the length of the fuel.

Vulnerability of animal trade networks to the spread of infectious diseases: a methodological approach applied to evaluation and emergency control strategies in cattle, France, 2005.

PubMed

Rautureau, S; Dufour, B; Durand, B

2011-04-01

Besides farming, trade of livestock is a major component of agricultural economy. However, the networks generated by live animal movements are the major support for the propagation of infectious agents between farms, and their structure strongly affects how fast a disease may spread. Structural characteristics may thus be indicators of network vulnerability to the spread of infectious disease. The method proposed here is based upon the analysis of specific subnetworks: the giant strongly connected components (GSCs). Their existence, size and geographic extent are used to assess network vulnerability. Their disappearance when targeted nodes are removed allows studying how network vulnerability may be controlled under emergency conditions. The method was applied to the cattle trade network in France, 2005. Giant strongly connected components were present and widely spread all over the country in yearly, monthly and weekly networks. Among several tested approaches, the most efficient way to make GSCs disappear was based on the ranking of nodes by decreasing betweenness centrality (the proportion of shortest paths between nodes on which a specific node lies). Giant strongly connected components disappearance was obtained after removal of <1% of network nodes. Under emergency conditions, suspending animal trade activities in a small subset of holdings may thus allow to control the spread of an infectious disease through the animal trade network. Nodes representing markets and dealers were widely affected by these simulated control measures. This confirms their importance as 'hubs' for infectious diseases spread. Besides emergency conditions, specific sensitization and preventive measures should be dedicated to this population. © 2010 Blackwell Verlag GmbH.

Spread-Spectrum Carrier Estimation With Unknown Doppler Shift

NASA Technical Reports Server (NTRS)

DeLeon, Phillip L.; Scaife, Bradley J.

1998-01-01

We present a method for the frequency estimation of a BPSK modulated, spread-spectrum carrier with unknown Doppler shift. The approach relies on a classic periodogram in conjunction with a spectral matched filter. Simulation results indicate accurate carrier estimation with processing gains near 40. A DSP-based prototype has been implemented for real-time carrier estimation for use in New Mexico State University's proposal for NASA's Demand Assignment Multiple Access service.

Collective Influence of Multiple Spreaders Evaluated by Tracing Real Information Flow in Large-Scale Social Networks

NASA Astrophysics Data System (ADS)

Teng, Xian; Pei, Sen; Morone, Flaviano; Makse, Hernán A.

2016-10-01

Identifying the most influential spreaders that maximize information flow is a central question in network theory. Recently, a scalable method called “Collective Influence (CI)” has been put forward through collective influence maximization. In contrast to heuristic methods evaluating nodes’ significance separately, CI method inspects the collective influence of multiple spreaders. Despite that CI applies to the influence maximization problem in percolation model, it is still important to examine its efficacy in realistic information spreading. Here, we examine real-world information flow in various social and scientific platforms including American Physical Society, Facebook, Twitter and LiveJournal. Since empirical data cannot be directly mapped to ideal multi-source spreading, we leverage the behavioral patterns of users extracted from data to construct “virtual” information spreading processes. Our results demonstrate that the set of spreaders selected by CI can induce larger scale of information propagation. Moreover, local measures as the number of connections or citations are not necessarily the deterministic factors of nodes’ importance in realistic information spreading. This result has significance for rankings scientists in scientific networks like the APS, where the commonly used number of citations can be a poor indicator of the collective influence of authors in the community.

Collective Influence of Multiple Spreaders Evaluated by Tracing Real Information Flow in Large-Scale Social Networks

PubMed Central

Teng, Xian; Pei, Sen; Morone, Flaviano; Makse, Hernán A.

2016-01-01

Identifying the most influential spreaders that maximize information flow is a central question in network theory. Recently, a scalable method called “Collective Influence (CI)” has been put forward through collective influence maximization. In contrast to heuristic methods evaluating nodes’ significance separately, CI method inspects the collective influence of multiple spreaders. Despite that CI applies to the influence maximization problem in percolation model, it is still important to examine its efficacy in realistic information spreading. Here, we examine real-world information flow in various social and scientific platforms including American Physical Society, Facebook, Twitter and LiveJournal. Since empirical data cannot be directly mapped to ideal multi-source spreading, we leverage the behavioral patterns of users extracted from data to construct “virtual” information spreading processes. Our results demonstrate that the set of spreaders selected by CI can induce larger scale of information propagation. Moreover, local measures as the number of connections or citations are not necessarily the deterministic factors of nodes’ importance in realistic information spreading. This result has significance for rankings scientists in scientific networks like the APS, where the commonly used number of citations can be a poor indicator of the collective influence of authors in the community. PMID:27782207

Antimicrobial resistance in Saudi Arabia

PubMed Central

Zowawi, Hosam M.

2016-01-01

Antimicrobial resistance (AMR) is increasingly being highlighted as an urgent public and animal health issue worldwide. This issue is well demonstrated in bacteria that are resistant to last-line antibiotics, suggesting a future with untreatable infections. International agencies have suggested combating strategies against AMR. Saudi Arabia has several challenges that can stimulate the emergence and spread of multidrug-resistant bacteria. Tackling these challenges need efforts from multiple sectors to successfully control the spread and emergence of AMR in the country. Actions should include active surveillance to monitor the emergence and spread of AMR. Infection prevention and control precautions should also be optimized to limit further spread. Raising awareness is essential to limit inappropriate antibiotics use, and the antibiotic stewardship programs in hospital settings, outpatients, and community pharmacies, should regulate the ongoing use of antimicrobials. PMID:27570847

Channel Measurement and Modeling for 5G Urban Microcellular Scenarios.

PubMed

Peter, Michael; Weiler, Richard J; Göktepe, Barış; Keusgen, Wilhelm; Sakaguchi, Kei

2016-08-20

In order to support the development of channel models for higher frequency bands, multiple urban microcellular measurement campaigns have been carried out in Berlin, Germany, at 60 and 10 GHz. In this paper, the collected data is uniformly analyzed with focus on the path loss (PL) and the delay spread (DS). It reveals that the ground reflection has a dominant impact on the fading behavior. For line-of-sight conditions, the PL exponents are close to free space propagation at 60 GHz, but slightly smaller (1.62) for the street canyon at 10 GHz. The DS shows a clear dependence on the scenario (median values between 16 and 38 ns) and a strong distance dependence for the open square and the wide street canyon. The dependence is less distinct for the narrow street canyon with residential buildings. This behavior is consistent with complementary ray tracing simulations, though the simplified model tends to overestimate the DS.

Modeling infectious disease dynamics in the complex landscape of global health

PubMed Central

Heesterbeek, Hans; Anderson, Roy; Andreasen, Viggo; Bansal, Shweta; De Angelis, Daniela; Dye, Chris; Eames, Ken; Edmunds, John; Frost, Simon; Funk, Sebastian; Hollingsworth, Deirdre; House, Thomas; Isham, Valerie; Klepac, Petra; Lessler, Justin; Lloyd-Smith, James; Metcalf, Jessica; Mollison, Denis; Pellis, Lorenzo; Pulliam, Juliet; Roberts, Mick; Viboud, Cecile

2015-01-01

Despite some notable successes in the control of infectious diseases, transmissible pathogens still pose an enormous threat to human and animal health. The ecological and evolutionary dynamics of infections play out on a wide range of interconnected temporal, organizational and spatial scales, which even within a single pathogen often span hours to months, cellular to ecosystem levels, and local to pandemic spread. Some pathogens are directly transmitted between individuals of a single species, while others circulate among multiple hosts, need arthropod vectors, or can survive in environmental reservoirs. Many factors, including increasing antimicrobial resistance, increased human connectivity, and dynamic human behavior, raise prevention and control from formerly national to international issues. In the face of this complexity, mathematical models offer essential tools for synthesizing information to understand epidemiological patterns, and for developing the quantitative evidence base for decision-making in global health. PMID:25766240

ICC '86; Proceedings of the International Conference on Communications, Toronto, Canada, June 22-25, 1986, Conference Record. Volumes 1, 2, & 3

NASA Astrophysics Data System (ADS)

Papers are presented on ISDN, mobile radio systems and techniques for digital connectivity, centralized and distributed algorithms in computer networks, communications networks, quality assurance and impact on cost, adaptive filters in communications, the spread spectrum, signal processing, video communication techniques, and digital satellite services. Topics discussed include performance evaluation issues for integrated protocols, packet network operations, the computer network theory and multiple-access, microwave single sideband systems, switching architectures, fiber optic systems, wireless local communications, modulation, coding, and synchronization, remote switching, software quality, transmission, and expert systems in network operations. Consideration is given to wide area networks, image and speech processing, office communications application protocols, multimedia systems, customer-controlled network operations, digital radio systems, channel modeling and signal processing in digital communications, earth station/on-board modems, computer communications system performance evaluation, source encoding, compression, and quantization, and adaptive communications systems.

A Proteomic Characterization of Factors Enriched at Nascent DNA Molecules

PubMed Central

Lopez-Contreras, Andres J.; Ruppen, Isabel; Nieto-Soler, Maria; Murga, Matilde; Rodriguez-Acebes, Sara; Remeseiro, Silvia; Rodrigo-Perez, Sara; Rojas, Ana M.; Mendez, Juan; Muñoz, Javier; Fernandez-Capetillo, Oscar

2013-01-01

SUMMARY DNA replication is facilitated by multiple factors that concentrate in the vicinity of replication forks. Here, we developed an approach that combines the isolation of proteins on nascent DNA chains with mass spectrometry (iPOND-MS), allowing a comprehensive proteomic characterization of the human replisome and replisome-associated factors. In addition to known replisome components, we provide a broad list of proteins that reside in the vicinity of the replisome, some of which were not previously associated with replication. For instance, our data support a link between DNA replication and the Williams-Beuren syndrome and identify ZNF24 as a replication factor. In addition, we reveal that SUMOylation is wide-spread for factors that concentrate near replisomes, which contrasts with lower UQylation levels at these sites. This resource provides a panoramic view of the proteins that concentrate in the surroundings of the replisome, which should facilitate future investigations on DNA replication and genome maintenance. PMID:23545495

The Environmental Dimensions of Migration

PubMed Central

Hunter, Lori M.; Luna, Jessie K.; Norton, Rachel M.

2017-01-01

Research on the environmental dimensions of human migration has made important strides in recent years. However, findings have been spread across multiple disciplines with wide ranging methodologies and limited theoretical development. This article reviews key findings of the field and identifies future directions for sociological research. We contend that the field has moved beyond linear environmental “push” theories towards a greater integration of context, including micro-, meso-, and macro-level interactions. We highlight findings that migration is often a household strategy to diversify risk (NELM), interacting with household composition, individual characteristics, social networks, and historical, political and economic contexts. We highlight promising developments in the field, including the recognition that migration is a long-standing form of environmental adaptation and yet only one among many forms of adaptation. Finally, we argue that sociologists could contribute significantly to migration-environment inquiry through attention to issues of inequality, perceptions, and agency vis-à-vis structure. PMID:29861536

Modeling infectious disease dynamics in the complex landscape of global health.

PubMed

Heesterbeek, Hans; Anderson, Roy M; Andreasen, Viggo; Bansal, Shweta; De Angelis, Daniela; Dye, Chris; Eames, Ken T D; Edmunds, W John; Frost, Simon D W; Funk, Sebastian; Hollingsworth, T Deirdre; House, Thomas; Isham, Valerie; Klepac, Petra; Lessler, Justin; Lloyd-Smith, James O; Metcalf, C Jessica E; Mollison, Denis; Pellis, Lorenzo; Pulliam, Juliet R C; Roberts, Mick G; Viboud, Cecile

2015-03-13

Despite some notable successes in the control of infectious diseases, transmissible pathogens still pose an enormous threat to human and animal health. The ecological and evolutionary dynamics of infections play out on a wide range of interconnected temporal, organizational, and spatial scales, which span hours to months, cells to ecosystems, and local to global spread. Moreover, some pathogens are directly transmitted between individuals of a single species, whereas others circulate among multiple hosts, need arthropod vectors, or can survive in environmental reservoirs. Many factors, including increasing antimicrobial resistance, increased human connectivity and changeable human behavior, elevate prevention and control from matters of national policy to international challenge. In the face of this complexity, mathematical models offer valuable tools for synthesizing information to understand epidemiological patterns, and for developing quantitative evidence for decision-making in global health. Copyright © 2015, American Association for the Advancement of Science.

An improved ChIP-seq peak detection system for simultaneously identifying post-translational modified transcription factors by combinatorial fusion, using SUMOylation as an example.

PubMed

Cheng, Chia-Yang; Chu, Chia-Han; Hsu, Hung-Wei; Hsu, Fang-Rong; Tang, Chung Yi; Wang, Wen-Ching; Kung, Hsing-Jien; Chang, Pei-Ching

2014-01-01

Post-translational modification (PTM) of transcriptional factors and chromatin remodelling proteins is recognized as a major mechanism by which transcriptional regulation occurs. Chromatin immunoprecipitation (ChIP) in combination with high-throughput sequencing (ChIP-seq) is being applied as a gold standard when studying the genome-wide binding sites of transcription factor (TFs). This has greatly improved our understanding of protein-DNA interactions on a genomic-wide scale. However, current ChIP-seq peak calling tools are not sufficiently sensitive and are unable to simultaneously identify post-translational modified TFs based on ChIP-seq analysis; this is largely due to the wide-spread presence of multiple modified TFs. Using SUMO-1 modification as an example; we describe here an improved approach that allows the simultaneous identification of the particular genomic binding regions of all TFs with SUMO-1 modification. Traditional peak calling methods are inadequate when identifying multiple TF binding sites that involve long genomic regions and therefore we designed a ChIP-seq processing pipeline for the detection of peaks via a combinatorial fusion method. Then, we annotate the peaks with known transcription factor binding sites (TFBS) using the Transfac Matrix Database (v7.0), which predicts potential SUMOylated TFs. Next, the peak calling result was further analyzed based on the promoter proximity, TFBS annotation, a literature review, and was validated by ChIP-real-time quantitative PCR (qPCR) and ChIP-reChIP real-time qPCR. The results show clearly that SUMOylated TFs are able to be pinpointed using our pipeline. A methodology is presented that analyzes SUMO-1 ChIP-seq patterns and predicts related TFs. Our analysis uses three peak calling tools. The fusion of these different tools increases the precision of the peak calling results. TFBS annotation method is able to predict potential SUMOylated TFs. Here, we offer a new approach that enhances ChIP-seq data analysis and allows the identification of multiple SUMOylated TF binding sites simultaneously, which can then be utilized for other functional PTM binding site prediction in future.

Comparative RNA-seq for the investigation of tolerance to Verticillium wilt in black raspberry

USDA-ARS?s Scientific Manuscript database

Verticillium dahliae Kleb., a cause of verticillium wilt, is a wide-spread, soil-borne fungal pathogen with a wide host range that includes many fruit and vegetable crops. Verticillium dahliae has been isolated from Rubus species showing symptoms of the disease. Very little is known about the intera...

Protective effects of Aloe vera-based diets in Eimeria maxima-infected broiler chickens

USDA-ARS?s Scientific Manuscript database

Aloes have been widely used for a broad range of pharmacological activities, including parasitic problems. Avian coccidiosis is the most costly and wide-spread parasitic disease in the poultry industry, and has been mainly controlled by the use of chemotherapeutic agents. Due to the emergence of dru...

Jurassic, slow-spreading ridge in the southeast Gulf of Mexico and its along-strike morpho-volcanic expression explained by a two-phase opening model

NASA Astrophysics Data System (ADS)

Lin, P.; Mann, P.

2016-12-01

Previous workers have used extensive grids of 2D seismic reflection data to describe the width, structural character, and adjacent oceanic crust of the late Jurassic, slow-spreading ridge in the southeast Gulf of Mexico (SEGOM). Characteristics of the now-buried SEGOM slow spreading ridge include: 1) wide, axial valley segments ranging from 5-20 km; 2) alternating, deep, axial valley segments up to 2 km in depth; 3) normal faults dipping towards the axial valleys; and 4) isolated seamounts within the axial valleys projecting 1 km above regional oceanic basement depth and reflecting along-strike variations in the ridge's magmatic supply. We have used additional seismic reflection, gravity, and magnetic data to map the ridge and its environs to its southern termination, a 2.6-km-high seamount - informally named here Buffler seamount. The southernmost, 427-km long section of the SEGOM ridge from Buffler seamount northwest to the southwestern limit of the DeSoto Canyon arch can be divided into four alternating ridge segments with two distinctive morphologies: 1) wide and deep axial valleys lying below regional oceanic basement depth and characterized by gravity high and magnetic lows; and 2) elevated, linear areas of clustered, seamounts characterized by gravity low and magnetic highs. The continental margins of both Yucatan and Florida exhibit a prominent N60E magnetic fabric created by Phase 1, NW-SE Triassic-early Jurassic continental rifting of the GOM that was subsequently offset at right angles by Phase 2, NE-SW late Jurassic stretching and oceanic spreading. Removal of the V-shaped area of oceanic crust of the SEGOM shows that the wide, axial valleys of the late Jurassic spreading ridge coincide with rifted areas of thicker crust on the "arches" or horst blocks of Triassic-early Jurassic, Phase 1 rifting (Sarasota, Middle Ground) while the elevated areas of elevated and clustered seamounts coincide with thinner crust of the intervening rifts (Apalachicola, Tampa, South Florida). The later SW-NE re-rifting of crust during the late Jurassic that was rifted earlier in the Triassic and early Jurassic in a NW-SE direction is supportive of the widely accepted two-phase opening model for the SEGOM and GOM as a whole.

Infections on the move: how transient phases of host movement influence disease spread

PubMed Central

Fenton, A.; Dell, A. I.

2017-01-01

Animal movement impacts the spread of human and wildlife diseases, and there is significant interest in understanding the role of migrations, biological invasions and other wildlife movements in spatial infection dynamics. However, the influence of processes acting on infections during transient phases of host movement is poorly understood. We propose a conceptual framework that explicitly considers infection dynamics during transient phases of host movement to better predict infection spread through spatial host networks. Accounting for host transient movement captures key processes that occur while hosts move between locations, which together determine the rate at which hosts spread infections through networks. We review theoretical and empirical studies of host movement and infection spread, highlighting the multiple factors that impact the infection status of hosts. We then outline characteristics of hosts, parasites and the environment that influence these dynamics. Recent technological advances provide disease ecologists unprecedented ability to track the fine-scale movement of organisms. These, in conjunction with experimental testing of the factors driving infection dynamics during host movement, can inform models of infection spread based on constituent biological processes. PMID:29263283

A prospective, randomized comparison between single- and multiple-injection techniques for ultrasound-guided subgluteal sciatic nerve block.

PubMed

Yamamoto, Hiroto; Sakura, Shinichi; Wada, Minori; Shido, Akemi

2014-12-01

It is believed that local anesthetic injected to obtain circumferential spread around nerves produces a more rapid onset and successful blockade after some ultrasound-guided peripheral nerve blocks. However, evidence demonstrating this point is limited only to the popliteal sciatic nerve block, which is relatively easy to perform by via a high-frequency linear transducer. In the present study, we tested the hypothesis that multiple injections of local anesthetic to make circumferential spread would improve the rate of sensory and motor blocks compared with a single-injection technique for ultrasound-guided subgluteal sciatic nerve block, which is considered a relatively difficult block conducted with a low-frequency, curved-array transducer. Ninety patients undergoing knee surgery were divided randomly into 2 groups to receive the ultrasound-guided subgluteal approach to sciatic nerve block with 20 mL of 1.5% mepivacaine with epinephrine. For group M (the multiple-injection technique), the local anesthetic was injected to create circumferential spread around the sciatic nerve without limitation on the number of needle passes. For group S (the single-injection technique), the number of needle passes was limited to 1, and the local anesthetic was injected to create spread along the dorsal surface of the sciatic nerve, during which no adjustment of the needle tip was made. Sensory and motor blockade were assessed in double-blind fashion for 30 minutes after completion of the block. The primary outcome was sensory blockade of all sciatic components tested, including tibial, superficial peroneal, and sural nerves at 30 minutes after injection. Data from 86 patients (43 in each group) were analyzed. Block execution took more time for group M than group S. The proportion of patients with complete sensory blockade of all sciatic components at 30 minutes after injection was significantly larger for group M than group S (41.9% vs 16.3%, P = 0.018). Complete motor blockade of foot and toes extension also was observed more frequently in group M than in group S (67.4% vs 34.9%, P = 0.005 and 51.2% vs 25.6%, P = 0.027, respectively). When ultrasound-guided subgluteal sciatic nerve block is conducted, multiple injections of local anesthetic to make a circumferential spread around the sciatic nerve improve the rate of sensory and motor blocks compared with a single injection.

Comparison of CDMA and FDMA for the MobileStar(sm) system

NASA Technical Reports Server (NTRS)

Jacobs, I. M.; Gilhousen, K. S.; Weaver, L. A.; Renshaw, K.; Murphy, T.

1988-01-01

Spread-spectrum code division multiple access (CDMA) and single channel per carrier frequency division multiple access (FDMA) systems are compared for spectrum efficiency. CDMA is shown to have greater maximum throughput than FDMA for the MobileStar(sm) system which uses digital voice activated carriers and directive circularly polarized satellite antennas.

Moving Cell Boundaries Drive Nuclear Shaping during Cell Spreading.

PubMed

Li, Yuan; Lovett, David; Zhang, Qiao; Neelam, Srujana; Kuchibhotla, Ram Anirudh; Zhu, Ruijun; Gundersen, Gregg G; Lele, Tanmay P; Dickinson, Richard B

2015-08-18

The nucleus has a smooth, regular appearance in normal cells, and its shape is greatly altered in human pathologies. Yet, how the cell establishes nuclear shape is not well understood. We imaged the dynamics of nuclear shaping in NIH3T3 fibroblasts. Nuclei translated toward the substratum and began flattening during the early stages of cell spreading. Initially, nuclear height and width correlated with the degree of cell spreading, but over time, reached steady-state values even as the cell continued to spread. Actomyosin activity, actomyosin bundles, microtubules, and intermediate filaments, as well as the LINC complex, were all dispensable for nuclear flattening as long as the cell could spread. Inhibition of actin polymerization as well as myosin light chain kinase with the drug ML7 limited both the initial spreading of cells and flattening of nuclei, and for well-spread cells, inhibition of myosin-II ATPase with the drug blebbistatin decreased cell spreading with associated nuclear rounding. Together, these results show that cell spreading is necessary and sufficient to drive nuclear flattening under a wide range of conditions, including in the presence or absence of myosin activity. To explain this observation, we propose a computational model for nuclear and cell mechanics that shows how frictional transmission of stress from the moving cell boundaries to the nuclear surface shapes the nucleus during early cell spreading. Our results point to a surprisingly simple mechanical system in cells for establishing nuclear shapes. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Moving Cell Boundaries Drive Nuclear Shaping during Cell Spreading

PubMed Central

Li, Yuan; Lovett, David; Zhang, Qiao; Neelam, Srujana; Kuchibhotla, Ram Anirudh; Zhu, Ruijun; Gundersen, Gregg G.; Lele, Tanmay P.; Dickinson, Richard B.

2015-01-01

The nucleus has a smooth, regular appearance in normal cells, and its shape is greatly altered in human pathologies. Yet, how the cell establishes nuclear shape is not well understood. We imaged the dynamics of nuclear shaping in NIH3T3 fibroblasts. Nuclei translated toward the substratum and began flattening during the early stages of cell spreading. Initially, nuclear height and width correlated with the degree of cell spreading, but over time, reached steady-state values even as the cell continued to spread. Actomyosin activity, actomyosin bundles, microtubules, and intermediate filaments, as well as the LINC complex, were all dispensable for nuclear flattening as long as the cell could spread. Inhibition of actin polymerization as well as myosin light chain kinase with the drug ML7 limited both the initial spreading of cells and flattening of nuclei, and for well-spread cells, inhibition of myosin-II ATPase with the drug blebbistatin decreased cell spreading with associated nuclear rounding. Together, these results show that cell spreading is necessary and sufficient to drive nuclear flattening under a wide range of conditions, including in the presence or absence of myosin activity. To explain this observation, we propose a computational model for nuclear and cell mechanics that shows how frictional transmission of stress from the moving cell boundaries to the nuclear surface shapes the nucleus during early cell spreading. Our results point to a surprisingly simple mechanical system in cells for establishing nuclear shapes. PMID:26287620

Evolutionary dynamics and genetic diversity from three genes of Anguillid rhabdovirus.

PubMed

Bellec, Laure; Cabon, Joelle; Bergmann, Sven; de Boisséson, Claire; Engelsma, Marc; Haenen, Olga; Morin, Thierry; Olesen, Niels Jørgen; Schuetze, Heike; Toffan, Anna; Way, Keith; Bigarré, Laurent

2014-11-01

Wild freshwater eel populations have dramatically declined in recent past decades in Europe and America, partially through the impact of several factors including the wide spread of infectious diseases. The anguillid rhabdoviruses eel virus European X (EVEX) and eel virus American (EVA) potentially play a role in this decline, even if their real contribution is still unclear. In this study, we investigate the evolutionary dynamics and genetic diversity of anguiillid rhabdoviruses by analysing sequences from the glycoprotein, nucleoprotein and phosphoprotein (P) genes of 57 viral strains collected from seven countries over 40 years using maximum-likelihood and Bayesian approaches. Phylogenetic trees from the three genes are congruent and allow two monophyletic groups, European and American, to be clearly distinguished. Results of nucleotide substitution rates per site per year indicate that the P gene is expected to evolve most rapidly. The nucleotide diversity observed is low (2-3 %) for the three genes, with a significantly higher variability within the P gene, which encodes multiple proteins from a single genomic RNA sequence, particularly a small C protein. This putative C protein is a potential molecular marker suitable for characterization of distinct genotypes within anguillid rhabdoviruses. This study provides, to our knowledge, the first molecular characterization of EVA, brings new insights to the evolutionary dynamics of two genotypes of Anguillid rhabdovirus, and is a baseline for further investigations on the tracking of its spread.

Global phylogeography of the widely introduced North West Pacific ascidian Styela clava.

PubMed

Goldstien, Sharyn J; Dupont, Lise; Viard, Frédérique; Hallas, Paul J; Nishikawa, Teruaki; Schiel, David R; Gemmell, Neil J; Bishop, John D D

2011-02-22

The solitary ascidian Styela clava Herdman, 1882 is considered to be native to Japan, Korea, northern China and the Russian Federation in the NW Pacific, but it has spread globally over the last 80 years and is now established as an introduced species on the east and west coasts of North America, Europe, Australia and New Zealand. In eastern Canada it reaches sufficient density to be a serious pest to aquaculture concerns. We sequenced a fragment of the cytochrome oxidase subunit I mitochondrial gene (COI) from a total of 554 individuals to examine the genetic relationships of 20 S. clava populations sampled throughout the introduced and native ranges, in order to investigate invasive population characteristics. The data presented here show a moderate level of genetic diversity throughout the northern hemisphere. The southern hemisphere (particularly New Zealand) displays a greater amount of haplotype and nucleotide diversity in comparison. This species, like many other invasive species, shows a range of genetic diversities among introduced populations independent of the age of incursion. The successful establishment of this species appears to be associated with multiple incursions in many locations, while other locations appear to have experienced rapid expansion from a potentially small population with reduced genetic diversity. These contrasting patterns create difficulties when attempting to manage and mitigate a species that continues to spread among ports and marinas around the world.

An Easy Phylogenetically Informative Method to Trace the Globally Invasive Potamopyrgus Mud Snail from River's eDNA.

PubMed

Clusa, Laura; Ardura, Alba; Gower, Fiona; Miralles, Laura; Tsartsianidou, Valentina; Zaiko, Anastasija; Garcia-Vazquez, Eva

2016-01-01

Potamopyrgus antipodarum (New Zealand mud snail) is a prosobranch mollusk native to New Zealand with a wide invasive distribution range. Its non-indigenous populations are reported from Australia, Asia, Europe and North America. Being an extremely tolerant species, Potamopyrgus is capable to survive in a great range of salinity and temperature conditions, which explains its high invasiveness and successful spread outside the native range. Here we report the first finding of Potamopyrgus antipodarum in a basin of the Cantabrian corridor in North Iberia (Bay of Biscay, Spain). Two haplotypes already described in Europe were found in different sectors of River Nora (Nalon basin), suggesting the secondary introductions from earlier established invasive populations. To enhance the surveillance of the species and tracking its further spread in the region, we developed a specific set of primers for the genus Potamopyrgus that amplify a fragment of 16S rDNA. The sequences obtained from PCR on DNA extracted from tissue and water samples (environmental DNA, eDNA) were identical in each location, suggesting clonal reproduction of the introduced individuals. Multiple introduction events from different source populations were inferred from our sequence data. The eDNA tool developed here can serve for tracing New Zealand mud snail populations outside its native range, and for inventorying mud snail population assemblages in the native settings if high throughput sequencing methodologies are employed.

An Easy Phylogenetically Informative Method to Trace the Globally Invasive Potamopyrgus Mud Snail from River’s eDNA

PubMed Central

Clusa, Laura; Ardura, Alba; Gower, Fiona; Miralles, Laura; Tsartsianidou, Valentina; Zaiko, Anastasija; Garcia-Vazquez, Eva

2016-01-01

Potamopyrgus antipodarum (New Zealand mud snail) is a prosobranch mollusk native to New Zealand with a wide invasive distribution range. Its non-indigenous populations are reported from Australia, Asia, Europe and North America. Being an extremely tolerant species, Potamopyrgus is capable to survive in a great range of salinity and temperature conditions, which explains its high invasiveness and successful spread outside the native range. Here we report the first finding of Potamopyrgus antipodarum in a basin of the Cantabrian corridor in North Iberia (Bay of Biscay, Spain). Two haplotypes already described in Europe were found in different sectors of River Nora (Nalon basin), suggesting the secondary introductions from earlier established invasive populations. To enhance the surveillance of the species and tracking its further spread in the region, we developed a specific set of primers for the genus Potamopyrgus that amplify a fragment of 16S rDNA. The sequences obtained from PCR on DNA extracted from tissue and water samples (environmental DNA, eDNA) were identical in each location, suggesting clonal reproduction of the introduced individuals. Multiple introduction events from different source populations were inferred from our sequence data. The eDNA tool developed here can serve for tracing New Zealand mud snail populations outside its native range, and for inventorying mud snail population assemblages in the native settings if high throughput sequencing methodologies are employed. PMID:27706172

Genomic epidemiology of global Klebsiella pneumoniae carbapenemase (KPC)-producing Escherichia coli.

PubMed

Stoesser, N; Sheppard, A E; Peirano, G; Anson, L W; Pankhurst, L; Sebra, R; Phan, H T T; Kasarskis, A; Mathers, A J; Peto, T E A; Bradford, P; Motyl, M R; Walker, A S; Crook, D W; Pitout, J D

2017-07-19

The dissemination of carbapenem resistance in Escherichia coli has major implications for the management of common infections. bla KPC , encoding a transmissible carbapenemase (KPC), has historically largely been associated with Klebsiella pneumoniae, a predominant plasmid (pKpQIL), and a specific transposable element (Tn4401, ~10 kb). Here we characterize the genetic features of bla KPC emergence in global E. coli, 2008-2013, using both long- and short-read whole-genome sequencing. Amongst 43/45 successfully sequenced bla KPC -E. coli strains, we identified substantial strain diversity (n = 21 sequence types, 18% of annotated genes in the core genome); substantial plasmid diversity (≥9 replicon types); and substantial bla KPC -associated, mobile genetic element (MGE) diversity (50% not within complete Tn4401 elements). We also found evidence of inter-species, regional and international plasmid spread. In several cases bla KPC was found on high copy number, small Col-like plasmids, previously associated with horizontal transmission of resistance genes in the absence of antimicrobial selection pressures. E. coli is a common human pathogen, but also a commensal in multiple environmental and animal reservoirs, and easily transmissible. The association of bla KPC with a range of MGEs previously linked to the successful spread of widely endemic resistance mechanisms (e.g. bla TEM , bla CTX-M ) suggests that it may become similarly prevalent.

47 CFR 74.433 - Temporary authorizations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... broadcast station must include full particulars including: licensee's name and address, facility... of events of wide-spread interest and importance which cannot be transmitted successfully on these...

Spreading History of a Segment of the Southern Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Stock, J. M.; Clayton, R. W.

2001-12-01

The Falkland-Agulhas fracture zone in the South Atlantic Ocean separates crust that records the entire Cenozoic history of South America-Africa spreading (on the north) from crust on the south that experienced a more complicated plate motion history including major ridge jumps, an additional plate (Malvinas), and plate reorganizations in early Cenozoic time. The Nathaniel B. Palmer cruise 01-02 in April 2001 measured gravity, magnetics, and swath bathymetry on a transit from Cape Town to Punta Arenas, including a survey line in Cenozoic crust on the north side of, and parallel to, the Falkland-Agulhas fracture zone. The objectives were to test previous models of Cenozoic plate motions for this region, and to examine the structure of the Falkland-Agulhas fracture zone by collection of limited single-channel seismic data. From 5° W to 3° W longitude, several seismic lines with accompanying SeaBeam data across the northern flank of the fracture zone reveal it to be a wide zone characterized by multiple parallel southward-facing fault scarps whose strike is 70-80° E of N. From chron 12 time to chron 6 time, the spreading history for this segment of the ridge was relatively simple, with slightly asymmetric spreading rates (more crust accreted to South America than to Africa), as has been previously noted for this part of the southern Mid-Atlantic Ridge. Between chron 5c and chron 2a, the magnetic anomalies are complex and disrupted, suggesting possible small-scale ridge jumps and continued asymmetric spreading. The modern ridge axis is 40 km east of the topographic high ("ridge crest"). The zones of disrupted magnetic anomalies may be due to the effects of pseudofault traces in the same spreading corridor, visible in satellite gravity data in younger seafloor north of the transit. We recorded late Cretaceous and younger magnetic anomalies (chrons 34y to 18) on the Africa plate to improve the distribution of known magnetic anomaly locations in this part of the South Atlantic. The observations are in excellent agreement with previous plate rotation models for Africa-South America motion (e.g. Cande et al. 1988) and conjugate magnetic anomaly positions from the South America plate. Members of the NBP0102 science party: H. Ai, J. Clinton, R. Decesari, A. Jacobs, M. Kumar, B. Lane, J. Parra, B. Smith, N. Villaume, Z. Yan. >http://www.gps.caltech.edu/ ~jstock/Ge211.html

Integrated defense system overlaps as a disease model: with examples for multiple chemical sensitivity.

PubMed Central

Rowat, S C

1998-01-01

The central nervous, immune, and endocrine systems communicate through multiple common messengers. Over evolutionary time, what may be termed integrated defense system(s) (IDS) have developed to coordinate these communications for specific contexts; these include the stress response, acute-phase response, nonspecific immune response, immune response to antigen, kindling, tolerance, time-dependent sensitization, neurogenic switching, and traumatic dissociation (TD). These IDSs are described and their overlap is examined. Three models of disease production are generated: damage, in which IDSs function incorrectly; inadequate/inappropriate, in which IDS response is outstripped by a changing context; and evolving/learning, in which the IDS learned response to a context is deemed pathologic. Mechanisms of multiple chemical sensitivity (MCS) are developed from several IDS disease models. Model 1A is pesticide damage to the central nervous system, overlapping with body chemical burdens, TD, and chronic zinc deficiency; model 1B is benzene disruption of interleukin-1, overlapping with childhood developmental windows and hapten-antigenic spreading; and model 1C is autoimmunity to immunoglobulin-G (IgG), overlapping with spreading to other IgG-inducers, sudden spreading of inciters, and food-contaminating chemicals. Model 2A is chemical and stress overload, including comparison with the susceptibility/sensitization/triggering/spreading model; model 2B is genetic mercury allergy, overlapping with: heavy metals/zinc displacement and childhood/gestational mercury exposures; and model 3 is MCS as evolution and learning. Remarks are offered on current MCS research. Problems with clinical measurement are suggested on the basis of IDS models. Large-sample patient self-report epidemiology is described as an alternative or addition to clinical biomarker and animal testing. Images Figure 1 Figure 2 Figure 3 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:9539008

Computational And Experimental Studies Of Three-Dimensional Flame Spread Over Liquid Fuel Pools

NASA Technical Reports Server (NTRS)

Ross, Howard D. (Technical Monitor); Cai, Jinsheng; Liu, Feng; Sirignano, William A.; Miller, Fletcher J.

2003-01-01

Schiller, Ross, and Sirignano (1996) studied ignition and flame spread above liquid fuels initially below the flashpoint temperature by using a two-dimensional computational fluid dynamics code that solves the coupled equations of both the gas and the liquid phases. Pulsating flame spread was attributed to the establishment of a gas-phase recirculation cell that forms just ahead of the flame leading edge because of the opposing effect of buoyancy-driven flow in the gas phase and the thermocapillary-driven flow in the liquid phase. Schiller and Sirignano (1996) extended the same study to include flame spread with forced opposed flow in the gas phase. A transitional flow velocity was found above which an originally uniform spreading flame pulsates. The same type of gas-phase recirculation cell caused by the combination of forced opposed flow, buoyancy-driven flow, and thermocapillary-driven concurrent flow was responsible for the pulsating flame spread. Ross and Miller (1998) and Miller and Ross (1998) performed experimental work that corroborates the computational findings of Schiller, Ross, and Sirignano (1996) and Schiller and Sirignano (1996). Cai, Liu, and Sirignano (2002) developed a more comprehensive three-dimensional model and computer code for the flame spread problem. Many improvements in modeling and numerical algorithms were incorporated in the three-dimensional model. Pools of finite width and length were studied in air channels of prescribed height and width. Significant three-dimensional effects around and along the pool edge were observed. The same three-dimensional code is used to study the detailed effects of pool depth, pool width, opposed air flow velocity, and different levels of air oxygen concentration (Cai, Liu, and Sirignano, 2003). Significant three-dimensional effects showing an unsteady wavy flame front for cases of wide pool width are found for the first time in computation, after being noted previously by experimental observers (Ross and Miller, 1999). Regions of uniform and pulsating flame spread are mapped for the flow conditions of pool depth, opposed flow velocity, initial pool temperature, and air oxygen concentration under both normal and microgravity conditions. Details can be found in Cai et al. (2002, 2003). Experimental results recently performed at NASA Glenn of flame spread across a wide, shallow pool as a function of liquid temperature are also presented here.

Cannibalism amplifies the spread of vertically transmitted pathogens.

PubMed

Sadeh, Asaf; Rosenheim, Jay A

2016-08-01

Cannibalism is a widespread behavior. Abundant empirical evidence demonstrates that cannibals incur a risk of contracting pathogenic infections when they consume infected conspecifics. However, current theory suggests that cannibalism generally impedes disease spread, because each victim is usually consumed by a single cannibal, such that cannibalism does not function as a spreading process. Consequently, cannibalism cannot be the only mode of transmission of most parasites. We develop simple, but general epidemiological models to analyze the interaction of cannibalism and vertical transmission. We show that cannibalism increases the prevalence of vertically transmitted pathogens whenever the host population density is not solely regulated by cannibalism. This mechanism, combined with additional, recently published, theoretical mechanisms, presents a strong case for the role of cannibalism in the spread of infectious diseases across a wide range of parasite-host systems. © 2016 by the Ecological Society of America.

Emergence and global spread of epidemic healthcare-associated Clostridium difficile

PubMed Central

He, Miao; Miyajima, Fabio; Roberts, Paul; Ellison, Louise; Pickard, Derek J.; Martin, Melissa J.; Connor, Thomas R.; Harris, Simon R.; Fairley, Derek; Bamford, Kathleen B.; D’Arc, Stephanie; Brazier, Jon; Brown, Derek; Coia, John E.; Douce, Gill; Gerding, Dale; Kim, Hee Jung; Koh, Tse Hsien; Kato, Haru; Senoh, Mitsutoshi; Louie, Tom; Michell, Stephen; Butt, Emma; Peacock, Sharon J.; Brown, Nick M.; Riley, Tom; Songer, Glen; Wilcox, Mark; Pirmohamed, Munir; Kuijper, Ed; Hawkey, Peter; Wren, Brendan W.; Dougan, Gordon; Parkhill, Julian; Lawley, Trevor D.

2012-01-01

Epidemic Clostridium difficile (027/BI/NAP1) rapidly emerged in the past decade as the leading cause of antibiotic-associated diarrhea worldwide. However, the key moments in the evolutionary history leading to its emergence and subsequent patterns of global spread remain unknown. Here we define the global population structure of C. difficile 027/BI/NAP1 based on whole-genome sequencing and phylogenetic analysis. We demonstrate that two distinct epidemic lineages, FQR1 and FQR2, not one as previously thought, emerged in North America within a relatively short period after acquiring the same fluoroquinolone resistance mutation and a highly-related conjugative transposon. The two epidemic lineages displayed distinct patterns of global spread, and the FQR2 lineage spread more widely leading to healthcare outbreaks in the UK, continental Europe and Australia. Our analysis identifies key genetic changes linked to the rapid trans-continental dissemination of epidemic C. difficile 027/BI/NAP1 and highlights the routes by which it spreads through the global healthcare system. PMID:23222960

Topological data analysis of contagion maps for examining spreading processes on networks.

PubMed

Taylor, Dane; Klimm, Florian; Harrington, Heather A; Kramár, Miroslav; Mischaikow, Konstantin; Porter, Mason A; Mucha, Peter J

2015-07-21

Social and biological contagions are influenced by the spatial embeddedness of networks. Historically, many epidemics spread as a wave across part of the Earth's surface; however, in modern contagions long-range edges-for example, due to airline transportation or communication media-allow clusters of a contagion to appear in distant locations. Here we study the spread of contagions on networks through a methodology grounded in topological data analysis and nonlinear dimension reduction. We construct 'contagion maps' that use multiple contagions on a network to map the nodes as a point cloud. By analysing the topology, geometry and dimensionality of manifold structure in such point clouds, we reveal insights to aid in the modelling, forecast and control of spreading processes. Our approach highlights contagion maps also as a viable tool for inferring low-dimensional structure in networks.

Topological data analysis of contagion maps for examining spreading processes on networks

NASA Astrophysics Data System (ADS)

Taylor, Dane; Klimm, Florian; Harrington, Heather A.; Kramár, Miroslav; Mischaikow, Konstantin; Porter, Mason A.; Mucha, Peter J.

2015-07-01

Social and biological contagions are influenced by the spatial embeddedness of networks. Historically, many epidemics spread as a wave across part of the Earth's surface; however, in modern contagions long-range edges--for example, due to airline transportation or communication media--allow clusters of a contagion to appear in distant locations. Here we study the spread of contagions on networks through a methodology grounded in topological data analysis and nonlinear dimension reduction. We construct `contagion maps' that use multiple contagions on a network to map the nodes as a point cloud. By analysing the topology, geometry and dimensionality of manifold structure in such point clouds, we reveal insights to aid in the modelling, forecast and control of spreading processes. Our approach highlights contagion maps also as a viable tool for inferring low-dimensional structure in networks.

47 CFR 74.633 - Temporary authorizations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... name and address, facility identification number of the associated broadcast station(s) (if any), call... wide-spread interest and importance which cannot be transmitted successfully on these frequencies...

Evolution of dispersal and life history interact to drive accelerating spread of an invasive species.

PubMed

Perkins, T Alex; Phillips, Benjamin L; Baskett, Marissa L; Hastings, Alan

2013-08-01

Populations on the edge of an expanding range are subject to unique evolutionary pressures acting on their life-history and dispersal traits. Empirical evidence and theory suggest that traits there can evolve rapidly enough to interact with ecological dynamics, potentially giving rise to accelerating spread. Nevertheless, which of several evolutionary mechanisms drive this interaction between evolution and spread remains an open question. We propose an integrated theoretical framework for partitioning the contributions of different evolutionary mechanisms to accelerating spread, and we apply this model to invasive cane toads in northern Australia. In doing so, we identify a previously unrecognised evolutionary process that involves an interaction between life-history and dispersal evolution during range shift. In roughly equal parts, life-history evolution, dispersal evolution and their interaction led to a doubling of distance spread by cane toads in our model, highlighting the potential importance of multiple evolutionary processes in the dynamics of range expansion. © 2013 John Wiley & Sons Ltd/CNRS.

Spatial spread of the West Africa Ebola epidemic.

PubMed

Kramer, Andrew M; Pulliam, J Tomlin; Alexander, Laura W; Park, Andrew W; Rohani, Pejman; Drake, John M

2016-08-01

Controlling Ebola outbreaks and planning an effective response to future emerging diseases are enhanced by understanding the role of geography in transmission. Here we show how epidemic expansion may be predicted by evaluating the relative probability of alternative epidemic paths. We compared multiple candidate models to characterize the spatial network over which the 2013-2015 West Africa epidemic of Ebola virus spread and estimate the effects of geographical covariates on transmission during peak spread. The best model was a generalized gravity model where the probability of transmission between locations depended on distance, population density and international border closures between Guinea, Liberia and Sierra Leone and neighbouring countries. This model out-performed alternative models based on diffusive spread, the force of infection, mobility estimated from cell phone records and other hypothesized patterns of spread. These findings highlight the importance of integrated geography to epidemic expansion and may contribute to identifying both the most vulnerable unaffected areas and locations of maximum intervention value.

Spatial spread of the West Africa Ebola epidemic

PubMed Central

Pulliam, J. Tomlin; Alexander, Laura W.; Rohani, Pejman; Drake, John M.

2016-01-01

Controlling Ebola outbreaks and planning an effective response to future emerging diseases are enhanced by understanding the role of geography in transmission. Here we show how epidemic expansion may be predicted by evaluating the relative probability of alternative epidemic paths. We compared multiple candidate models to characterize the spatial network over which the 2013–2015 West Africa epidemic of Ebola virus spread and estimate the effects of geographical covariates on transmission during peak spread. The best model was a generalized gravity model where the probability of transmission between locations depended on distance, population density and international border closures between Guinea, Liberia and Sierra Leone and neighbouring countries. This model out-performed alternative models based on diffusive spread, the force of infection, mobility estimated from cell phone records and other hypothesized patterns of spread. These findings highlight the importance of integrated geography to epidemic expansion and may contribute to identifying both the most vulnerable unaffected areas and locations of maximum intervention value. PMID:27853607

Mid-latitude spread- F structure

NASA Astrophysics Data System (ADS)

From, W. R.; Meehan, D. H.

1988-07-01

Spread- F has been observed at frequencies of 1.98, 3.84 and 5.80 MHz and multiple angles of arrival have been resolved using an HF radar near Brisbane (27°S, 153°E). The spreading of the ionogram trace has been shown to be due to a spread in angles of arrival of echoes, rather than any 'vertical' spreading. The reflection process appears to involve total specular reflection rather than scattering. The previously reported very strong bias for angles of arrival from the north-west at Brisbane is supported. The direction of movement of the reflection points is not radial and therefore, the structure cannot be purely frontal with purely linear movement, as is often supposed. The velocities are much less than for coexisting travelling ionospheric disturbances. The variations of angle of arrival, range and rate of change of range with frequency do not fit previously proposed ideas of the plasma distribution and an alternative is suggested in which the distortions of the isoionic surfaces resemble small, elongated, asymmetrical 'hills' or 'dips'.

Interactive social contagions and co-infections on complex networks

NASA Astrophysics Data System (ADS)

Liu, Quan-Hui; Zhong, Lin-Feng; Wang, Wei; Zhou, Tao; Eugene Stanley, H.

2018-01-01

What we are learning about the ubiquitous interactions among multiple social contagion processes on complex networks challenges existing theoretical methods. We propose an interactive social behavior spreading model, in which two behaviors sequentially spread on a complex network, one following the other. Adopting the first behavior has either a synergistic or an inhibiting effect on the spread of the second behavior. We find that the inhibiting effect of the first behavior can cause the continuous phase transition of the second behavior spreading to become discontinuous. This discontinuous phase transition of the second behavior can also become a continuous one when the effect of adopting the first behavior becomes synergistic. This synergy allows the second behavior to be more easily adopted and enlarges the co-existence region of both behaviors. We establish an edge-based compartmental method, and our theoretical predictions match well with the simulation results. Our findings provide helpful insights into better understanding the spread of interactive social behavior in human society.

Uncovering multiple populations in NGC 7099 (M 30) using Washington photometry

NASA Astrophysics Data System (ADS)

Frelijj, H.; Geisler, D.; Cummings, J.; Cohen, R. E.; Mauro, F.; Munoz, C.; Villanova, S.; Tang, B.

2017-12-01

Over the last decade, the classical definition of globular clusters (GCs) as simple stellar populations was revolutionized due to the discovery of 'multiple populations' (MPs). However, our knowledge of this phenomenon and its characteristics is still lacking greatly observationally, and there is currently no scenario which adequately explains its origin. It is therefore important to study as many GCs as possible to characterize whether or not they have MPs, and determine their detailed behaviour to enlighten formation scenarios, using a wide range of techniques. The Washington photometric system has proved to be useful to find MPs, thanks mainly to the ultraviolet (UV)-sensitivity and high efficiency of the C filter. We search for MPs in the Galactic GC NGC 7099 (M30), the second GC being searched for MPs using this system. We obtained photometric data using the Swope 1-m telescope at Las Campanas Observatory, as well as the 4-m SOAR facility. Our reduction procedure included Addstar experiments to properly assess photometric errors. We find a clear signal of MPs based on an intrinsically wide colour spread on the RGB, in particular due to a relatively small fraction of stars significantly bluer than the main RGB locus. These stars should correspond to so-called first-generation stars, which we estimate to be roughly 15 per cent of the total. However, we find these first-generation stars to be more spatially concentrated than their second-generation counterparts, which is the opposite to the general trend found in other clusters. We briefly discuss possible explanations for this phenomenon.

Reduction in spread of excitation from current focusing at multiple cochlear locations in cochlear implant users.

PubMed

Padilla, Monica; Landsberger, David M

2016-03-01

Channel interaction from a broad spread of excitation is likely to be a limiting factor in performance by cochlear implant users. Although partial tripolar stimulation has been shown to reduce spread of excitation, the magnitude of the reduction is highly variable across subjects. Because the reduction in spread of excitation is typically only measured at one electrode for a given subject, the degree of variability across cochlear locations is unknown. The first goal of the present study was to determine if the reduction in spread of excitation observed from partial tripolar current focusing systematically varies across the cochlea. The second goal was to measure the variability in reduction of spread of excitation relative to monopolar stimulation across the cochlea. The third goal was to expand upon previous results that suggest that scaling of verbal descriptors can be used to predict the reduction in spread of excitation, by increasing the limited number of sites previously evaluated and verify the relationships remain with the larger dataset. The spread of excitation for monopolar and partial tripolar stimulation was measured at 5 cochlear locations using a psychophysical forward masking task. Results of the present study suggest that although partial tripolar stimulation typically reduces spread of excitation, the degree of reduction in spread of excitation was found to be highly variable and no effect of cochlear location was found. Additionally, subjective scaling of certain verbal descriptors (Clean/Dirty, Pure/Noisy) correlated with the reduction in spread of excitation suggesting sound quality scaling might be used as a quick clinical estimate of channels providing a reduction in spread of excitation. This quick scaling technique might help clinicians determine which patients would be most likely to benefit from a focused strategy. Copyright © 2016 Elsevier B.V. All rights reserved.

Reduction in Spread of Excitation from Current Focusing at Multiple Cochlear Locations in Cochlear Implant Users

PubMed Central

Padilla, Monica; Landsberger, David M.

2016-01-01

Channel interaction from a broad spread of excitation is likely to be a limiting factor in performance by cochlear implant users. Although partial tripolar stimulation has been shown to reduce spread of excitation, the magnitude of the reduction is highly variable across subjects. Because the reduction in spread of excitation is typically only measured at one electrode for a given subject, the degree of variability across cochlear locations is unknown. The first goal of the present study was to determine if the reduction in spread of excitation observed from partial tripolar current focusing systematically varies across the cochlea. The second goal was to measure the variability in reduction of spread of excitation relative to monopolar stimulation across the cochlea. The third goal was to expand upon previous results that suggest that scaling of verbal descriptors can be used to predict the reduction in spread of excitation, by increasing the limited number of sites previously evaluated and verify the relationships remain with the larger dataset. The spread of excitation for monopolar and partial tripolar stimulation was measured at 5 cochlear locations using a psychophysical forward masking task. Results of the present study suggest that although partial tripolar stimulation typically reduces spread of excitation, the degree of reduction in spread of excitation was found to be highly variable and no effect of cochlear location was found. Additionally, subjective scaling of certain verbal descriptors (Clean/Dirty, Pure/Noisy) correlated with the reduction in spread of excitation suggesting sound quality scaling might be used as a quick clinical estimate of channels providing a reduction in spread of excitation. This quick scaling technique might help clinicians determine which patients would be most likely to benefit from a focused strategy. PMID:26778546

Binary Sequences for Spread-Spectrum Multiple-Access Communication

DTIC Science & Technology

1977-08-01

Massey, J. L., and Uhran, J. J., Jr., "Sub-baud coding," Proceedings of the Thirteenth Annual Allerton Conference on Circuit and System Theory, pp. 539...sequences in a multipl.e access environment," Proceedings of the Thirteenth Annual AIlerton Conference on Circuit and System Theory, pp. 21-27, October...34 Proceedings of the Thirteenth Annual Allertcn Conference on Circuit and System Theory, pp. 548-559, October 1975. Yao, K., *Performance bounds on

Effectiveness of the Area-wide Pest Management Program to Control Asian Tiger Mosquito in New Jersey: Evidence from a Household Survey

USDA-ARS?s Scientific Manuscript database

Households’ behaviors can both mitigate and measure the spread of urban mosquitos. Beginning in 2009, a comprehensive area-wide pest management (AWPM) project to control Aedes albopictus was implemented in 4 areas in Monmouth and Mercer Counties, New Jersey. Including other activities, the project f...

Effectiveness of the area wide pest management program to control asian tiger mosquito in New Jersey: evidence from a household survey

USDA-ARS?s Scientific Manuscript database

Households’ behaviors can both mitigate and measure the spread of urban mosquito species. Beginning in 2009, an area-wide pest management (AWPM) project to control Ae. Albopictus was implemented in 6 areas in Monmouth and Mercer counties, NJ. Including other activities, the project focused on increa...

Human infection of novel avian influenza A(H7N4) virus.

PubMed

Tong, Xue-Cheng; Weng, Shan-Shan; Xue, Feng; Wu, Xing; Xu, Tian-Min; Zhang, Wen-Hong

2018-06-10

Multiple reassortant strains of novel, highly pathogenic avian influenza A have recently emerged and spread over the world. Here we report on a 68-year-old woman in Jiangsu, China, with influenza A(H7N4) infection and associated illness, which strongly demonstrating the ability of the virus to spread from animals to humans and thus emphasizing the importance of continuous surveillance of the emerging viruses. Copyright © 2018. Published by Elsevier Ltd.

Strategies for Managing and Leading an Academic Staff in Multiple Countries

ERIC Educational Resources Information Center

Hughes, Rebecca

2011-01-01

Faculty are a critical component to the success of the academic branch campus. In an environment where academic quality is constantly in question, the management and leadership of the academic staff are important, particularly when that staff is spread across multiple geographic locations. In this chapter, the author begins by describing the broad…

Interaction between HIV awareness, knowledge, safe sex practice and HIV prevalence: evidence from Botswana.

PubMed

Ray, Ranjan; Sinha, Kompal

2012-05-01

This paper makes methodological and empirical contributions to the study of HIV in the context of Botswana, a country with high HIV prevalence. Comparable evidence is presented from India to put the Botswana results in perspective. The results point to the strong role played by affluence and education in increasing HIV knowledge, promoting safe sex and reducing HIV prevalence. The study presents African evidence on the role played by the empowerment of women in promoting safe sex practices such as condom use. The lack of significant association between HIV prevalence and safe sex practice points to the danger of HIV-infected individuals spreading the disease through multiple sex partners and unprotected sex. This danger is underlined by the finding that females with multiple sex partners are at higher risk of being infected with HIV. These results take on special policy significance in the context of Botswana, where the issue of multiple sex partners has not been adequately addressed in the programme to contain the spread of HIV.

Pamidronate Injection

MedlinePlus

... also used along with cancer chemotherapy to treat bone damage caused by multiple myeloma (cancer that begins ... by breast cancer that has spread to the bones. Pamidronate is also used to treat Paget's disease ( ...

Public Health Risks of Multiple-Drug-Resistant Enterococcus spp. in Southeast Asia

PubMed Central

Lee, Sui Mae; Rahman, Sadequr

2015-01-01

Enterococci rank as one of the leading causes of nosocomial infections, such as urinary tract infections, surgical wound infections, and endocarditis, in humans. These infections can be hard to treat because of the rising incidence of antibiotic resistance. Enterococci inhabiting nonhuman reservoirs appear to play a critical role in the acquisition and dissemination of antibiotic resistance determinants. The spread of antibiotic resistance has become a major concern in both human and veterinary medicine, especially in Southeast Asia, where many developing countries have poor legislation and regulations to control the supply and excessive use of antimicrobials. This review addresses the occurrence of antibiotic-resistant enterococci in Association of Southeast Asian Nations countries and proposes infection control measures that should be applied to limit the spread of multiple-drug-resistant enterococci. PMID:26150452

A performance analysis of DS-CDMA and SCPC VSAT networks

NASA Technical Reports Server (NTRS)

Hayes, David P.; Ha, Tri T.

1990-01-01

Spread-spectrum and single-channel-per-carrier (SCPC) transmission techniques work well in very small aperture terminal (VSAT) networks for multiple-access purposes while allowing the earth station antennas to remain small. Direct-sequence code-division multiple-access (DS-CDMA) is the simplest spread-spectrum technique to use in a VSAT network since a frequency synthesizer is not required for each terminal. An examination is made of the DS-CDMA and SCPC Ku-band VSAT satellite systems for low-density (64-kb/s or less) communications. A method for improving the standardf link analysis of DS-CDMA satellite-switched networks by including certain losses is developed. The performance of 50-channel full mesh and star network architectures is analyzed. The selection of operating conditions producing optimum performance is demonstrated.

New Synthesis of Ocean Crust Velocity Structure From Two-Dimensional Profiles

NASA Astrophysics Data System (ADS)

Christeson, G. L.; Goff, J.; Carlson, R. L.; Reece, R.

2017-12-01

The velocity structure of typical oceanic crust consists of Layer 2, where velocities increase rapidly with depth from seafloor, and Layer 3, which is thicker and has a lower velocity gradient. Previous syntheses have found no correlation of velocity structure with spreading rate, even though we know that magmatic processes differ between slow-spreading and fast-spreading crust. We present a new synthesis of ocean crust velocity structure, compiling observations from two-dimensional studies in the Atlantic, Pacific, and Indian ocean basins. The Layer 2/3 boundary was picked from each publication at a change in gradient either on velocity-depth functions or contour plots (with at least 0.5 km/s contour interval), or from the appropriate layer boundary for layered models. We picked multiple locations at each seismic refraction profile if warranted by model variability. Preliminary results show statistically significant differences in average Layer 2 and Layer 3 thicknesses between slow-spreading and superfast-spreading crust, with Layer 2 thinner and Layer 3 thicker for the higher spreading rate crust. The thickness changes are about equivalent, resulting in no change in mean crustal thickness. The Layer 2/3 boundary is often interpreted as the top of the gabbros; however, a comparison with mapped magma lens depths at the ridge axis shows that the boundary is typically deeper than average axial melt lens depth at superfast-spreading crust, and shallower at intermediate-spreading crust.

Potential for broad-scale transmission of Ebola virus disease during the West Africa crisis: lessons for the Global Health security agenda.

PubMed

Undurraga, Eduardo A; Carias, Cristina; Meltzer, Martin I; Kahn, Emily B

2017-12-01

The 2014-2016 Ebola crisis in West Africa had approximately eight times as many reported deaths as the sum of all previous Ebola outbreaks. The outbreak magnitude and occurrence of multiple Ebola cases in at least seven countries beyond Liberia, Sierra Leone, and Guinea, hinted at the possibility of broad-scale transmission of Ebola. Using a modeling tool developed by the US Centers for Disease Control and Prevention during the Ebola outbreak, we estimated the number of Ebola cases that might have occurred had the disease spread beyond the three countries in West Africa to cities in other countries at high risk for disease transmission (based on late 2014 air travel patterns). We estimated Ebola cases in three scenarios: a delayed response, a Liberia-like response, and a fast response scenario. Based on our estimates of the number of Ebola cases that could have occurred had Ebola spread to other countries beyond the West African foci, we emphasize the need for improved levels of preparedness and response to public health threats, which is the goal of the Global Health Security Agenda. Our estimates suggest that Ebola could have potentially spread widely beyond the West Africa foci, had local and international health workers and organizations not committed to a major response effort. Our results underscore the importance of rapid detection and initiation of an effective, organized response, and the challenges faced by countries with limited public health systems. Actionable lessons for strengthening local public health systems in countries at high risk of disease transmission include increasing health personnel, bolstering primary and critical healthcare facilities, developing public health infrastructure (e.g. laboratory capacity), and improving disease surveillance. With stronger local public health systems infectious disease outbreaks would still occur, but their rapid escalation would be considerably less likely, minimizing the impact of public health threats such as Ebola. The Ebola outbreak could have potentially spread to other countries, where limited public health surveillance and response capabilities may have resulted in additional foci. Health security requires robust local health systems that can rapidly detect and effectively respond to an infectious disease outbreak.

Improving performance of DS-CDMA systems using chaotic complex Bernoulli spreading codes

NASA Astrophysics Data System (ADS)

Farzan Sabahi, Mohammad; Dehghanfard, Ali

2014-12-01

The most important goal of spreading spectrum communication system is to protect communication signals against interference and exploitation of information by unintended listeners. In fact, low probability of detection and low probability of intercept are two important parameters to increase the performance of the system. In Direct Sequence Code Division Multiple Access (DS-CDMA) systems, these properties are achieved by multiplying the data information in spreading sequences. Chaotic sequences, with their particular properties, have numerous applications in constructing spreading codes. Using one-dimensional Bernoulli chaotic sequence as spreading code is proposed in literature previously. The main feature of this sequence is its negative auto-correlation at lag of 1, which with proper design, leads to increase in efficiency of the communication system based on these codes. On the other hand, employing the complex chaotic sequences as spreading sequence also has been discussed in several papers. In this paper, use of two-dimensional Bernoulli chaotic sequences is proposed as spreading codes. The performance of a multi-user synchronous and asynchronous DS-CDMA system will be evaluated by applying these sequences under Additive White Gaussian Noise (AWGN) and fading channel. Simulation results indicate improvement of the performance in comparison with conventional spreading codes like Gold codes as well as similar complex chaotic spreading sequences. Similar to one-dimensional Bernoulli chaotic sequences, the proposed sequences also have negative auto-correlation. Besides, construction of complex sequences with lower average cross-correlation is possible with the proposed method.

Wave directional spreading from point field measurements.

PubMed

McAllister, M L; Venugopal, V; Borthwick, A G L

2017-04-01

Ocean waves have multidirectional components. Most wave measurements are taken at a single point, and so fail to capture information about the relative directions of the wave components directly. Conventional means of directional estimation require a minimum of three concurrent time series of measurements at different spatial locations in order to derive information on local directional wave spreading. Here, the relationship between wave nonlinearity and directionality is utilized to estimate local spreading without the need for multiple concurrent measurements, following Adcock & Taylor (Adcock & Taylor 2009 Proc. R. Soc. A 465 , 3361-3381. (doi:10.1098/rspa.2009.0031)), with the assumption that directional spreading is frequency independent. The method is applied to measurements recorded at the North Alwyn platform in the northern North Sea, and the results compared against estimates of wave spreading by conventional measurement methods and hindcast data. Records containing freak waves were excluded. It is found that the method provides accurate estimates of wave spreading over a range of conditions experienced at North Alwyn, despite the noisy chaotic signals that characterize such ocean wave data. The results provide further confirmation that Adcock and Taylor's method is applicable to metocean data and has considerable future promise as a technique to recover estimates of wave spreading from single point wave measurement devices.

Wave directional spreading from point field measurements

PubMed Central

Venugopal, V.; Borthwick, A. G. L.

2017-01-01

Ocean waves have multidirectional components. Most wave measurements are taken at a single point, and so fail to capture information about the relative directions of the wave components directly. Conventional means of directional estimation require a minimum of three concurrent time series of measurements at different spatial locations in order to derive information on local directional wave spreading. Here, the relationship between wave nonlinearity and directionality is utilized to estimate local spreading without the need for multiple concurrent measurements, following Adcock & Taylor (Adcock & Taylor 2009 Proc. R. Soc. A 465, 3361–3381. (doi:10.1098/rspa.2009.0031)), with the assumption that directional spreading is frequency independent. The method is applied to measurements recorded at the North Alwyn platform in the northern North Sea, and the results compared against estimates of wave spreading by conventional measurement methods and hindcast data. Records containing freak waves were excluded. It is found that the method provides accurate estimates of wave spreading over a range of conditions experienced at North Alwyn, despite the noisy chaotic signals that characterize such ocean wave data. The results provide further confirmation that Adcock and Taylor's method is applicable to metocean data and has considerable future promise as a technique to recover estimates of wave spreading from single point wave measurement devices. PMID:28484326

Visualization of the Eastern Renewable Generation Integration Study: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gruchalla, Kenny; Novacheck, Joshua; Bloom, Aaron

The Eastern Renewable Generation Integration Study (ERGIS), explores the operational impacts of the wide spread adoption of wind and solar photovoltaics (PV) resources in the U.S. Eastern Interconnection and Quebec Interconnection (collectively, EI). In order to understand some of the economic and reliability challenges of managing hundreds of gigawatts of wind and PV generation, we developed state of the art tools, data, and models for simulating power system operations using hourly unit commitment and 5-minute economic dispatch over an entire year. Using NREL's high-performance computing capabilities and new methodologies to model operations, we found that the EI, as simulated withmore » evolutionary change in 2026, could balance the variability and uncertainty of wind and PV at a 5-minute level under a variety of conditions. A large-scale display and a combination of multiple coordinated views and small multiples were used to visually analyze the four large highly multivariate scenarios with high spatial and temporal resolutions. state of the art tools, data, and models for simulating power system operations using hourly unit commitment and 5-minute economic dispatch over an entire year. Using NRELs high-performance computing capabilities and new methodologies to model operations, we found that the EI, as simulated with evolutionary change in 2026, could balance the variability and uncertainty of wind and PV at a 5-minute level under a variety of conditions. A large-scale display and a combination of multiple coordinated views and small multiples were used to visually analyze the four large highly multivariate scenarios with high spatial and temporal resolutions.« less

From traditional medicine to witchcraft: why medical treatments are not always efficacious.

PubMed

Tanaka, Mark M; Kendal, Jeremy R; Laland, Kevin N

2009-01-01

Complementary medicines, traditional remedies and home cures for medical ailments are used extensively world-wide, representing more than US$60 billion sales in the global market. With serious doubts about the efficacy and safety of many treatments, the industry remains steeped in controversy. Little is known about factors affecting the prevalence of efficacious and non-efficacious self-medicative treatments. Here we develop mathematical models which reveal that the most efficacious treatments are not necessarily those most likely to spread. Indeed, purely superstitious remedies, or even maladaptive practices, spread more readily than efficacious treatments under specified circumstances. Low-efficacy practices sometimes spread because their very ineffectiveness results in longer, more salient demonstration and a larger number of converts, which more than compensates for greater rates of abandonment. These models also illuminate a broader range of phenomena, including the spread of innovations, medical treatment of animals, foraging behaviour, and self-medication in non-human primates.

Suppressing epidemics with a limited amount of immunization units.

PubMed

Schneider, Christian M; Mihaljev, Tamara; Havlin, Shlomo; Herrmann, Hans J

2011-12-01

The way diseases spread through schools, epidemics through countries, and viruses through the internet is crucial in determining their risk. Although each of these threats has its own characteristics, its underlying network determines the spreading. To restrain the spreading, a widely used approach is the fragmentation of these networks through immunization, so that epidemics cannot spread. Here we develop an immunization approach based on optimizing the susceptible size, which outperforms the best known strategy based on immunizing the highest-betweenness links or nodes. We find that the network's vulnerability can be significantly reduced, demonstrating this on three different real networks: the global flight network, a school friendship network, and the internet. In all cases, we find that not only is the average infection probability significantly suppressed, but also for the most relevant case of a small and limited number of immunization units the infection probability can be reduced by up to 55%.

The Age Related Properties of Solar Type Stars

NASA Technical Reports Server (NTRS)

Soderblom, David

1999-01-01

The studies of lithium in solar-type stars in clusters of a wide range of ages has provided critical information on a tracer of convective processes, especially among very young stars. Our most recent work has been on a pre-main sequence cluster (NGC 2264) that took place after this grant expired, but was founded on it. The spread seen in Li in Zero-Age Main Sequence clusters like the Pleiades is huge and possibly related to rotation. No clear spread in seen in NGC 2264, so it does not have its origins in the conditions of formation but is instead a result of processes occurring during PMS evolution. Our observations of M67 were particularly interesting because this cluster is the same age as the Sun, i.e.,very old. Clear evidence was seen for a spread in Li there too, indicating that the spread seen in very young stars perpetuates itself into old age.

Finite size effects in epidemic spreading: the problem of overpopulated systems

NASA Astrophysics Data System (ADS)

Ganczarek, Wojciech

2013-12-01

In this paper we analyze the impact of network size on the dynamics of epidemic spreading. In particular, we investigate the pace of infection in overpopulated systems. In order to do that, we design a model for epidemic spreading on a finite complex network with a restriction to at most one contamination per time step, which can serve as a model for sexually transmitted diseases spreading in some student communes. Because of the highly discrete character of the process, the analysis cannot use the continuous approximation widely exploited for most models. Using a discrete approach, we investigate the epidemic threshold and the quasi-stationary distribution. The main results are two theorems about the mixing time for the process: it scales like the logarithm of the network size and it is proportional to the inverse of the distance from the epidemic threshold.

An in vivo evaluation of the antiseizure activity and acute neurotoxicity of agmatine.

PubMed

Bence, Aimee K; Worthen, David R; Stables, James P; Crooks, Peter A

2003-02-01

Agmatine, an endogenous cationic amine, exerts a wide range of biological effects, including modulation of glutamate-activated N-methyl-D-aspartate (NMDA) receptor function in the central nervous system (CNS). Since glutamate and the NMDA receptor have been implicated in the initiation and spread of seizure activity, the capacity of agmatine to inhibit seizure spread was evaluated in vivo. Orally administered agmatine (30 mg/kg) protected against maximal electroshock seizure (MES)-induced seizure spread in rats as rapidly as 15 min and for as long as 6 h after administration. Inhibition of MES-induced seizure spread was also observed when agmatine was administered intraperitoneally. Agmatine's antiseizure activity did not appear to be dose-dependent. An in vivo neurotoxicity screen indicated that agmatine was devoid of any acute neurological toxicity at the doses tested. These preliminary data suggest that agmatine has promising anticonvulsant activity.

Steganography on multiple MP3 files using spread spectrum and Shamir's secret sharing

NASA Astrophysics Data System (ADS)

Yoeseph, N. M.; Purnomo, F. A.; Riasti, B. K.; Safiie, M. A.; Hidayat, T. N.

2016-11-01

The purpose of steganography is how to hide data into another media. In order to increase security of data, steganography technique is often combined with cryptography. The weakness of this combination technique is the data was centralized. Therefore, a steganography technique is develop by using combination of spread spectrum and secret sharing technique. In steganography with secret sharing, shares of data is created and hidden in several medium. Medium used to concealed shares were MP3 files. Hiding technique used was Spread Spectrum. Secret sharing scheme used was Shamir's Secret Sharing. The result showed that steganography with spread spectrum combined with Shamir's Secret Share using MP3 files as medium produce a technique that could hid data into several cover. To extract and reconstruct the data hidden in stego object, it is needed the amount of stego object which more or equal to its threshold. Furthermore, stego objects were imperceptible and robust.

The spread of Ras activity triggered by activation of a single dendritic spine.

PubMed

Harvey, Christopher D; Yasuda, Ryohei; Zhong, Haining; Svoboda, Karel

2008-07-04

In neurons, individual dendritic spines isolate N-methyl-d-aspartate (NMDA) receptor-mediated calcium ion (Ca2+) accumulations from the dendrite and other spines. However, the extent to which spines compartmentalize signaling events downstream of Ca2+ influx is not known. We combined two-photon fluorescence lifetime imaging with two-photon glutamate uncaging to image the activity of the small guanosine triphosphatase Ras after NMDA receptor activation at individual spines. Induction of long-term potentiation (LTP) triggered robust Ca2+-dependent Ras activation in single spines that decayed in approximately 5 minutes. Ras activity spread over approximately 10 micrometers of dendrite and invaded neighboring spines by diffusion. The spread of Ras-dependent signaling was necessary for the local regulation of the threshold for LTP induction. Thus, Ca2+-dependent synaptic signals can spread to couple multiple synapses on short stretches of dendrite.

Multiple Scattering Effects on Pulse Propagation in Optically Turbid Media.

NASA Astrophysics Data System (ADS)

Joelson, Bradley David

The effects of multiple scattering in a optically turbid media is examined for an impulse solution to the radiative transfer equation for a variety of geometries and phase functions. In regions where the complexities of the phase function proved too cumbersome for analytic methods Monte Carlo techniques were developed to describe the entire scalar radiance distribution. The determination of a general spread function is strongly dependent on geometry and particular regions where limits can be placed on the variables of the problem. Hence, the general spread function is first simplified by considering optical regions which reduce the complexity of the variable dependence. First, in the small-angle limit we calculate some contracted spread functions along with their moments and then use Monte Carlo techniques to establish the limitations imposed by the small-angle approximation in planar geometry. The point spread function (PSF) for a spherical geometry is calculated for the full angular spread in the forward direction of ocean waters using Monte Carlo methods in the optically thin and moderate depths and analytic methods in the diffusion domain. The angular dependence of the PSF for various ocean waters is examined for a range of optical parameters. The analytic method used in the diffusion calculation is justified by examining the angular dependence of the radiance of a impulse solution in a planar geometry for a prolongated Henyey-Greenstein phase function of asymmetry factor approximately equal to that of the ocean phase functions. The Legendre moments of the radiance are examined in order to examine the viability of the diffusion approximation which assumes a linearly anisotropic angular distribution for the radiance. A realistic lidar calculation is performed for a variety of ocean waters to determine the effects of multiple scattering on the determination of the speed of sound by using the range gated frequency spectrum of the lidar signal. It is shown that the optical properties of the ocean help to ensure single scatter form for the frequency spectra of the lidar signal. This spectra can then be used to compute the speed of sound and backscatter probability.

Fast and accurate detection of spread source in large complex networks.

PubMed

Paluch, Robert; Lu, Xiaoyan; Suchecki, Krzysztof; Szymański, Bolesław K; Hołyst, Janusz A

2018-02-06

Spread over complex networks is a ubiquitous process with increasingly wide applications. Locating spread sources is often important, e.g. finding the patient one in epidemics, or source of rumor spreading in social network. Pinto, Thiran and Vetterli introduced an algorithm (PTVA) to solve the important case of this problem in which a limited set of nodes act as observers and report times at which the spread reached them. PTVA uses all observers to find a solution. Here we propose a new approach in which observers with low quality information (i.e. with large spread encounter times) are ignored and potential sources are selected based on the likelihood gradient from high quality observers. The original complexity of PTVA is O(N α ), where α ∈ (3,4) depends on the network topology and number of observers (N denotes the number of nodes in the network). Our Gradient Maximum Likelihood Algorithm (GMLA) reduces this complexity to O (N 2 log (N)). Extensive numerical tests performed on synthetic networks and real Gnutella network with limitation that id's of spreaders are unknown to observers demonstrate that for scale-free networks with such limitation GMLA yields higher quality localization results than PTVA does.

The risk of disease to great apes: simulating disease spread in orang-utan (Pongo pygmaeus wurmbii) and chimpanzee (Pan troglodytes schweinfurthii) association networks.

PubMed

Carne, Charlotte; Semple, Stuart; Morrogh-Bernard, Helen; Zuberbühler, Klaus; Lehmann, Julia

2014-01-01

All great ape species are endangered, and infectious diseases are thought to pose a particular threat to their survival. As great ape species vary substantially in social organisation and gregariousness, there are likely to be differences in susceptibility to disease types and spread. Understanding the relation between social variables and disease is therefore crucial for implementing effective conservation measures. Here, we simulate the transmission of a range of diseases in a population of orang-utans in Sabangau Forest (Central Kalimantan) and a community of chimpanzees in Budongo Forest (Uganda), by systematically varying transmission likelihood and probability of subsequent recovery. Both species have fission-fusion social systems, but differ considerably in their level of gregariousness. We used long-term behavioural data to create networks of association patterns on which the spread of different diseases was simulated. We found that chimpanzees were generally far more susceptible to the spread of diseases than orang-utans. When simulating different diseases that varied widely in their probability of transmission and recovery, it was found that the chimpanzee community was widely and strongly affected, while in orang-utans even highly infectious diseases had limited spread. Furthermore, when comparing the observed association network with a mean-field network (equal contact probability between group members), we found no major difference in simulated disease spread, suggesting that patterns of social bonding in orang-utans are not an important determinant of susceptibility to disease. In chimpanzees, the predicted size of the epidemic was smaller on the actual association network than on the mean-field network, indicating that patterns of social bonding have important effects on susceptibility to disease. We conclude that social networks are a potentially powerful tool to model the risk of disease transmission in great apes, and that chimpanzees are particularly threatened by infectious disease outbreaks as a result of their social structure.

The Risk of Disease to Great Apes: Simulating Disease Spread in Orang-Utan (Pongo pygmaeus wurmbii) and Chimpanzee (Pan troglodytes schweinfurthii) Association Networks

PubMed Central

Carne, Charlotte; Semple, Stuart; Morrogh-Bernard, Helen; Zuberbühler, Klaus; Lehmann, Julia

2014-01-01

All great ape species are endangered, and infectious diseases are thought to pose a particular threat to their survival. As great ape species vary substantially in social organisation and gregariousness, there are likely to be differences in susceptibility to disease types and spread. Understanding the relation between social variables and disease is therefore crucial for implementing effective conservation measures. Here, we simulate the transmission of a range of diseases in a population of orang-utans in Sabangau Forest (Central Kalimantan) and a community of chimpanzees in Budongo Forest (Uganda), by systematically varying transmission likelihood and probability of subsequent recovery. Both species have fission-fusion social systems, but differ considerably in their level of gregariousness. We used long-term behavioural data to create networks of association patterns on which the spread of different diseases was simulated. We found that chimpanzees were generally far more susceptible to the spread of diseases than orang-utans. When simulating different diseases that varied widely in their probability of transmission and recovery, it was found that the chimpanzee community was widely and strongly affected, while in orang-utans even highly infectious diseases had limited spread. Furthermore, when comparing the observed association network with a mean-field network (equal contact probability between group members), we found no major difference in simulated disease spread, suggesting that patterns of social bonding in orang-utans are not an important determinant of susceptibility to disease. In chimpanzees, the predicted size of the epidemic was smaller on the actual association network than on the mean-field network, indicating that patterns of social bonding have important effects on susceptibility to disease. We conclude that social networks are a potentially powerful tool to model the risk of disease transmission in great apes, and that chimpanzees are particularly threatened by infectious disease outbreaks as a result of their social structure. PMID:24740263

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, C.; Kewisch, J.; Huang, H.

At RHIC, the spin polarization is preserved with a pair of Siberian snakes on the oppo- site sides in each ring. The polarized proton beam with finite spin tune spread might cross spin resonances multiple times in two cases, one is when beam going through strong spin intrinsic resonances during acceleration, the other is when sweeping spin flipper’ frequency across the spin tune to flip the direction of spin polarization. The consequence is loss of spin polarization in both cases. Therefore, a scheme of min- imizing the spin tune spread by matching the dispersion primes at the two snakes wasmore » introduced based on the fact that the spin tune spread is proportional to the difference of dispersion primes at the two snakes. The scheme was implemented at fixed energies for the spin flipper study and during beam acceleration for better spin polarization transmission efficiency. The effect of minimizing the spin tune spread by matching the dispersion primes was observed and confirmed experimentally. The principle of minimizing the spin tune spread by matching the dispersion primes, the impact on the beam optics, and the effect of a narrower spin tune spread are presented in this report.« less

Transit time spreads in biased paracentric hemispherical deflection analyzers

NASA Astrophysics Data System (ADS)

Sise, Omer; Zouros, Theo J. M.

2016-02-01

The biased paracentric hemispherical deflection analyzers (HDAs) are an alternative to conventional (centric) HDAs maintaining greater dispersion, lower angular aberrations, and hence better energy resolution without the use of any additional fringing field correctors. In the present work, the transit time spread of the biased paracentric HDA is computed over a wide range of analyzer parameters. The combination of high energy resolution with good time resolution and simplicity of design makes the biased paracentric analyzers very promising for both coincidence and singles spectroscopy applications.

Interconexión de la Estación Astrofísica de Bosque Alegre y la red local de datos del Observatorio Astronómico de Córdoba

NASA Astrophysics Data System (ADS)

Nicotra, M. A.; Anun, S.; Montes, M.; Goldes, G.; Carranza, G.

We describe the outlines of a project for the interconnection between the Astrophysical Station of Bosque Alegre and the wide area network of the University of Córdoba. The Astrophysical Station is located 38.55 km (23.96 milles) from the Observatory of Córdoba. This location is suitable for radio links in the range of centimeters wavelenghts. In the last years, Spread-Spectrum technology equipments has become popular. Spread-Spectrum signals, contrary to narrow band radio signals, operates within a widthband 20 to 200 times broader than the widthband of the modulated information. Signals are modulated by special spreading codes, in such a way that emulates noisy signals. These codes are known under the generic designation of pseudo-random or pseudo-noise. In addition, the wide band is correlated with a low power density in the emitted signals. Spread-Spectrum equipment links are stable, exhibits low interferences with conventional radio transmitters, and their commercial prices are remarkably lower than those for the conventional microwave devices. Data links are compliant with Ethernet protocol networks and operates with data tramsmition rates up to 4 Mbits per second. The described equipment will enable the access to full-Internet services for visitor astronomers in Bosque Alegre. Also, it will be possible fast transfer for the observational data from telescope to computers in the local area network at Córdoba. This project must be considered as the second stage of another wide purpose project, which has the main purpose in transforming the Bosque Alegre Station as a fully robotic station controlled from the computational center at the Observatory in Cordoba. The advantages of robotic telescopes has recently been the subject of several discussions. However, it is now widely accepted that an automatic station enables some important options in the use of the astronomical instruments, such us the possibility of performing parallel programs, one of which is selected accordingly to environmental conditions in the instant of the observation.

Hybrid spread spectrum radio system

DOEpatents

Smith, Stephen F.; Dress, William B.

2010-02-02

Systems and methods are described for hybrid spread spectrum radio systems. A method includes modulating a signal by utilizing a subset of bits from a pseudo-random code generator to control an amplification circuit that provides a gain to the signal. Another method includes: modulating a signal by utilizing a subset of bits from a pseudo-random code generator to control a fast hopping frequency synthesizer; and fast frequency hopping the signal with the fast hopping frequency synthesizer, wherein multiple frequency hops occur within a single data-bit time.

How do long-offset oceanic transforms adapt to plate motion changes? The example of the Western Pacific-Antarctic plate boundary

NASA Astrophysics Data System (ADS)

Lodolo, Emanuele; Coren, Franco; Ben-Avraham, Zvi

2013-03-01

Oceanic transform faults respond to changes in the direction of relative plate motion. Studies have shown that short-offset transforms generally adjust with slight bends near the ridge axis, while long-offset ones have a remarkably different behavior. The western Pacific-Antarctic plate boundary highlights these differences. A set of previously unpublished seismic profiles, in combination with magnetic anomaly identifications, shows how across a former, ~1250 km long transform (the Emerald Fracture Zone), plate motion changes have produced a complex geometric readjustment. Three distinct sections are recognized along this plate boundary: an eastern section, characterized by parallel, multiple fault strand lineaments; a central section, shallower than the rest of the ridge system, overprinted by a mantle plume track; and a western section, organized in a cascade of short spreading axes/transform lineaments. This configuration was produced by changes that occurred since 30 Ma in the Australia-Pacific relative plate motion, combined with a gradual clockwise change in Pacific-Antarctic plate motion. These events caused extension along the former Emerald Fracture Zone, originally linking the Pacific-Antarctic spreading ridge system with the Southeast Indian ridge. Then an intra-transform propagating ridge started to develop in response to a ~6 Ma change in the Pacific-Antarctic spreading direction. The close proximity of the Euler poles of rotation amplified the effects of the geometric readjustments that occurred along the transform system. This analysis shows that when a long-offset transform older than 20 Ma is pulled apart by changes in spreading velocity vectors, it responds with the development of multiple discrete, parallel fault strands, whereas in younger lithosphere, locally modified by thermal anisotropies, tensional stresses generate an array of spreading axes offset by closely spaced transforms.

High-energy multiple muons and heavy primary cosmic-rays

NASA Technical Reports Server (NTRS)

Mizutani, K.; Sato, T.; Takahashi, T.; Higashi, S.

1985-01-01

Three-dimensional simulations were carried out on high-energy multiple muons. On the lateral spread, the comparison with the deep underground observations indicates that the primary cosmic rays include heavy nuclei of high content. A method to determine the average mass number of primary particles in the energy around 10 to the 15th power eV is suggested.

High security chaotic multiple access scheme for visible light communication systems with advanced encryption standard interleaving

NASA Astrophysics Data System (ADS)

Qiu, Junchao; Zhang, Lin; Li, Diyang; Liu, Xingcheng

2016-06-01

Chaotic sequences can be applied to realize multiple user access and improve the system security for a visible light communication (VLC) system. However, since the map patterns of chaotic sequences are usually well known, eavesdroppers can possibly derive the key parameters of chaotic sequences and subsequently retrieve the information. We design an advanced encryption standard (AES) interleaving aided multiple user access scheme to enhance the security of a chaotic code division multiple access-based visible light communication (C-CDMA-VLC) system. We propose to spread the information with chaotic sequences, and then the spread information is interleaved by an AES algorithm and transmitted over VLC channels. Since the computation complexity of performing inverse operations to deinterleave the information is high, the eavesdroppers in a high speed VLC system cannot retrieve the information in real time; thus, the system security will be enhanced. Moreover, we build a mathematical model for the AES-aided VLC system and derive the theoretical information leakage to analyze the system security. The simulations are performed over VLC channels, and the results demonstrate the effectiveness and high security of our presented AES interleaving aided chaotic CDMA-VLC system.

Disease spreading in real-life networks

NASA Astrophysics Data System (ADS)

Gallos, Lazaros; Argyrakis, Panos

2002-08-01

In recent years the scientific community has shown a vivid interest in the network structure and dynamics of real-life organized systems. Many such systems, covering an extremely wide range of applications, have been recently shown to exhibit scale-free character in their connectivity distribution, meaning that they obey a power law. Modeling of epidemics on lattices and small-world networks suffers from the presence of a critical infection threshold, above which the entire population is infected. For scale-free networks, the original assumption was that the formation of a giant cluster would lead to an epidemic spreading in the same way as in simpler networks. Here we show that modeling epidemics on a scale-free network can greatly improve the predictions on the rate and efficiency of spreading, as compared to lattice models and small-world networks. We also show that the dynamics of a disease are greatly influenced by the underlying population structure. The exact same model can describe a plethora of networks, such as social networks, virus spreading in the Web, rumor spreading, signal transmission etc.

Using the Gravity Model to Estimate the Spatial Spread of Vector-Borne Diseases

PubMed Central

Barrios, José Miguel; Verstraeten, Willem W.; Maes, Piet; Aerts, Jean-Marie; Farifteh, Jamshid; Coppin, Pol

2012-01-01

The gravity models are commonly used spatial interaction models. They have been widely applied in a large set of domains dealing with interactions amongst spatial entities. The spread of vector-borne diseases is also related to the intensity of interaction between spatial entities, namely, the physical habitat of pathogens’ vectors and/or hosts, and urban areas, thus humans. This study implements the concept behind gravity models in the spatial spread of two vector-borne diseases, nephropathia epidemica and Lyme borreliosis, based on current knowledge on the transmission mechanism of these diseases. Two sources of information on vegetated systems were tested: the CORINE land cover map and MODIS NDVI. The size of vegetated areas near urban centers and a local indicator of occupation-related exposure were found significant predictors of disease risk. Both the land cover map and the space-borne dataset were suited yet not equivalent input sources to locate and measure vegetated areas of importance for disease spread. The overall results point at the compatibility of the gravity model concept and the spatial spread of vector-borne diseases. PMID:23202882

Using the gravity model to estimate the spatial spread of vector-borne diseases.

PubMed

Barrios, José Miguel; Verstraeten, Willem W; Maes, Piet; Aerts, Jean-Marie; Farifteh, Jamshid; Coppin, Pol

2012-11-30

The gravity models are commonly used spatial interaction models. They have been widely applied in a large set of domains dealing with interactions amongst spatial entities. The spread of vector-borne diseases is also related to the intensity of interaction between spatial entities, namely, the physical habitat of pathogens’ vectors and/or hosts, and urban areas, thus humans. This study implements the concept behind gravity models in the spatial spread of two vector-borne diseases, nephropathia epidemica and Lyme borreliosis, based on current knowledge on the transmission mechanism of these diseases. Two sources of information on vegetated systems were tested: the CORINE land cover map and MODIS NDVI. The size of vegetated areas near urban centers and a local indicator of occupation-related exposure were found significant predictors of disease risk. Both the land cover map and the space-borne dataset were suited yet not equivalent input sources to locate and measure vegetated areas of importance for disease spread. The overall results point at the compatibility of the gravity model concept and the spatial spread of vector-borne diseases.

From the diabetic foot ulcer and beyond: how do foot infections spread in patients with diabetes?

PubMed Central

Aragón-Sánchez, Javier; Lázaro-Martínez, Jose Luis; Pulido-Duque, Juan; Maynar, Manuel

2012-01-01

A diabetic foot infection is usually the result of a pre-existing foot ulceration and is the leading cause of lower extremity amputation in patients with diabetes. It is widely accepted that diabetic foot infections may be challenging to treat for several reasons. The devastating effects of hyperglycemia on host defense, ischemia, multi-drug resistant bacteria and spreading of infection through the foot may complicate the course of diabetic foot infections. Understanding the ways in which infections spread through the diabetic foot is a pivotal factor in order to decide the best approach for the patient's treatment. The ways in which infections spread can be explained by the anatomical division of the foot into compartments, the tendons included in the compartments, the initial location of the point of entry of the infection and the type of infection that the patient has. The aim of this paper is to further comment on the existed and proposed anatomical principles of the spread of infection through the foot in patients with diabetes. PMID:23050067

Antimicrobial use and antimicrobial resistance in food animals.

PubMed

Xiong, Wenguang; Sun, Yongxue; Zeng, Zhenling

2018-05-25

Antimicrobials have been widely used in food animals for growth promotion since the 1950s. Antimicrobial resistance emerges in animal production settings and frequently spreads to humans through the food chain and direct contact. There have been international efforts to restrict or ban antimicrobials used for both humans and animals. Denmark has taken positive strides in the development of a comprehensive database DANMAP to track antimicrobial usage and resistance. Although food animals are sources of antimicrobial resistance, there is little evidence that antimicrobial resistance originates from food animals. This review comprehensively introduces the history and trends of antimicrobial use, the emergence and spread of antimicrobial resistance in food animals provides suggestions to tackle the problems of the spread of antimicrobial resistance.

Effects of human dynamics on epidemic spreading in Côte d'Ivoire

NASA Astrophysics Data System (ADS)

Li, Ruiqi; Wang, Wenxu; Di, Zengru

2017-02-01

Understanding and predicting outbreaks of contagious diseases are crucial to the development of society and public health, especially for underdeveloped countries. However, challenging problems are encountered because of complex epidemic spreading dynamics influenced by spatial structure and human dynamics (including both human mobility and human interaction intensity). We propose a systematical model to depict nationwide epidemic spreading in Côte d'Ivoire, which integrates multiple factors, such as human mobility, human interaction intensity, and demographic features. We provide insights to aid in modeling and predicting the epidemic spreading process by data-driven simulation and theoretical analysis, which is otherwise beyond the scope of local evaluation and geometrical views. We show that the requirement that the average local basic reproductive number to be greater than unity is not necessary for outbreaks of epidemics. The observed spreading phenomenon can be roughly explained as a heterogeneous diffusion-reaction process by redefining mobility distance according to the human mobility volume between nodes, which is beyond the geometrical viewpoint. However, the heterogeneity of human dynamics still poses challenges to precise prediction.

Human ectoparasites and the spread of plague in Europe during the Second Pandemic

PubMed Central

Krauer, Fabienne; Walløe, Lars; Bramanti, Barbara; Stenseth, Nils Chr.; Schmid, Boris V.

2018-01-01

Plague, caused by the bacterium Yersinia pestis, can spread through human populations by multiple transmission pathways. Today, most human plague cases are bubonic, caused by spillover of infected fleas from rodent epizootics, or pneumonic, caused by inhalation of infectious droplets. However, little is known about the historical spread of plague in Europe during the Second Pandemic (14–19th centuries), including the Black Death, which led to high mortality and recurrent epidemics for hundreds of years. Several studies have suggested that human ectoparasite vectors, such as human fleas (Pulex irritans) or body lice (Pediculus humanus humanus), caused the rapidly spreading epidemics. Here, we describe a compartmental model for plague transmission by a human ectoparasite vector. Using Bayesian inference, we found that this model fits mortality curves from nine outbreaks in Europe better than models for pneumonic or rodent transmission. Our results support that human ectoparasites were primary vectors for plague during the Second Pandemic, including the Black Death (1346–1353), ultimately challenging the assumption that plague in Europe was predominantly spread by rats. PMID:29339508

Human ectoparasites and the spread of plague in Europe during the Second Pandemic.

PubMed

Dean, Katharine R; Krauer, Fabienne; Walløe, Lars; Lingjærde, Ole Christian; Bramanti, Barbara; Stenseth, Nils Chr; Schmid, Boris V

2018-02-06

Plague, caused by the bacterium Yersinia pestis , can spread through human populations by multiple transmission pathways. Today, most human plague cases are bubonic, caused by spillover of infected fleas from rodent epizootics, or pneumonic, caused by inhalation of infectious droplets. However, little is known about the historical spread of plague in Europe during the Second Pandemic (14-19th centuries), including the Black Death, which led to high mortality and recurrent epidemics for hundreds of years. Several studies have suggested that human ectoparasite vectors, such as human fleas ( Pulex irritans ) or body lice ( Pediculus humanus humanus ), caused the rapidly spreading epidemics. Here, we describe a compartmental model for plague transmission by a human ectoparasite vector. Using Bayesian inference, we found that this model fits mortality curves from nine outbreaks in Europe better than models for pneumonic or rodent transmission. Our results support that human ectoparasites were primary vectors for plague during the Second Pandemic, including the Black Death (1346-1353), ultimately challenging the assumption that plague in Europe was predominantly spread by rats. Copyright © 2018 the Author(s). Published by PNAS.

A trait-based approach for predicting species responses to environmental change from sparse data: how well might terrestrial mammals track climate change?

PubMed

Santini, Luca; Cornulier, Thomas; Bullock, James M; Palmer, Stephen C F; White, Steven M; Hodgson, Jenny A; Bocedi, Greta; Travis, Justin M J

2016-07-01

Estimating population spread rates across multiple species is vital for projecting biodiversity responses to climate change. A major challenge is to parameterise spread models for many species. We introduce an approach that addresses this challenge, coupling a trait-based analysis with spatial population modelling to project spread rates for 15 000 virtual mammals with life histories that reflect those seen in the real world. Covariances among life-history traits are estimated from an extensive terrestrial mammal data set using Bayesian inference. We elucidate the relative roles of different life-history traits in driving modelled spread rates, demonstrating that any one alone will be a poor predictor. We also estimate that around 30% of mammal species have potential spread rates slower than the global mean velocity of climate change. This novel trait-space-demographic modelling approach has broad applicability for tackling many key ecological questions for which we have the models but are hindered by data availability. © 2016 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

Uncontrolled concrete bridge parapet cracking.

DOT National Transportation Integrated Search

2013-06-01

The Ohio Department of Transportation has recently identified the problem of wide-spread premature cracking of concrete bridge : parapets throughout its District 12 region (Northeast Ohio). Many of the bridge decks that contain these prematurely crac...

[A worrisome scintigraphy].

PubMed

Cardano, Sergio; Cornaglia, Gabriella; Monteverde, Anna Irene

2006-01-01

This report describes a patient who was admitted to the hospital with suspicion of occult neoplasia, widely spreading to bone. In fact, he had osteoporosis and osteomalacia due to hypovitaminosis D caused by chronic use of antiepileptic drugs.

Regeneration of Cassava Plants from Apical Meristems,

DTIC Science & Technology

widely for human consumption. Propagation through stem cuttings encourages the spread of many virus diseases, such as cassava mosaic virus. This paper reports on procedures for regenerating cassava plants from the apical meristems.

Malaspina Glacier, Alaska

NASA Image and Video Library

2003-05-01

Malaspina Glacier in southeastern Alaska is considered the classic example of a piedmont glacier. Piedmont glaciers occur where valley glaciers exit a mountain range onto broad lowlands, are no longer laterally confined, and spread to become wide lobes.

Mineral resources of Novokuznetsk administrative district of Kemerovo region (metallic and non-metallic minerals)

NASA Astrophysics Data System (ADS)

Gutak, Ja M.

2017-09-01

The article summarizes data on metallic and non-metallic minerals of Novokuznetsk district of Kemerovo region. Consistently reviewed are iron deposits (Tersinskaya group of deposits), gold deposits (placer accumulations and vein gold deposits), mineral water deposits (Tersinskoe deposit), deposit of refractory clay (Barkinskoe) and wide spread mineral deposits such as brick clay, keramzite materials, sand and gravel, building stones, ornamental stones, facing stones, peat, materials for lime production. It is indicated that resource base of metallic and nonmetallic minerals is inferior to that of mineral coal. At the same time it can be of considerable interest to small and medium-size businesses as objects with quick return of investment (facing and ornamental stones). For a number of wide spread mineral resources (brick clay, keramzite materials, sand and gravel) it is an important component of local industry.

Migration histories of multidrug-resistant tuberculosis patients from the Thailand-Myanmar border, 2012-2014.

PubMed

Thi, S S; Parker, D M; Swe, L L; Pukrittayakamee, S; Ling, C L; Amornpaisarnloet, K; Vincenti-Delmas, M; Nosten, F H

2017-07-01

Multidrug-resistant tuberculosis (MDR-TB) is a growing public health threat in South-East Asia. TB is typically a disease of poverty and can be spread by infectious humans who migrate from one region to another. We interviewed 20 MDR-TB patients on the Thailand-Myanmar border with regard to their migration histories. Migration origins and destinations were mapped. All but one participant had a history of migration, and maps of migration ranges revealed wide geographic dispersal. Most described living and work conditions that could contribute to the spread of drug-resistant TB, including numerous contacts and crowded living quarters. Our results show that at least some migrant workers in the region carry MDR-TB, and indicate that this subgroup of the population is important with regard to the transmission of MDR-TB throughout the region. Migrants in this region come into contact with high numbers of people and may be able to spread the disease across wide geographic ranges. Access to diagnosis and treatment and socio-economic development are at least as important as any TB control measures, meaning that innovative and bold approaches that extend across international borders are needed to address these problems.

Searching for superspreaders of information in real-world social media.

PubMed

Pei, Sen; Muchnik, Lev; Andrade, José S; Zheng, Zhiming; Makse, Hernán A

2014-07-03

A number of predictors have been suggested to detect the most influential spreaders of information in online social media across various domains such as Twitter or Facebook. In particular, degree, PageRank, k-core and other centralities have been adopted to rank the spreading capability of users in information dissemination media. So far, validation of the proposed predictors has been done by simulating the spreading dynamics rather than following real information flow in social networks. Consequently, only model-dependent contradictory results have been achieved so far for the best predictor. Here, we address this issue directly. We search for influential spreaders by following the real spreading dynamics in a wide range of networks. We find that the widely-used degree and PageRank fail in ranking users' influence. We find that the best spreaders are consistently located in the k-core across dissimilar social platforms such as Twitter, Facebook, Livejournal and scientific publishing in the American Physical Society. Furthermore, when the complete global network structure is unavailable, we find that the sum of the nearest neighbors' degree is a reliable local proxy for user's influence. Our analysis provides practical instructions for optimal design of strategies for "viral" information dissemination in relevant applications.

Searching for superspreaders of information in real-world social media

NASA Astrophysics Data System (ADS)

Pei, Sen; Muchnik, Lev; Andrade, José S., Jr.; Zheng, Zhiming; Makse, Hernán A.

2014-07-01

A number of predictors have been suggested to detect the most influential spreaders of information in online social media across various domains such as Twitter or Facebook. In particular, degree, PageRank, k-core and other centralities have been adopted to rank the spreading capability of users in information dissemination media. So far, validation of the proposed predictors has been done by simulating the spreading dynamics rather than following real information flow in social networks. Consequently, only model-dependent contradictory results have been achieved so far for the best predictor. Here, we address this issue directly. We search for influential spreaders by following the real spreading dynamics in a wide range of networks. We find that the widely-used degree and PageRank fail in ranking users' influence. We find that the best spreaders are consistently located in the k-core across dissimilar social platforms such as Twitter, Facebook, Livejournal and scientific publishing in the American Physical Society. Furthermore, when the complete global network structure is unavailable, we find that the sum of the nearest neighbors' degree is a reliable local proxy for user's influence. Our analysis provides practical instructions for optimal design of strategies for ``viral'' information dissemination in relevant applications.

Searching for superspreaders of information in real-world social media

PubMed Central

Pei, Sen; Muchnik, Lev; Andrade, Jr., José S.; Zheng, Zhiming; Makse, Hernán A.

2014-01-01

A number of predictors have been suggested to detect the most influential spreaders of information in online social media across various domains such as Twitter or Facebook. In particular, degree, PageRank, k-core and other centralities have been adopted to rank the spreading capability of users in information dissemination media. So far, validation of the proposed predictors has been done by simulating the spreading dynamics rather than following real information flow in social networks. Consequently, only model-dependent contradictory results have been achieved so far for the best predictor. Here, we address this issue directly. We search for influential spreaders by following the real spreading dynamics in a wide range of networks. We find that the widely-used degree and PageRank fail in ranking users' influence. We find that the best spreaders are consistently located in the k-core across dissimilar social platforms such as Twitter, Facebook, Livejournal and scientific publishing in the American Physical Society. Furthermore, when the complete global network structure is unavailable, we find that the sum of the nearest neighbors' degree is a reliable local proxy for user's influence. Our analysis provides practical instructions for optimal design of strategies for “viral” information dissemination in relevant applications. PMID:24989148

The spreading of misinformation online.

PubMed

Del Vicario, Michela; Bessi, Alessandro; Zollo, Fabiana; Petroni, Fabio; Scala, Antonio; Caldarelli, Guido; Stanley, H Eugene; Quattrociocchi, Walter

2016-01-19

The wide availability of user-provided content in online social media facilitates the aggregation of people around common interests, worldviews, and narratives. However, the World Wide Web (WWW) also allows for the rapid dissemination of unsubstantiated rumors and conspiracy theories that often elicit rapid, large, but naive social responses such as the recent case of Jade Helm 15--where a simple military exercise turned out to be perceived as the beginning of a new civil war in the United States. In this work, we address the determinants governing misinformation spreading through a thorough quantitative analysis. In particular, we focus on how Facebook users consume information related to two distinct narratives: scientific and conspiracy news. We find that, although consumers of scientific and conspiracy stories present similar consumption patterns with respect to content, cascade dynamics differ. Selective exposure to content is the primary driver of content diffusion and generates the formation of homogeneous clusters, i.e., "echo chambers." Indeed, homogeneity appears to be the primary driver for the diffusion of contents and each echo chamber has its own cascade dynamics. Finally, we introduce a data-driven percolation model mimicking rumor spreading and we show that homogeneity and polarization are the main determinants for predicting cascades' size.

Evolution of male strategies with sex-ratio-dependent pay-offs: connecting pair bonds with grandmothering.

PubMed

Loo, Sara L; Hawkes, Kristen; Kim, Peter S

2017-09-19

Men's provisioning of mates and offspring has been central to ideas about human evolution because paternal provisioning is absent in our closest evolutionary cousins, the great apes, and is widely assumed to result in pair bonding, which distinguishes us from them. Yet mathematical modelling has shown that paternal care does not readily spread in populations where competition for multiple mates is the common male strategy. Here we add to models that point to the mating sex ratio as an explanation for pairing as pay-offs to mate guarding rise with a male-biased sex ratio. This is of interest for human evolution because our grandmothering life history shifts the mating sex ratio from female- to male-biased. Using a difference equation model, we explore the relative pay-offs for three competing male strategies (dependant care, multiple mating, mate guarding) in response to changing adult sex ratios. When fertile females are abundant, multiple mating prevails. As they become scarce, mate guarding triumphs. The threshold for this shift depends on guarding efficiency. Combined with mating sex ratios of hunter-gatherer and chimpanzee populations, these results strengthen the hypothesis that the evolution of our grandmothering life history propelled the shift to pair bonding in the human lineage.This article is part of the themed issue 'Adult sex ratios and reproductive decisions: a critical re-examination of sex differences in human and animal societies'. © 2017 The Author(s).

Genetic analysis across different spatial scales reveals multiple dispersal mechanisms for the invasive hydrozoan Cordylophora in the Great Lakes.

PubMed

Darling, John A; Folino-Rorem, Nadine C

2009-12-01

Discerning patterns of post-establishment spread by invasive species is critically important for the design of effective management strategies and the development of appropriate theoretical models predicting spatial expansion of introduced populations. The globally invasive colonial hydrozoan Cordylophora produces propagules both sexually and vegetatively and is associated with multiple potential dispersal mechanisms, making it a promising system to investigate complex patterns of population structure generated throughout the course of rapid range expansion. Here, we explore genetic patterns associated with the spread of this taxon within the North American Great Lakes basin. We collected intensively from eight harbours in the Chicago area in order to conduct detailed investigation of local population expansion. In addition, we collected from Lakes Michigan, Erie, and Ontario, as well as Lake Cayuga in the Finger Lakes of upstate New York in order to assess genetic structure on a regional scale. Based on data from eight highly polymorphic microsatellite loci we examined the spatial extent of clonal genotypes, assessed levels of neutral genetic diversity, and explored patterns of migration and dispersal at multiple spatial scales through assessment of population level genetic differentiation (pairwise F(ST) and factorial correspondence analysis), Bayesian inference of population structure, and assignment tests on individual genotypes. Results of these analyses indicate that Cordylophora populations in this region spread predominantly through sexually produced propagules, and that while limited natural larval dispersal can drive expansion locally, regional expansion likely relies on anthropogenic dispersal vectors.

Cascades in multiplex financial networks with debts of different seniority

NASA Astrophysics Data System (ADS)

Brummitt, Charles D.; Kobayashi, Teruyoshi

2015-06-01

The seniority of debt, which determines the order in which a bankrupt institution repays its debts, is an important and sometimes contentious feature of financial crises, yet its impact on systemwide stability is not well understood. We capture seniority of debt in a multiplex network, a graph of nodes connected by multiple types of edges. Here an edge between banks denotes a debt contract of a certain level of seniority. Next we study cascading default. There exist multiple kinds of bankruptcy, indexed by the highest level of seniority at which a bank cannot repay all its debts. Self-interested banks would prefer that all their loans be made at the most senior level. However, mixing debts of different seniority levels makes the system more stable in that it shrinks the set of network densities for which bankruptcies spread widely. We compute the optimal ratio of senior to junior debts, which we call the optimal seniority ratio, for two uncorrelated Erdős-Rényi networks. If institutions erode their buffer against insolvency, then this optimal seniority ratio rises; in other words, if default thresholds fall, then more loans should be senior. We generalize the analytical results to arbitrarily many levels of seniority and to heavy-tailed degree distributions.

Cascades in multiplex financial networks with debts of different seniority.

PubMed

Brummitt, Charles D; Kobayashi, Teruyoshi

2015-06-01

The seniority of debt, which determines the order in which a bankrupt institution repays its debts, is an important and sometimes contentious feature of financial crises, yet its impact on systemwide stability is not well understood. We capture seniority of debt in a multiplex network, a graph of nodes connected by multiple types of edges. Here an edge between banks denotes a debt contract of a certain level of seniority. Next we study cascading default. There exist multiple kinds of bankruptcy, indexed by the highest level of seniority at which a bank cannot repay all its debts. Self-interested banks would prefer that all their loans be made at the most senior level. However, mixing debts of different seniority levels makes the system more stable in that it shrinks the set of network densities for which bankruptcies spread widely. We compute the optimal ratio of senior to junior debts, which we call the optimal seniority ratio, for two uncorrelated Erdős-Rényi networks. If institutions erode their buffer against insolvency, then this optimal seniority ratio rises; in other words, if default thresholds fall, then more loans should be senior. We generalize the analytical results to arbitrarily many levels of seniority and to heavy-tailed degree distributions.

Spatial layout optimization design of multi-type LEDs lighting source based on photoelectrothermal coupling theory

NASA Astrophysics Data System (ADS)

Xue, Lingyun; Li, Guang; Chen, Qingguang; Rao, Huanle; Xu, Ping

2018-03-01

Multiple LED-based spectral synthesis technology has been widely used in the fields of solar simulator, color mixing, and artificial lighting of plant factory and so on. Generally, amounts of LEDs are spatially arranged with compact layout to obtain the high power density output. Mutual thermal spreading among LEDs will produce the coupled thermal effect which will additionally increase the junction temperature of LED. Affected by the Photoelectric thermal coupling effect of LED, the spectrum of LED will shift and luminous efficiency will decrease. Correspondingly, the spectral synthesis result will mismatch. Therefore, thermal management of LED spatial layout plays an important role for multi-LEDs light source system. In the paper, the thermal dissipation network topology model considering the mutual thermal spreading effect among the LEDs is proposed for multi-LEDs system with various types of power. The junction temperature increment cased by the thermal coupling has the great relation with the spatial arrangement. To minimize the thermal coupling effect, an optimized method of LED spatial layout for the specific light source structure is presented and analyzed. The results showed that layout of LED with high-power are arranged in the corner and low-power in the center. Finally, according to this method, it is convenient to determine the spatial layout of LEDs in a system having any kind of light source structure, and has the advantages of being universally applicable to facilitate adjustment.

Chemical study of the metal-rich globular cluster NGC 5927

NASA Astrophysics Data System (ADS)

Mura-Guzmán, A.; Villanova, S.; Muñoz, C.; Tang, B.

2018-03-01

Globular clusters (GCs) are natural laboratories where stellar and chemical evolution can be studied in detail. In addition, their chemical patterns and kinematics can tell us to which Galactic structure (disc, bulge, halo or extragalactic) the cluster belongs to. NGC 5927 is one of most metal-rich GCs in the Galaxy and its kinematics links it to the thick disc. We present abundance analysis based on high-resolution spectra of seven giant stars. The data were obtained using Fibre Large Array Multi Element Spectrograph/Ultraviolet Echelle Spectrograph (UVES) spectrograph mounted on UT2 telescope of the European Southern Observatory. The principal objective of this work is to perform a wide and detailed chemical abundance analysis of the cluster and look for possible Multiple Populations (MPs). We determined stellar parameters and measured 22 elements corresponding to light (Na, Al), alpha (O, Mg, Si, Ca, Ti), iron-peak (Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn), and heavy elements (Y, Zr, Ba, Ce, Nd, Eu). We found a mean iron content of [Fe/H] = -0.47 ± 0.02 (error on the mean). We confirm the existence of MPs in this GC with an O-Na anti-correlation, and moderate spread in Al abundances. We estimate a mean [α/Fe] = 0.25 ± 0.08. Iron-peak elements show no significant spread. The [Ba/Eu] ratios indicate a predominant contribution from SNeII for the formation of the cluster.

Occurrence of Multidrug-Resistant and Toxic-Metal Tolerant Enterococci in Fresh Feces from Urban Pigeons in Brazil

PubMed Central

da Silva, Vânia Lúcia; Caçador, Natália Cândido; dos Santos Fernandes da Silva, Carolina; Fontes, Cláudia Oliveira; Garcia, Gizele Duarte; Nicoli, Jacques Robert; Diniz, Cláudio Galuppo

2012-01-01

Enterococcus are emerging as important putative pathogens resistant to chemicals that are widely released into the environment, and urban pigeons might act as a natural reservoir contributing to the spread of resistant strains. This study aimed to evaluate the occurrence of Enterococcus in pigeon feces and their antimicrobial and toxic metal susceptibility. Bacteria were isolated and identified from 150 fresh feces by phenotypic and genetic techniques. Antimicrobial and toxic metal susceptibility was determined by the agar dilution method, and the multiple antibiotic resistance index (MAR) was calculated. Out of 120 isolates, no resistance was observed against penicillin and vancomycin, but was observed against gentamicin (55.8%), chloramphenicol (21.7%), tetracycline (13.3%), ciprofloxacin (8.4%) and rifampin (2.5%). 18.3% presented a MAR index ≥0.2, ranging between 0.14 to 0.57, indicating resistance to more than one antimicrobial. All samples were tolerant to >1024 μg mL−1 zinc and chromium. Minimal inhibitory concentration (MIC) of 1,024 μg mL−1 was observed for copper (100%) and nickel (71.4%). Mercury inhibited 88.4% at 32 μg mL−1 and the MIC for cadmium ranged from 0.125–128 μg mL−1. Since pigeons were found to harbor drug-resistant Enterococcus, our data support that their presence in the urban environment may contribute to the spread of resistance, with an impact on public health. PMID:22791051

Molecular characterization of antibiotic resistance in cultivable multidrug-resistant bacteria from livestock manure.

PubMed

Yang, Qingxiang; Tian, Tiantian; Niu, Tianqi; Wang, Panliang

2017-10-01

Diverse antibiotic-resistance genes (ARGs) are frequently reported to have high prevalence in veterinary manure samples due to extensive use of antibiotics in farm animals. However, the characteristics of the distribution and transmission of ARGs among bacteria, especially among different species of multiple antibiotic-resistant bacteria (MARB), have not been well explored. By applying high-throughput sequencing methods, our study uncovered a vast MARB reservoir in livestock manure. The genera Escherichia, Myroides, Acinetobacter, Proteus, Ignatzschineria, Alcaligenes, Providencia and Enterococcus were the predominant cultivable MARB, with compositions of 40.6%-85.7%. From chicken manure isolates, 33 MARB were selected for investigation of the molecular characteristics of antibiotic resistance. A total of 61 ARGs and 18 mobile genetic elements (MGEs) were investigated. We found that 47 ARGs were widely distributed among the 33 MARB isolates. Each isolate carried 27-36 genes responsible for resistance to eight classes of antibiotics frequently used in clinic or veterinary settings. ARGs to the six classes of antibiotics other than streptogramins and vancomycin were present in all 33 MARB isolates with a prevalence of 80%-100%. A total of 12 MGEs were widely distributed among the 33 MARB, with intI1, IS26, ISaba1, and ISEcp1 simultaneously present in 100% of isolates. In addition, 9 gene cassettes within integrons and ISCR1 were detected among MARB isolates encoding resistance to different antibiotic classes. This is the first report revealing the general co-presence of multiple ARGs, various MGEs and ARG cassettes in different species of individual MARB isolates in chicken manure. The results highlight a much higher risk of ARGs spreading through livestock manure to humans than we expected. Copyright © 2017 Elsevier Ltd. All rights reserved.

Yellow-Poplar Rooting Habits

Treesearch

John K. Francis

1979-01-01

Although the configuration of pole-sized yellow-poplar root systems in Tennessee is quite variable, a branched taproot with several widely spreading laterals is typical. Rooting depth is particularly limited by clayey texture, wetness, and firmness of subsoils.

47 CFR 87.479 - Harmful interference to radionavigation land stations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... to establish wide-band systems using frequency-hopping spread spectrum techniques in the 960-1215 MHz.... Transmissions will be automatically prevented if: (1) The frequency-hopping mode fails to distribute the JTIDS...

Galaxies Grow from Inside Out

NASA Image and Video Library

2013-10-31

Evidence from NASA Wide-field Infrared Survey Explorer and Galaxy Evolution Explorer missions provide support for the inside-out theory of galaxy evolution, which holds that star formation starts at the core of the galaxy and spreads outward.

Steric antisense inhibition of AMPA receptor Q/R editing reveals tight coupling to intronic editing sites and splicing

PubMed Central

Penn, Andrew C.; Balik, Ales; Greger, Ingo H.

2013-01-01

Adenosine-to-Inosine (A-to-I) RNA editing is a post-transcriptional mechanism, evolved to diversify the transcriptome in metazoa. In addition to wide-spread editing in non-coding regions protein recoding by RNA editing allows for fine tuning of protein function. Functional consequences are only known for some editing sites and the combinatorial effect between multiple sites (functional epistasis) is currently unclear. Similarly, the interplay between RNA editing and splicing, which impacts on post-transcriptional gene regulation, has not been resolved. Here, we describe a versatile antisense approach, which will aid resolving these open questions. We have developed and characterized morpholino oligos targeting the most efficiently edited site—the AMPA receptor GluA2 Q/R site. We show that inhibition of editing closely correlates with intronic editing efficiency, which is linked to splicing efficiency. In addition to providing a versatile tool our data underscore the unique efficiency of a physiologically pivotal editing site. PMID:23172291

Stenotrophomonas maltophilia is highly prevalent among houseflies (Musca domestica).

PubMed

Fukuda, Akira; Usui, Masaru; Wakao, Hideyuki; Boonla, Chanchai; Tamura, Yutaka

2017-08-04

Stenotrophomonas maltophilia is capable of surviving in a wide variety of environments and is considered to be among the antimicrobial-resistant bacteria of greatest public health concern in hospital settings. To clarify the role of houseflies (Musca domestica) in disseminating this bacterium, we collected 99 individuals from 15 locations (9 farms and 6 urban areas) in Thailand. S. maltophilia was isolated from 39 % (39/99) of these houseflies, with the isolation rates being similar in farms and urban areas. Multiple-antimicrobial resistance was evident among the S. maltophilia isolates obtained. Of note, the rate of resistance to trimethoprim/sulfamethoxazole (TMP/SMX), the recommended first-line antimicrobial for S. maltophilia infection, was relatively high (30 %). Almost all of the isolates had a different PFGE pattern. These results suggest that houseflies ingest and host S. maltophilia from several different environmental sources. In conclusion, houseflies may facilitate the spread of antimicrobial-resistant (including TMP/SMX-resistant) S. maltophilia from environmental sources to humans.

Antimicrobial susceptibility and molecular characterization of macrolide resistance of Mycoplasma bovis isolates from multiple provinces in China

PubMed Central

KONG, Ling-Cong; GAO, Duo; JIA, Bo-Yan; WANG, Zi; GAO, Yun-Hang; PEI, Zhi-Hua; LIU, Shu-Ming; XIN, Jiu-Qing; MA, Hong-Xia

2015-01-01

Mycoplasma bovis has spread widely throughout the world via animal movement and has become an important pathogen of bovine respiratory disease. However, the minimum inhibitory concentrations of antimicrobials for Mycoplasma bovis have not been studied in China. The objective of this study was to determine the prevalence and antibiotic resistance of Mycoplasma bovis isolated from young cattle with respiratory infection in China. Mycoplasma bovis was detected in 32/45 bovine respiratory infection outbreaks at beef farms in 8 provinces in China. The isolates were susceptible or had medium sensitivity to ciprofloxacin, enrofloxacin and doxycycline, but were frequently resistant to macrolides (13/32, 41%). An A2058G (Escherichia coli Numbering) mutation located in the rrnA operon in domain V of 23S rRNA was observed in strains that were resistant to macrolides. This single mutations at the rrnA operon in domain V of 23S rRNA may play an important role in the resistance of Mycoplasma bovis strains to macrolides. PMID:26346744

Delayed onset pulmonary glue emboli in a ventilated patient: a rare complication following endoscopic cyanoacrylate injection for gastric variceal haemorrhage

PubMed Central

Chew, Joyce Ruo Yi; Balan, Anu; Griffiths, William; Herre, Jurgen

2014-01-01

Cyanoacrylate injection is a recognised endoscopic treatment option for variceal haemorrhage. We describe a 34-year old man with hepatitis B cirrhosis who presented to the hospital with upper gastrointestinal haemorrhage from gastric and oesophageal varices. Haemostasis was achieved via cyanoacrylate injection sclerotherapy and banding. Ten days later, the patient developed acute hypoxia and fever. His chest radiograph showed wide-spread pulmonary shadowing. A non-contrast CT scan confirmed multiple emboli of injected glue material from the varix with parenchymal changes either suggesting acute lung injury or pulmonary oedema. He gradually recovered with supportive treatment and was discharged home. On follow-up, he remained asymptomatic from a chest perspective. This case report discusses the rare complication of pulmonary embolisation of cyanoacrylate glue from variceal injection sites and the diagnostic dilemmas involved. Emphasis is placed on the importance of maintaining high index of clinical suspicion when assessing patients with possible procedure related complications. PMID:25320260

Learning of Alignment Rules between Concept Hierarchies

NASA Astrophysics Data System (ADS)

Ichise, Ryutaro; Takeda, Hideaki; Honiden, Shinichi

With the rapid advances of information technology, we are acquiring much information than ever before. As a result, we need tools for organizing this data. Concept hierarchies such as ontologies and information categorizations are powerful and convenient methods for accomplishing this goal, which have gained wide spread acceptance. Although each concept hierarchy is useful, it is difficult to employ multiple concept hierarchies at the same time because it is hard to align their conceptual structures. This paper proposes a rule learning method that inputs information from a source concept hierarchy and finds suitable location for them in a target hierarchy. The key idea is to find the most similar categories in each hierarchy, where similarity is measured by the κ(kappa) statistic that counts instances belonging to both categories. In order to evaluate our method, we conducted experiments using two internet directories: Yahoo! and LYCOS. We map information instances from the source directory into the target directory, and show that our learned rules agree with a human-generated assignment 76% of the time.

Transverse strain measurements using fiber optic grating based sensors

NASA Technical Reports Server (NTRS)

Udd, Eric (Inventor)

1998-01-01

A system and method to sense the application of transverse stress to an optical fiber which includes a light source that producing a relatively wide spectrum light beam. The light beam is reflected or transmitted off of an optical grating in the core of an optical fiber that is transversely stressed either directly or by the exposure to pressure when the fiber is bifringent so that the optical fiber responds to the pressure to transversely stress its core. When transversely stressed, the optical grating produces a reflection or transmission from the light beam that has two peaks or minimums in its frequency spectrum whose spacing and/or spread are indicative of the forces applied to the fiber. One or more detectors sense the reflection or transmissions from the optical grating to produce an output representative of the applied force. Multiple optical gratings and detectors may be employed to simultaneously measure temperature or the forces at different locations along the fiber.

Detecting Signatures of Positive Selection along Defined Branches of a Population Tree Using LSD.

PubMed

Librado, Pablo; Orlando, Ludovic

2018-06-01

Identifying the genomic basis underlying local adaptation is paramount to evolutionary biology, and bears many applications in the fields of conservation biology, crop, and animal breeding, as well as personalized medicine. Although many approaches have been developed to detect signatures of positive selection within single populations and population pairs, the increasing wealth of high-throughput sequencing data requires improved methods capable of handling multiple, and ideally large number of, populations in a single analysis. In this study, we introduce LSD (levels of exclusively shared differences), a fast and flexible framework to perform genome-wide selection scans, along the internal and external branches of a given population tree. We use forward simulations to demonstrate that LSD can identify branches targeted by positive selection with remarkable sensitivity and specificity. We illustrate a range of potential applications by analyzing data from the 1000 Genomes Project and uncover a list of adaptive candidates accompanying the expansion of anatomically modern humans out of Africa and their spread to Europe.

Microbiology and risk factors associated with war-related wound infections in the Middle East.

PubMed

Sahli, Z T; Bizri, A R; Abu-Sittah, G S

2016-10-01

The Middle East region is plagued with repeated armed conflicts that affect both civilians and soldiers. Injuries sustained during war are common and frequently associated with multiple life-threatening complications. Wound infections are major consequences of these war injuries. The microbiology of war-related wound infections is variable with predominance of Gram-negative bacteria in later stages. The emergence of antimicrobial resistance among isolates affecting war-related wound injuries is a serious problem with major regional and global implications. Factors responsible for the increase in multidrug-resistant pathogens include timing and type of surgical management, wide use of antimicrobial drugs, and the presence of metallic or organic fragments in the wound. Nosocomial transmission is the most important factor in the spread of multidrug-resistant pathogens. Wound management of war-related injuries merits a multidisciplinary approach. This review aims to describe the microbiology of war-related wound infections and factors affecting their incidence from conflict areas in Iraq, Syria, Israel, and Lebanon.

An overview of distributed microgrid state estimation and control for smart grids.

PubMed

Rana, Md Masud; Li, Li

2015-02-12

Given the significant concerns regarding carbon emission from the fossil fuels, global warming and energy crisis, the renewable distributed energy resources (DERs) are going to be integrated in the smart grid. This grid can spread the intelligence of the energy distribution and control system from the central unit to the long-distance remote areas, thus enabling accurate state estimation (SE) and wide-area real-time monitoring of these intermittent energy sources. In contrast to the traditional methods of SE, this paper proposes a novel accuracy dependent Kalman filter (KF) based microgrid SE for the smart grid that uses typical communication systems. Then this article proposes a discrete-time linear quadratic regulation to control the state deviations of the microgrid incorporating multiple DERs. Therefore, integrating these two approaches with application to the smart grid forms a novel contributions in green energy and control research communities. Finally, the simulation results show that the proposed KF based microgrid SE and control algorithm provides an accurate SE and control compared with the existing method.

Properties of branching exponential flights in bounded domains

NASA Astrophysics Data System (ADS)

Zoia, A.; Dumonteil, E.; Mazzolo, A.

2012-11-01

In a series of recent works, important results have been reported concerning the statistical properties of exponential flights evolving in bounded domains, a widely adopted model for finite-speed transport phenomena (Blanco S. and Fournier R., Europhys. Lett., 61 (2003) 168; Mazzolo A., Europhys. Lett., 68 (2004) 350; Bénichou O. et al., Europhys. Lett., 70 (2005) 42). Motivated by physical and biological systems where random spatial displacements are coupled with Galton-Watson birth-death mechanisms, such as neutron multiplication, diffusion of reproducing bacteria or spread of epidemics, in this letter we extend those results in two directions, via a Feynman-Kac formalism. First, we characterize the occupation statistics of exponential flights in the presence of absorption and branching, and give explicit moment formulas for the total length travelled by the walker and the number of performed collisions in a given domain. Then, we show that the survival and escape probability can be derived as well by resorting to a similar approach.

Adapted to change: The rapid development of symbiosis in newly settled, fast-maturing chemosymbiotic mussels in the deep sea.

PubMed

Laming, Sven R; Duperron, Sébastien; Gaudron, Sylvie M; Hilário, Ana; Cunha, Marina R

2015-12-01

Symbioses between microbiota and marine metazoa occur globally at chemosynthetic habitats facing imminent threat from anthropogenic disturbance, yet little is known concerning the role of symbiosis during early development in chemosymbiotic metazoans: a critical period in any benthic species' lifecycle. The emerging symbiosis of Idas (sensu lato) simpsoni mussels undergoing development is assessed over a post-larval-to-adult size spectrum using histology and fluorescence in situ hybridisation (FISH). Post-larval development shows similarities to that of both heterotrophic and chemosymbiotic mussels. Data from newly settled specimens confirm aposymbiotic, planktotrophic larval development. Sulphur-oxidising (SOX) symbionts subsequently colonise multiple exposed, non-ciliated epithelia shortly after metamorphosis, but only become abundant on gills as these expand with greater host size. This wide-spread bathymodiolin recorded from sulphidic wood, bone and cold-seep habitats, displays a suite of adaptive traits that could buffer against anthropogenic disturbance. Copyright © 2015 Elsevier Ltd. All rights reserved.

Symbiosis limits establishment of legumes outside their native range at a global scale

PubMed Central

Simonsen, Anna K.; Dinnage, Russell; Barrett, Luke G.; Prober, Suzanne M.; Thrall, Peter H.

2017-01-01

Microbial symbiosis is integral to plant growth and reproduction, but its contribution to global patterns of plant distribution is unknown. Legumes (Fabaceae) are a diverse and widely distributed plant family largely dependent on symbiosis with nitrogen-fixing rhizobia, which are acquired from soil after germination. This dependency is predicted to limit establishment in new geographic areas, owing to a disruption of compatible host-symbiont associations. Here we compare non-native establishment patterns of symbiotic and non-symbiotic legumes across over 3,500 species, covering multiple independent gains and losses of rhizobial symbiosis. We find that symbiotic legume species have spread to fewer non-native regions compared to non-symbiotic legumes, providing strong support for the hypothesis that lack of suitable symbionts or environmental conditions required for effective nitrogen-fixation are driving these global introduction patterns. These results highlight the importance of mutualisms in predicting non-native species establishment and the potential impacts of microbial biogeography on global plant distributions. PMID:28387250

HIV Test: MedlinePlus Lab Test Information

MedlinePlus

... with an HIV-infected partner Have had multiple sex partners Have injected drugs, such as heroin , or shared drug needles with someone else HIV can spread from mother to child during birth and through breast milk, ...

Upward Flame Spread Over Thin Solids in Partial Gravity

NASA Technical Reports Server (NTRS)

Feier, I. I.; Shih, H. Y.; Sacksteder, K. R.; Tien, J. S.

2001-01-01

The effects of partial-gravity, reduced pressure, and sample width on upward flame spread over a thin cellulose fuel were studied experimentally and the results were compared to a numerical flame spread simulation. Fuel samples 1-cm, 2-cm, and 4-cm wide were burned in air at reduced pressures of 0.2 to 0.4 atmospheres in simulated gravity environments of 0.1-G, 0.16-G (Lunar), and 0.38-G (Martian) onboard the NASA KC-135 aircraft and in normal-gravity tests. Observed steady flame propagation speeds and pyrolysis lengths were approximately proportional to the gravity level. Flames spread more quickly and were longer with the wider samples and the variations with gravity and pressure increased with sample width. A numerical simulation of upward flame spread was developed including three-dimensional Navier-Stokes equations, one-step Arrhenius kinetics for the gas phase flame and for the solid surface decomposition, and a fuel-surface radiative loss. The model provides detailed structure of flame temperatures, the flow field interactions with the flame, and the solid fuel mass disappearance. The simulation agrees with experimental flame spread rates and their dependence on gravity level but predicts a wider flammable region than found by experiment. Some unique three-dimensional flame features are demonstrated in the model results.

Optimal dynamic control of invasions: applying a systematic conservation approach.

PubMed

Adams, Vanessa M; Setterfield, Samantha A

2015-06-01

The social, economic, and environmental impacts of invasive plants are well recognized. However, these variable impacts are rarely accounted for in the spatial prioritization of funding for weed management. We examine how current spatially explicit prioritization methods can be extended to identify optimal budget allocations to both eradication and control measures of invasive species to minimize the costs and likelihood of invasion. Our framework extends recent approaches to systematic prioritization of weed management to account for multiple values that are threatened by weed invasions with a multi-year dynamic prioritization approach. We apply our method to the northern portion of the Daly catchment in the Northern Territory, which has significant conservation values that are threatened by gamba grass (Andropogon gayanus), a highly invasive species recognized by the Australian government as a Weed of National Significance (WONS). We interface Marxan, a widely applied conservation planning tool, with a dynamic biophysical model of gamba grass to optimally allocate funds to eradication and control programs under two budget scenarios comparing maximizing gain (MaxGain) and minimizing loss (MinLoss) optimization approaches. The prioritizations support previous findings that a MinLoss approach is a better strategy when threats are more spatially variable than conservation values. Over a 10-year simulation period, we find that a MinLoss approach reduces future infestations by ~8% compared to MaxGain in the constrained budget scenarios and ~12% in the unlimited budget scenarios. We find that due to the extensive current invasion and rapid rate of spread, allocating the annual budget to control efforts is more efficient than funding eradication efforts when there is a constrained budget. Under a constrained budget, applying the most efficient optimization scenario (control, minloss) reduces spread by ~27% compared to no control. Conversely, if the budget is unlimited it is more efficient to fund eradication efforts and reduces spread by ~65% compared to no control.

Plant viruses in aqueous environment - survival, water mediated transmission and detection.

PubMed

Mehle, Nataša; Ravnikar, Maja

2012-10-15

The presence of plant viruses outside their plant host or insect vectors has not been studied intensively. This is due, in part, to the lack of effective detection methods that would enable their detection in difficult matrixes and in low titres, and support the search for unknown viruses. Recently, new and sensitive methods for detecting viruses have resulted in a deeper insight into plant virus movement through, and transmission between, plants. In this review, we have focused on plant viruses found in environmental waters and their detection. Infectious plant pathogenic viruses from at least 7 different genera have been found in aqueous environment. The majority of the plant pathogenic viruses so far recovered from environmental waters are very stable, they can infect plants via the roots without the aid of a vector and often have a wide host range. The release of such viruses from plants can lead to their dissemination in streams, lakes, and rivers, thereby ensuring the long-distance spread of viruses that otherwise, under natural conditions, would remain restricted to limited areas. The possible sources and survival of plant viruses in waters are therefore discussed. Due to the widespread use of hydroponic systems and intensive irrigation in horticulture, the review is focused on the possibility and importance of spreading viral infection by water, together with measures for preventing the spread of viruses. The development of new methods for detecting multiple plant viruses at the same time, like microarrays or new generation sequencing, will facilitate the monitoring of environmental waters and waters used for irrigation and in hydroponic systems. It is reasonable to expect that the list of plant viruses found in waters will thereby be expanded considerably. This will emphasize the need for further studies to determine the biological significance of water-mediated transport. Copyright © 2012 Elsevier Ltd. All rights reserved.

Sheet intrusions and deformation of Piton des Neiges, and their implication for the volcano-tectonics of La Réunion

NASA Astrophysics Data System (ADS)

Chaput, Marie; Famin, Vincent; Michon, Laurent

2017-10-01

To understand the volcano-tectonic history of Piton des Neiges (the dormant volcano of La Réunion), we measured in the field the orientation of sheeted intrusions and deformation structures, and interpreted the two datasets separately with a paleostress inversion. Results show that the multiple proposed rift zones may be simplified into three trends: (1) a N30°E, 5 km wide linear rift zone running to the south of the edifice, active in the shield building (≥ 2.48-0.43 Ma) and terminal stages (190-22 ka); (2) a curved N110 to N160°E rift zone, widening from 5 km to 10 km toward the NW flank, essentially active during the early emerged shield building (≥ 1.3 Ma); and (3) two sill zones, ≤ 1 km thick in total, in the most internal parts of the volcano, active in the shield building and terminal stages. In parallel, deformation structures reveal that the tectonics of the edifice consisted in three end-member stress regimes sharing common stress axes: (1) NW-SE extension affecting in priority the south of the edifice near the N30°E rift zone; (2) NNE-SSW extension on the northern half of the volcano near the N110-160°E rift zone; (3) compression occurring near the sill zones, with a NE-SW or NW-SE maximum principal stress. These three stress regimes are spatially correlated and mechanically compatible with the injection trends. Combined together, our data show that the emerged Piton des Neiges underwent sector spreading delimited by perpendicular rift zones, as observed on Piton de la Fournaise (the active volcano of La Réunion). Analogue experiments attribute such sector spreading to brittle edifices built on a weaker substratum. We therefore conclude that La Réunion volcanoes are both brittle, as opposed to Hawaiian volcanoes or Mount Etna whose radial spreading is usually attributed to a ductile body within the edifices.

Research on the middle-of-receiver-spread assumption of the MASW method

USGS Publications Warehouse

Luo, Y.; Xia, J.; Liu, J.; Xu, Y.; Liu, Q.

2009-01-01

The multichannel analysis of surface wave (MASW) method has been effectively used to determine near-surface shear- (S-) wave velocity. Estimating the S-wave velocity profile from Rayleigh-wave measurements is straightforward. A three-step process is required to obtain S-wave velocity profiles: acquisition of a multiple number of multichannel records along a linear survey line by use of the roll-along mode, extraction of dispersion curves of Rayleigh waves, and inversion of dispersion curves for an S-wave velocity profile for each shot gather. A pseudo-2D S-wave velocity section can be generated by aligning 1D S-wave velocity models. In this process, it is very important to understand where the inverted 1D S-wave velocity profile should be located: the midpoint of each spread (a middle-of-receiver-spread assumption) or somewhere between the source and the last receiver. In other words, the extracted dispersion curve is determined by the geophysical structure within the geophone spread or strongly affected by the source geophysical structure. In this paper, dispersion curves of synthetic datasets and a real-world example are calculated by fixing the receiver spread and changing the source location. Results demonstrate that the dispersion curves are mainly determined by structures within a receiver spread. ?? 2008 Elsevier Ltd. All rights reserved.

Spread spectrum communications. Volume 1, 2 & 3

NASA Technical Reports Server (NTRS)

Simon, M. K.; Levitt, B. K.; Omura, J. K.; Scholtz, R. A.

1985-01-01

The design and operation of spread-spectrum (SS) communication systems are examined in an introductory text intended for graduate engineering students and practicing engineers. Chapters are devoted to an overview of SS systems, the historical origins of SS, basic concepts and system models, antijam communication systems, pseudonoise generators, coherent direct-sequence systems, noncoherent frequency-hopped systems, coherent and differentially coherent modulation techniques, pseudonoise acquisition and tracking in direct-sequence receivers, time and frequency synchronization of frequency-hopped receivers, low-probability-of-intercept communication, and multiple-access communication. Graphs, diagrams, and photographs are provided.

A mechanism for decoupling within the oceanic lithosphere revealed in the Troodos ophiolite

USGS Publications Warehouse

Agar, Susan M.; Klitgord, Kim D.

1995-01-01

Contrasting kinematic histories recorded in the sheeted dykes and underlying plutonic rocks of the Troodos ophiolite provide a new perspective on the mechanical evolution of oceanic spreading centres. The kinematic framework of the decoupling zone that partitions deformation between the sheeted dykes and plutonics contrasts with low-angle detachment models for slow-spreading ridges based on continental-rift analogues. A model for the generation of multiple, horizontal decoupling horizons, linked by planar normal faults, demonstrates new possibilities for the kinematic and rheological significance of seismic reflectors in oceanic lithosphere.

Theoretical analysis of microwave propagation

NASA Astrophysics Data System (ADS)

Parl, S.; Malaga, A.

1984-04-01

This report documents a comprehensive investigation of microwave propagation. The structure of line-of-sight multipath is determined and the impact on practical diversity is discussed. A new model of diffraction propagation for multiple rounded obstacles is developed. A troposcatter model valid at microwave frequencies is described. New results for the power impulse response, and the delay spread and Doppler spread are developed. A 2-component model separating large and small scale scatter effects is proposed. The prediction techniques for diffraction and troposcatter have been implemented in a computer program intended as a tool to analyze propagation experiments.

Coaxial airblast atomizers

NASA Technical Reports Server (NTRS)

Hardalupas, Y.; Whitelaw, J. H.

1993-01-01

An experimental investigation was performed to quantify the characteristics of the sprays of coaxial injectors with particular emphasis on those aspects relevant to the performance of rocket engines. Measurements for coaxial air blast atomizers were obtained using air to represent the gaseous stream and water to represent the liquid stream. A wide range of flow conditions were examined for sprays with and without swirl for gaseous streams. The parameters varied include Weber number, gas flow rate, liquid flow rate, swirl, and nozzle geometry. Measurements were made with a phase Doppler velocimeter. Major conclusions of the study focused upon droplet size as a function of Weber number, effect of gas flow rate on atomization and spray spread, effect of nozzle geometry on atomization and spread, effect of swirl on atomization, spread, jet recirculation and breakup, and secondary atomization.

A network-patch methodology for adapting agent-based models for directly transmitted disease to mosquito-borne disease.

PubMed

Manore, Carrie A; Hickmann, Kyle S; Hyman, James M; Foppa, Ivo M; Davis, Justin K; Wesson, Dawn M; Mores, Christopher N

2015-01-01

Mosquito-borne diseases cause significant public health burden and are widely re-emerging or emerging. Understanding, predicting, and mitigating the spread of mosquito-borne disease in diverse populations and geographies are ongoing modelling challenges. We propose a hybrid network-patch model for the spread of mosquito-borne pathogens that accounts for individual movement through mosquito habitats, extending the capabilities of existing agent-based models (ABMs) to include vector-borne diseases. The ABM are coupled with differential equations representing 'clouds' of mosquitoes in patches accounting for mosquito ecology. We adapted an ABM for humans using this method and investigated the importance of heterogeneity in pathogen spread, motivating the utility of models of individual behaviour. We observed that the final epidemic size is greater in patch models with a high risk patch frequently visited than in a homogeneous model. Our hybrid model quantifies the importance of the heterogeneity in the spread of mosquito-borne pathogens, guiding mitigation strategies.

Hepatitis A

MedlinePlus

... Editor & Contributors Sponsors Sponsorship Opportunities Spread the Word Shop AAP Find a Pediatrician ... Body Hepatitis means “inflammation of the liver.” This inflammation can be caused by a wide variety of toxins, drugs, and metabolic diseases, as well as infection. There ...

Layer-switching cost and optimality in information spreading on multiplex networks

PubMed Central

Min, Byungjoon; Gwak, Sang-Hwan; Lee, Nanoom; Goh, K. -I.

2016-01-01

We study a model of information spreading on multiplex networks, in which agents interact through multiple interaction channels (layers), say online vs. offline communication layers, subject to layer-switching cost for transmissions across different interaction layers. The model is characterized by the layer-wise path-dependent transmissibility over a contact, that is dynamically determined dependently on both incoming and outgoing transmission layers. We formulate an analytical framework to deal with such path-dependent transmissibility and demonstrate the nontrivial interplay between the multiplexity and spreading dynamics, including optimality. It is shown that the epidemic threshold and prevalence respond to the layer-switching cost non-monotonically and that the optimal conditions can change in abrupt non-analytic ways, depending also on the densities of network layers and the type of seed infections. Our results elucidate the essential role of multiplexity that its explicit consideration should be crucial for realistic modeling and prediction of spreading phenomena on multiplex social networks in an era of ever-diversifying social interaction layers. PMID:26887527

Hand held lasers, a hazard to aircraft: How do we address this?

NASA Astrophysics Data System (ADS)

Barat, K.

2015-10-01

The availability of hand held lasers, commonly termed "laser pointers" is easy and wide spread, through commercial web sites and brick & mortar stores. The output of these hand held devices ranges from 1-5 milliWatts (mW) the legal laser pointer output limit, to 5000mW (5Watts). This is thousand times the maximum limit for pointers. Sadly the abuse of these devices is also wide spread. Over the last few years over 3000 aircraft are exposed to laser hits per year. While these aircraft exposures are of no danger to the aircraft frame but they can cause pilot distractions with the potential to cause a serve accident. The presentation will discuss the problem review visual effects, the regulatory response and how educators need to be aware of the problem and can take steps to educate students in the hope of having an effect.

Xist recruits the X chromosome to the nuclear lamina to enable chromosome-wide silencing.

PubMed

Chen, Chun-Kan; Blanco, Mario; Jackson, Constanza; Aznauryan, Erik; Ollikainen, Noah; Surka, Christine; Chow, Amy; Cerase, Andrea; McDonel, Patrick; Guttman, Mitchell

2016-10-28

The Xist long noncoding RNA orchestrates X chromosome inactivation, a process that entails chromosome-wide silencing and remodeling of the three-dimensional (3D) structure of the X chromosome. Yet, it remains unclear whether these changes in nuclear structure are mediated by Xist and whether they are required for silencing. Here, we show that Xist directly interacts with the Lamin B receptor, an integral component of the nuclear lamina, and that this interaction is required for Xist-mediated silencing by recruiting the inactive X to the nuclear lamina and by doing so enables Xist to spread to actively transcribed genes across the X. Our results demonstrate that lamina recruitment changes the 3D structure of DNA, enabling Xist and its silencing proteins to spread across the X to silence transcription. Copyright © 2016, American Association for the Advancement of Science.

Varroa destructor Mites Can Nimbly Climb from Flowers onto Foraging Honey Bees.

PubMed

Peck, David T; Smith, Michael L; Seeley, Thomas D

2016-01-01

Varroa destructor, the introduced parasite of European honey bees associated with massive colony deaths, spreads readily through populations of honey bee colonies, both managed colonies living crowded together in apiaries and wild colonies living widely dispersed in natural settings. Mites are hypothesized to spread between most managed colonies via phoretically riding forager bees when they engage in robbing colonies or they drift between hives. However, widely spaced wild colonies show Varroa infestation despite limited opportunities for robbing and little or no drifting of bees between colonies. Both wild and managed colonies may also exchange mites via another mechanism that has received remarkably little attention or study: floral transmission. The present study tested the ability of mites to infest foragers at feeders or flowers. We show that Varroa destructor mites are highly capable of phoretically infesting foraging honey bees, detail the mechanisms and maneuvers by which they do so, and describe mite behaviors post-infestation.

The wide-spread presence of rib-like patterns in basal shear of ice streams detected by surface data inversion

NASA Astrophysics Data System (ADS)

Sergienko, O. V.

2013-12-01

The direct observations of the basal conditions under continental-scale ice sheets are logistically impossible. A possible approach to estimate conditions at the ice - bed interface is from surface observations by means of inverse methods. The recent advances in remote and ground-based observations have allowed to acquire a wealth observations from Greenland and Antarctic ice sheets. Using high-resolution data sets of ice surface and bed elevations and surface velocities, inversions for basal conditions have been performed for several ice streams in Greenland and Antarctica. The inversion results reveal the wide-spread presence of rib-like spatial structures in basal shear. The analysis of the hydraulic potential distribution shows that these rib-like structures co-locate with highs of the gradient of hydraulic potential. This suggests that subglacial water plays a role in the development and evolution of the basal shear ribs.

An all-digital receiver for satellite audio broadcasting signals using trellis coded quasi-orthogonal code-division multiplexing

NASA Astrophysics Data System (ADS)

Braun, Walter; Eglin, Peter; Abello, Ricard

1993-02-01

Spread Spectrum Code Division Multiplex is an attractive scheme for the transmission of multiple signals over a satellite transponder. By using orthogonal or quasi-orthogonal spreading codes the interference between the users can be virtually eliminated. However, the acquisition and tracking of the spreading code phase can not take advantage of the code orthogonality since sequential acquisition and Delay-Locked loop tracking depend on correlation with code phases other than the optimal despreading phase. Hence, synchronization is a critical issue in such a system. A demonstration hardware for the verification of the orthogonal CDM synchronization and data transmission concept is being designed and implemented. The system concept, the synchronization scheme, and the implementation are described. The performance of the system is discussed based on computer simulations.

[Interaction between clinical and research towards venture business].

PubMed

Sumida, Iori

2014-01-01

The author as a medical physicist has supported multiple institutions where the advanced radiation therapies as well as the conventional radiation therapy have been performed. Since the advanced radiation treatment techniques have spread rapidly, the quality assurance (QA) has been more important and complex that results in the increase of QA items. In order to maintain the quality of radiation therapy as accurate as possible, the efficient and objective approach for performing QA should be important. Author has developed some QA software which has solved those approaches based on the experiment. In this paper the background in multiple institutions as a view point of radiation treatment situation is presented and what author contributes to those institutions by a medical physics support is shown, finally it is considered that how the developed software has spread in Japan and used for many institutions via venture business.

Orthogonal Multi-Carrier DS-CDMA with Frequency-Domain Equalization

NASA Astrophysics Data System (ADS)

Tanaka, Ken; Tomeba, Hiromichi; Adachi, Fumiyuki

Orthogonal multi-carrier direct sequence code division multiple access (orthogonal MC DS-CDMA) is a combination of orthogonal frequency division multiplexing (OFDM) and time-domain spreading, while multi-carrier code division multiple access (MC-CDMA) is a combination of OFDM and frequency-domain spreading. In MC-CDMA, a good bit error rate (BER) performance can be achieved by using frequency-domain equalization (FDE), since the frequency diversity gain is obtained. On the other hand, the conventional orthogonal MC DS-CDMA fails to achieve any frequency diversity gain. In this paper, we propose a new orthogonal MC DS-CDMA that can obtain the frequency diversity gain by applying FDE. The conditional BER analysis is presented. The theoretical average BER performance in a frequency-selective Rayleigh fading channel is evaluated by the Monte-Carlo numerical computation method using the derived conditional BER and is confirmed by computer simulation of the orthogonal MC DS-CDMA signal transmission.

Characterizing super-spreading in microblog: An epidemic-based information propagation model

NASA Astrophysics Data System (ADS)

Liu, Yu; Wang, Bai; Wu, Bin; Shang, Suiming; Zhang, Yunlei; Shi, Chuan

2016-12-01

As the microblogging services are becoming more prosperous in everyday life for users on Online Social Networks (OSNs), it is more favorable for hot topics and breaking news to gain more attraction very soon than ever before, which are so-called "super-spreading events". In the information diffusion process of these super-spreading events, messages are passed on from one user to another and numerous individuals are influenced by a relatively small portion of users, a.k.a. super-spreaders. Acquiring an awareness of super-spreading phenomena and an understanding of patterns of wide-ranged information propagations benefits several social media data mining tasks, such as hot topic detection, predictions of information propagation, harmful information monitoring and intervention. Taking into account that super-spreading in both information diffusion and spread of a contagious disease are analogous, in this study, we build a parameterized model, the SAIR model, based on well-known epidemic models to characterize super-spreading phenomenon in tweet information propagation accompanied with super-spreaders. For the purpose of modeling information diffusion, empirical observations on a real-world Weibo dataset are statistically carried out. Both the steady-state analysis on the equilibrium and the validation on real-world Weibo dataset of the proposed model are conducted. The case study that validates the proposed model shows that the SAIR model is much more promising than the conventional SIR model in characterizing a super-spreading event of information propagation. In addition, numerical simulations are carried out and discussed to discover how sensitively the parameters affect the information propagation process.

Current status of genome editing in vector mosquitoes: A review.

PubMed

Reegan, Appadurai Daniel; Ceasar, Stanislaus Antony; Paulraj, Michael Gabriel; Ignacimuthu, Savarimuthu; Al-Dhabi, Naif Abdullah

2017-01-16

Mosquitoes pose a major threat to human health as they spread many deadly diseases like malaria, dengue, chikungunya, filariasis, Japanese encephalitis and Zika. Identification and use of novel molecular tools are essential to combat the spread of vector borne diseases. Genome editing tools have been used for the precise alterations of the gene of interest for producing the desirable trait in mosquitoes. Deletion of functional genes or insertion of toxic genes in vector mosquitoes will produce either knock-out or knock-in mutants that will check the spread of vector-borne diseases. Presently, three types of genome editing tools viz., zinc finger nuclease (ZFN), transcription activator-like effector nucleases (TALEN) and clustered regulatory interspaced short palindromic repeats (CRISPR) and CRISPR associated protein 9 (Cas9) are widely used for the editing of the genomes of diverse organisms. These tools are also applied in vector mosquitoes to control the spread of vector-borne diseases. A few studies have been carried out on genome editing to control the diseases spread by vector mosquitoes and more studies need to be performed with the utilization of more recently invented tools like CRISPR/Cas9 to combat the spread of deadly diseases by vector mosquitoes. The high specificity and flexibility of CRISPR/Cas9 system may offer possibilities for novel genome editing for the control of important diseases spread by vector mosquitoes. In this review, we present the current status of genome editing research on vector mosquitoes and also discuss the future applications of vector mosquito genome editing to control the spread of vectorborne diseases.

The continent-ocean transition on the northwestern South China Sea

NASA Astrophysics Data System (ADS)

Cameselle, Alejandra L.; Ranero, César R.; Franke, Dieter; Barckhausen, Udo

2015-04-01

Rifted margins are created as a result of stretching and breakup of continental lithosphere that eventually leads to oceanic spreading and formation of a new oceanic basin. A cornerstone for understanding how rift characteristics vary along strike in the same system and what processes control the final transition to seafloor spreading is the continent-ocean transition (COT). We use four regional multichannel seismic profiles and published magnetic lineations to study the structure and variability of COT on the northwest subbasin (NWSB) of the South China Sea and to discern continental from oceanic domains. The continental domain is characterized by tilted fault blocks overlaid by thick syn-rift sedimentary units and fairly continuous Moho reflections typically at 8-10 s twtt. Thickness of the continental crust changes from ~20-25 km under the uppermost slope to ~9-6 km under the lower slope. The oceanic domain is interpreted where a highly reflective top of basement, little faulting, no syntectonic strata, and fairly constant thickness basement (4-8 km) occur. The COT is imaged as a ~5-10 km wide zone where oceanic-type features abut continental-type structures. The South China margin is deformed by abundant normal faults dissecting the continental crust, whereas the conjugate Macclesfield Bank margin displays comparatively abrupt thinning and little faulting. Seismic profiles show an along-strike variation in the tectonic structure of the continental margin. The NE-most lines display ~20-40 km wide segments of intense faulting under the slope and associated continental-crust thinning. Towards the SW, faulting and thinning of the continental crust occurs across a ~100-110 km wide segment. We interpret this 3D structural variability and the narrow COT as a consequence of the abrupt termination of continental rifting tectonics by the NE to SW propagation of a spreading center. We suggest that breakup occurred by spreading center propagation to a larger degree than by lithospheric thinning during continental rifting. Based on the sedimentary successions overlying the oceanic crust, we propose a kinematic evolution for the oceanic domain of the NWSB consisting of a southward spreading center propagation followed by a first narrow ridge jump to the north, and then a younger larger jump to the SW into the east subbasin.

Actualizing Flexible National Security Space Systems

DTIC Science & Technology

2011-01-01

single launch vehicle is a decision unique to small satellites that adds an extra dimension to the launch risk calculation. While bundling...following a launch failure. The ability to bundle multiple payloads on a single launch vehicle is a decision unique to small satellites that adds an extra ... dimension to the launch risk calculation. While bundling multiple small satellites on a single launch vehicle spreads the initial launch cost across

How events determine spreading patterns: information transmission via internal and external influences on social networks

NASA Astrophysics Data System (ADS)

Liu, Chuang; Zhan, Xiu-Xiu; Zhang, Zi-Ke; Sun, Gui-Quan; Hui, Pak Ming

2015-11-01

Recently, information transmission models motivated by the classical epidemic propagation, have been applied to a wide-range of social systems, generally assume that information mainly transmits among individuals via peer-to-peer interactions on social networks. In this paper, we consider one more approach for users to get information: the out-of-social-network influence. Empirical analyzes of eight typical events’ diffusion on a very large micro-blogging system, Sina Weibo, show that the external influence has significant impact on information spreading along with social activities. In addition, we propose a theoretical model to interpret the spreading process via both internal and external channels, considering three essential properties: (i) memory effect; (ii) role of spreaders; and (iii) non-redundancy of contacts. Experimental and mathematical results indicate that the information indeed spreads much quicker and broader with mutual effects of the internal and external influences. More importantly, the present model reveals that the event characteristic would highly determine the essential spreading patterns once the network structure is established. The results may shed some light on the in-depth understanding of the underlying dynamics of information transmission on real social networks.

A spread willingness computing-based information dissemination model.

PubMed

Huang, Haojing; Cui, Zhiming; Zhang, Shukui

2014-01-01

This paper constructs a kind of spread willingness computing based on information dissemination model for social network. The model takes into account the impact of node degree and dissemination mechanism, combined with the complex network theory and dynamics of infectious diseases, and further establishes the dynamical evolution equations. Equations characterize the evolutionary relationship between different types of nodes with time. The spread willingness computing contains three factors which have impact on user's spread behavior: strength of the relationship between the nodes, views identity, and frequency of contact. Simulation results show that different degrees of nodes show the same trend in the network, and even if the degree of node is very small, there is likelihood of a large area of information dissemination. The weaker the relationship between nodes, the higher probability of views selection and the higher the frequency of contact with information so that information spreads rapidly and leads to a wide range of dissemination. As the dissemination probability and immune probability change, the speed of information dissemination is also changing accordingly. The studies meet social networking features and can help to master the behavior of users and understand and analyze characteristics of information dissemination in social network.

Tectonic and magmatic processes of the post-spreading ridge in the Southwest Sub-basin, South China Sea

NASA Astrophysics Data System (ADS)

Li, J.; Zhang, J.; Ruan, A.; Niu, X.; Ding, W.

2016-12-01

We report here a 3D ocean bottom seismometer experiment on the fossil spreading ridge in the Southwest Sub-basin of the South China Sea. An extreme asymmetric crustal structure across the axis is revealed and caused by lower crust thinning and upper mantle uplifting located on NW side of the ridge. Such crustal extension proposed a low-angle oceanic detachment fault throughout the whole crust on the last or post spreading stages. A low-velocity (7.6-7.9 km/s) on the uplifting upper mantle is possibly induced by both mantle serpentinization and/or decompression melting through the detachment fault. Velocity models also demonstrate that a post-spreading volcano erupted on the axis is mainly formed by an extrusive process with an extrusive/intrusive ratio of 1.92. Very low velocity of upper crust (3.1-4.8 km/s) of the volcano is attributed to the composition of volcaniclastic rocks and high-porosity basalts, which have been observed in the borehole and dredged samples on the seamounts nearby. KEY WORDS post-spreading ridge; wide-angle seismic refraction; crustal structure; South China Sea; Southwest Sub-basin

A Spread Willingness Computing-Based Information Dissemination Model

PubMed Central

Cui, Zhiming; Zhang, Shukui

2014-01-01

This paper constructs a kind of spread willingness computing based on information dissemination model for social network. The model takes into account the impact of node degree and dissemination mechanism, combined with the complex network theory and dynamics of infectious diseases, and further establishes the dynamical evolution equations. Equations characterize the evolutionary relationship between different types of nodes with time. The spread willingness computing contains three factors which have impact on user's spread behavior: strength of the relationship between the nodes, views identity, and frequency of contact. Simulation results show that different degrees of nodes show the same trend in the network, and even if the degree of node is very small, there is likelihood of a large area of information dissemination. The weaker the relationship between nodes, the higher probability of views selection and the higher the frequency of contact with information so that information spreads rapidly and leads to a wide range of dissemination. As the dissemination probability and immune probability change, the speed of information dissemination is also changing accordingly. The studies meet social networking features and can help to master the behavior of users and understand and analyze characteristics of information dissemination in social network. PMID:25110738

Inhibition of HSV cell-to-cell spread by lactoferrin and lactoferricin.

PubMed

Jenssen, Håvard; Sandvik, Kjersti; Andersen, Jeanette H; Hancock, Robert E W; Gutteberg, Tore J

2008-09-01

The milk protein lactoferrin (Lf) has multiple functions, including immune stimulation and antiviral activity towards herpes simplex virus 1 and 2 (HSV-1 and HSV-2); antiviral activity has also been reported for the N-terminal pepsin-derived fragment lactoferricin (Lfcin). The anti-HSV mode of action of Lf and Lfcin is assumed to involve, in part, their interaction with the cell surface glycosaminoglycan heparan sulfate, thereby blocking of viral entry. In this study we investigated the ability of human and bovine Lf and Lfcin to inhibit viral cell-to-cell spread as well as the involvement of cell surface glycosaminoglycans during viral cell-to-cell spread. Lf and Lfcin from both human and bovine origin, inhibited cell-to-cell spread of both HSV-1 and HSV-2. Inhibition of cell-to-cell spread by bovine Lfcin involved cell surface chondroitin sulfate. Based on transmission electron microscopy studies, human Lfcin, like bovine Lfcin, was randomly distributed intracellularly, thus differences in their antiviral activity could not be explained by differences in their distribution. In contrast, the cellular localization of iron-saturated (holo)-Lf appeared to differ from that of apo-Lf, indicating that holo- and apo-Lf may exhibit different antiviral mechanisms.

Spreading properties of cosmetic emollients: Use of synthetic skin surface to elucidate structural effect.

PubMed

Douguet, Marine; Picard, Céline; Savary, Géraldine; Merlaud, Fabien; Loubat-Bouleuc, Nathalie; Grisel, Michel

2017-06-01

The study focuses on the impact of structural and physicochemical properties of emollients on their spreadability. Fifty-three emollients, among which esters, silicones, vegetable and mineral oils, have been characterized. Their viscosity, surface tension, density and spreadability have been measured. Vitro-skin ® , an artificial skin substitute, was used as an artificial porous substrate to measure spreadability. Two different methods have been selected to characterize spreadability, namely contact angle and spreading value. Dynamic contact angle measurements showed that emollient spreadability is first governed by spontaneous spreading and that, in a second phase, absorption and migration into the porous substrate becomes the driver of the extension of the spreading area. Statistical analysis of physicochemical and spreading value data revealed that viscosity has a major impact on the spreading behavior of emollients whatever their chemical type. A special emphasis was placed on the ester family in which chemical diversity is very wide. The results highlighted a difference between "high viscosity esters" for which viscosity is the main factor impacting spreadability and "low viscosity esters" for which structural variations (mono/diester, saturated/unsaturated chain, linear/branched chain) have to be considered in addition to viscosity. Linear regressions were used to express spreading value as a function of viscosity for each of the four emollient families tested (esters, silicones, vegetable and mineral oils). These regressions allowed the development of reliable predictive models as a powerful tool for formulators to forecast spreadability of emollients. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of yellow birch nursery stock not affected by transplanting

Treesearch

William B. Leak

1959-01-01

In nursery seedbeds, severe root competition soon develops among seedlings of yellow birch (Betula alleghaniensis). This is due to the characteristic root system of the species - wide-spreading lateral growth with little downward penetration (fig. 1).

7 CFR 301.45 - Notice of quarantine; restriction on interstate movement of specified regulated articles.

Code of Federal Regulations, 2010 CFR

2010-01-01

... prevent the spread of the gypsy moth, Lymantria dispar (Linnaeus), a dangerous insect injurious to forests and shade trees and not theretofore widely prevalent or distributed within or throughout the United...

7 CFR 301.45 - Notice of quarantine; restriction on interstate movement of specified regulated articles.

Code of Federal Regulations, 2012 CFR

2012-01-01

... prevent the spread of the gypsy moth, Lymantria dispar (Linnaeus), a dangerous insect injurious to forests and shade trees and not theretofore widely prevalent or distributed within or throughout the United...

7 CFR 301.45 - Notice of quarantine; restriction on interstate movement of specified regulated articles.

Code of Federal Regulations, 2011 CFR

2011-01-01

... prevent the spread of the gypsy moth, Lymantria dispar (Linnaeus), a dangerous insect injurious to forests and shade trees and not theretofore widely prevalent or distributed within or throughout the United...

7 CFR 301.45 - Notice of quarantine; restriction on interstate movement of specified regulated articles.

Code of Federal Regulations, 2014 CFR

2014-01-01

... prevent the spread of the gypsy moth, Lymantria dispar (Linnaeus), a dangerous insect injurious to forests and shade trees and not theretofore widely prevalent or distributed within or throughout the United...

7 CFR 301.45 - Notice of quarantine; restriction on interstate movement of specified regulated articles.

Code of Federal Regulations, 2013 CFR

2013-01-01

... prevent the spread of the gypsy moth, Lymantria dispar (Linnaeus), a dangerous insect injurious to forests and shade trees and not theretofore widely prevalent or distributed within or throughout the United...

Boron

USDA-ARS?s Scientific Manuscript database

Boron is an essential micronutrient element required for plant growth. Boron deficiency is wide-spread in crop plants throughout the world especially in coarse-textured soils in humid areas. Boron toxicity can also occur, especially in arid regions under irrigation. Plants respond directly to the...

7 CFR 2201.1 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Index United States Television Household Estimates. Generally Accepted Accounting Principles (GAAP) means a common set of accounting standards and procedures that are either promulgated by an authoritative accounting rulemaking body or accepted as appropriate due to wide-spread application in the United...

Solid surface combustion experiment flame spread in a quiescent, microgravity environment implications of spread rate and flame structure

NASA Technical Reports Server (NTRS)

Bundy, Matthew; West, Jeff; Thomas, Peter C.; Bhattacharjee, Subrata; Tang, Lin; Altenkirch, Robert A.; Sacksteder, Kurt

1995-01-01

A unique environment in which flame spreading, a phenomenon of fundamental, scientific interest, has importance to fire safety is that of spacecraft in which the gravitational acceleration is low compared with that of the Earth, i.e., microgravity. Experiments aboard eight Space Shuttle missions between October 1990 and February 1995 were conducted using the Solid Surface Combustion Experiment (SSCE) payload apparatus in an effort to determine the mechanisms of gas-phase flame spread over solid fuel surfaces in the absence of any buoyancy induced or externally imposed oxidizer flow. The overall SSCE effort began in December of 1984. The SSCE apparatus consists of a sealed container, approximately 0.039 cu m, that is filled with a specified O2/N2 mixture at a prescribed pressure. Five of the experiments used a thin cellulosic fuel, ashless filter paper, 3 cm wide x 10 cm long, 0.00825 cm half-thickness, ignited in five different ambient conditions. Three of the experiments, the most recent, used thick polymethylmethacrylate (PMMA) samples 0.635 cm wide x 2 cm long, 0.32 cm half-thickness. Three experiments, STS 41, 40 and 43, were designed to evaluate the effect of ambient pressure on flame spread over the thin cellulosic fuel while flights STS 50 and 47 were at the same pressure as two of the earlier flights but at a lower oxygen concentration in order to evaluate the effect of ambient oxygen level on the flame spread process at microgravity. For the PMMA flights, two experiments, STS 54 and 63, were at the same pressure but different oxygen concentrations while STS 64 was at the same oxygen concentration as STS 63 but at a higher pressure. Two orthogonal views of the experiments were recorded on 16 mm cine-cameras operating at 24 frames/s. In addition to filmed images of the side view of the flames and surface view of the burning samples, solid- and gas-phase temperatures were recorded using thermocouples. The experiment is battery powered and follows an automated sequence upon activation by the Shuttle Crew. In this study we separate the SSCE data into two groups according to the fuel type: (1) thin cellulose; and (2) thick PMMA. The experimental spread rates are compared with prediction from a number of models in an effort to uncover the important physics that characterize microgravity flame spread. Both steady and unsteady solutions are employed to explore the flame evolution, especially for thick fuels. Finally, the flame structure in downward spread is compared with the microgravity flame structure and modeling results to delineate the difference between the two configurations and the influence of normal gravity.

Substrate Curvature Restricts Spreading and Induces Differentiation of Human Mesenchymal Stem Cells.

PubMed

Lee, Sang Joo; Yang, Shengyuan

2017-09-01

While cells attach, spread, migrate, proliferate, and differentiate in three-dimensional (3D) micromechanical environments, the mechanical factors of these environments influence the shapes, sizes, and adhesion forces of the cells. Here, the authors culture human mesenchymal stem cells (hMSCs) on a unique class of curvature-defined substrates, micro glass ball embedded polyacrylamide gels, prepared with an improved protocol, and investigate the spreading responses of the hMSCs on the glass balls to study the effects of substrate curvature on the spreading of hMSCs. The authors find that, among the used diameters of glass balls, the minimum diameter of a glass ball on which an hMSC can attach and spread is 500 μm. In contrast to the well-spread morphologies with randomly-multiple lamellipodia for the hMSCs growing on the flat glass plates, the morphologies of the hMSCs growing on the glass balls are almost uniformly spindle-shaped with two lamellipodia. The sensitivities of the attachment and spreading morphology of an hMSC to substrate curvature are very different from those of a fibroblast. The RT-PCR analysis reveals that the substrate curvature alone can induce adipogenesis of the hMSCs. These findings imply that substrate curvature has profound effects on stem cell behaviors, and detailed and in-depth studies on these effects and their underlying biophysical mechanisms are necessary. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The spreading of misinformation online

PubMed Central

Del Vicario, Michela; Bessi, Alessandro; Zollo, Fabiana; Petroni, Fabio; Caldarelli, Guido; Stanley, H. Eugene; Quattrociocchi, Walter

2016-01-01

The wide availability of user-provided content in online social media facilitates the aggregation of people around common interests, worldviews, and narratives. However, the World Wide Web (WWW) also allows for the rapid dissemination of unsubstantiated rumors and conspiracy theories that often elicit rapid, large, but naive social responses such as the recent case of Jade Helm 15––where a simple military exercise turned out to be perceived as the beginning of a new civil war in the United States. In this work, we address the determinants governing misinformation spreading through a thorough quantitative analysis. In particular, we focus on how Facebook users consume information related to two distinct narratives: scientific and conspiracy news. We find that, although consumers of scientific and conspiracy stories present similar consumption patterns with respect to content, cascade dynamics differ. Selective exposure to content is the primary driver of content diffusion and generates the formation of homogeneous clusters, i.e., “echo chambers.” Indeed, homogeneity appears to be the primary driver for the diffusion of contents and each echo chamber has its own cascade dynamics. Finally, we introduce a data-driven percolation model mimicking rumor spreading and we show that homogeneity and polarization are the main determinants for predicting cascades’ size. PMID:26729863

Imaging Cajal’s neuronal avalanche: how wide-field optical imaging of the point-spread advanced the understanding of neocortical structure–function relationship

PubMed Central

Frostig, Ron D.; Chen-Bee, Cynthia H.; Johnson, Brett A.; Jacobs, Nathan S.

2017-01-01

Abstract. This review brings together a collection of studies that specifically use wide-field high-resolution mesoscopic level imaging techniques (intrinsic signal optical imaging; voltage-sensitive dye optical imaging) to image the cortical point spread (PS): the total spread of cortical activation comprising a large neuronal ensemble evoked by spatially restricted (point) stimulation of the sensory periphery (e.g., whisker, pure tone, point visual stimulation). The collective imaging findings, combined with supporting anatomical and electrophysiological findings, revealed some key aspects about the PS including its very large (radius of several mm) and relatively symmetrical spatial extent capable of crossing cytoarchitectural borders and trespassing into other cortical areas; its relationship with underlying evoked subthreshold activity and underlying anatomical system of long-range horizontal projections within gray matter, both also crossing borders; its contextual modulation and plasticity; the ability of its relative spatiotemporal profile to remain invariant to major changes in stimulation parameters; its potential role as a building block for integrative cortical activity; and its ubiquitous presence across various cortical areas and across mammalian species. Together, these findings advance our understanding about the neocortex at the mesoscopic level by underscoring that the cortical PS constitutes a fundamental motif of neocortical structure–function relationship. PMID:28630879

Imaging Cajal's neuronal avalanche: how wide-field optical imaging of the point-spread advanced the understanding of neocortical structure-function relationship.

PubMed

Frostig, Ron D; Chen-Bee, Cynthia H; Johnson, Brett A; Jacobs, Nathan S

2017-07-01

This review brings together a collection of studies that specifically use wide-field high-resolution mesoscopic level imaging techniques (intrinsic signal optical imaging; voltage-sensitive dye optical imaging) to image the cortical point spread (PS): the total spread of cortical activation comprising a large neuronal ensemble evoked by spatially restricted (point) stimulation of the sensory periphery (e.g., whisker, pure tone, point visual stimulation). The collective imaging findings, combined with supporting anatomical and electrophysiological findings, revealed some key aspects about the PS including its very large (radius of several mm) and relatively symmetrical spatial extent capable of crossing cytoarchitectural borders and trespassing into other cortical areas; its relationship with underlying evoked subthreshold activity and underlying anatomical system of long-range horizontal projections within gray matter, both also crossing borders; its contextual modulation and plasticity; the ability of its relative spatiotemporal profile to remain invariant to major changes in stimulation parameters; its potential role as a building block for integrative cortical activity; and its ubiquitous presence across various cortical areas and across mammalian species. Together, these findings advance our understanding about the neocortex at the mesoscopic level by underscoring that the cortical PS constitutes a fundamental motif of neocortical structure-function relationship.

Quadriphase DS-CDMA wireless communication systems employing the generalized detector

NASA Astrophysics Data System (ADS)

Tuzlukov, Vyacheslav

2012-05-01

Probability of bit-error Per performance of asynchronous direct-sequence code-division multiple-access (DS-CDMA) wireless communication systems employing the generalized detector (GD) constructed based on the generalized approach to signal processing in noise is analyzed. The effects of pulse shaping, quadriphase or direct sequence quadriphase shift keying (DS-QPSK) spreading, aperiodic spreading sequences are considered in DS-CDMA based on GD and compared with the coherent Neyman-Pearson receiver. An exact Per expression and several approximations: one using the characterristic function method, a simplified expression for the improved Gaussian approximation (IGA) and the simplified improved Gaussian approximation are derived. Under conditions typically satisfied in practice and even with a small number of interferers, the standard Gaussian approximation (SGA) for the multiple-access interference component of the GD statistic and Per performance is shown to be accurate. Moreover, the IGA is shown to reduce to the SGA for pulses with zero excess bandwidth. Second, the GD Per performance of quadriphase DS-CDMA is shown to be superior to that of bi-phase DS-CDMA. Numerical examples by Monte Carlo simulation are presented to illustrate the GD Per performance for square-root raised-cosine pulses and spreading factors of moderate to large values. Also, a superiority of GD employment in CDMA systems over the Neyman-Pearson receiver is demonstrated

Comparison of PSF maxima and minima of multiple annuli coded aperture (MACA) and complementary multiple annuli coded aperture (CMACA) systems

NASA Astrophysics Data System (ADS)

Ratnam, Challa; Lakshmana Rao, Vadlamudi; Lachaa Goud, Sivagouni

2006-10-01

In the present paper, and a series of papers to follow, the Fourier analytical properties of multiple annuli coded aperture (MACA) and complementary multiple annuli coded aperture (CMACA) systems are investigated. First, the transmission function for MACA and CMACA is derived using Fourier methods and, based on the Fresnel-Kirchoff diffraction theory, the formulae for the point spread function are formulated. The PSF maxima and minima are calculated for both the MACA and CMACA systems. The dependence of these properties on the number of zones is studied and reported in this paper.

Detailed seismic velocity structure of the ultra-slow spread crust at the Mid-Cayman Spreading Center from travel-time tomography and synthetic seismograms

NASA Astrophysics Data System (ADS)

Harding, J.; Van Avendonk, H. J.; Hayman, N. W.; Grevemeyer, I.; Peirce, C.

2017-12-01

The Mid-Cayman Spreading Center (MCSC), an ultraslow-spreading center in the Caribbean Sea, has formed highly variable oceanic crust. Seafloor dredges have recovered extrusive basalts in the axial deeps as well as gabbro on bathymetric highs and exhumed mantle peridotite along the only 110 km MCSC. Wide-angle refraction data were collected with active-source ocean bottom seismometers in April, 2015, along lines parallel and across the MCSC. Travel-time tomography produces relatively smooth 2-D tomographic models of compressional wave velocity. These velocity models reveal large along- and across-axis variations in seismic velocity, indicating possible changes in crustal thickness, composition, faulting, and magmatism. It is difficult, however, to differentiate between competing interpretations of seismic velocity using these tomographic models alone. For example, in some areas the seismic velocities may be explained by either thin igneous crust or exhumed, serpentinized mantle. Distinguishing between these two interpretations is important as we explore the relationships between magmatism, faulting, and hydrothermal venting at ultraslow-spreading centers. We therefore improved our constraints on the shallow seismic velocity structure of the MCSC by modeling the amplitude of seismic refractions in the wide-angle data set. Synthetic seismograms were calculated with a finite-difference method for a range of models with different vertical velocity gradients. Small-scale features in the velocity models, such as steep velocity gradients and Moho boundaries, were explored systematically to best fit the real data. With this approach, we have improved our understanding of the compressional velocity structure of the MCSC along with the geological interpretations that are consistent with three seismic refraction profiles. Line P01 shows a variation in the thinness of lower seismic velocities along the axis, indicating two segment centers, while across-axis lines P02 and P03 show variations in igneous crustal thickness and exhumed mantle in some areas.

[Violent computergames: distribution via and discussion on the Internet].

PubMed

Nagenborg, Michael

2005-11-01

The spread and use of computer-games including (interactive) depictions of violence are considered a moral problem, particularly if played by children and youths. This essay expresses an opinion on H. Volper's (2004) demand of condemning certain contents by media ethics. At the same time, an overview on the spread and use of "violent games" by children and youths is offered. As a matter of fact, the share of these titles in the complete range must not be estimated too high, certain titles on the other hand are extremely wide-spread. Finally, Fritz's and Fehr's thesis of the cultural conflict "computer game" (2004) is discussed, demonstrated at the example of the discussion on the Internet, and on the basis of this thesis a mediating position between the two cultures including audience ethics (Funiok 1999) is presented.

Swine vesicular disease in northern Italy: diffusion through densely populated pig areas.

PubMed

Bellini, S; Alborali, L; Zanardi, G; Bonazza, V; Brocchi, E

2010-12-01

At the end of 2006, a recrudescence of swine vesicular disease (SVD) was recorded in Italy and the disease spread widely throughout the northern regions. Lombardy, a densely populated pig area, was most affected and the presence of the disease caused heavy economic losses to the entire pig industry. Although SVD is considered only moderately contagious, the epidemic in the north was characterised by a rapid spread of the condition. Numerous difficulties were encountered in eradicating it. Over the past decade, there has been a significant increase in the population of pigs in Lombardy, concentrated mainly in a few areas which were the most severely affected during the 2006 to 2007 SVD epidemic. Increases in both the pig population and animal movements, combined with weak biosecurity measures, increased the spread rate of the disease and hampered eradication activities.

Novel antimicrobial compounds from microbial sources

USDA-ARS?s Scientific Manuscript database

The use of antibiotics for agricultural and industrial applications is a controversial practice. In food animal production, antibiotics are widely administered through medicated feed to treat subclinical infections, as well as to prevent the spread of disease throughout the herd or flock. Antibiotic...

Cutting-edge technologies: GPS/Satellite communications-based tracking

USDA-ARS?s Scientific Manuscript database

Despite wide-spread adoption of GPS and satellite-communication technologies within the freight and transportation industries, commercially-available telemetry tracking systems have not kept pace with the evolving demands of ecological research. Commercial GPS tracking collars are costly ($1,500 to...

Zu Problemen statistischer Methoden in der Sprachwissenschaft (Problems of Statistical Methods in Linguistics)

ERIC Educational Resources Information Center

Zorn, Klaus

1973-01-01

Discussion of statistical apparatus employed in L. Doncheva-Mareva's article on the wide-spread usage of the present and future tense forms with future meaning in German letters, Deutsch als Fremdsprache, n1 1971. (RS)

Pathways of Toxicity

EPA Science Inventory

Despite wide-spread consensus on the need to transform toxicology and risk assessment in order to keep pace with technological and computational changes that have revolutionized the life sciences, there remains much work to be done to achieve the vision of toxicology based on a m...

Role for migratory wild birds in the global spread of avian influenza H5N8

USGS Publications Warehouse

,; Ip, Hon S.

2016-01-01

Avian influenza viruses affect both poultry production and public health. A subtype H5N8 (clade 2.3.4.4) virus, following an outbreak in poultry in South Korea in January 2014, rapidly spread worldwide in 2014–2015. Our analysis of H5N8 viral sequences, epidemiological investigations, waterfowl migration, and poultry trade showed that long-distance migratory birds can play a major role in the global spread of avian influenza viruses. Further, we found that the hemagglutinin of clade 2.3.4.4 virus was remarkably promiscuous, creating reassortants with multiple neuraminidase subtypes. Improving our understanding of the circumpolar circulation of avian influenza viruses in migratory waterfowl will help to provide early warning of threats from avian influenza to poultry, and potentially human, health.

Social networks and spreading of epidemics

NASA Astrophysics Data System (ADS)

Trimper, Steffen; Zheng, Dafang; Brandau, Marian

2004-05-01

Epidemiological processes are studied within a recently proposed social network model using the susceptible-infected-refractory dynamics (SIR) of an epidemic. Within the network model, a population of individuals may be characterized by H independent hierarchies or dimensions, each of which consists of groupings of individuals into layers of subgroups. Detailed numerical simulations reveals that for H > 1, the global spreading results regardless of the degree of homophily α of the individuals forming a social circle. For H = 1, a transition from a global to a local spread occurs as the population becomes decomposed into increasingly homophilous groups. Multiple dimensions in classifying individuals (nodes) thus make a society (computer network) highly susceptible to large scale outbreaks of infectious diseases (viruses). The SIR-model can be extended by the inclusion of waiting times resulting in modified distribution function of the recovered.

Environmental Adaptations, Ecological Filtering, and Dispersal Central to Insect Invasions.

PubMed

Renault, David; Laparie, Mathieu; McCauley, Shannon J; Bonte, Dries

2018-01-07

Insect invasions, the establishment and spread of nonnative insects in new regions, can have extensive economic and environmental consequences. Increased global connectivity accelerates rates of introductions, while climate change may decrease the barriers to invader species' spread. We follow an individual-level insect- and arachnid-centered perspective to assess how the process of invasion is influenced by phenotypic heterogeneity associated with dispersal and stress resistance, and their coupling, across the multiple steps of the invasion process. We also provide an overview and synthesis on the importance of environmental filters during the entire invasion process for the facilitation or inhibition of invasive insect population spread. Finally, we highlight important research gaps and the relevance and applicability of ongoing natural range expansions in the context of climate change to gain essential mechanistic insights into insect invasions.

The simple rules of social contagion.

PubMed

Hodas, Nathan O; Lerman, Kristina

2014-03-11

It is commonly believed that information spreads between individuals like a pathogen, with each exposure by an informed friend potentially resulting in a naive individual becoming infected. However, empirical studies of social media suggest that individual response to repeated exposure to information is far more complex. As a proxy for intervention experiments, we compare user responses to multiple exposures on two different social media sites, Twitter and Digg. We show that the position of exposing messages on the user-interface strongly affects social contagion. Accounting for this visibility significantly simplifies the dynamics of social contagion. The likelihood an individual will spread information increases monotonically with exposure, while explicit feedback about how many friends have previously spread it increases the likelihood of a response. We provide a framework for unifying information visibility, divided attention, and explicit social feedback to predict the temporal dynamics of user behavior.

The Simple Rules of Social Contagion

NASA Astrophysics Data System (ADS)

Hodas, Nathan O.; Lerman, Kristina

2014-03-01

It is commonly believed that information spreads between individuals like a pathogen, with each exposure by an informed friend potentially resulting in a naive individual becoming infected. However, empirical studies of social media suggest that individual response to repeated exposure to information is far more complex. As a proxy for intervention experiments, we compare user responses to multiple exposures on two different social media sites, Twitter and Digg. We show that the position of exposing messages on the user-interface strongly affects social contagion. Accounting for this visibility significantly simplifies the dynamics of social contagion. The likelihood an individual will spread information increases monotonically with exposure, while explicit feedback about how many friends have previously spread it increases the likelihood of a response. We provide a framework for unifying information visibility, divided attention, and explicit social feedback to predict the temporal dynamics of user behavior.

On the relation between fluvio-deltaic flood basin geomorphology and the wide-spread occurrence of arsenic pollution in shallow aquifers.

PubMed

Donselaar, Marinus E; Bhatt, Ajay G; Ghosh, Ashok K

2017-01-01

Pollution of groundwater with natural (geogenic) arsenic occurs on an enormous, world-wide scale, and causes wide-spread, serious health risks for an estimated more than hundred million people who depend on the use of shallow aquifers for drinking and irrigation water. A literature review of key studies on arsenic concentration levels yields that Holocene fluvial and deltaic flood basins are the hotspots of arsenic pollution, and that the dominant geomorphological setting of the arsenic-polluted areas consists of shallow-depth meandering-river deposits with sand-prone fluvial point-bar deposits surrounded by clay-filled (clay plug) abandoned meander bends (oxbow lakes). Analysis of the lithofacies distribution and related permeability contrasts of the geomorphological elements in two cored wells in a point bar and adjacent clay plug along the Ganges River, in combination with data of arsenic concentrations and organic matter content reveals that the low-permeable clay-plug deposits have a high organic matter content and the adjacent permeable point-bar sands show high but spatially very variable arsenic concentrations. On the basis of the geomorphological juxtaposition, the analysis of fluvial depositional processes and lithofacies characteristics, inherent permeability distribution and the omnipresence of the two geomorphological elements in Holocene flood basins around the world, a generic model is presented for the wide-spread arsenic occurrence. The anoxic deeper part (hypolimnion) of the oxbow lake, and the clay plugs are identified as the loci of reactive organic carbon and microbial respiration in an anoxic environment that triggers the reductive dissolution of iron oxy-hydroxides and the release of arsenic on the scale of entire fluvial floodplains and deltaic basins. The adjacent permeable point-bar sands are identified as the effective trap for the dissolved arsenic, and the internal permeability heterogeneity is the cause for aquifer compartmentalization, with large arsenic concentration differences between neighboring compartments. Copyright © 2016 Elsevier B.V. All rights reserved.

Graphical Neuroimaging Informatics: Application to Alzheimer’s Disease

PubMed Central

Bowman, Ian; Joshi, Shantanu H.; Greer, Vaughan

2013-01-01

The Informatics Visualization for Neuroimaging (INVIZIAN) framework allows one to graphically display image and meta-data information from sizeable collections of neuroimaging data as a whole using a dynamic and compelling user interface. Users can fluidly interact with an entire collection of cortical surfaces using only their mouse. In addition, users can cluster and group brains according in multiple ways for subsequent comparison using graphical data mining tools. In this article, we illustrate the utility of INVIZIAN for simultaneous exploration and mining a large collection of extracted cortical surface data arising in clinical neuroimaging studies of patients with Alzheimer’s Disease, mild cognitive impairment, as well as healthy control subjects. Alzheimer’s Disease is particularly interesting due to the wide-spread effects on cortical architecture and alterations of volume in specific brain areas associated with memory. We demonstrate INVIZIAN’s ability to render multiple brain surfaces from multiple diagnostic groups of subjects, showcase the interactivity of the system, and showcase how INVIZIAN can be employed to generate hypotheses about the collection of data which would be suitable for direct access to the underlying raw data and subsequent formal statistical analysis. Specifically, we use INVIZIAN show how cortical thickness and hippocampal volume differences between group are evident even in the absence of more formal hypothesis testing. In the context of neurological diseases linked to brain aging such as AD, INVIZIAN provides a unique means for considering the entirety of whole brain datasets, look for interesting relationships among them, and thereby derive new ideas for further research and study. PMID:24203652

Wildfire Health and Economic Impacts Case Study###

EPA Science Inventory

Since 2008 eastern North Carolina experienced 6 major wildfires, far exceeding the historic 50 year expected rate of return. Initiated by the lighting strikes, these fires spread across multiple feet deep, dry and extremely vulnerable peat bogs. The fires produced massive amounts...

Gambling and the Law(®): Endless fields of dreams.

PubMed

Rose, I N

1995-03-01

This article examines the current trends of proliferation of commercial gaming, especially in the United States, in the context of the "third wave" of legalization of gambling that has been experienced since the founding of the nation. The author looks at the historic foundations of the spread of casino-style gambling, and notes the types of casino gaming that have led the way in the current expansion. He also points out why it is reasonable to expect that this wave too may come crashing down, as general acceptance of wide-spread casino gaming in America may indeed be short-lived.

Advanced Optimal Extraction for the Spitzer/IRS

NASA Astrophysics Data System (ADS)

Lebouteiller, V.; Bernard-Salas, J.; Sloan, G. C.; Barry, D. J.

2010-02-01

We present new advances in the spectral extraction of pointlike sources adapted to the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. For the first time, we created a supersampled point-spread function of the low-resolution modules. We describe how to use the point-spread function to perform optimal extraction of a single source and of multiple sources within the slit. We also examine the case of the optimal extraction of one or several sources with a complex background. The new algorithms are gathered in a plug-in called AdOpt which is part of the SMART data analysis software.

Multidrug-Resistant Gram-Negative Bacilli: Infection Control Implications.

PubMed

Adler, Amos; Friedman, N Deborah; Marchaim, Dror

2016-12-01

Antimicrobial resistance is a common iatrogenic complication of both modern life and medical care. Certain multidrug resistant and extensively drug resistant Gram-negative organisms pose the biggest challenges to health care today, predominantly owing to a lack of therapeutic options. Containing the spread of these organisms is challenging, and in reality, the application of multiple control measures during an evolving outbreak makes it difficult to measure the relative impact of each measure. This article reviews the usefulness of various infection control measures in containing the spread of multidrug-resistant Gram-negative bacilli. Copyright © 2016 Elsevier Inc. All rights reserved.

Buoyant Effects on the Flammability of Silicone Samples Planned for the Spacecraft Fire Experiment (Saffire)

NASA Technical Reports Server (NTRS)

Niehaus, Justin E.; Ferkul, Paul V.; Gokoglu, Suleyman A.; Ruff, Gary A.

2015-01-01

Flammability experiments on silicone samples were conducted in anticipation of the Spacecraft Fire Experiment (Saffire). The sample geometry was chosen to match the NASA 6001 Test 1 specification, namely 5 cm wide by 30 cm tall. Four thicknesses of silicone (0.25, 0.36, 0.61 and 1.00 mm) were examined. Tests included traditional upward buoyant flame spread using Test 1 procedures, downward opposed-flow flame spread, horizontal and angled flame spread, and forced-flow upward and downward flame spread. In addition to these configurations, upward and downward tests were conducted in a chamber with varying oxygen concentrations. In the upward buoyant flame spread tests, the flame generally did not burn the entire sample. As thickness was increased, the flame spread distance decreased before flame extinguishment. For the thickest sample, ignition could not be achieved. In the downward tests, the two thinnest samples permitted the flame to burn the entire sample, but the spread rate was lower compared to the corresponding upward values. The other two thicknesses could not be ignited in the downward configuration. The increased flammability for downward spreading flames relative to upward ones is uncommon. The two thinnest samples also burned completely in the horizontal configuration, as well as at angles up to 75 degrees from the horizontal. Upward tests in air with an added forced flow were more flammable. The upward and downward flammability behavior was compared in atmospheres of varying oxygen concentration to determine a maximum oxygen concentration for each configuration. Complementary analyses using EDS, TGA, and SEM techniques suggest the importance of the silica layer deposited downstream onto the unburned sample surface.

Modelling the effects of phylogeny and body size on within-host pathogen replication and immune response.

PubMed

Banerjee, Soumya; Perelson, Alan S; Moses, Melanie

2017-11-01

Understanding how quickly pathogens replicate and how quickly the immune system responds is important for predicting the epidemic spread of emerging pathogens. Host body size, through its correlation with metabolic rates, is theoretically predicted to impact pathogen replication rates and immune system response rates. Here, we use mathematical models of viral time courses from multiple species of birds infected by a generalist pathogen (West Nile Virus; WNV) to test more thoroughly how disease progression and immune response depend on mass and host phylogeny. We use hierarchical Bayesian models coupled with nonlinear dynamical models of disease dynamics to incorporate the hierarchical nature of host phylogeny. Our analysis suggests an important role for both host phylogeny and species mass in determining factors important for viral spread such as the basic reproductive number, WNV production rate, peak viraemia in blood and competency of a host to infect mosquitoes. Our model is based on a principled analysis and gives a quantitative prediction for key epidemiological determinants and how they vary with species mass and phylogeny. This leads to new hypotheses about the mechanisms that cause certain taxonomic groups to have higher viraemia. For example, our models suggest that higher viral burst sizes cause corvids to have higher levels of viraemia and that the cellular rate of virus production is lower in larger species. We derive a metric of competency of a host to infect disease vectors and thereby sustain the disease between hosts. This suggests that smaller passerine species are highly competent at spreading the disease compared with larger non-passerine species. Our models lend mechanistic insight into why some species (smaller passerine species) are pathogen reservoirs and some (larger non-passerine species) are potentially dead-end hosts for WNV. Our techniques give insights into the role of body mass and host phylogeny in the spread of WNV and potentially other zoonotic diseases. The major contribution of this work is a computational framework for infectious disease modelling at the within-host level that leverages data from multiple species. This is likely to be of interest to modellers of infectious diseases that jump species barriers and infect multiple species. Our method can be used to computationally determine the competency of a host to infect mosquitoes that will sustain WNV and other zoonotic diseases. We find that smaller passerine species are more competent in spreading the disease than larger non-passerine species. This suggests the role of host phylogeny as an important determinant of within-host pathogen replication. Ultimately, we view our work as an important step in linking within-host viral dynamics models to between-host models that determine spread of infectious disease between different hosts. © 2017 The Author(s).

Molecular techniques to distinguish morphologically similar Hydrilla verticillata, Egeria densa, Elodea nuttallii, and Elodea canadensis

USGS Publications Warehouse

Rybicki, Nancy B.; Kirshtein, Julie D.; Voytek, Mary A.

2013-01-01

The four submerged aquatic species, hydrilla (Hydrilla verticillata [monoecious and dioecious]), Brazilian waterweed (Egeria densa), Canadian waterweed (Elodea canadensis), and western waterweed (Elodea nuttallii), are difficult to positively identify because of their morphological similarity to each other, resulting in possible misidentification. This limits our ability to understand their past and present distribution, which is important in aquatic plant management. We investigated a molecular technique to identify these species, which are problematic because of their invasive nature on multiple continents. Approximately 100 samples of these species, ranging in age from 40-yr-old herbarium samples to recently collected plants, were collected from regions across the United States. The distribution and range of the samples collected in this research were compared to those reported in the literature. We confirmed information on the current wide distribution of both hydrilla biotypes in the United States and discovered that hydrilla had actually invaded the waterways near Washington, DC 6 yr earlier than originally reported. In addition, we found evidence of the confusion, dating back to the 1980s, between Canadian waterweed and western waterweed in the mid-Atlantic region of the United States. Canadian waterweed was previously reported as common and western waterweed as rare; however, our samples indicate the opposite is true. This information indicates there is a need for investigators to anticipate the spread of hydrilla populations to northern U.S. waterways, where it will compete with existing plant species, including Canadian and western waterweeds. Our ability to confirm distribution and pace of spread of invasive and noninvasive species will improve with increased application of molecular techniques.

Glial reactions to argon laser photocoagulation injury in rabbit and rat retinas

NASA Astrophysics Data System (ADS)

Humphrey, Martin F.; Chu, Yi; Sharp, Claudia; Moore, Stephen; Mann, Krishna; Rakoczy, Piroska; Constable, Ian J.

1996-04-01

Argon laser photocoagulation is a standard and effective clinical technique for a variety of disease conditions. However there is evidence that coagulation produces more widespread alterations in the retina than the local scarring at the injury site. For example, in diabetic retinopathy multiple photocoagulations in the retinal periphery can control blood vessel growth in the central retina. Therefore we have studied the changes in retinal glial cells following photocoagulation using immunocytochemical techniques with an emphasis on the spread of cellular reactions by using whole, flatmounted retinal preparations. Muller glial cells do not normally express the cytoskeletal protein GFAP (glial fibrillary acidic protein) but do so after a variety of injuries. We found that there is a very widespread expression of GFAP by Muller cells even after very focal coagulations and that this persists for 1 - 1.5 months after coagulation. The microglial cells are primed to react to injury and can release very powerful effector molecules and we therefore also examined the microglial reaction to see whether it correlated with the Muller cell reaction. However, we found that the microglial response, in terms of anatomical changes, was very focally confined to regions of direct cellular injury. We also examined MHC II expression to see whether microglia expressed this activity related protein without anatomical changes but we found no evidence of wide spread changes. In summary we find that inflammatory reactions are very localized after coagulation but the macroglial changes are more widespread and therefore the distant effects of photocoagulation may be more related to macroglial reactions.

HOLOCENE MASS-WASTING EVENTS IN LAGO FAGNANO, TIERRA DEL FUEGO (54°S): IMPLICATIONS FOR PALEOSEISMICITY OF THE MAGALLANES-FAGNANO TRANSFORM FAULT

NASA Astrophysics Data System (ADS)

Ariztegui, D.; Waldmann, N.; Austin, J. A.; Anselmetti, F.; Moy, C.; Dunbar, R. B.

2009-12-01

High-resolution seismic imaging and sediment coring in Lago Fagnano, located along the Magallanes-Fagnano plate boundary in Tierra del Fuego, have revealed a chronologic catalog of Holocene mass-wasting events. These event layers are interpreted as resulting from slope instabilities that load the slope-adjacent lake floor during mass flow deposition thus mobilizing basin floor sediments through gravity spreading. A total of 22 mass flow deposits have been identified combining results from an 800 km-long dense grid of seismic profiles with a series of sediment cores. Successions of up to 6 m-thick mass-flow deposits pond the basin floor spreading eastward and westward following the main axis of the eastern sub-basin of Lago Fagnano. An age model on the basis of information from previous studies and from new radiocarbon dating allowed establishing a well-constrained chronologic mass-wasting event catalogue covering the last ~15000 years. Simultaneously-triggered basin-wide lateral slope failure and the formation of multiple debris flow and megaturbidite deposits are interpreted as the fingerprint of paleo-seismic activity along the Magallanes-Fagnano transform fault that runs along the entire lake basin. The slope failures and megaturbidites are interpreted as recording large earthquakes occurring along the transform fault since the early Holocene. The results from this study provide new data about the frequency and possible magnitude of Holocene earthquakes in Tierra del Fuego, which can be applied in the context of seismic hazard assessment in southernmost Patagonia.

Exploring the future change space for fire weather in southeast Australia

NASA Astrophysics Data System (ADS)

Clarke, Hamish; Evans, Jason P.

2018-05-01

High-resolution projections of climate change impacts on fire weather conditions in southeast Australia out to 2080 are presented. Fire weather is represented by the McArthur Forest Fire Danger Index (FFDI), calculated from an objectively designed regional climate model ensemble. Changes in annual cumulative FFDI vary widely, from - 337 (- 21%) to + 657 (+ 24%) in coastal areas and - 237 (- 12%) to + 1143 (+ 26%) in inland areas. A similar spread is projected in extreme FFDI values. In coastal regions, the number of prescribed burning days is projected to change from - 11 to + 10 in autumn and - 10 to + 3 in spring. Across the ensemble, the most significant increases in fire weather and decreases in prescribed burn windows are projected to take place in spring. Partial bias correction of FFDI leads to similar projections but with a greater spread, particularly in extreme values. The partially bias-corrected FFDI performs similarly to uncorrected FFDI compared to the observed annual cumulative FFDI (ensemble root mean square error spans 540 to 1583 for uncorrected output and 695 to 1398 for corrected) but is generally worse for FFDI values above 50. This emphasizes the need to consider inter-variable relationships when bias-correcting for complex phenomena such as fire weather. There is considerable uncertainty in the future trajectory of fire weather in southeast Australia, including the potential for less prescribed burning days and substantially greater fire danger in spring. Selecting climate models on the basis of multiple criteria can lead to more informative projections and allow an explicit exploration of uncertainty.

Areas of potential suitability and survival of Dendroctonus valens in China under extreme climate warming scenario.

PubMed

He, S Y; Ge, X Z; Wang, T; Wen, J B; Zong, S X

2015-08-01

The areas in China with climates suitable for the potential distribution of the pest species red turpentine beetle (RTB) Dendroctonus valens LeConte (Coleoptera: Scolytidae) were predicted by CLIMEX based on historical climate data and future climate data with warming estimated. The model used a historical climate data set (1971-2000) and a simulated climate data set (2010-2039) provided by the Tyndall Centre for Climate Change (TYN SC 2.0). Based on the historical climate data, a wide area was available in China with a suitable climate for the beetle in which every province might contain suitable habitats for this pest, particularly all of the southern provinces. The northern limit of the distribution of the beetle was predicted to reach Yakeshi and Elunchun in Inner Mongolia, and the western boundary would reach to Keerkezi in Xinjiang Province. Based on a global-warming scenario, the area with a potential climate suited to RTB in the next 30 years (2010-2039) may extend further to the northeast. The northern limit of the distribution could reach most parts of south Heilongjiang Province, whereas the western limit would remain unchanged. Combined with the tendency for RTB to spread, the variation in suitable habitats within the scenario of extreme climate warming and the multiple geographical elements of China led us to assume that, within the next 30 years, RTB would spread towards the northeast, northwest, and central regions of China and could be a potentially serious problem for the forests of China.

Hydrothermal mineralization at seafloor spreading centers

NASA Astrophysics Data System (ADS)

Rona, Peter A.

1984-01-01

The recent recognition that metallic mineral deposits are concentrated by hydrothermal processes at seafloor spreading centers constitutes a scientific breakthrough that opens active sites at seafloor spreading centers as natural laboratories to investigate ore-forming processes of such economically useful deposits as massive sulfides in volcanogenic rocks on land, and that enhances the metallic mineral potential of oceanic crust covering two-thirds of the Earth both beneath ocean basins and exposed on land in ophiolite belts. This paper reviews our knowledge of processes of hydrothermal mineralization and the occurrence and distribution of hydrothermal mineral deposits at the global oceanic ridge-rift system. Sub-seafloor hydrothermal convection involving circulation of seawater through fractured rocks of oceanic crust driven by heat supplied by generation of new lithosphere is nearly ubiquitous at seafloor spreading centers. However, ore-forming hydrothermal systems are extremely localized where conditions of anomalously high thermal gradients and permeability increase hydrothermal activity from the ubiquitous low-intensity background level (⩽ 200°C) to high-intensity characterized by high temperatures ( > 200-c.400°C), and a rate and volume of flow sufficient to sustain chemical reactions that produce acid, reducing, metal-rich primary hydrothermal solutions. A series of mineral phases with sulfides and oxides as high- and low-temperature end members, respectively, are precipitated along the upwelling limb and in the discharge zone of single-phase systems as a function of increasing admixture of normal seawater. The occurrence of hydrothermal mineral deposits is considered in terms of spatial and temporal frames of reference. Spatial frames of reference comprise structural features along-axis (linear sections that are the loci of seafloor spreading alternating with transform faults) and perpendicular to axis (axial zone of volcanic extrusion and marginal zones of active extension) common to all spreading centers, regional tectonic setting determined by stage (early, advanced), and rate (slow, intermediate-to-fast) of opening of an ocean basin about a spreading center, and local tectonic sub-setting that incorporates anomalous structural and thermal conditions conducive to mineral concentration (thermal gradient, permeability, system geometry, leaky versus tight hydrothermal systems). Temporal frames of reference comprise the relation between mineral concentration and timing of regional plutonic, volcanic and tectonic cycles and of episodic local physical and chemical events (transient stress, fluctuating heat transfer, intrusion-extrusion, fracturing, sealing, etc.). Types of hydrothermal deposits are not uniquely associated with specific tectonic settings and subsettings. Similar types of hydrothermal deposits may occur in different tectonic settings as a consequence of convergence of physical and chemical processes of concentration. Local tectonic sub-settings with conditions conducive to hydrothermal mineralization at slow-spreading centers (half rate ≤ 2cm y -1; length c. 28,000 km), characterized by an estimated average convective heat transfer of 15.1·10 8 cal. cm -2, deep-level ( > 3 km), relative narrow (< 5 km wide at base) magma chambers, and high topographic relief (1-5 km) are: (1) basins along linear sections of the axial zone of volcanic extrusion near transform faults at an early stage of opening, represented by a large stratiform sulfide deposit (estimated 32.5·10 6 metric tons) of the Atlantis II Deep of the Red Sea; (2) the wall along linear sections of the rift valley in the marginal zone of active extension at an advanced stage of opening, represented by encrustations and layered deposits of manganese and iron oxides, hydroxides and silicates inferred to be underlain by stockwork sulfides at the TAG Hydrothermal Field at latitude 26°C on the Mid-Atlantic Ridge; (3) transform faults, especially those with large ridge-ridge offset ( > 30 km), at an advanced stage of opening, represented by stockwork sulfides exposed in the walls of equatorial fracture zones of the Atlantic Ocean and Indian Ocean; (4) the axial zone of volcanic extrusion at an advanced stage of opening. Local tectonic sub-settings with conditions conducive to hydrothermal mineralization at intermediate- to fast-spreading centers (half rate > 2cm y -1; length c. 22,000 km) characterized by an estimated average convective heat transfer of 11.5·10 8 cal. cm -2, relatively wide (up to 20 km at base), shallow-level (c. 1-3 km) magma chambers, and low topographic relief (< 1 km), are: (1) basins along linear sections of the axial zone of volcanic extrusion at an early stage of opening, represented by massive sulfide deposits of the Guaymas Basin of the Gulf of California; (2) the axial zone of volcanic extrusion at an advanced stage of opening, represented by individually small (c. 1·10 3 metric tons), massive sulfide mounds surmounted by chimneys of the East Pacific Rise at latitude 21°N; (3) the marginal zone of active extension at an advanced stage of opening represented by a large, massive sulfide deposit (preliminary tentative estimate c.10·10 6 metric tons) at a double-rifted section of the Galapagos Spreading Center; (4) transform faults, especially those with large ridge-ridge offset ( > 50 km) represented by manganese encrustations in a transform fault at the Galapagos Spreading Center; (5) volcanic seamounts related to persistent hot spots at spreading centers, represented by oxide and sulfide deposits on seamounts off the axis of the East Pacific Rise; (6) portions of spreading centers with anomalous configurations such as multiple, bent or extended rifts, represented by massive sulfide deposits at a double-rifted section of the Galapagos Spreading Center, suggesting the operation of a thermal-structural feedback mechanism indicative of the presence of hydrothermal mineralization; (7) discrete spreading centers in back-arc basins represented by hydrothermal deposits at sites in marginal seas of the western Pacific. Ore-forming processes appear to be least efficient in the axial zone of volcanic extrusion of oceanic ridges at an advanced stage of opening irrespective of spreading rate, where tight hydrothermal systems dissipate a major portion of contained metals by precipitation and dispersion in particulate form from "black smokers" that discharge into the water column. Ore-forming processes appear to be most efficient at sites in basins at linear sections of the axial zone of volcanic extrusion near transform faults during an early stage of opening, and at marginal zones of active extension along linear sections of a spreading center during an advanced stage of opening, irrespective of spreading rate, where both tight and leaky hydrothermal systems may conserve their contained metals to concentrate large sulfide deposits. Resemblances in mineralization between stockwork sulfides at seafloor spreading centers and porphyry copper-type deposits in volcanogenic rocks on land suggest the possibility for the occurrence of large tonnage, low-grade porphyry copper-like deposits concentrated by leaky hydrothermal systems at spreading centers. Systematic application of composite exploration procedures is leading to the discovery of numerous additional deposits. It is inferred from the limited data base available that the occurrence of hydrothermal mineral deposits is more frequent at intermediate-to-fast-than at slow-spreading centers, but the potential for the accumulation of large hydrothermal mineral deposits is greater at slow-spreading centers. Current knowledge of the distribution of hydrothermal mineral deposits at seafloor spreading centers is limited to about 55 sites at this early stage of exploration. Estimates of the distribution of either fields of hydrothermal mineral deposits or high-intensity ore-forming hydrothermal systems at seafloor spreading centers, deduced from various considerations, range from one such occurrence between 15 and 265 km along slow-spreading centers, and 1 and 100 km along intermediate- to fast-spreading centers. However, the distribution of sizable deposits will remain sporadic owing to the special structural and thermal conditions necessary to sustain and to retain high-intensity ore-forming hydrothermal systems.

Seafloor Volcanic and Structural Features Adjacent to the 90deg 50'N Transform - Galapagos Spreading Center: Clues for Understanding Plate Boundary Kinematics and Lithospheric Melting Processes (Invited)

NASA Astrophysics Data System (ADS)

Fornari, D. J.; Soule, S.; Harpp, K. S.; Mittelstaedt, E. L.; Geist, D.; Kurz, M. D.; R/v Melville Mv1007 Cruise Scientific Party

2010-12-01

High-resolution EM122 multibeam and MR-1 sidescan sonar data collected over a wide area of seafloor west and east of the 90deg 50’N transform along the Galapagos Spreading Center (GSC) reveal seafloor morpho-structural fabric created along this intermediate spreading plate boundary. In concert with geochemical and geophysical data collected during the cruise, these data will be used to help unravel the kinematics of hotspot-ridge interactions in the northern Galapagos. West of the transform, the seafloor is dominated by three prominent NW-SE trending seamount lineaments, each ~20-30 km wide, including the prominent Wolf-Darwin Lineament (WDL) as well as two other smaller volcanic chains east of the WDL, which are oriented along intermediate trends that become more subparallel to the N-S trend of the transform from west to east. This suggests a possible strong controlling influence of the transform on the orientation of lithospheric fractures involved in supplying magmas to the volcanic centers. Interestingly, each seamount lineament west of the transform appears to have nascent volcanoes nucleating immediately south of the GSC axis at locations that mark along-axis discontinuities of the spreading center, suggesting ridge-related magmatic focusing is also influencing crustal generation on the Nazca plate in this region. The tectonized terrain associated with the transform is 60 km wide, whereas the transform valley is only 20 km wide. The northern 40 km of the transform has a well-defined linear shear zone and bounding faults. The southern 50 km of the transform are characterized by a wide zone of extensive oblique shear structures that trend NW-SE. Within this zone are numerous small volcanic cones and ridges that decorate the margins and axis of the transform domain. The structural evolution of the transform appears to be undergoing a transition along its length with intra-transform volcanism in the south and more normal shear in the north, however the tectonic imprint of the oblique structures is observed along nearly all of the length of the transform out to 15-20 km from the margins of the transform valley. Terrain east of the transform is markedly different in morphological character and structural elements. A series of five, generally E-W ridges, some of which display clear volcanic constructional terrain, extend from the eastern margin of the oblique fabric associated with the transform domain. Some of these E-W features are linked by N-S structures, creating a general patchwork pattern of seafloor that is unlike any we have observed at well-mapped ridge-transform intersections at fast and intermediate spreading mid-ocean ridges. The terrain bears some similarities to structures developed at microplates. We also note that this region lies at the southwestern extremity of the Cocos Ridge, an aseismic ridge that has undergone a complex history of volcanic and tectonic construction associated with hotspot magmatism and ridge jumps.

Distributed Water Pollution Source Localization with Mobile UV-Visible Spectrometer Probes in Wireless Sensor Networks.

PubMed

Ma, Junjie; Meng, Fansheng; Zhou, Yuexi; Wang, Yeyao; Shi, Ping

2018-02-16

Pollution accidents that occur in surface waters, especially in drinking water source areas, greatly threaten the urban water supply system. During water pollution source localization, there are complicated pollutant spreading conditions and pollutant concentrations vary in a wide range. This paper provides a scalable total solution, investigating a distributed localization method in wireless sensor networks equipped with mobile ultraviolet-visible (UV-visible) spectrometer probes. A wireless sensor network is defined for water quality monitoring, where unmanned surface vehicles and buoys serve as mobile and stationary nodes, respectively. Both types of nodes carry UV-visible spectrometer probes to acquire in-situ multiple water quality parameter measurements, in which a self-adaptive optical path mechanism is designed to flexibly adjust the measurement range. A novel distributed algorithm, called Dual-PSO, is proposed to search for the water pollution source, where one particle swarm optimization (PSO) procedure computes the water quality multi-parameter measurements on each node, utilizing UV-visible absorption spectra, and another one finds the global solution of the pollution source position, regarding mobile nodes as particles. Besides, this algorithm uses entropy to dynamically recognize the most sensitive parameter during searching. Experimental results demonstrate that online multi-parameter monitoring of a drinking water source area with a wide dynamic range is achieved by this wireless sensor network and water pollution sources are localized efficiently with low-cost mobile node paths.

Distributed Water Pollution Source Localization with Mobile UV-Visible Spectrometer Probes in Wireless Sensor Networks

PubMed Central

Zhou, Yuexi; Wang, Yeyao; Shi, Ping

2018-01-01

Pollution accidents that occur in surface waters, especially in drinking water source areas, greatly threaten the urban water supply system. During water pollution source localization, there are complicated pollutant spreading conditions and pollutant concentrations vary in a wide range. This paper provides a scalable total solution, investigating a distributed localization method in wireless sensor networks equipped with mobile ultraviolet-visible (UV-visible) spectrometer probes. A wireless sensor network is defined for water quality monitoring, where unmanned surface vehicles and buoys serve as mobile and stationary nodes, respectively. Both types of nodes carry UV-visible spectrometer probes to acquire in-situ multiple water quality parameter measurements, in which a self-adaptive optical path mechanism is designed to flexibly adjust the measurement range. A novel distributed algorithm, called Dual-PSO, is proposed to search for the water pollution source, where one particle swarm optimization (PSO) procedure computes the water quality multi-parameter measurements on each node, utilizing UV-visible absorption spectra, and another one finds the global solution of the pollution source position, regarding mobile nodes as particles. Besides, this algorithm uses entropy to dynamically recognize the most sensitive parameter during searching. Experimental results demonstrate that online multi-parameter monitoring of a drinking water source area with a wide dynamic range is achieved by this wireless sensor network and water pollution sources are localized efficiently with low-cost mobile node paths. PMID:29462929

[Osteoarticular coccidioidomicosis. Clinical and pathological study of 36 Mexican patients].

PubMed

Torres-Nájera, Manuel; de la Garza-Galván, Sergio; Cerda-Flores, Ricardo M; Nocedal-Rustrián, Fausto C; Calderón-Garcidueñas, Ana Laura

2006-01-01

Coccidioidomycosis (CM) is primarily a lung disease. Systemic spread occurs in 1% of cases and one of its manifestation is osteoarthritis. To describe the clinical and pathological characteristics of 36 patients with osteoarthritis by Coccidioides immitis (COA). The surgical pathology records of two medical institutions were reviewed; patients with clinical diagnosis of osteoarthritis and definitive histopathological diagnosis of COA were included in the study. Results were analyzed by contingence tables (RXC) and chi2 test. Twenty six adults (19 men, seven women) and 10 children (seven males, three females) were studied. The chi2 analysis demonstrated a predominance of disease in men (72.2%, p = 0.008). There was no difference between males and females in relation to history of mycotic disease or diagnosis of lung disease after the diagnosis of COA. Bone involvement (76% of cases) was more frequent that pure joint lesions and the predominant radiological lesion was of lytic type. 30.5% of patients (11 cases) had multiple bone lesions and eight of them were men with multiple vertebral bone lesions. The COA was the only manifestation of disease in 83% of the patients. Therefore is important to consider this etiology in patients of endemic area. The clinical and radiological spectrum of COA is wide and may include a dentigerous and synovial cyst or simulates metastatic disease. The recognition of the clinical manifestations of COA may contribute to an opportune diagnosis and treatment.

Examining Models for the Pharmacokinetics of Perfluorooctanoic Acid

EPA Science Inventory

Perfluorooctanoate (PFOA) is a man-made surfactant used in a variety of industrial and consumer applications. Because of its wide-spread environmental distribution and stability, PFOA is found in human blood from the general population (Calafat et al., 2007). PFOA displays compl...

Cabomba caroliniana Gray cabomba

USDA-ARS?s Scientific Manuscript database

Cabomba caroliniana is a submerged aquatic plant from South America that is becoming a serious weed worldwide. It spreads by seed and by fragmentation and has extremely wide climatic range, invading lakes and ponds from tropical (Darwin, Australia: latitude 12º) to cold temperate regions (Peterborou...

Historic perspective: Prebiotics, probiotics, and other alternatives to antibiotics

USDA-ARS?s Scientific Manuscript database

Antibiotic applications in agricultural and human medical arenas have resulted in tremendous increases in food animal production and historically unprecedented gains in human health protection. Successes attributed to wide-spread antibiotic use have been accompanied by the inadvertent emergence of r...

RENEWABLE ENERGY-POWERED BULK MILK COOLING FOR SMALLHOLDER DAIRY FARMERS

EPA Science Inventory

We will show that the cooler can successfully add the evening milk to the cold chain and that it’s wide spread use has potential to reduce the amount of methane released into the atmospheres from smallholder dairy farms.

Spread of hybridization between native westslope cutthroat trout, Oncorhynchus clarki lewisi, and nonnative rainbow trout, Oncorhynchus mykiss

USGS Publications Warehouse

Hitt, Nathaniel P.; Frissell, Christopher A.; Muhlfeld, Clint C.; Fred W. Allendorf,

2003-01-01

We examined spatial and temporal patterns of hybridization between native westslope cutthroat trout, Oncorhynchus clarki lewisi, and nonnative rainbow trout, O. mykiss, in streams of the Flathead River system in Montana, U.S.A. We detected hybridization in 24 of 42 sites sampled from 1998 to 2001. We found new Oncorhynchus mykiss introgression in seven of 11 sample populations that were determined to be nonhybridized in 1984. Patterns of spatial autocorrelation and linkage disequilibrium indicated that hybridization is spreading among sites and is advancing primarily via post-F1 hybrids. Although hybridized populations were distributed widely throughout the study area, the genetic contribution from O. mykiss decreased with increasing upstream distance from the Flathead River mainstem, suggesting that O. mykiss introgression is spreading in an upstream direction. The spread of hybridization may be constrained more by demographic than by environmental factors, given that (i) hybridized populations generally encompassed the range of environmental variability in nonhybridized populations, and (ii) hybridization status was more strongly associated with neighborhood statistics than measured environmental gradients.

Transport and Chemical Effects on Concurrent and Opposed-Flow Flame Spread at Microgravity

NASA Technical Reports Server (NTRS)

Honda, L. K.; Ronney, P. D.

1999-01-01

With support from a previous NASA grant, NAG3-161 1, the PI studied the effects of diluent type, the addition of sub-flammability-limit concentrations of combustible gases, and the effects of concurrent buoyant flow on flame spread processes. The results of these studies are reported and directions for the current grant outlined. Most experiments were conducted in a 20 liter combustion chamber. Exactly the same apparatus was used for 1 g and microgravity tests. The effect of inert gases He, Ar, N2, CO2 and SF6 on flame spread were tested since they provide a variety of radiative properties and oxygen Lewis numbers. CO and CH4 were used for the gaseous fuels in partially-premixed atmosphere tests, plus H2, C3H8 and NH3 for 1 g tests only. In most experiments 5 cm wide Kimwipe samples 15 cm long were used and were held by aluminum quenching plates. The samples were ignited by an electrically-heated Kanthal wire. The flame spread process was imaged via three video cameras and a laser shearing interferometer.

78 FR 23952 - Notice of Temporary Closure on Public Lands in Elmore County, ID

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-23

...-grouse habitat. The closure will help to slow the spread of noxious weeds; allow planted shrub, forb, and... in the burned area to provide multiple age classes of shrubs in the burned area. Accessible areas of...

Providing context: antimicrobial resistance from multiple environmental sources

USDA-ARS?s Scientific Manuscript database

Background: Animal agriculture has been identified as encouraging the spread of resistance due to the use of large quantities of antimicrobials for animal production purposes. When antimicrobial resistance (AMR) is reported in agricultural settings without comparison to other environments there is a...

Propagation of Wide Bandwidth Signals through Strongly Turbulent Ionized Media

DTIC Science & Technology

1982-03-15

through random ionized media. This work is applicable to the problems of satel- lite communication and space based radar observation through a disturbed...REALIZATIONS 87 3.2 FORMULATION 88 3.2.1 Wide Bandwidth Signals 91 3.2.2 Total Phase Shift, Time Delay, and Doppler Frequency 95 3.2.3 Impulse Response...scattering limit. The 20 Gaussian form corresponds to pulse wander and dispersion while the expo- nential form corresponds to diffractive pulse spreading

Maximizing the Performance of Automated Low Cost All-sky Cameras

NASA Technical Reports Server (NTRS)

Bettonvil, F.

2011-01-01

Thanks to the wide spread of digital camera technology in the consumer market, a steady increase in the number of active All-sky camera has be noticed European wide. In this paper I look into the details of such All-sky systems and try to optimize the performance in terms of accuracy of the astrometry, the velocity determination and photometry. Having autonomous operation in mind, suggestions are done for the optimal low cost All-sky camera.

Quantum internet using code division multiple access

PubMed Central

Zhang, Jing; Liu, Yu-xi; Özdemir, Şahin Kaya; Wu, Re-Bing; Gao, Feifei; Wang, Xiang-Bin; Yang, Lan; Nori, Franco

2013-01-01

A crucial open problem inS large-scale quantum networks is how to efficiently transmit quantum data among many pairs of users via a common data-transmission medium. We propose a solution by developing a quantum code division multiple access (q-CDMA) approach in which quantum information is chaotically encoded to spread its spectral content, and then decoded via chaos synchronization to separate different sender-receiver pairs. In comparison to other existing approaches, such as frequency division multiple access (FDMA), the proposed q-CDMA can greatly increase the information rates per channel used, especially for very noisy quantum channels. PMID:23860488

High resolution multiple excitation spot optical microscopy

NASA Astrophysics Data System (ADS)

Dilipkumar, Shilpa; Mondal, Partha Pratim

2011-06-01

We propose fundamental improvements in three-dimensional (3D) resolution of multiple excitation spot optical microscopy. The excitation point spread function (PSF) is generated by two interfering counter-propagating depth-of-focus beams along the optical axis. Detection PSF is obtained by coherently interfering the emitted fluorescent light (collected by both the objectives) at the detector. System PSF shows upto 14-fold reduction in focal volume as compared to confocal, and almost 2-fold improvement in lateral resolution. Proposed PSF has the ability to simultaneously excite multiple 3D-spots of sub-femtoliter volume. Potential applications are in fluorescence microscopy and nanobioimaging.

Application of field dependent polynomial model

NASA Astrophysics Data System (ADS)

Janout, Petr; Páta, Petr; Skala, Petr; Fliegel, Karel; Vítek, Stanislav; Bednář, Jan

2016-09-01

Extremely wide-field imaging systems have many advantages regarding large display scenes whether for use in microscopy, all sky cameras, or in security technologies. The Large viewing angle is paid by the amount of aberrations, which are included with these imaging systems. Modeling wavefront aberrations using the Zernike polynomials is known a longer time and is widely used. Our method does not model system aberrations in a way of modeling wavefront, but directly modeling of aberration Point Spread Function of used imaging system. This is a very complicated task, and with conventional methods, it was difficult to achieve the desired accuracy. Our optimization techniques of searching coefficients space-variant Zernike polynomials can be described as a comprehensive model for ultra-wide-field imaging systems. The advantage of this model is that the model describes the whole space-variant system, unlike the majority models which are partly invariant systems. The issue that this model is the attempt to equalize the size of the modeled Point Spread Function, which is comparable to the pixel size. Issues associated with sampling, pixel size, pixel sensitivity profile must be taken into account in the design. The model was verified in a series of laboratory test patterns, test images of laboratory light sources and consequently on real images obtained by an extremely wide-field imaging system WILLIAM. Results of modeling of this system are listed in this article.

The Effects of Ridge Axis Width on Mantle Melting at Mid-Ocean Ridges

NASA Astrophysics Data System (ADS)

Montesi, L.; Magni, V.; Gaina, C.

2017-12-01

Mantle upwelling in response to plate divergence produces melt at mid-ocean ridges. Melt starts when the solidus is crossed and stops when conductive cooling overcomes heat advection associated with the upwelling. Most mid-ocean ridge models assume that divergence takes place only in a narrow zone that defines the ridge axis, resulting in a single upwelling. However, more complex patterns of divergence are occasionally observed. The rift axis can be 20 km wide at ultraslow spreading center. Overlapping spreading center contain two parallel axes. Rifting in backarc basins is sometimes organized as a series of parallel spreading centers. Distributing plate divergence over several rifts reduces the intensity of upwelling and limits melting. Can this have a significant effect on the expected crustal thickness and on the mode of melt delivery at the seafloor? We address this question by modeling mantle flow and melting underneath two spreading centers separated by a rigid block. We adopt a non-linear rheology that includes dislocation creep, diffusion creep and yielding and include hydrothermal cooling by enhancing thermal conductivity where yielding takes place. The crustal thickness decreases if the rifts are separated by 30 km or more but only if the half spreading rate is between 1 and 2 cm/yr. At melting depth, a single upwelling remains the norm until the separation of the rifts exceeds a critical value ranging from 15 km in the fastest ridges to more than 50 km at ultraslow spreading centers. The stability of the central upwelling is due to hydrothermal cooling, which prevents hot mantle from reaching the surface at each spreading center. When hydrothermal cooling is suppressed, or the spreading centers are sufficiently separated, the rigid block becomes extremely cold and separates two distinct, highly asymmetric upwellings that may focus melt beyond the spreading center. In that case, melt delivery might drive further and further the divergence centers, whereas, when a single upwelling is retained, melt delivery would drive the spreading centers closer together. Thus, the system composed of two rifts is unstable and, if observed in nature, indicates either a transient geodynamic regime, like a recent change in spreading rates, or control structural or stress heterogeneities.

Bridging the gap between data analysis and data collection in FIA and forest monitoring globally: successes, research findings, and lessons learned from the Western US and Southeast Asia

Treesearch

Leif Mortenson

2015-01-01

Globally, national forest inventories (NFI) require a large work force typically consisting of multiple teams spread across multiple locations in order to successfully capture a given nation’s forest resources. This is true of the Forest Inventory and Analysis (FIA) program in the US and in many inventories in developing countries that are supported by USFS...

Qualitative exploration of HIV-related sexual behaviours and multiple partnerships among Chinese men who have sex with men living in a rural area of Yunnan Province, China.

PubMed

Chow, Eric P F; Gao, Liangmin; Koo, Fung Kuen; Chen, Liang; Fu, Xiaoxing; Jing, Jun; Wilson, David P; Zhang, Lei

2013-12-01

The HIV epidemic has been spreading rapidly among men who have sex with men (MSM) in China. The present study explored the pattern of HIV-related high-risk sexual practices among MSM in a rural Chinese setting. Data were collected by semistructured in-depth interviews conducted among 15 MSM in Yuxi Prefecture, Yunnan Province, China. Fifteen respondents were recruited through a local non-governmental organisation via purposive sampling. Thematic analysis was used. Technological changes, risk behaviours, social stigma and high migration rates have played a significant role in the spread of HIV among MSM in rural China. The Internet has become the primary channel for soliciting casual sex partners in the MSM community. Bisexuality and having concurrent and multiple sexual partners were common among rural MSM. A large number of sexual partners and low condom use in all MSM partnership types were noted. Due to Chinese cultural traditions and social stigma, Chinese rural MSM were reluctant to disclose their homosexuality. Rural-to-urban migrant MSM were often engaged in the commercial sex trade. Rural MSM is a distinctive and complex population with multiple identities in China. Concurrent multiple sexual partnerships, high mobility and low disclosure rate are the major challenges for HIV prevention and intervention programs in MSM.

Going beyond the vertical: leveraging a national HIV quality improvement programme to address other health priorities in Haiti.

PubMed

Joseph, Jean Paul; Jerome, Gregory; Lambert, Wesler; Almazor, Patrick; Cupidon, Colette Eugene; Hirschhorn, Lisa R

2015-07-01

Although the central role of quality to achieve targeted population health goals is widely recognized, how to spread the capacity to measure and improve quality across programmes has not been widely studied. We describe the successful leveraging of expertise and framework of a national HIV quality improvement programme to spread capacity and improve quality across a network of clinics in HIV and other targeted areas of healthcare delivery in rural Haiti.The work was led by Zamni LaSante, a Haitian nongovernment organization and its sister organization, Partners In Health working in partnership with the Haitian Ministry of Health in the Plateau Central and Lower Artibonite regions in 12 public sector facilities.Data included routinely collected organizational assessments of facility quality improvement capacity, national HIV performance measures and Zamni LaSante programme records.We found that facility quality improvement capacity increased with spread from HIV to other areas of inpatient and outpatient care, including tuberculosis (TB), maternal health and inpatient services in all 12 supported healthcare facilities. A significant increase in the quality of HIV care was also seen in most areas, including CD4 monitoring, TB screening, HIV treatment (all P < 0.01) and nutritional assessment and prevention of mother-to-child transmission (both P < .05), with an increase in average facility performance from 39 to 72% (P < .01).In conclusion, using a diagonal approach to leverage a national vertical programme for wider benefit resulted in accelerated change in professional culture and increased capacity to spread quality improvement activities across facilities and areas of healthcare delivery. This led to improvement within and beyond HIV care and contributed to the goal of quality of care for all.

Spreading dynamic of viscous volcanic ash in stimulated jet engine conditions

NASA Astrophysics Data System (ADS)

song, wenjia; Lavallée, Yan; Hess, Kai-Uwe; Kueppers, Ulrich; Cimarelli, Corrado

2016-04-01

The ingestion of volcanic ash is widely recognised as a potentially fatal hazard for aircraft operation. The volcanic ash deposition process in a jet turbine is potentially complex. Volcanic ash in the air stream enters the inner liners of the combustors and partially or completely melts under the flames up to 2000 °C, at which point part of the ash deposits in the combustor fuel nozzle. Molten volcanic particles within high energy airflow escape the combustor to enter the turbine and impact the stationary (e.g., inlet nozzle guide vanes) and rotating airfoils (e.g., first stage high-pressure turbine blades) at high speed (up to Mach 1.25) in different directions, with the result that ash may stick, flow and remain liquid or solidify. Thus, the wetting behaviour of molten volcanic ash particle is fundamental to investigate impingement phenomena of ash droplet on the surface of real jet engine operation. The topic of wetting has received tremendous interest from both fundamental and applied points of view. However, due to the interdisciplinary gap between jet engine engineering and geology science, explicit investigation of wetting behaviour of volcanic ash at high temperature is in its infancy. We have taken a big step towards meeting this challenge. Here, we experimentally and theoretically investigate the wetting behaviour of viscous volcanic ash over a wide temperature range from 1100 to 1550 °C using an improved sessile-drop method. The results of our experiment demonstrate that temperature and viscosity play a critical role in determining the wetting possibility and governing the spreading kinetics of volcanic ash at high temperatures. Our systemic analysis of spreading of molten volcanic ash systems allows us to report on the fundamental differences between the mechanisms controlling spreading of organic liquids at room temperature and molten volcanic ash droplets.

The Emergence and Spread of Multiple Livestock-Associated Clonal Complex 398 Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus Strains among Animals and Humans in the Republic of Ireland, 2010–2014

PubMed Central

Brennan, Gráinne I.; Abbott, Yvonne; Burns, Aisling; Leonard, Finola; McManus, Brenda A.; O’Connell, Brian; Coleman, David C.; Shore, Anna C.

2016-01-01

Clonal complex (CC) 398 methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) are associated with carriage and infection among animals and humans but only a single case of CC398 MRSA has been reported in the Republic of Ireland (ROI). The present study investigated the molecular epidemiology of CC398 MRSA (n = 22) and MSSA (n = 10) from animals and humans in the ROI from 2010–2014. Isolates underwent antimicrobial susceptibility testing, spa typing, DNA microarray profiling and PCR for CC398-associated resistance genes. All MRSA underwent SCCmec IV or V subtyping. Four distinct CC398-MRSA incidents were identified from (i) a man in a nursing home (spa type t011-SCCmec IVa, immune evasion complex (IEC) negative), (ii) a horse and veterinarian who had recently travelled to Belgium (t011-IVa, IEC positive), (iii) pigs (n = 9) and farm workers (n = 9) on two farms, one which had been restocked with German gilts and the other which was a finisher farm (t034-VT, IEC negative, 3/9 pigs; t011- VT, IEC negative, 6/9 pigs & 9/9 farm workers), and (iv) a child who had worked on a pig farm in the UK (t034-VT, IEC negative). Isolates also carried different combinations of multiple resistance genes including erm(A), erm(B), tet(K), tet(M) & tet(L), fexA, spc, dfrG, dfrK aacA-aphD and aadD further highlighting the presence of multiple CC398-MRSA strains. CC398 MSSA were recovered from pigs (n = 8) and humans (n = 2). CC398 MSSA transmission was identified among pigs but zoonotic transmission was not detected with animal and human isolates exhibiting clade-specific traits. This study highlights the importation and zoonotic spread of CC398 MRSA in the ROI and the spread of CC398 MSSA among pigs. Increased surveillance is warranted to prevent further CC398 MRSA importation and spread in a country that was considered CC398 MRSA free. PMID:26886749

Competing spreading processes on multiplex networks: awareness and epidemics.

PubMed

Granell, Clara; Gómez, Sergio; Arenas, Alex

2014-07-01

Epidemiclike spreading processes on top of multilayered interconnected complex networks reveal a rich phase diagram of intertwined competition effects. A recent study by the authors [C. Granell et al., Phys. Rev. Lett. 111, 128701 (2013).] presented an analysis of the interrelation between two processes accounting for the spreading of an epidemic, and the spreading of information awareness to prevent infection, on top of multiplex networks. The results in the case in which awareness implies total immunization to the disease revealed the existence of a metacritical point at which the critical onset of the epidemics starts, depending on completion of the awareness process. Here we present a full analysis of these critical properties in the more general scenario where the awareness spreading does not imply total immunization, and where infection does not imply immediate awareness of it. We find the critical relation between the two competing processes for a wide spectrum of parameters representing the interaction between them. We also analyze the consequences of a massive broadcast of awareness (mass media) on the final outcome of the epidemic incidence. Importantly enough, the mass media make the metacritical point disappear. The results reveal that the main finding, i.e., existence of a metacritical point, is rooted in the competition principle and holds for a large set of scenarios.

Drop impact and wettability: From hydrophilic to superhydrophobic surfaces

NASA Astrophysics Data System (ADS)

Antonini, Carlo; Amirfazli, Alidad; Marengo, Marco

2012-10-01

Experiments to understand the effect of surface wettability on impact characteristics of water drops onto solid dry surfaces were conducted. Various surfaces were used to cover a wide range of contact angles (advancing contact angle from 48° to 166°, and contact angle hysteresis from 5° to 56°). Several different impact conditions were analyzed (12 impact velocities on 9 different surfaces, among which 2 were superhydrophobic). Results from impact tests with millimetric drops show that two different regimes can be identified: a moderate Weber number regime (30 < We < 200), in which wettability affects both drop maximum spreading and spreading characteristic time; and a high Weber number regime (We > 200), in which wettability effect is secondary, because capillary forces are overcome by inertial effects. In particular, results show the role of advancing contact angle and contact angle hysteresis as fundamental wetting parameters to allow understanding of different phases of drop spreading and beginning of recoiling. It is also shown that drop spreading on hydrophilic and superhydrophobic surfaces occurs with different time scales. Finally, if the surface is superhydrophobic, eventual impalement, i.e., transition from Cassie to Wenzel wetting state, which might occur in the vicinity of the drop impact area, does not influence drop maximum spreading.

Identifying influential spreaders in complex networks through local effective spreading paths

NASA Astrophysics Data System (ADS)

Wang, Xiaojie; Zhang, Xue; Yi, Dongyun; Zhao, Chengli

2017-05-01

How to effectively identify a set of influential spreaders in complex networks is of great theoretical and practical value, which can help to inhibit the rapid spread of epidemics, promote the sales of products by word-of-mouth advertising, and so on. A naive strategy is to select the top ranked nodes as identified by some centrality indices, and other strategies are mainly based on greedy methods and heuristic methods. However, most of those approaches did not concern the connections between nodes. Usually, the distances between the selected spreaders are very close, leading to a serious overlapping of their influence. As a consequence, the global influence of the spreaders in networks will be greatly reduced, which largely restricts the performance of those methods. In this paper, a simple and efficient method is proposed to identify a set of discrete yet influential spreaders. By analyzing the spreading paths in the network, we present the concept of effective spreading paths and measure the influence of nodes via expectation calculation. The numerical analysis in undirected and directed networks all show that our proposed method outperforms many other centrality-based and heuristic benchmarks, especially in large-scale networks. Besides, experimental results on different spreading models and parameters demonstrates the stability and wide applicability of our method.

Experience with recurrent respiratory papillomatosis in a developing country: impact of tracheostomy.

PubMed

Orji, Foster Tochukwu; Okorafor, Ijeoma A; Akpeh, James O

2013-02-01

The frequent relapses of recurrent respiratory papillomatosis (RRP) sometimes demand repeated surgical excision with tracheostomy. This situation plays a vital role in the management of RRP in developing countries such as ours because of late presentation. This study was conducted to evaluate our experience with RRP and to determine the incidence and impact of tracheostomy in the overall management and outcomes of our patients. The records of 59 patients with histologically confirmed RRP treated between 1994 and 2008 at our tertiary institution were reviewed. We collected data such as age at onset, tracheostomy frequency and duration, number of required surgical excisions, papilloma spread to the lower airways. Patients' characteristics and the course of the disease were compared between a juvenile-onset papillomatosis (JoRRP) group and an adult-onset group (AdRRP). Overall, 68 % of our patients were in the JoRRP group (ages 2-11 years, mean 6 years). The other 32 % were 22-58 years of age (AdRRP group). Two cases of JoRRP continued into adult life. Multiple RRP dominated in the JoRRP group (93 %), whereas solitary papillomas predominated in the AdRRP group (63 %). Tracheostomy was performed because of upper airway obstruction in 42 % of our patients, with children accounting for 72 %. The mean duration of tracheostomy was 3.5 months, with 80 % lasting <4 months. Significantly more JoRRP patients had severe upper airway obstruction, required tracheostomy, and underwent multiple surgical excisions (p = 0.04, 0.02, and 0.009, respectively). Tracheobronchial spread occurred in a patient with prolonged tracheostomy. Multiple laryngeal papillomatosis clearly followed a more severe and less predictable course than the solitary type in both groups. Although there was a high incidence of tracheostomy in this study, short-duration tracheostomies accounted for the low incidence of extralaryngeal spread.

Morphoregulatory functions of the RNA-binding motif protein 3 in cell spreading, polarity and migration.

PubMed

Pilotte, J; Kiosses, W; Chan, S W; Makarenkova, H P; Dupont-Versteegden, E; Vanderklish, P W

2018-05-09

RNA-binding proteins are emerging as key regulators of transitions in cell morphology. The RNA-binding motif protein 3 (RBM3) is a cold-inducible RNA-binding protein with broadly relevant roles in cellular protection, and putative functions in cancer and development. Several findings suggest that RBM3 has morphoregulatory functions germane to its roles in these contexts. For example, RBM3 helps maintain the morphological integrity of cell protrusions during cell stress and disease. Moreover, it is highly expressed in migrating neurons of the developing brain and in cancer invadopodia, suggesting roles in migration. We here show that RBM3 regulates cell polarity, spreading and migration. RBM3 was present in spreading initiation centers, filopodia and blebs that formed during cell spreading in cell lines and primary myoblasts. Reducing RBM3 triggered exaggerated spreading, increased RhoA expression, and a loss of polarity that was rescued by Rho kinase inhibition and overexpression of CRMP2. High RBM3 expression enhanced the motility of cells migrating by a mesenchymal mode involving extension of long protrusions, whereas RBM3 knockdown slowed migration, greatly reducing the ability of cells to extend protrusions and impairing multiple processes that require directional migration. These data establish novel functions of RBM3 of potential significance to tissue repair, metastasis and development.

Quantifying spillover spreading for comparing instrument performance and aiding in multicolor panel design.

PubMed

Nguyen, Richard; Perfetto, Stephen; Mahnke, Yolanda D; Chattopadhyay, Pratip; Roederer, Mario

2013-03-01

After compensation, the measurement errors arising from multiple fluorescences spilling into each detector become evident by the spreading of nominally negative distributions. Depending on the instrument configuration and performance, and reagents used, this "spillover spreading" (SS) affects sensitivity in any given parameter. The degree of SS had been predicted theoretically to increase with measurement error, i.e., by the square root of fluorescence intensity, as well as directly related to the spectral overlap matrix coefficients. We devised a metric to quantify SS between any pair of detectors. This metric is intrinsic, as it is independent of fluorescence intensity. The combination of all such values for one instrument can be represented as a spillover spreading matrix (SSM). Single-stained controls were used to determine the SSM on multiple instruments over time, and under various conditions of signal quality. SSM values reveal fluorescence spectrum interactions that can limit the sensitivity of a reagent in the presence of brightly-stained cells on a different color. The SSM was found to be highly reproducible; its non-trivial values show a CV of less than 30% across a 2-month time frame. In addition, the SSM is comparable between similarly-configured instruments; instrument-specific differences in the SSM reveal underperforming detectors. Quantifying and monitoring the SSM can be a useful tool in instrument quality control to ensure consistent sensitivity and performance. In addition, the SSM is a key element for predicting the performance of multicolor immunofluorescence panels, which will aid in the optimization and development of new panels. We propose that the SSM is a critical component of QA/QC in evaluation of flow cytometer performance. Published 2013 Wiley Periodicals, Inc.

Crustal structure across the post-spreading magmatic ridge of the East Sub-basin in the South China Sea: Tectonic significance

NASA Astrophysics Data System (ADS)

He, Enyuan; Zhao, Minghui; Qiu, Xuelin; Sibuet, Jean-Claude; Wang, Jian; Zhang, Jiazheng

2016-05-01

The 140-km wide last phase of opening of the South China Sea (SCS) corresponds to a N145° direction of spreading with rift features identified on swath bathymetric data trending N055° (Sibuet et al., 2016). These N055° seafloor spreading features of the East Sub-basin are cut across by a post-spreading volcanic ridge oriented approximately E-W in its western part (Zhenbei-Huangyan seamounts chain). The knowledge of the deep crustal structure beneath this volcanic ridge is essential to elucidate not only the formation and tectonic evolution of the SCS, but also the mechanism of emplacement of the post-spreading magmatism. We use air-gun shots recorded by ocean bottom seismometers to image the deep crustal structure along the N-S oriented G8G0 seismic profile, which is perpendicular to the Zhenbei-Huangyan seamounts chain but located in between the Zhenbei and Huangyan seamounts, where topographic changes are minimum. The velocity structure presents obvious lateral variations. The crust north and south of the Zhenbei-Huangyan seamounts chain is ca. 4-6 km in thickness and velocities are largely comparable with those of normal oceanic crust of Atlantic type. To the south, the Jixiang seamount with a 7.2-km thick crust, seems to be a tiny post-spreading volcanic seamount intruded along the former extinct spreading ridge axis. In the central part, a 1.5-km thick low velocity zone (3.3-3.7 km/s) in the uppermost crust is explained by the presence of extrusive rocks intercalated with thin sedimentary layers as those drilled at IODP Site U1431. Both the Jixiang seamount and the Zhenbei-Huangyan seamounts chain started to form by the intrusion of decompressive melt resulting from the N-S post-spreading phase of extension and intruded through the already formed oceanic crust. The Jixiang seamount probably formed before the emplacement of the E-W post-spreading seamounts chain.

Asian Lineage of Peste des Petits Ruminants Virus, Africa

PubMed Central

Kwiatek, Olivier; Ali, Yahia Hassan; Saeed, Intisar Kamil; Khalafalla, Abdelmelik Ibrahim; Mohamed, Osama Ishag; Abu Obeida, Ali; Abdelrahman, Magdi Badawi; Osman, Halima Mohamed; Taha, Khalid Mohamed; Abbas, Zakia; El Harrak, Mehdi; Lhor, Youssef; Diallo, Adama; Lancelot, Renaud; Albina, Emmanuel

2011-01-01

Interest in peste des petits ruminants virus (PPRV) has been stimulated by recent changes in its host and geographic distribution. For this study, biological specimens were collected from camels, sheep, and goats clinically suspected of having PPRV infection in Sudan during 2000–2009 and from sheep soon after the first reported outbreaks in Morocco in 2008. Reverse transcription PCR analysis confirmed the wide distribution of PPRV throughout Sudan and spread of the virus in Morocco. Molecular typing of 32 samples positive for PPRV provided strong evidence of the introduction and broad spread of Asian lineage IV. This lineage was defined further by 2 subclusters; one consisted of camel and goat isolates and some of the sheep isolates, while the other contained only sheep isolates, a finding with suggests a genetic bias according to the host. This study provides evidence of the recent spread of PPRV lineage IV in Africa. PMID:21762576

The impact of heterogeneous response on coupled spreading dynamics in multiplex networks

NASA Astrophysics Data System (ADS)

Nie, Xiaoyu; Tang, Ming; Zou, Yong; Guan, Shuguang; Zhou, Jie

2017-10-01

Many recent studies have demonstrated that individual awareness of disease may significantly affect the spreading process of infectious disease. In the majority of these studies, the response of the awareness is generally treated homogeneously. Considering of diversity and heterogeneity in the human behavior which widely exist under different circumstances, in this paper we study heterogeneous response when people are aware of the prevalence of infectious diseases. Specifically, we consider that an individual with more neighbors may take more preventive measures as a reaction when he is aware of the disease. A suppression strength is introduced to describe such heterogeneity, and we find that a more evident heterogeneity may cause a more effective suppressing effect to the spreading of epidemics. A mean-field theory is developed to support the results which are verified on the multiplex networks with different interlayer degree correlation.

Collapse displacements for a mechanism of spreading-induced supports in a masonry arch

NASA Astrophysics Data System (ADS)

Coccia, Simona; Di Carlo, Fabio; Rinaldi, Zila

2015-09-01

Masonry arch systems and vaulted structures constitute a structural typology widely spread in the historical building heritage. Small displacements of the supports, due to different causes, among which subsidence of foundation systems or movements of underlying structures can lead the masonry arch to a condition of collapse because of gradual change in its geometry. This paper presents a tool, based on a kinematic approach, for the computation of the magnitude of the displacements that cause the collapse of circular arches subject to dead loads, and allows the evaluation of the related thrust value. A parametric study has been carried out in order to develop a deeper understanding of the influence of the involved parameters. In addition, analytic formulations of the maximum allowed displacement and the associated thrust are proposed. Finally, a case study related to the behavior of a masonry arch on spreading-induced abutments is undertaken and discussed.

Absence of influential spreaders in rumor dynamics

NASA Astrophysics Data System (ADS)

Borge-Holthoefer, Javier; Moreno, Yamir

2012-02-01

Recent research [Kitsak, Gallos, Havlin, Liljeros, Muchnik, Stanley, and Makse, Nature Physics1745-247310.1038/nphys1746 6, 888 (2010)] has suggested that coreness, and not degree, constitutes a better topological descriptor to identify influential spreaders in complex networks. This hypothesis has been verified in the context of disease spreading. Here, we instead focus on rumor spreading models, which are more suited for social contagion and information propagation. To this end, we perform extensive computer simulations on top of several real-world networks and find opposite results. Namely, we show that the spreading capabilities of the nodes do not depend on their k-core index, which instead determines whether or not a given node prevents the diffusion of a rumor to a system-wide scale. Our findings are relevant both for sociological studies of contagious dynamics and for the design of efficient commercial viral processes.

Nano-focusing effect simulation of metal film with subwavelength pattern structures

NASA Astrophysics Data System (ADS)

Wei, Dong; Yu, Yue; Li, Dapeng; Wu, Yong; Xin, Zhaowei; Xie, Xingwang; Zhang, Xinyu; Wang, Haiwei; Xie, Changsheng

2018-02-01

Surface plasmon polarizations (SPP) is a nano-scale photon control technology which can converge the spread of oscillation electron driven by incident light. In recent years, SPP has become an advanced research hotspot and has been studied more and more widely. The convergence effect of SPP has extensive applications, such as Schottky barrier detector in which the higher power hotspot, the lower signal-to-noise ratio. In this paper, studies have been done about the interaction of light and matter. Different geometric shapes have been simulated, which were obtained by graphic clipping. Via comparing the power of the hot spot and the minimum location on the transmittance line, we concluded the relationship of the interaction and the structure. It's found that every absorption peak corresponds a mode of LSPP spread. Therefore, we can design figure to control the spread of the SPP, and achieve fantastic goal. Finally, a typical figure with high power hotspot was given.

Tracing information flow on a global scale using Internet chain-letter data

PubMed Central

Liben-Nowell, David; Kleinberg, Jon

2008-01-01

Although information, news, and opinions continuously circulate in the worldwide social network, the actual mechanics of how any single piece of information spreads on a global scale have been a mystery. Here, we trace such information-spreading processes at a person-by-person level using methods to reconstruct the propagation of massively circulated Internet chain letters. We find that rather than fanning out widely, reaching many people in very few steps according to “small-world” principles, the progress of these chain letters proceeds in a narrow but very deep tree-like pattern, continuing for several hundred steps. This suggests a new and more complex picture for the spread of information through a social network. We describe a probabilistic model based on network clustering and asynchronous response times that produces trees with this characteristic structure on social-network data. PMID:18353985

Wheat rusts in the United States in 2015

USDA-ARS?s Scientific Manuscript database

In 2015 wheat stripe rust caused by Puccinia striiformis f. sp. graminis was widespread throughout the United States. Cool temperatures and abundant rainfall in the southern Great Plains allowed stripe rust to become widely established and spread throughout the Great Plains and eastern United States...

Blog Impossible

ERIC Educational Resources Information Center

Cole, Meryl B.; Gray, Christian L.; Romaine, Cindy A.

2012-01-01

Amid the sea change that libraries and information centers currently face, people are starting to see compelling solutions and bold initiatives from their colleagues. The challenge now becomes how to "spread the gospel"--how to inform widely dispersed information professionals about the successes they record. In 2011, volunteers within the Special…

Effects of Environmentally Relevant Concentrations of Bisphenol A on the Fathead Minnow

EPA Science Inventory

Bisphenol A (BPA) is a wide-spread environmental contaminant of concern due, in part, to possible effects on the vertebrate hypothalamic-pituitary-gonadal (HPG) axis, including activation of the estrogen receptor (ER). There is a reasonable amount of toxicological information fo...

Does livestock grazing influence spatial patterns of woody plant proliferation?

USDA-ARS?s Scientific Manuscript database

Patterns of woody plant proliferation in grasslands and savannas influence rates of erosion, spread of disturbance, and nutrient pools.  Spatial pattern is the outcome of plant dispersal, recruitment, competition/facilitation, and disturbance. We quantified effects of livestock grazing, a widely cit...

Wide Area UXO Screening with the Multi-Sensor Fixed-Wing Airborne System MARS

DTIC Science & Technology

2008-02-01

snakes, lizards, and spiders may contain sufficient poison to warrant medical attention. In addition, ticks can spread Rocky Mountain spotted fever ...is extremely serious • Systemic hypothermia manifests itself in five stages of symptoms, including: (1) shivering ; (2) apathy, listlessness

Flipped Classroom Approach

ERIC Educational Resources Information Center

Ozdamli, Fezile; Asiksoy, Gulsum

2016-01-01

Flipped classroom is an active, student-centered approach that was formed to increase the quality of period within class. Generally this approach whose applications are done mostly in Physical Sciences, also attracts the attention of educators and researchers in different disciplines recently. Flipped classroom learning which wide-spreads rapidly…

Development Policies and Performance--World Issues and World Conferences.

ERIC Educational Resources Information Center

Gitta, Cosmas, Ed.

2000-01-01

In the business of development, breakthroughs require international communication to help spread potential benefits widely. Obstacles demand international commitment to marshal vision, resources, and effort sufficient to the challenge. This issue of "Cooperation South" contains a two part focus, conveying innovations in development…

Wheat rusts in the United States in 2016

USDA-ARS?s Scientific Manuscript database

In 2016, wheat stripe rust caused by Puccinia striiformis f. sp. graminis was widespread throughout the United States. Cool temperatures and abundant rainfall in the southern Great Plains allowed stripe rust to become widely established and spread throughout the Great Plains and eastern United State...

Analysis of zolpidem in postmortem fluids and tissues using ultra-performance liquid chromatography-mass spectrometry.

DOT National Transportation Integrated Search

2014-02-01

Zolpidem is a nonbenzodiazepine sedative hypnotic drug used for the short-term treatment of insomnia. Its : use is common and wide-spread. While quite effective in producing sedation, zolpidem has potentially : hazardous side effects when put in the ...

Varroa destructor Mites Can Nimbly Climb from Flowers onto Foraging Honey Bees

PubMed Central

Smith, Michael L.; Seeley, Thomas D.

2016-01-01

Varroa destructor, the introduced parasite of European honey bees associated with massive colony deaths, spreads readily through populations of honey bee colonies, both managed colonies living crowded together in apiaries and wild colonies living widely dispersed in natural settings. Mites are hypothesized to spread between most managed colonies via phoretically riding forager bees when they engage in robbing colonies or they drift between hives. However, widely spaced wild colonies show Varroa infestation despite limited opportunities for robbing and little or no drifting of bees between colonies. Both wild and managed colonies may also exchange mites via another mechanism that has received remarkably little attention or study: floral transmission. The present study tested the ability of mites to infest foragers at feeders or flowers. We show that Varroa destructor mites are highly capable of phoretically infesting foraging honey bees, detail the mechanisms and maneuvers by which they do so, and describe mite behaviors post-infestation. PMID:27942015

The applications of mobile telecommunications in new rural areas

NASA Astrophysics Data System (ADS)

Chen, Xia; Lu, Ting-jie

2009-07-01

With the current popularity of information and telecommunication technologies, more and more farmers recognize the important role of information. The urgent need for Chinese farmers is how to make use of information to get rich. Contrast in the newspapers, television, radio and other traditional media, mobile information services have unmatched advantages, such as wide spread in very low cost, spread source of widely dispersed, and diverse forms of communication, simple and easy to operate, with strong participatory and interactive, and so on. The paper proposes that Mobile operators can supply different information in accordance with personalized demands of farmers with various agencies, such as government departments, supply and marketing cooperatives, hospitals, banks, veterinary clinics, agricultural stations. They can unite to supply a number of convenience people, rich people, and love for the people's business through the message, voice, WAP and other forms to meet the needs of farmers. Besides, the paper points out that those farmers can order information on personalized service.

Mobile Life - Innovation in the Wild

NASA Astrophysics Data System (ADS)

Höök, Kristina

After a decade of work in our research labs on mobile and ubiquitous technology, often formed by the early visions of ubiquitous computing, with the urge to move interaction from the desktop out into the wild, these technologies have now moved out into the world - into the wild. We are in the middle of a second IT-revolution, caused by the spread of mobile and ubiquitous services, in combination with a broad consumer-oriented market pull. The first ITrevolution, the introduction and deployment of Internet and the World Wide Web during the 1990’s, had a major impact on all parts of our society. As mobile, ubiquitous technology now becomes wide-spread, the design and evaluation of mobile services - i.e. information technology that can be accessed and used in virtually any setting - represents an important business arena for the IT- and telecom industry. Together we have to look for a sustainable web of work, leisure and ubiquitous technology we can call the mobile life.

The Simple Rules of Social Contagion

PubMed Central

Hodas, Nathan O.; Lerman, Kristina

2014-01-01

It is commonly believed that information spreads between individuals like a pathogen, with each exposure by an informed friend potentially resulting in a naive individual becoming infected. However, empirical studies of social media suggest that individual response to repeated exposure to information is far more complex. As a proxy for intervention experiments, we compare user responses to multiple exposures on two different social media sites, Twitter and Digg. We show that the position of exposing messages on the user-interface strongly affects social contagion. Accounting for this visibility significantly simplifies the dynamics of social contagion. The likelihood an individual will spread information increases monotonically with exposure, while explicit feedback about how many friends have previously spread it increases the likelihood of a response. We provide a framework for unifying information visibility, divided attention, and explicit social feedback to predict the temporal dynamics of user behavior. PMID:24614301

Role for migratory wild birds in the global spread of avian influenza H5N8.

PubMed

2016-10-14

Avian influenza viruses affect both poultry production and public health. A subtype H5N8 (clade 2.3.4.4) virus, following an outbreak in poultry in South Korea in January 2014, rapidly spread worldwide in 2014-2015. Our analysis of H5N8 viral sequences, epidemiological investigations, waterfowl migration, and poultry trade showed that long-distance migratory birds can play a major role in the global spread of avian influenza viruses. Further, we found that the hemagglutinin of clade 2.3.4.4 virus was remarkably promiscuous, creating reassortants with multiple neuraminidase subtypes. Improving our understanding of the circumpolar circulation of avian influenza viruses in migratory waterfowl will help to provide early warning of threats from avian influenza to poultry, and potentially human, health. Copyright © 2016, American Association for the Advancement of Science.

Animal migration and risk of spread of viral infections: Chapter 9

USGS Publications Warehouse

Prosser, Diann J.; Nagel, Jessica; Takekawa, John Y.; Edited by Singh, Sunit K.

2013-01-01

The potential contribution of migration towards the spread of disease is as varied as the ecology of the pathogens themselves and their host populations. This chapter outlines multiple examples of viral diseases in animal populations and their mechanisms of viral spread. Many species of insects, mammals, fish, and birds exhibit migratory behavior and have the potential to disperse diseases over long distances. The majority of studies available on viral zoonoses have focused on birds and bats, due to their highly migratory life histories. A number of studies have reported evidence of changes in the timing of animal migrations in response to climate change. The majority indicate an advancement of spring migration, with few or inconclusive results for fall migration. Predicting the combined effects of climate change on migratory patterns of host species and epidemiology of viral pathogens is complex and not fully realistic.

Long-range epidemic spreading in a random environment.

PubMed

Juhász, Róbert; Kovács, István A; Iglói, Ferenc

2015-03-01

Modeling long-range epidemic spreading in a random environment, we consider a quenched, disordered, d-dimensional contact process with infection rates decaying with distance as 1/rd+σ. We study the dynamical behavior of the model at and below the epidemic threshold by a variant of the strong-disorder renormalization-group method and by Monte Carlo simulations in one and two spatial dimensions. Starting from a single infected site, the average survival probability is found to decay as P(t)∼t-d/z up to multiplicative logarithmic corrections. Below the epidemic threshold, a Griffiths phase emerges, where the dynamical exponent z varies continuously with the control parameter and tends to zc=d+σ as the threshold is approached. At the threshold, the spatial extension of the infected cluster (in surviving trials) is found to grow as R(t)∼t1/zc with a multiplicative logarithmic correction and the average number of infected sites in surviving trials is found to increase as Ns(t)∼(lnt)χ with χ=2 in one dimension.

Theoretical analysis of the performance of code division multiple access communications over multimode optical fiber channels. Part 1: Transmission and detection

NASA Astrophysics Data System (ADS)

Walker, Ernest L.

1994-05-01

This paper presents results of a theoretical investigation to evaluate the performance of code division multiple access communications over multimode optical fiber channels in an asynchronous, multiuser communication network environment. The system is evaluated using Gold sequences for spectral spreading of the baseband signal from each user employing direct-sequence biphase shift keying and intensity modulation techniques. The transmission channel model employed is a lossless linear system approximation of the field transfer function for the alpha -profile multimode optical fiber. Due to channel model complexity, a correlation receiver model employing a suboptimal receive filter was used in calculating the peak output signal at the ith receiver. In Part 1, the performance measures for the system, i.e., signal-to-noise ratio and bit error probability for the ith receiver, are derived as functions of channel characteristics, spectral spreading, number of active users, and the bit energy to noise (white) spectral density ratio. In Part 2, the overall system performance is evaluated.

How multiple social networks affect user awareness: The information diffusion process in multiplex networks

NASA Astrophysics Data System (ADS)

Li, Weihua; Tang, Shaoting; Fang, Wenyi; Guo, Quantong; Zhang, Xiao; Zheng, Zhiming

2015-10-01

The information diffusion process in single complex networks has been extensively studied, especially for modeling the spreading activities in online social networks. However, individuals usually use multiple social networks at the same time, and can share the information they have learned from one social network to another. This phenomenon gives rise to a new diffusion process on multiplex networks with more than one network layer. In this paper we account for this multiplex network spreading by proposing a model of information diffusion in two-layer multiplex networks. We develop a theoretical framework using bond percolation and cascading failure to describe the intralayer and interlayer diffusion. This allows us to obtain analytical solutions for the fraction of informed individuals as a function of transmissibility T and the interlayer transmission rate θ . Simulation results show that interaction between layers can greatly enhance the information diffusion process. And explosive diffusion can occur even if the transmissibility of the focal layer is under the critical threshold, due to interlayer transmission.

Genomic Epidemiology Reconstructs the Introduction and Spread of Zika Virus in Central America and Mexico.

PubMed

Thézé, Julien; Li, Tony; du Plessis, Louis; Bouquet, Jerome; Kraemer, Moritz U G; Somasekar, Sneha; Yu, Guixia; de Cesare, Mariateresa; Balmaseda, Angel; Kuan, Guillermina; Harris, Eva; Wu, Chieh-Hsi; Ansari, M Azim; Bowden, Rory; Faria, Nuno R; Yagi, Shigeo; Messenger, Sharon; Brooks, Trevor; Stone, Mars; Bloch, Evan M; Busch, Michael; Muñoz-Medina, José E; González-Bonilla, Cesar R; Wolinsky, Steven; López, Susana; Arias, Carlos F; Bonsall, David; Chiu, Charles Y; Pybus, Oliver G

2018-06-13

The Zika virus (ZIKV) epidemic in the Americas established ZIKV as a major public health threat and uncovered its association with severe diseases, including microcephaly. However, genetic epidemiology in some at-risk regions, particularly Central America and Mexico, remains limited. We report 61 ZIKV genomes from this region, generated using metagenomic sequencing with ZIKV-specific enrichment, and combine phylogenetic, epidemiological, and environmental data to reconstruct ZIKV transmission. These analyses revealed multiple independent ZIKV introductions to Central America and Mexico. One introduction, likely from Brazil via Honduras, led to most infections and the undetected spread of ZIKV through the region from late 2014. Multiple lines of evidence indicate biannual peaks of ZIKV transmission in the region, likely driven by varying local environmental conditions for mosquito vectors and herd immunity. The spatial and temporal heterogeneity of ZIKV transmission in Central America and Mexico challenges arbovirus surveillance and disease control measures. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Design and optimization of an energy degrader with a multi-wedge scheme based on Geant4

NASA Astrophysics Data System (ADS)

Liang, Zhikai; Liu, Kaifeng; Qin, Bin; Chen, Wei; Liu, Xu; Li, Dong; Xiong, Yongqian

2018-05-01

A proton therapy facility based on an isochronous superconducting cyclotron is under construction in Huazhong University of Science and Technology (HUST). To meet the clinical requirements, an energy degrader is essential in the beamline to modulate the fixed beam energy extracted from the cyclotron. Because of the multiple Coulomb scattering in the degrader, the beam emittance and the energy spread will be considerably increased during the energy degradation process. Therefore, a set of collimators is designed to restrict the increase in beam emittance after the energy degradation. The energy spread will be reduced in the following beam line which is not discussed in this paper. In this paper, the design considerations of an energy degrader and collimators are introduced, and the properties of the degrader material, degrader structure and the initial beam parameters are discussed using the Geant4 Monte-Carlo toolkit, with the main purpose of improving the overall performance of the degrader by multiple parameter optimization.

Genome-wide evidence for local DNA methylation spreading from small RNA-targeted sequences in Arabidopsis.

PubMed

Ahmed, Ikhlak; Sarazin, Alexis; Bowler, Chris; Colot, Vincent; Quesneville, Hadi

2011-09-01

Transposable elements (TEs) and their relics play major roles in genome evolution. However, mobilization of TEs is usually deleterious and strongly repressed. In plants and mammals, this repression is typically associated with DNA methylation, but the relationship between this epigenetic mark and TE sequences has not been investigated systematically. Here, we present an improved annotation of TE sequences and use it to analyze genome-wide DNA methylation maps obtained at single-nucleotide resolution in Arabidopsis. We show that although the majority of TE sequences are methylated, ∼26% are not. Moreover, a significant fraction of TE sequences densely methylated at CG, CHG and CHH sites (where H = A, T or C) have no or few matching small interfering RNA (siRNAs) and are therefore unlikely to be targeted by the RNA-directed DNA methylation (RdDM) machinery. We provide evidence that these TE sequences acquire DNA methylation through spreading from adjacent siRNA-targeted regions. Further, we show that although both methylated and unmethylated TE sequences located in euchromatin tend to be more abundant closer to genes, this trend is least pronounced for methylated, siRNA-targeted TE sequences located 5' to genes. Based on these and other findings, we propose that spreading of DNA methylation through promoter regions explains at least in part the negative impact of siRNA-targeted TE sequences on neighboring gene expression.

Using Nanomaterials to Solve Environmental Problems: Advancing the Science and Engineering of Photocatalysis

NASA Astrophysics Data System (ADS)

Brame, Jonathon Andrew

Photocatalysis is a process by which materials can transfer light energy into chemical energy in the form of reactive oxygen species (ROS), which can then oxidize chemical and biological contaminants in water. Whereas photocatalysis offers the potential to treat many recalcitrant priority pollutants in a cost-effective manner, it has yet to become a viable, wide-spread treatment option due to implementation barriers that include limitations in treatment efficiency and relatively high costs of some photocatalytic material. This thesis seeks to increase the applicability and understanding of nanomaterial-enhanced photocatalytic oxidation processes to help overcome these barriers. Increased photocatalytic efficiency can be accomplished through informed choice of ROS-producing materials. For example, hydroxyl radicals are shown to be much more susceptible to hindrance by natural organic matter (NOM), phosphate and wastewater treatment plant effluent than 1O 2, which is only slightly inhibited by NOM and not by phosphate or wastewater effluent. Additionally, a novel crystallization mechanism for photocatalytic TiO2 nanotubes enabled photo-production of multiple ROS types. This "cocktail" of reactive oxygen species contributed to increased efficiency. Novel applications for nanotechnology-enhanced photocatalysis were demonstrated at the lab scale. These include (1) photocatalytic pre-treatment of weathered oil from the 2010 Gulf oil spill, which increased soluble organic carbon content (indicative of increased bioavailability) by 60% and enhanced subsequent biodegradation by 37%; and (2) a water disinfection case study in rural Swaziland, which produced a prototype fluidized bed photoreactor capable of removing 99.9% of bacteria and viruses in <60 seconds. These projects show both a variety of applications for photocatalysis, and ways to increase its efficiency and effectiveness. To achieve wide-spread implementation, however, the price of photocatalysis must be reduced. Extensive reuse of treatment materials (>60 cycles), and utilization of less-purified starting materials (>90% cost reduction) highlight possible ways to reduce the cost of nanomaterial photocatalysis. By reducing financial implementation barriers, defining niches where photocatalysis can be superiorly effective, engineering reactor systems that enable real-world testing of this technology, and increasing understanding of photocatalytic inhibition mechanisms, photocatalysis can become a tool to help solve global water challenges.

Actin-Related Protein 2 (ARP2) and Virus-Induced Filopodia Facilitate Human Respiratory Syncytial Virus Spread

PubMed Central

McCarty, Thomas; Martin, Scott E.; Le Nouën, Cyril; Buehler, Eugen; Chen, Yu-Chi; Smelkinson, Margery; Ganesan, Sundar; Fischer, Elizabeth R.; Brock, Linda G.; Liang, Bo; Munir, Shirin; Collins, Peter L.; Buchholz, Ursula J.

2016-01-01

Human respiratory syncytial virus (RSV) is an enveloped RNA virus that is the most important viral cause of acute pediatric lower respiratory tract illness worldwide, and lacks a vaccine or effective antiviral drug. The involvement of host factors in the RSV replicative cycle remains poorly characterized. A genome-wide siRNA screen in human lung epithelial A549 cells identified actin-related protein 2 (ARP2) as a host factor involved in RSV infection. ARP2 knockdown did not reduce RSV entry, and did not markedly reduce gene expression during the first 24 hr of infection, but decreased viral gene expression thereafter, an effect that appeared to be due to inhibition of viral spread to neighboring cells. Consistent with reduced spread, there was a 10-fold reduction in the release of infectious progeny virions in ARP2-depleted cells at 72 hr post-infection. In addition, we found that RSV infection induced filopodia formation and increased cell motility in A549 cells and that this phenotype was ARP2 dependent. Filopodia appeared to shuttle RSV to nearby uninfected cells, facilitating virus spread. Expression of the RSV F protein alone from a plasmid or heterologous viral vector in A549 cells induced filopodia, indicating a new role for the RSV F protein, driving filopodia induction and virus spread. Thus, this study identified roles for ARP2 and filopodia in RSV-induced cell motility, RSV production, and RSV cell-to-cell spread. PMID:27926942

Climate model diversity in the Northern Hemisphere Polar vortex response to climate change.

NASA Astrophysics Data System (ADS)

Simpson, I.; Seager, R.; Hitchcock, P.; Cohen, N.

2017-12-01

Global climate models vary widely in their predictions of the future of the Northern Hemisphere stratospheric polar vortex, with some showing a significant strengthening of the vortex, some showing a significant weakening and others displaying a response that is not outside of the range expected from internal variability alone. This inter-model spread in stratospheric predictions may account for some inter-model spread in tropospheric predictions with important implications for the storm tracks and regional climate change, particularly for the North Atlantic sector. Here, our current state of understanding of this model spread and its tropospheric impacts will be reviewed. Previous studies have proposed relationships between a models polar vortex response to climate change and its present day vortex climatology while others have demonstrated links between a models polar vortex response and changing wave activity coming up from the troposphere below under a warming climate. The extent to which these mechanisms can account for the spread in polar vortex changes exhibited by the Coupled Model Intercomparison Project, phase 5 models will be assessed. In addition, preliminary results from a series of idealized experiments with the Community Atmosphere Model will be presented. In these experiments, nudging of the stratospheric zonal mean state has been imposed to mimic the inter-model spread in the polar vortex response to climate change so that the downward influence of the spread in zonal mean stratospheric responses on the tropospheric circulation can be assessed within one model.

The Role of Cell Volume in the Dynamics of Seizure, Spreading Depression, and Anoxic Depolarization

PubMed Central

Ullah, Ghanim; Wei, Yina; Dahlem, Markus A; Wechselberger, Martin; Schiff, Steven J

2015-01-01

Cell volume changes are ubiquitous in normal and pathological activity of the brain. Nevertheless, we know little of how cell volume affects neuronal dynamics. We here performed the first detailed study of the effects of cell volume on neuronal dynamics. By incorporating cell swelling together with dynamic ion concentrations and oxygen supply into Hodgkin-Huxley type spiking dynamics, we demonstrate the spontaneous transition between epileptic seizure and spreading depression states as the cell swells and contracts in response to changes in osmotic pressure. Our use of volume as an order parameter further revealed a dynamical definition for the experimentally described physiological ceiling that separates seizure from spreading depression, as well as predicted a second ceiling that demarcates spreading depression from anoxic depolarization. Our model highlights the neuroprotective role of glial K buffering against seizures and spreading depression, and provides novel insights into anoxic depolarization and the relevant cell swelling during ischemia. We argue that the dynamics of seizures, spreading depression, and anoxic depolarization lie along a continuum of the repertoire of the neuron membrane that can be understood only when the dynamic ion concentrations, oxygen homeostasis,and cell swelling in response to osmotic pressure are taken into consideration. Our results demonstrate the feasibility of a unified framework for a wide range of neuronal behaviors that may be of substantial importance in the understanding of and potentially developing universal intervention strategies for these pathological states. PMID:26273829

Bluetongue virus spread in Europe is a consequence of climatic, landscape and vertebrate host factors as revealed by phylogeographic inference

PubMed Central

Palmarini, Massimo; Mertens, Peter

2017-01-01

Spatio-temporal patterns of the spread of infectious diseases are commonly driven by environmental and ecological factors. This is particularly true for vector-borne diseases because vector populations can be strongly affected by host distribution as well as by climatic and landscape variables. Here, we aim to identify environmental drivers for bluetongue virus (BTV), the causative agent of a major vector-borne disease of ruminants that has emerged multiple times in Europe in recent decades. In order to determine the importance of climatic, landscape and host-related factors affecting BTV diffusion across Europe, we fitted different phylogeographic models to a dataset of 113 time-stamped and geo-referenced BTV genomes, representing multiple strains and serotypes. Diffusion models using continuous space revealed that terrestrial habitat below 300 m altitude, wind direction and higher livestock densities were associated with faster BTV movement. Results of discrete phylogeographic analysis involving generalized linear models broadly supported these findings, but varied considerably with the level of spatial partitioning. Contrary to common perception, we found no evidence for average temperature having a positive effect on BTV diffusion, though both methodological and biological reasons could be responsible for this result. Our study provides important insights into the drivers of BTV transmission at the landscape scale that could inform predictive models of viral spread and have implications for designing control strategies. PMID:29021180

Multiple UAV Cooperation for Wildfire Monitoring

NASA Astrophysics Data System (ADS)

Lin, Zhongjie

Wildfires have been a major factor in the development and management of the world's forest. An accurate assessment of wildfire status is imperative for fire management. This thesis is dedicated to the topic of utilizing multiple unmanned aerial vehicles (UAVs) to cooperatively monitor a large-scale wildfire. This is achieved through wildfire spreading situation estimation based on on-line measurements and wise cooperation strategy to ensure efficiency. First, based on the understanding of the physical characteristics of the wildfire propagation behavior, a wildfire model and a Kalman filter-based method are proposed to estimate the wildfire rate of spread and the fire front contour profile. With the enormous on-line measurements from on-board sensors of UAVs, the proposed method allows a wildfire monitoring mission to benefit from on-line information updating, increased flexibility, and accurate estimation. An independent wildfire simulator is utilized to verify the effectiveness of the proposed method. Second, based on the filter analysis, wildfire spreading situation and vehicle dynamics, the influence of different cooperation strategies of UAVs to the overall mission performance is studied. The multi-UAV cooperation problem is formulated in a distributed network. A consensus-based method is proposed to help address the problem. The optimal cooperation strategy of UAVs is obtained through mathematical analysis. The derived optimal cooperation strategy is then verified in an independent fire simulation environment to verify its effectiveness.

Is Global Warming likely to cause an increased incidence of Malaria?

PubMed

Nabi, Sa; Qader, Ss

2009-03-01

The rise in the average temperature of earth has been described as global warming which is mainly attributed to the increasing phenomenon of the greenhouse effect. It is believed that global warming can have several harmful effects on human health, both directly and indirectly. Since malaria is greatly influenced by climatic conditions because of its direct relationship with the mosquito population, it is widely assumed that its incidence is likely to increase in a future warmer world.This review article discusses the two contradictory views regarding the association of global warming with an increased incidence of malaria. On one hand, there are many who believe that there is a strong association between the recent increase in malaria incidence and global warming. They predict that as global warming continues, malaria is set to spread in locations where previously it was limited, due to cooler climate. On the other hand, several theories have been put forward which are quite contrary to this prediction. There are multiple other factors which are accountable for the recent upsurge of malaria: for example drug resistance, mosquito control programs, public health facilities, and living standards.

Ensemble of One-Class Classifiers for Personal Risk Detection Based on Wearable Sensor Data.

PubMed

Rodríguez, Jorge; Barrera-Animas, Ari Y; Trejo, Luis A; Medina-Pérez, Miguel Angel; Monroy, Raúl

2016-09-29

This study introduces the One-Class K-means with Randomly-projected features Algorithm (OCKRA). OCKRA is an ensemble of one-class classifiers built over multiple projections of a dataset according to random feature subsets. Algorithms found in the literature spread over a wide range of applications where ensembles of one-class classifiers have been satisfactorily applied; however, none is oriented to the area under our study: personal risk detection. OCKRA has been designed with the aim of improving the detection performance in the problem posed by the Personal RIsk DEtection(PRIDE) dataset. PRIDE was built based on 23 test subjects, where the data for each user were captured using a set of sensors embedded in a wearable band. The performance of OCKRA was compared against support vector machine and three versions of the Parzen window classifier. On average, experimental results show that OCKRA outperformed the other classifiers for at least 0.53% of the area under the curve (AUC). In addition, OCKRA achieved an AUC above 90% for more than 57% of the users.

Ensemble of One-Class Classifiers for Personal Risk Detection Based on Wearable Sensor Data

PubMed Central

Rodríguez, Jorge; Barrera-Animas, Ari Y.; Trejo, Luis A.; Medina-Pérez, Miguel Angel; Monroy, Raúl

2016-01-01

This study introduces the One-Class K-means with Randomly-projected features Algorithm (OCKRA). OCKRA is an ensemble of one-class classifiers built over multiple projections of a dataset according to random feature subsets. Algorithms found in the literature spread over a wide range of applications where ensembles of one-class classifiers have been satisfactorily applied; however, none is oriented to the area under our study: personal risk detection. OCKRA has been designed with the aim of improving the detection performance in the problem posed by the Personal RIsk DEtection(PRIDE) dataset. PRIDE was built based on 23 test subjects, where the data for each user were captured using a set of sensors embedded in a wearable band. The performance of OCKRA was compared against support vector machine and three versions of the Parzen window classifier. On average, experimental results show that OCKRA outperformed the other classifiers for at least 0.53% of the area under the curve (AUC). In addition, OCKRA achieved an AUC above 90% for more than 57% of the users. PMID:27690054

Procedure to Measure Effect of Excess Body Mass on Musculoskeleture: I. Foundation

NASA Astrophysics Data System (ADS)

Shaibani, Saami J.

2008-03-01

Increasing levels of obesity are having an increasingly adverse impact on individual and societal health. While much effort is directed to the harmful consequences of excess body mass on the cardiovascular system, there is relatively little research on how obesity compromises the response of the musculoskeletal system across the complete range of body types. This shortfall is addressed here by a comprehensive physics-based approach to produce a wide spectrum of representative adults, who are carefully chosen to cover both sexes, a full spread of percentiles for stature, and multiple weight levels. The latter encompass healthy, overweight and obese conditions defined by the standard parameter, body mass index (BMI). The distribution of body mass is computed for female and male subjects at all height percentiles and values of BMI to generate a detailed description of a diverse population. This cohort can then be examined for more advanced aspects of musculoskeleture, an important precursor for which is included here by calculating the extent of excess body mass at each body part as a function of BMI.

The effectiveness of 3D animations to enhance understanding of cranial cruciate ligament rupture.

PubMed

Clements, Dylan N; Broadhurst, Henry; Clarke, Stephen P; Farrell, Michael; Bennett, David; Mosley, John R; Mellanby, Richard J

2013-01-01

Cranial cruciate ligament (CCL) rupture is one of the most important orthopedic diseases taught to veterinary undergraduates. The complexity of the anatomy of the canine stifle joint combined with the plethora of different surgical interventions available for the treatment of the disease means that undergraduate veterinary students often have a poor understanding of the pathophysiology and treatment of CCL rupture. We designed, developed, and tested a three dimensional (3D) animation to illustrate the pertinent clinical anatomy of the stifle joint, the effects of CCL rupture, and the mechanisms by which different surgical techniques can stabilize the joint with CCL rupture. When compared with a non-animated 3D presentation, students' short-term retention of functional anatomy improved although they could not impart a better explanation of how different surgical techniques worked. More students found the animation useful than those who viewed a comparable non-animated 3D presentation. Multiple peer-review testing is required to maximize the usefulness of 3D animations during development. Free and open access to such tools should improve student learning and client understanding through wide-spread uptake and use.

Multiple subduction imprints in the mantle below Italy detected in a single lava flow

NASA Astrophysics Data System (ADS)

Nikogosian, Igor; Ersoy, Özlem; Whitehouse, Martin; Mason, Paul R. D.; de Hoog, Jan C. M.; Wortel, Rinus; van Bergen, Manfred J.

2016-09-01

Post-collisional magmatism reflects the regional subduction history prior to collision but the link between the two is complex and often poorly understood. The collision of continents along a convergent plate boundary commonly marks the onset of a variety of transitional geodynamic processes. Typical responses include delamination of subducting lithosphere, crustal thickening in the overriding plate, slab detachment and asthenospheric upwelling, or the complete termination of convergence. A prominent example is the Western-Central Mediterranean, where the ongoing slow convergence of Africa and Europe (Eurasia) has been accommodated by a variety of spreading and subduction systems that dispersed remnants of subducted lithosphere into the mantle, creating a compositionally wide spectrum of magmatism. Using lead isotope compositions of a set of melt inclusions in magmatic olivine crystals we detect exceptional heterogeneity in the mantle domain below Central Italy, which we attribute to the presence of continental material, introduced initially by Alpine and subsequently by Apennine subduction. We show that superimposed subduction imprints of a mantle source can be tapped during a melting episode millions of years later, and are recorded in a single lava flow.

Life-history evolution in ants: the case of Cardiocondyla

PubMed Central

2017-01-01

Ants are important components of most terrestrial habitats, and a better knowledge of the diversity of their life histories is essential to understand many aspects of ecosystem functioning. The myrmicine genus Cardiocondyla shows a wide range of colony structures, reproductive behaviours, queen and male lifespans, and habitat use. Reconstructing the evolutionary pathways of individual and social phenotypic traits suggests that the ancestral life history of Cardiocondyla was characterized by the presence of multiple, short-lived queens in small-sized colonies and a male polyphenism with winged dispersers and wingless fighters, which engage in lethal combat over female sexuals within their natal nests. Single queening, queen polyphenism, the loss of winged males and tolerance among wingless males appear to be derived traits that evolved with changes in nesting habits, colony size and the spread from tropical to seasonal environments. The aim of this review is to bring together the information on life-history evolution in Cardiocondyla and to highlight the suitability of this genus for functional genomic studies of adaptation, phenotypic plasticity, senescence, invasiveness and other key life-history traits of ants. PMID:28298341

Vapor compression heat pump system field tests at the tech complex

NASA Astrophysics Data System (ADS)

Baxter, Van D.

1985-11-01

The Tennessee Energy Conservation In Housing (TECH) complex has been utilized since 1977 as a field test site for several novel and conventional heat pump systems for space conditioning and water heating. Systems tested include the Annual Cycle Energy System (ACES), solar assisted heat pumps (SAHP) both parallel and series, two conventional air-to-air heat pumps, an air-to-air heat pump with desuperheater water heater, and horizontal coil and multiple shallow vertical coil ground-coupled heat pumps (GCHP). A direct comparison of the measured annual performance of the test systems was not possible. However, a cursory examination revealed that the ACES had the best performance, however, its high cost makes it unlikely that it will achieve wide-spread use. Costs for the SAHP systems are similar to those of the ACES but their performance is not as good. Integration of water heating and space conditioning functions with a desuperheater yielded significant efficiency improvement at modest cost. The GCHP systems performed much better for heating than for cooling and may well be the most efficient alternative for residences in cold climates.

[Prospects of the integration of dry blood spot technology with human health and environmental population studies].

PubMed

Pomelova, V G; Osin, N S

2007-01-01

This literature review is dedicated to prospects of the use of whole blood dried on special filter paper as a source of biological material for human health and environmental population studies. Evident advantages of this low-invasive approach include the following: it is easy to take a blood sample from a patient's finger ofa neonate's heel; the cost of sampling as well as transportation and storage of samples is low; paper blanks are safe to manipulate with and convenient to mail in sealed plastic packages. Many analytes, such as DNA, become more stable after drying, which allows for the detection of phenotypic and genotypic markers, as well as multiple gene mutations by multiplex DNA amplification. Modern diagnostic techniques make it possible to detect a wide spectrum of biomarkers characterizing the condition of the endocrine, cardiovascular, reproductive, and immune systems of the organism in a single drop of blood. This allows considering paper blanks with dry blood the key component of multilevel interdisciplinary population studies on neonatal screening, disease spread surveillance, seroepidemiological monitoring, and ecological and genetic research.

An Overview of Distributed Microgrid State Estimation and Control for Smart Grids

PubMed Central

Rana, Md Masud; Li, Li

2015-01-01

Given the significant concerns regarding carbon emission from the fossil fuels, global warming and energy crisis, the renewable distributed energy resources (DERs) are going to be integrated in the smart grid. This grid can spread the intelligence of the energy distribution and control system from the central unit to the long-distance remote areas, thus enabling accurate state estimation (SE) and wide-area real-time monitoring of these intermittent energy sources. In contrast to the traditional methods of SE, this paper proposes a novel accuracy dependent Kalman filter (KF) based microgrid SE for the smart grid that uses typical communication systems. Then this article proposes a discrete-time linear quadratic regulation to control the state deviations of the microgrid incorporating multiple DERs. Therefore, integrating these two approaches with application to the smart grid forms a novel contributions in green energy and control research communities. Finally, the simulation results show that the proposed KF based microgrid SE and control algorithm provides an accurate SE and control compared with the existing method. PMID:25686316

Digging deeper for new physics in the LHC data

NASA Astrophysics Data System (ADS)

Asadi, Pouya; Buckley, Matthew R.; DiFranzo, Anthony; Monteux, Angelo; Shih, David

2017-11-01

In this paper, we describe a novel, model-independent technique of "rectangular aggregations" for mining the LHC data for hints of new physics. A typical (CMS) search now has hundreds of signal regions, which can obscure potentially interesting anomalies. Applying our technique to the two CMS jets+MET SUSY searches, we identify a set of previously overlooked ˜ 3 σ excesses. Among these, four excesses survive tests of inter-and intra-search compatibility, and two are especially interesting: they are largely overlappingbetween the jets+MET searches and are characterized by low jet multiplicity, zero b-jets, and low MET and H T . We find that resonant color-triplet production decaying to a quark plus an invisible particle provides an excellent fit to these two excesses and all other data — including the ATLAS jets+MET search, which actually sees a correlated excess. We discuss the additional constraints coming from dijet resonance searches, monojet searches and pair production. Based on these results, we believe the wide-spread view that the LHC data contains no interesting excesses is greatly exaggerated.

The scaling of human interactions with city size

PubMed Central

Schläpfer, Markus; Bettencourt, Luís M. A.; Grauwin, Sébastian; Raschke, Mathias; Claxton, Rob; Smoreda, Zbigniew; West, Geoffrey B.; Ratti, Carlo

2014-01-01

The size of cities is known to play a fundamental role in social and economic life. Yet, its relation to the structure of the underlying network of human interactions has not been investigated empirically in detail. In this paper, we map society-wide communication networks to the urban areas of two European countries. We show that both the total number of contacts and the total communication activity grow superlinearly with city population size, according to well-defined scaling relations and resulting from a multiplicative increase that affects most citizens. Perhaps surprisingly, however, the probability that an individual's contacts are also connected with each other remains largely unaffected. These empirical results predict a systematic and scale-invariant acceleration of interaction-based spreading phenomena as cities get bigger, which is numerically confirmed by applying epidemiological models to the studied networks. Our findings should provide a microscopic basis towards understanding the superlinear increase of different socioeconomic quantities with city size, that applies to almost all urban systems and includes, for instance, the creation of new inventions or the prevalence of certain contagious diseases. PMID:24990287

Design, construction and measurements of an alpha magnet as a solution for compact bunch compressor for the electron beam from Thermionic RF Gun

NASA Astrophysics Data System (ADS)

Rajabi, A.; Jazini, J.; Fathi, M.; Sharifian, M.; Shokri, B.

2018-03-01

The beam produced by a thermionic RF gun has wide energy spread that makes it unsuitable for direct usage in photon sources. Here in the present work, we optimize the extracted beam from a thermionic RF gun by a compact economical bunch compressor. A compact magnetic bunch compressor (Alpha magnet) is designed and constructed. A comparison between simulation results and experimental measurements shows acceptable conformity. The beam dynamics simulation results show a reduction of the energy spread as well as a compression of length less than 1 ps with 2.3 mm-mrad emittance.

Bursting endemic bubbles in an adaptive network

NASA Astrophysics Data System (ADS)

Sherborne, N.; Blyuss, K. B.; Kiss, I. Z.

2018-04-01

The spread of an infectious disease is known to change people's behavior, which in turn affects the spread of disease. Adaptive network models that account for both epidemic and behavioral change have found oscillations, but in an extremely narrow region of the parameter space, which contrasts with intuition and available data. In this paper we propose a simple susceptible-infected-susceptible epidemic model on an adaptive network with time-delayed rewiring, and show that oscillatory solutions are now present in a wide region of the parameter space. Altering the transmission or rewiring rates reveals the presence of an endemic bubble—an enclosed region of the parameter space where oscillations are observed.

DNA extracellular traps are part of the immune repertoire of Periplaneta americana.

PubMed

Nascimento, M T C; Silva, K P; Garcia, M C F; Medeiros, M N; Machado, E A; Nascimento, S B; Saraiva, E M

2018-07-01

Extracellular traps (ETs), web-like structures composed of DNA and histones, are released by innate immune cells in a wide range of organisms. ETs capture microorganisms, thereby avoiding their spread, and also concentrate antimicrobial molecules, which helps to kill microbes. Although vertebrate innate immune systems share homology with the insect immune system, ETosis have yet to be characterized in insects. Here, we report that the hemocytes of the hemimetabolous insect Periplaneta americana release ETs upon in vitro stimulation. We further discuss the relationship between ETs and nodulation and in controlling bacterial spread in vivo. Copyright © 2018 Elsevier Ltd. All rights reserved.

The AIDS epidemic: the spread of a deadly disease in the biotech era.

PubMed

Noë, A; Verhofstede, C; Plum, J

2004-01-01

In the last two decades we have witnessed the progression of a newly introduced infection in humans. It is sobering that despite a world-wide effort and the tremendous progression of technical capabilities and scientific knowledge we are still not able to control the global epidemic of HIV. In 2004 more than 40 million people were infected. Educational approaches to modify risk-taking behavior is still the most critical component of prevention and the most important measure to limit the spread of the infection. Vaccine development, which is still far from promising, is probably the only way to control the disease in the future.

Genocide and public health: German doctors and Polish Jews, 1939-41.

PubMed

Browning, Christopher R

1988-01-01

German doctors in the General Government played an important role in providing the medical rationalization for ghettoization and mass murder. Their desire to prevent the spread of disease to Germans led them to favour providing adequate health care for Poles. The same self-interest engendered their persistent advocacy of ghettoization for Jews, who were believed to be natural carriers of spotted fever. When ghetto conditions created a self-fulfilling prophecy of wide-spread disease, the doctors advocated tighter sealing of the ghettos. By late 1941, this self-induced threat to public health made the doctors receptive to a mass murder solution.

Delayed P100-Like Latencies in Multiple Sclerosis: A Preliminary Investigation Using Visual Evoked Spread Spectrum Analysis

PubMed Central

Kiiski, Hanni S. M.; Ní Riada, Sinéad; Lalor, Edmund C.; Gonçalves, Nuno R.; Nolan, Hugh; Whelan, Robert; Lonergan, Róisín; Kelly, Siobhán; O'Brien, Marie Claire; Kinsella, Katie; Bramham, Jessica; Burke, Teresa; Ó Donnchadha, Seán; Hutchinson, Michael; Tubridy, Niall; Reilly, Richard B.

2016-01-01

Conduction along the optic nerve is often slowed in multiple sclerosis (MS). This is typically assessed by measuring the latency of the P100 component of the Visual Evoked Potential (VEP) using electroencephalography. The Visual Evoked Spread Spectrum Analysis (VESPA) method, which involves modulating the contrast of a continuous visual stimulus over time, can produce a visually evoked response analogous to the P100 but with a higher signal-to-noise ratio and potentially higher sensitivity to individual differences in comparison to the VEP. The main objective of the study was to conduct a preliminary investigation into the utility of the VESPA method for probing and monitoring visual dysfunction in multiple sclerosis. The latencies and amplitudes of the P100-like VESPA component were compared between healthy controls and multiple sclerosis patients, and multiple sclerosis subgroups. The P100-like VESPA component activations were examined at baseline and over a 3-year period. The study included 43 multiple sclerosis patients (23 relapsing-remitting MS, 20 secondary-progressive MS) and 42 healthy controls who completed the VESPA at baseline. The follow-up sessions were conducted 12 months after baseline with 24 MS patients (15 relapsing-remitting MS, 9 secondary-progressive MS) and 23 controls, and again at 24 months post-baseline with 19 MS patients (13 relapsing-remitting MS, 6 secondary-progressive MS) and 14 controls. The results showed P100-like VESPA latencies to be delayed in multiple sclerosis compared to healthy controls over the 24-month period. Secondary-progressive MS patients had most pronounced delay in P100-like VESPA latency relative to relapsing-remitting MS and controls. There were no longitudinal P100-like VESPA response differences. These findings suggest that the VESPA method is a reproducible electrophysiological method that may have potential utility in the assessment of visual dysfunction in multiple sclerosis. PMID:26726800

Horizontal Dissemination of Antimicrobial Resistance Determinants in Multiple Salmonella Serotypes following Isolation from the Commercial Swine Operation Environment after Manure Application.

PubMed

Pornsukarom, Suchawan; Thakur, Siddhartha

2017-10-15

The aim of this study was to characterize the plasmids carrying antimicrobial resistance (AMR) determinants in multiple Salmonella serotypes recovered from the commercial swine farm environment after manure application on land. Manure and soil samples were collected on day 0 before and after manure application on six farms in North Carolina, and sequential soil samples were recollected on days 7, 14, and 21 from the same plots. All environmental samples were processed for Salmonella , and their plasmid contents were further characterized. A total of 14 isolates including Salmonella enterica serotypes Johannesburg ( n = 2), Ohio ( n = 2), Rissen ( n = 1), Typhimurium var5- ( n = 5), Worthington ( n = 3), and 4,12:i:- ( n = 1), representing different farms, were selected for plasmid analysis. Antimicrobial susceptibility testing was done by broth microdilution against a panel of 14 antimicrobials on the 14 confirmed transconjugants after conjugation assays. The plasmids were isolated by modified alkaline lysis, and PCRs were performed on purified plasmid DNA to identify the AMR determinants and the plasmid replicon types. The plasmids were sequenced for further analysis and to compare profiles and create phylogenetic trees. A class 1 integron with an ANT(2″)-Ia- aadA2 cassette was detected in the 50-kb IncN plasmids identified in S Worthington isolates. We identified 100-kb and 90-kb IncI1 plasmids in S Johannesburg and S Rissen isolates carrying the bla CMY-2 and tet (A) genes, respectively. An identical 95-kb IncF plasmid was widely disseminated among the different serotypes and across different farms. Our study provides evidence on the importance of horizontal dissemination of resistance determinants through plasmids of multiple Salmonella serotypes distributed across commercial swine farms after manure application. IMPORTANCE The horizontal gene transfer of antimicrobial resistance (AMR) determinants located on plasmids is considered to be the main reason for the rapid proliferation and spread of drug resistance. The deposition of manure generated in swine production systems into the environment is identified as a potential source of AMR dissemination. In this study, AMR gene-carrying plasmids were detected in multiple Salmonella serotypes across different commercial swine farms in North Carolina. The plasmid profiles were characterized based on Salmonella serotype donors and incompatibility (Inc) groups. We found that different Inc plasmids showed evidence of AMR gene transfer in multiple Salmonella serotypes. We detected an identical 95-kb plasmid that was widely distributed across swine farms in North Carolina. These conjugable resistance plasmids were able to persist on land after swine manure application. Our study provides strong evidence of AMR determinant dissemination present in plasmids of multiple Salmonella serotypes in the environment after manure application. Copyright © 2017 American Society for Microbiology.

M-Learning Pilot at Sofia University

ERIC Educational Resources Information Center

Gourova, Elissaveta; Dulev, Pavlin; Petrova-Antonova, Dessislava; Bontchev, Boyan

2014-01-01

Many universities have designed specialized Learning Management Systems in order to facilitate the management of education, the access to knowledge and educational resources, and the communications with all stakeholders involved. With the wide spread of mobile technologies nowadays, new challenges emerge for adapting the available systems to the…

Evaluation of Alternative Causes of Wide-Spread, Low Concentration Perchlorate Impacts to Groundwater

DTIC Science & Technology

2011-07-01

lasting impacts of past fertilization practices on some regional watersheds ( Fogg et al., 1998). Through funding provided by the Department of...3213-3218. Fogg , G.E., E.M. LaBolle, G.S. Weissmann. 1998. Groundwater vulnerability assessment: hydrogeologic perspective and example from

Phenotypic characterization of Cercospora sojina isolates collected from wide geographical areas

USDA-ARS?s Scientific Manuscript database

Frogeye Leaf Spot (FLS), caused by Cercospora sojina, is common in the southern and southeastern soybean production region of the USA. Recently, FLS has spread further northward into Midwestern soybean growing states, including Ohio, Indiana, Wisconsin, Michigan, Illinois, Iowa, and Missouri and sou...

Using a spatially explicit analysis model to evaluate spatial variation of corn yield

USDA-ARS?s Scientific Manuscript database

Spatial irrigation of agricultural crops using site-specific variable-rate irrigation (VRI) systems is beginning to have wide-spread acceptance. However, optimizing the management of these VRI systems to conserve natural resources and increase profitability requires an understanding of the spatial ...

Assessing spatial variation of corn response to irrigation using a bayesian semiparametric model

USDA-ARS?s Scientific Manuscript database

Spatial irrigation of agricultural crops using site-specific variable-rate irrigation (VRI) systems is beginning to have wide-spread acceptance. However, optimizing the management of these VRI systems to conserve natural resources and increase profitability requires an understanding of the spatial ...

Non-School Influences and Educational Disadvantage: Pre and Post-natal Nutritional Deprivation

ERIC Educational Resources Information Center

Doll, Russell C.

1973-01-01

Deals with pre and post-natal malnutrition and its possible influence on the child, focusing on these points: How wide-spread and severe is the malnutrition? What might be the effects of the malnutrition at certain critical points in development? (Author/JM)

Identifying and organizing objectives across the 28 National Estuary Programs

EPA Science Inventory

The National Estuary Program (NEP), established in 1987 by amendments to the Clean Water Act, is intended to support local communities to restore, protect and manage estuaries of national significance. Currently there a 28 NEPs spread widely across the U.S. and its territories. E...

JPRS Report, East Europe

DTIC Science & Technology

1988-05-06

fall silent. In SR Croatia, which I represent as a delegate, there is ferment around a set of fresh ideas aimed at optimalizing the system, at...spreads and yogurts . It makes a wide variety of meat products (head cheese, salami, ham, and 18 different kinds of regional meat products). Also

Epidemics and dimensionality in hierarchical networks

NASA Astrophysics Data System (ADS)

Zheng, Da-Fang; Hui, P. M.; Trimper, Steffen; Zheng, Bo

2005-07-01

Epidemiological processes are studied within a recently proposed hierarchical network model using the susceptible-infected-refractory dynamics of an epidemic. Within the network model, a population may be characterized by H independent hierarchies or dimensions, each of which consists of groupings of individuals into layers of subgroups. Detailed numerical simulations reveal that for H>1, global spreading results regardless of the degree of homophily of the individuals forming a social circle. For H=1, a transition from global to local spread occurs as the population becomes decomposed into increasingly homophilous groups. Multiple dimensions in classifying individuals (nodes) thus make a society (computer network) highly susceptible to large-scale outbreaks of infectious diseases (viruses).

Global, Multi-Objective Trajectory Optimization With Parametric Spreading

NASA Technical Reports Server (NTRS)

Vavrina, Matthew A.; Englander, Jacob A.; Phillips, Sean M.; Hughes, Kyle M.

2017-01-01

Mission design problems are often characterized by multiple, competing trajectory optimization objectives. Recent multi-objective trajectory optimization formulations enable generation of globally-optimal, Pareto solutions via a multi-objective genetic algorithm. A byproduct of these formulations is that clustering in design space can occur in evolving the population towards the Pareto front. This clustering can be a drawback, however, if parametric evaluations of design variables are desired. This effort addresses clustering by incorporating operators that encourage a uniform spread over specified design variables while maintaining Pareto front representation. The algorithm is demonstrated on a Neptune orbiter mission, and enhanced multidimensional visualization strategies are presented.

Modeling the spread and control of dengue with limited public health resources.

PubMed

Abdelrazec, Ahmed; Bélair, Jacques; Shan, Chunhua; Zhu, Huaiping

2016-01-01

A deterministic model for the transmission dynamics of dengue fever is formulated to study, with a nonlinear recovery rate, the impact of available resources of the health system on the spread and control of the disease. Model results indicate the existence of multiple endemic equilibria, as well as coexistence of an endemic equilibrium with a periodic solution. Additionally, our model exhibits the phenomenon of backward bifurcation. The results of this study could be helpful for public health authorities in their planning of a proper resource allocation for the control of dengue transmission. Copyright © 2015 Elsevier Inc. All rights reserved.

Genetic analysis across differential spatial scales reveals multiple dispersal mechanisms for the invasive hydrozoan Cordylophora in the Great Lakes

EPA Science Inventory

Understanding patterns of post-establishment spread by invasive species is critically important for the design of effective management strategies and the development of appropriate theoretical models predicting spatial expansion of introduced populations. Here we explore genetic ...

Wideband Channel Modeling in Real Atmospheric Environments with Experimental Evaluation

DTIC Science & Technology

2013-04-01

5] D. F. Gingras and P. Gerstoft. 1997. “The Effect of Propagation on Wideband DS - CDMA Systems in the Suburban Environment,” The First IEEE...are commonly used in spread spectrum communication systems such as Code Division Multiple Access ( CDMA ) systems. Narrowband interference mitigation

Roguing with replacement in perennial crops: conditions for successful disease management.

PubMed

Sisterson, Mark S; Stenger, Drake C

2013-02-01

Replacement of diseased plants with healthy plants is commonly used to manage spread of plant pathogens in perennial cropping systems. This strategy has two potential benefits. First, removing infected plants may slow pathogen spread by eliminating inoculum sources. Second, replacing infected plants with uninfected plants may offset yield losses due to disease. The extent to which these benefits are realized depends on multiple factors. In this study, sensitivity analyses of two spatially explicit simulation models were used to evaluate how assumptions concerning implementation of a plant replacement program and pathogen spread interact to affect disease suppression. In conjunction, effects of assumptions concerning yield loss associated with disease and rates of plant maturity on yields were simultaneously evaluated. The first model was used to evaluate effects of plant replacement on pathogen spread and yield on a single farm, consisting of a perennial crop monoculture. The second model evaluated effects of plant replacement on pathogen spread and yield in a 100 farm crop growing region, with all farms maintaining a monoculture of the same perennial crop. Results indicated that efficient replacement of infected plants combined with a high degree of compliance among farms effectively slowed pathogen spread, resulting in replacement of few plants and high yields. In contrast, inefficient replacement of infected plants or limited compliance among farms failed to slow pathogen spread, resulting in replacement of large numbers of plants (on farms practicing replacement) with little yield benefit. Replacement of infected plants always increased yields relative to simulations without plant replacement provided that infected plants produced no useable yield. However, if infected plants produced useable yields, inefficient removal of infected plants resulted in lower yields relative to simulations without plant replacement for perennial crops with long maturation periods in some cases.

Shuttle ku-band communications/radar technical concepts

NASA Technical Reports Server (NTRS)

Griffin, J. W.; Kelley, J. S.; Steiner, A. W.; Vang, H. A.; Zrubek, W. E.; Huth, G. K.

1985-01-01

Technical data on the Shuttle Orbiter K sub u-band communications/radar system are presented. The more challenging aspects of the system design and development are emphasized. The technical problems encountered and the advancements made in solving them are discussed. The radar functions are presented first. Requirements and design/implementation approaches are discussed. Advanced features are explained, including Doppler measurement, frequency diversity, multiple pulse repetition frequencies and pulse widths, and multiple modes. The communications functions that are presented include advances made because of the requirements for multiple communications modes. Spread spectrum, quadrature phase shift keying (QPSK), variable bit rates, and other advanced techniques are discussed. Performance results and conclusions reached are outlined.

Multiple excitation nano-spot generation and confocal detection for far-field microscopy.

PubMed

Mondal, Partha Pratim

2010-03-01

An imaging technique is developed for the controlled generation of multiple excitation nano-spots for far-field microscopy. The system point spread function (PSF) is obtained by interfering two counter-propagating extended depth-of-focus PSF (DoF-PSF), resulting in highly localized multiple excitation spots along the optical axis. The technique permits (1) simultaneous excitation of multiple planes in the specimen; (2) control of the number of spots by confocal detection; and (3) overcoming the point-by-point based excitation. Fluorescence detection from the excitation spots can be efficiently achieved by Z-scanning the detector/pinhole assembly. The technique complements most of the bioimaging techniques and may find potential application in high resolution fluorescence microscopy and nanoscale imaging.

Multiple excitation nano-spot generation and confocal detection for far-field microscopy

NASA Astrophysics Data System (ADS)

Mondal, Partha Pratim

2010-03-01

An imaging technique is developed for the controlled generation of multiple excitation nano-spots for far-field microscopy. The system point spread function (PSF) is obtained by interfering two counter-propagating extended depth-of-focus PSF (DoF-PSF), resulting in highly localized multiple excitation spots along the optical axis. The technique permits (1) simultaneous excitation of multiple planes in the specimen; (2) control of the number of spots by confocal detection; and (3) overcoming the point-by-point based excitation. Fluorescence detection from the excitation spots can be efficiently achieved by Z-scanning the detector/pinhole assembly. The technique complements most of the bioimaging techniques and may find potential application in high resolution fluorescence microscopy and nanoscale imaging.

The Evolution of Stellar Coronae: Initial Results from a ROSAT PSPC Observation of IC 2391

NASA Technical Reports Server (NTRS)

Patten, Brian M.; Simon, Theodore

1993-01-01

A 23 ks ROSAT PSPC image of the young star cluster, IC 2391, reveals 76 soft x-ray sources with L(sub x)(0.2-2.0 keV) greater than or equal to 2 x 10(exp 28) ergs/s in the direction of the cluster center. Nineteen of these sources are associated with known cluster members. We find that x-ray emission from the IC 2391 B stars deviates widely from the L(sub x)/L(sub bol) = 10(exp -7) relation based on Einstein observations of O and early B stars. Instead, we observe a wide range in L(sub x) with an order of magnitude spread at any given mass and no apparent dependence on spectral type. A comparison of the spread of L(sub x) as a function of B-V for low-mass stars between IC 2391 and the much older Hyades cluster shows that despite the factor of approx. 10 difference in their ages, these two clusters exhibit very similar dispersions in levels of stellar activity. We conclude that the low-mass stars in IC 2391 have arrived on the ZAMS with a wide range of coronal activity levels, from very strong to very weak, and that existing empirical activity-age scaling laws therefore cannot be valid.

76 FR 66726 - Government-Owned Inventions; Availability for Licensing

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-27

...-A12 peptide antigens. The TCRs recognize these antigens in the context of major histocompatibility... proteins to mediate tumor growth and spreading. The MAGE-A proteins are some of the most widely expressed... adapted to the depletion of hormones and continue to grow. Abnormal androgen receptor signaling is known...

State Policy Regimes and Charter School Performance

ERIC Educational Resources Information Center

Pelz, Mikael L.

2015-01-01

The policy diffusion framework is critical to understanding the spread of policy innovations such as charter schools in the United States. This framework, however, is less instructive in explaining the state-by-state configuration of these policies. What explains the wide variation in charter school policy among states? This study addresses this…

Engaging the Disciplines in Internationalising the Curriculum

ERIC Educational Resources Information Center

Clifford, Valerie Anne

2009-01-01

The claim by universities to be "international" has spread world-wide over the last two decades and this has been largely interpreted to mean the recruitment and support of international students. Little attention has been paid to what this means for curriculum development. This study was carried out to explore disciplinary…

The effects of downy brome invasion on mule deer habitat

USDA-ARS?s Scientific Manuscript database

Downy brome (Bromus tectorum), also widely known as cheatgrass, is a highly invasive exotic weed that has spread over millions of hectares of rangelands throughout the Intermountain West. Native to Eurasia, this early maturing annual provides a fine textured fuel that increases the chance, rate, sea...

Final Report from the Department of Kinetics of Chemical and Biological Processes, Institute of Chemical Physics of Russian Academy of Sciences

DTIC Science & Technology

1994-01-01

from polymer systems. Investigation of mechanisms of high-temperature pyrolysis and combustion reactions of network polymethacrylates. Rubailo V.L...are widely spread among agricultural important crops (i.e. cereals, fruits, grapevine, potato, cotton, tomato , leguminous) and ornamental plants

Sudden death syndrome of soybean in Argentina

USDA-ARS?s Scientific Manuscript database

Sudden death syndrome (SDS) is one of the most common and widely spread root disease affecting soybean [Glycine max (L.) Merr.] in Argentina where it is an economically important crop. This disease was first discovered in this country in 1992 in the Pampas Region, and the following year in Northwest...

Dealerships are a tipping point

NASA Astrophysics Data System (ADS)

Lynes, Jennifer

2018-06-01

Many consumers encounter electric vehicles for the first time at car dealerships when they are looking to buy a new vehicle. Now, research shows that interactions with sales personnel have an important and often detrimental influence on the purchase of electric vehicles, presenting a critical barrier to their wide-spread adoption.

ASSESSING THE WATER QUALITY OF MINE-IMPACTED STREAMS USING HYPERSPECTRAL DATA

EPA Science Inventory

Streoan degradation by mining activities is a wide spread problem in the eastern US. Drainage from coal and ferrous metal mines can produce large quantities of sediment and acidity, which can have a deleterious impact an receiving waters. The mineralogy of these sediments is ...

Using Baroque Techniques to Teach Improvisation in Your Classroom

ERIC Educational Resources Information Center

Yoo, Hyesoo

2015-01-01

Before our current notation system was widely adopted by musicians, improvisation was a key component of music throughout the Western world. One of the fundamental elements of the baroque style, namely, using improvised embellishment, offered musicians great artist liberty. During the baroque period, improvisation spread across Europe and beyond.…

US Activities in Making Life Cycle Inventory Data More Available to Users

EPA Science Inventory

The demand for LCA studies continues to grow, although, the lack of reliable, transparent Life Cycle Inventory (LCI) data is hampering the wide-spread application of LCA. This paper will present activities related to the development and accessibility of process LCI data in the U...

Recommended Practices and Parent Perspectives regarding AT Use in Early Intervention

ERIC Educational Resources Information Center

Wilcox, M. Jeanne; Dugan, Lauren M.; Campbell, Philippa H.; Guimond, Amy

2006-01-01

It frequently is suggested that parents underutilize assistive technology (AT) for their young children with disabilities despite wide spread recommended practices for providing optimal AT interventions (i.e., devices and services). However, neither parent perspectives of AT underutilization or families' experiences with AT have been reported in…

Area-wide management of Aedes albopictus: lessons learned.

USDA-ARS?s Scientific Manuscript database

Aedes albopictus, the Asian tiger mosquito, is the principal vector of chikungunya fever and a critical vector of dengue. This daytime biting pest often causes the majority of service requests from urban and suburban residents in New Jersey and many other states and nations where it has spread. Ou...

Robotics: Past, Present, and Future.

ERIC Educational Resources Information Center

Dunne, Maurice J.

Robots are finally receiving wide-spread attention as a means to realize the goal of automating factories. In the 1960's robot use was limited by unfavorable acquisition and operating costs and the affordable control technology limiting applications to relatively simple jobs. During the 1970's productivity of manufacturing organizations declined…

Differently Designed Playgrounds and Preschooler's Physical Activity Play

ERIC Educational Resources Information Center

Luchs, Antje; Fikus, Monika

2018-01-01

New playground concepts--favouring natural play characteristics--emerge. The aim of our free play study is to explore the relation between newly established natural playgrounds and the widely spread contemporary ones in terms of physical activity levels. The playground features differ in vegetation, topography, size and play equipment. The…

Resilience and Risk

ERIC Educational Resources Information Center

Brackenreed, Darlene

2010-01-01

In the age of the human Genome Project wide spread prodigious information technology, our system of education is unable to keep pace with and meet the demands for knowledge, skills, and identification and treatment of academic, emotional, social, mental and health concerns of our youth. As the Saskatchewan task force on the state of education in…

APPROACHING THE TOXICITY OF DISINFECTION BY-PRODUCTS IN DRINKING WATER AS A MIXTURE PROBLEM

EPA Science Inventory

Abstract
Assessment of human health risk from exposure to disinfection by-products (DBPs) in drinking water is of concern because of the wide spread exposure of persons who use disinfected water. Taken as a body of literature, epidemiologic studies on chlorinated drinking ...

Multiple Testing in the Context of Gene Discovery in Sickle Cell Disease Using Genome-Wide Association Studies.

PubMed

Kuo, Kevin H M

2017-01-01

The issue of multiple testing, also termed multiplicity, is ubiquitous in studies where multiple hypotheses are tested simultaneously. Genome-wide association study (GWAS), a type of genetic association study that has gained popularity in the past decade, is most susceptible to the issue of multiple testing. Different methodologies have been employed to address the issue of multiple testing in GWAS. The purpose of the review is to examine the methodologies employed in dealing with multiple testing in the context of gene discovery using GWAS in sickle cell disease complications.

Innovation Diffusion: Implications for Evaluation

ERIC Educational Resources Information Center

Ashley, Shena R.

2009-01-01

Whether looking at the spread and adoption of an intervention across a community, across multiple units, or within a single unit, an understanding of diffusion theory can help evaluators uncover patterns and impacts that might otherwise be overlooked. The theory alerts evaluators to examine why uptake of an intervention appeared different in…

Identification and integration of Picorna-like viruses in multiple insect taxa

USDA-ARS?s Scientific Manuscript database

Virus infection often leads to incorporation of a piece of the virus genetic code into the genome of the host organism, referred to as integration. Determining if the virus has integrated into the host genome provides valuable information needed to monitor disease spread. Detection of integrated vir...

Climate Change, Extreme Weather Events, and Fungal Disease Emergence and Spread

USDA-ARS?s Scientific Manuscript database

Empirical evidence from multiple sources show the Earth has been warming since the late 19th century. More recently, evidence for this warming trend is strongly supported by satellite data since the late 1970s from the cryosphere, atmosphere, oceans, and land that confirms increasing temperature tr...

Pneumorachis caused by metastatic gas gangrene.

PubMed

Thompson, George R; Crawford, George E

2009-01-01

Pneumorachis has previously been described only after spread from a contiguous site or after a traumatic event. Our patient experienced sepsis due to multiple enteric organisms, and gas was identified within the spinal canal on computed tomographic imaging. We present the 1st case of pneumorachis caused by disseminated infection.

"Internationalization" and Composition Studies: Reorienting the Discourse

ERIC Educational Resources Information Center

Donahue, Christiane

2009-01-01

While "internationalization" has become a buzzword in composition scholarship and teaching, our discourses tend toward fuzzy uses and understandings of the term and its multiple implications. We tend to focus on how our U.S. experience is being internationalized: how English and its teaching are spreading; how other countries, different…

Testing Like William the Conqueror: Cultural and Instrumental Uses of Examinations

ERIC Educational Resources Information Center

Dorn, Sherman

2014-01-01

The spread of academic testing for accountability purposes in multiple countries has obscured at least two historical purposes of academic testing: community ritual and management of the social structure. Testing for accountability is very different from the purpose of academic challenges one can identify in community "examinations" in…

Magma Supply at the Arctic Gakkel Ridge: Constraints from Peridotites and Basalts

NASA Astrophysics Data System (ADS)

Sun, C.; Dick, H. J.; Hellebrand, E.; Snow, J. E.

2015-12-01

Crustal thickness in global ridge systems is widely believed to be nearly uniform (~7 km) at slow- and fast-spreading mid-ocean ridges, but appears significantly thinner (< ~4 km) at ultraslow-spreading ridges. At the slowest-spreading Arctic Gakkel Ridge, the crust becomes extremely thin (1.4 - 2.9 km; [1]). The thin crust at the Gakkel and other ultraslow-spreading ridges, has been attributed to lithosphere thickening, ancient mantle depletion, lower mantle temperature, ridge obliquity, and melt retention/focusing. To better understand the magma supply at ultraslow-spreading ridges, we examined melting dynamics by linking peridotites and basalts dredged along the Gakkel Ridge. We analyzed rare earth elements in clinopyroxene from 84 residual peridotites, and estimated melting parameters for individual samples through nonlinear least squares analyses. The degrees of melting show a large variation but mainly center at around 7% assuming a somewhat arbitrary but widely used depleted MORB mantle starting composition. Thermobarometry on published primitive basaltic glasses from [2] indicates that the mantle potential temperature at the Gakkel Ridge is ~50°C cooler than that at the East Pacific Rise. The ridge-scale low-degree melting and lower mantle potential temperature place the final depth of melting at ~30 km and a melt thickness of 1.0 or 2.9 km for a triangular or trapezoidal melting regime, respectively. The final melting depth is consistent with excess conductive cooling and lithosphere thickening suggested by geodynamic models, while the estimated melt thickness is comparable to the seismic crust (1.4 - 2.9 km; [1]). The general agreement among geochemical analyses, seismic measurements, and geodynamic models supports that lower mantle potential temperature and thick lithosphere determine the ridge-scale low-degree melting and thin crust at the Gakkel Ridge, while melt retention/focusing and excess ancient mantle depletion are perhaps locally important at short length scales (e.g., < 50 - 100 km). [1] Jokat and Schmidt-Aursch (2007) Geophys. J. Int. (2007) 168, 983-998. [2] Gale et al. (2012) J. Petrology, 55, 1051-1082.

Spread in the magnitude of climate model interdecadal global temperature variability traced to disagreements over high-latitude oceans

NASA Astrophysics Data System (ADS)

Brown, Patrick T.; Li, Wenhong; Jiang, Jonathan H.; Su, Hui

2016-12-01

Unforced variability in global mean surface air temperature can obscure or exaggerate global warming on interdecadal time scales; thus, understanding both the magnitude and generating mechanisms of such variability is of critical importance for both attribution studies as well as decadal climate prediction. Coupled atmosphere-ocean general circulation models (climate models) simulate a wide range of magnitudes of unforced interdecadal variability in global mean surface air temperature (UITglobal), hampering efforts to quantify the influence of UITglobal on contemporary global temperature trends. Recently, a preliminary consensus has emerged that unforced interdecadal variability in local surface temperatures (UITlocal) over the tropical Pacific Ocean is particularly influential on UITglobal. Therefore, a reasonable hypothesis might be that the large spread in the magnitude of UITglobal across climate models can be explained by the spread in the magnitude of simulated tropical Pacific UITlocal. Here we show that this hypothesis is mostly false. Instead, the spread in the magnitude of UITglobal is linked much more strongly to the spread in the magnitude of UITlocal over high-latitude regions characterized by significant variability in oceanic convection, sea ice concentration, and energy flux at both the surface and the top of the atmosphere. Thus, efforts to constrain the climate model produced range of UITglobal magnitude would be best served by focusing on the simulation of air-sea interaction at high latitudes.

Discovery of a magma chamber and faults beneath a Mid-Atlantic Ridge hydrothermal field.

PubMed

Singh, Satish C; Crawford, Wayne C; Carton, Hélène; Seher, Tim; Combier, Violaine; Cannat, Mathilde; Pablo Canales, Juan; Düsünür, Doga; Escartin, Javier; Miranda, J Miguel

2006-08-31

Crust at slow-spreading ridges is formed by a combination of magmatic and tectonic processes, with magmatic accretion possibly involving short-lived crustal magma chambers. The reflections of seismic waves from crustal magma chambers have been observed beneath intermediate and fast-spreading centres, but it has been difficult to image such magma chambers beneath slow-spreading centres, owing to rough seafloor topography and associated seafloor scattering. In the absence of any images of magma chambers or of subsurface near-axis faults, it has been difficult to characterize the interplay of magmatic and tectonic processes in crustal accretion and hydrothermal circulation at slow-spreading ridges. Here we report the presence of a crustal magma chamber beneath the slow-spreading Lucky Strike segment of the Mid-Atlantic Ridge. The reflection from the top of the magma chamber, centred beneath the Lucky Strike volcano and hydrothermal field, is approximately 3 km beneath the sea floor, 3-4 km wide and extends up to 7 km along-axis. We suggest that this magma chamber provides the heat for the active hydrothermal vent field above it. We also observe axial valley bounding faults that seem to penetrate down to the magma chamber depth as well as a set of inward-dipping faults cutting through the volcanic edifice, suggesting continuous interactions between tectonic and magmatic processes.

Zealotry effects on opinion dynamics in the adaptive voter model

NASA Astrophysics Data System (ADS)

Klamser, Pascal P.; Wiedermann, Marc; Donges, Jonathan F.; Donner, Reik V.

2017-11-01

The adaptive voter model has been widely studied as a conceptual model for opinion formation processes on time-evolving social networks. Past studies on the effect of zealots, i.e., nodes aiming to spread their fixed opinion throughout the system, only considered the voter model on a static network. Here we extend the study of zealotry to the case of an adaptive network topology co-evolving with the state of the nodes and investigate opinion spreading induced by zealots depending on their initial density and connectedness. Numerical simulations reveal that below the fragmentation threshold a low density of zealots is sufficient to spread their opinion to the whole network. Beyond the transition point, zealots must exhibit an increased degree as compared to ordinary nodes for an efficient spreading of their opinion. We verify the numerical findings using a mean-field approximation of the model yielding a low-dimensional set of coupled ordinary differential equations. Our results imply that the spreading of the zealots' opinion in the adaptive voter model is strongly dependent on the link rewiring probability and the average degree of normal nodes in comparison with that of the zealots. In order to avoid a complete dominance of the zealots' opinion, there are two possible strategies for the remaining nodes: adjusting the probability of rewiring and/or the number of connections with other nodes, respectively.

Competing spreading processes on multiplex networks: Awareness and epidemics

NASA Astrophysics Data System (ADS)

Granell, Clara; Gómez, Sergio; Arenas, Alex

2014-07-01

Epidemiclike spreading processes on top of multilayered interconnected complex networks reveal a rich phase diagram of intertwined competition effects. A recent study by the authors [C. Granell et al., Phys. Rev. Lett. 111, 128701 (2013)., 10.1103/PhysRevLett.111.128701] presented an analysis of the interrelation between two processes accounting for the spreading of an epidemic, and the spreading of information awareness to prevent infection, on top of multiplex networks. The results in the case in which awareness implies total immunization to the disease revealed the existence of a metacritical point at which the critical onset of the epidemics starts, depending on completion of the awareness process. Here we present a full analysis of these critical properties in the more general scenario where the awareness spreading does not imply total immunization, and where infection does not imply immediate awareness of it. We find the critical relation between the two competing processes for a wide spectrum of parameters representing the interaction between them. We also analyze the consequences of a massive broadcast of awareness (mass media) on the final outcome of the epidemic incidence. Importantly enough, the mass media make the metacritical point disappear. The results reveal that the main finding, i.e., existence of a metacritical point, is rooted in the competition principle and holds for a large set of scenarios.

An easy “SteamDrop” method for high quality plant chromosome preparation

PubMed Central

2014-01-01

Background The chromosome preparation is a crucial step for obtaining satisfactory results in molecular cytogenetic researches. The preparation of plant chromosomes for molecular cytogenetic purposes remains a challenge for some species. In contrast to human chromosome preparation, the processes occurring during plant chromosome preparation and causing chromosome spreading are still poorly understood. Results We studied the dynamics of plant chromosome spreading after dropping cell suspension on slides. We showed that steam stimulates cytoplasm hydrolysis and rapid chromosome spreading and that chromosomes stretch during this chromosome spreading. Based on these observations, we developed a novel method, named “SteamDrop”, for the preparation of well-spread mitotic and pachytene chromosomes and successfully used it for 28 plant species with large and small chromosomes. We applied cell suspensions in ethanol instead of the commonly used ethanol/acetic acid fixative. Mitotic and meiotic chromosomes prepared via “SteamDrop” were used in fluorescent in situ hybridization (FISH) experiments with repetitive and unique DNA probes. Long storage of cell suspensions in ethanol did not impair the quality of chromosome preparations. Conclusion The SteamDrop procedure provides a robust and routine method for high quality plant chromosome preparations. The method can be applied for metaphase as well as pachytene chromosome preparation in wide range of species. The chromosomes prepared by SteamDrop are well suitable for repetitive and unique DNA visualization. PMID:24602284

Time-dependent changes in magmatic and hydrothermal activity at the Costa Rica Rift recorded by variations in oceanic crustal structure

NASA Astrophysics Data System (ADS)

Wilson, D. J.; Peirce, C.; Hobbs, R. W.; Gregory, E. P. M.; Zhang, L.

2016-12-01

Geophysical studies of crustal structure at a diverse range of ridges have provided evidence that the balance between spreading rate and magma supply determines whether spreading predominantly occurs by magmatic accretion of new oceanic crust or through tectonic stretching of the whole lithosphere. Asymmetric spreading, patterns of on- and off-axis volcanism, the evolution of oceanic core complexes and the distribution of hydrothermal systems all indicate that the process of spreading is not constant over geologically short timescales. The structure of the resulting crust reflects this complexity in origin. Studies along flow-lines across ridges spreading at intermediate rates suggest variations in topographic style and crustal structure have periodically occurred, controlled by the interplay between magmatic accretion and tectonic stretching, and coupled to the degree of hydrothermal activity. Seismic reflection images and tomographic models derived from wide-angle seismic data have enabled a detailed examination of the oceanic crust that formed at the fast-to-intermediate-spreading (36 mm yr-1) Costa Rica Rift over the last 6 Ma, to look for any temporal variation in basement topography, upper crust (layer 2) P-wave velocity/density structure and crustal thickness. Coincident marine gravity and magnetic data not only allow us to test the validity of the final velocity-density model but also review variability in half-spreading rate, respectively. Collectively our analyses allow us to investigate the timescale and cyclicity of crustal structure variations and, having determined the spreading rate over time, consider how this may reflect changes in magma supply and/or hydrothermal activity at the Costa Rica Rift, using borehole 504B as the ground-truth. This research is part of a major, interdisciplinary NERC-funded collaboration entitled: Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge (OSCAR).

Epidemic processes in complex networks

NASA Astrophysics Data System (ADS)

Pastor-Satorras, Romualdo; Castellano, Claudio; Van Mieghem, Piet; Vespignani, Alessandro

2015-07-01

In recent years the research community has accumulated overwhelming evidence for the emergence of complex and heterogeneous connectivity patterns in a wide range of biological and sociotechnical systems. The complex properties of real-world networks have a profound impact on the behavior of equilibrium and nonequilibrium phenomena occurring in various systems, and the study of epidemic spreading is central to our understanding of the unfolding of dynamical processes in complex networks. The theoretical analysis of epidemic spreading in heterogeneous networks requires the development of novel analytical frameworks, and it has produced results of conceptual and practical relevance. A coherent and comprehensive review of the vast research activity concerning epidemic processes is presented, detailing the successful theoretical approaches as well as making their limits and assumptions clear. Physicists, mathematicians, epidemiologists, computer, and social scientists share a common interest in studying epidemic spreading and rely on similar models for the description of the diffusion of pathogens, knowledge, and innovation. For this reason, while focusing on the main results and the paradigmatic models in infectious disease modeling, the major results concerning generalized social contagion processes are also presented. Finally, the research activity at the forefront in the study of epidemic spreading in coevolving, coupled, and time-varying networks is reported.

Genomic insights into the origin of farming in the ancient Near East.

PubMed

Lazaridis, Iosif; Nadel, Dani; Rollefson, Gary; Merrett, Deborah C; Rohland, Nadin; Mallick, Swapan; Fernandes, Daniel; Novak, Mario; Gamarra, Beatriz; Sirak, Kendra; Connell, Sarah; Stewardson, Kristin; Harney, Eadaoin; Fu, Qiaomei; Gonzalez-Fortes, Gloria; Jones, Eppie R; Roodenberg, Songül Alpaslan; Lengyel, György; Bocquentin, Fanny; Gasparian, Boris; Monge, Janet M; Gregg, Michael; Eshed, Vered; Mizrahi, Ahuva-Sivan; Meiklejohn, Christopher; Gerritsen, Fokke; Bejenaru, Luminita; Blüher, Matthias; Campbell, Archie; Cavalleri, Gianpiero; Comas, David; Froguel, Philippe; Gilbert, Edmund; Kerr, Shona M; Kovacs, Peter; Krause, Johannes; McGettigan, Darren; Merrigan, Michael; Merriwether, D Andrew; O'Reilly, Seamus; Richards, Martin B; Semino, Ornella; Shamoon-Pour, Michel; Stefanescu, Gheorghe; Stumvoll, Michael; Tönjes, Anke; Torroni, Antonio; Wilson, James F; Yengo, Loic; Hovhannisyan, Nelli A; Patterson, Nick; Pinhasi, Ron; Reich, David

2016-08-25

We report genome-wide ancient DNA from 44 ancient Near Easterners ranging in time between ~12,000 and 1,400 bc, from Natufian hunter-gatherers to Bronze Age farmers. We show that the earliest populations of the Near East derived around half their ancestry from a 'Basal Eurasian' lineage that had little if any Neanderthal admixture and that separated from other non-African lineages before their separation from each other. The first farmers of the southern Levant (Israel and Jordan) and Zagros Mountains (Iran) were strongly genetically differentiated, and each descended from local hunter-gatherers. By the time of the Bronze Age, these two populations and Anatolian-related farmers had mixed with each other and with the hunter-gatherers of Europe to greatly reduce genetic differentiation. The impact of the Near Eastern farmers extended beyond the Near East: farmers related to those of Anatolia spread westward into Europe; farmers related to those of the Levant spread southward into East Africa; farmers related to those of Iran spread northward into the Eurasian steppe; and people related to both the early farmers of Iran and to the pastoralists of the Eurasian steppe spread eastward into South Asia.

Discovery of Extended Main-sequence Turnoffs in Four Young Massive Clusters in the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Li, Chengyuan; de Grijs, Richard; Deng, Licai; Milone, Antonino P.

2017-08-01

An increasing number of young massive clusters (YMCs) in the Magellanic Clouds have been found to exhibit bimodal or extended main sequences (MSs) in their color-magnitude diagrams (CMDs). These features are usually interpreted in terms of a coeval stellar population with different stellar rotational rates, where the blue and red MS stars are populated by non- (or slowly) and rapidly rotating stellar populations, respectively. However, some studies have shown that an age spread of several million years is required to reproduce the observed wide turnoff regions in some YMCs. Here we present the ultraviolet-visual CMDs of four Large and Small Magellanic Cloud YMCs, NGC 330, NGC 1805, NGC 1818, and NGC 2164, based on high-precision Hubble Space Telescope photometry. We show that they all exhibit extended main-sequence turnoffs (MSTOs). The importance of age spreads and stellar rotation in reproducing the observations is investigated. The observed extended MSTOs cannot be explained by stellar rotation alone. Adopting an age spread of 35-50 Myr can alleviate this difficulty. We conclude that stars in these clusters are characterized by ranges in both their ages and rotation properties, but the origin of the age spread in these clusters remains unknown.

Genomic insights into the origin of farming in the ancient Near East

PubMed Central

Lazaridis, Iosif; Nadel, Dani; Rollefson, Gary; Merrett, Deborah C.; Rohland, Nadin; Mallick, Swapan; Fernandes, Daniel; Novak, Mario; Gamarra, Beatriz; Sirak, Kendra; Connell, Sarah; Stewardson, Kristin; Harney, Eadaoin; Fu, Qiaomei; Gonzalez-Fortes, Gloria; Jones, Eppie R.; Roodenberg, Songül Alpaslan; Lengyel, György; Bocquentin, Fanny; Gasparian, Boris; Monge, Janet M.; Gregg, Michael; Eshed, Vered; Mizrahi, Ahuva-Sivan; Meiklejohn, Christopher; Gerritsen, Fokke; Bejenaru, Luminita; Blüher, Matthias; Campbell, Archie; Cavalleri, Gianpiero; Comas, David; Froguel, Philippe; Gilbert, Edmund; Kerr, Shona M.; Kovacs, Peter; Krause, Johannes; McGettigan, Darren; Merrigan, Michael; Merriwether, D. Andrew; O'Reilly, Seamus; Richards, Martin B.; Semino, Ornella; Shamoon-Pour, Michel; Stefanescu, Gheorghe; Stumvoll, Michael; Tönjes, Anke; Torroni, Antonio; Wilson, James F.; Yengo, Loic; Hovhannisyan, Nelli A.; Patterson, Nick; Pinhasi, Ron; Reich, David

2016-01-01

We report genome-wide ancient DNA from 44 ancient Near Easterners ranging in time between ~12,000-1,400 BCE, from Natufian hunter-gatherers to Bronze Age farmers. We show that the earliest populations of the Near East derived around half their ancestry from a ‘Basal Eurasian’ lineage that had little if any Neanderthal admixture and that separated from other non-African lineages prior to their separation from each other. The first farmers of the southern Levant (Israel and Jordan) and Zagros Mountains (Iran) were strongly genetically differentiated, and each descended from local hunter-gatherers. By the time of the Bronze Age, these two populations and Anatolian-related farmers had mixed with each other and with the hunter-gatherers of Europe to drastically reduce genetic differentiation. The impact of the Near Eastern farmers extended beyond the Near East: farmers related to those of Anatolia spread westward into Europe; farmers related to those of the Levant spread southward into East Africa; farmers related to those from Iran spread northward into the Eurasian steppe; and people related to both the early farmers of Iran and to the pastoralists of the Eurasian steppe spread eastward into South Asia. PMID:27459054

Imaging the seismic structure beneath oceanic spreading centers using ocean bottom geophysical techniques

NASA Astrophysics Data System (ADS)

Zha, Yang

This dissertation focuses on imaging the crustal and upper mantle seismic velocity structure beneath oceanic spreading centers. The goals are to provide a better understanding of the crustal magmatic system and the relationship between mantle melting processes, crustal architecture and ridge characteristics. To address these questions I have analyzed ocean bottom geophysical data collected from the fast-spreading East Pacific Rise and the back-arc Eastern Lau Spreading Center using a combination of ambient noise tomography and seafloor compliance analysis. To characterize the crustal melt distribution at fast spreading ridges, I analyze seafloor compliance - the deformation under long period ocean wave forcing - measured during multiple expeditions between 1994 and 2007 at the East Pacific Rise 9º - 10ºN segment. A 3D numerical modeling technique is developed and used to estimate the effects of low shear velocity zones on compliance measurements. The forward modeling suggests strong variations of lower crustal shear velocity along the ridge axis, with zones of possible high melt fractions beneath certain segments. Analysis of repeated compliance measurements at 9º48'N indicates a decrease of crustal melt fraction following the 2005 - 2006 eruption. This temporal variability provides direct evidence for short-term variations of the magmatic system at a fast spreading ridge. To understand the relationship between mantle melting processes and crustal properties, I apply ambient noise tomography of ocean bottom seismograph (OBS) data to image the upper mantle seismic structure beneath the Eastern Lau Spreading Center (ELSC). The seismic images reveal an asymmetric upper mantle low velocity zone (LVZ) beneath the ELSC, representing a zone of partial melt. As the ridge migrates away from the volcanic arc, the LVZ becomes increasingly offset and separated from the sub-arc low velocity zone. The separation of the ridge and arc low velocity zones is spatially coincident with the abrupt transition in crustal composition and ridge morphology. Therefore these results confirm a previous prediction that the changing interaction between the arc and back-arc magmatic systems is responsible for the abrupt change in crustal properties along the ELSC. I further investigate the crustal structure along and across the ELSC using seafloor compliance. Compliance measurements are inverted for local crustal shear velocity structure as well as sediment thickness at 30 OBS locations using a Monte Carlo method. Sediment increases asymmetrically with seafloor age, with much a higher rate to the east of the ridge. Along the ELSC, upper crustal velocities increase from south to north as the ridge migrates away from the volcanic arc front, consistent with a less porous upper crust with possibly less subduction input. Furthermore, average upper crust shear velocities for crust produced at past ELSC when it was near the volcanic arc are considerably slower than crust produced at present day northern ELSC. I show that the implications of previous active seismic studies in the axial ELSC can be extended much farther off-axis and back in time. I also address a challenge of ocean bottom seismology and develop a new method for determining OBS horizontal orientations using multi-component ambient noise correlation. I demonstrate that the OBS orientations can be robustly estimated through maximizing the correlation between the diagonal and cross terms of the noise correlation function. This method is applied to the ELSC OBS experiment dataset and the obtained orientations are consistent with results from a conventional teleseismic method. The new method is promising for a wide range of applications.

Accounting for spatially heterogeneous conditions in local-scale surveillance strategies: case study of the biosecurity insect pest, grape phylloxera (Daktulosphaira vitifoliae (Fitch)).

PubMed

Triska, Maggie D; Powell, Kevin S; Collins, Cassandra; Pearce, Inca; Renton, Michael

2018-04-29

Surveillance strategies are often standardized and completed on grid patterns to detect pest incursions quickly; however, it may be possible to improve surveillance through more targeted surveillance that accounts for landscape heterogeneity, dispersal and the habitat requirements of the invading organism. We simulated pest spread at a local-scale, using grape phylloxera (Daktulosphaira vitifoliae (Fitch)) as a case study, and assessed the influence of incorporating spatial heterogeneity into surveillance strategies compared to current, standard surveillance strategies. Time to detection, spread within and spread beyond the vineyard were reduced by conducting surveys that target sampling effort in soil that is highly suitable to the invading pest in comparison to standard surveillance strategies. However, these outcomes were dependent on the virulence level of phylloxera as phylloxera is a complex pest with multiple genotypes that influence spread and detectability. Targeting surveillance strategies based on local-scale spatial heterogeneity can decrease the time to detection without increasing the survey cost and surveillance that targets highly suitable soil is the most efficient strategy for detecting new incursions. Additionally, combining targeted surveillance strategies with buffer zones and hygiene procedures, and updating surveillance strategies as additional species information becomes available, will further decrease the risk of pest spread. This article is protected by copyright. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burles, Kristin; Irwin, Chad R.; Burton, Robyn-Lee

Currently, little is known about the ankyrin/F-box protein B4. Here, we report that B4R-null viruses exhibited reduced plaque size in tissue culture, and decreased ability to spread, as assessed by multiple-step growth analysis. Electron microscopy indicated that B4R-null viruses still formed mature and extracellular virions; however, there was a slight decrease of virions released into the media following deletion of B4R. Deletion of B4R did not affect the ability of the virus to rearrange actin; however, VACV811, a large vaccinia virus deletion mutant missing 55 open reading frames, had decreased ability to produce actin tails. Using ectromelia virus, a naturalmore » mouse pathogen, we demonstrated that virus devoid of EVM154, the B4R homolog, showed decreased spread to organs and was attenuated during infection. This initial characterization suggests that B4 may play a role in virus spread, and that other unidentified mediators of actin tail formation may exist in vaccinia virus. - Highlights: • B4R-null viruses show reduced plaque size, and decreased ability to spread. • B4R-null viruses formed mature and extracellular virions; and rearranged actin. • Virus devoid of EVM154, the B4R homolog, was attenuated during infection. • Initial characterization suggests that B4 may play a role in virus spread. • Unidentified mediators of actin tail formation may exist in vaccinia virus.« less

Multiple non-syndromic odontogenic keratocysts in three siblings

PubMed Central

Nirwan, Amit; Wanjari, Sangeeta Panjab; Saikhedkar, Rashmi; Karun, Vinayak

2013-01-01

Occurrence of multiple cysts (MC) involving the jaw is rare. When multiple, it is usually associated with a syndrome. Occurrence of MC without syndromic association is extremely rare. Multiple odontogenic cysts mostly could be odontogenic keratocysts or dentigerous cysts. Odontogenic keratocyst shows involvement of mandible over maxilla, with peak incidence in second and third decade and it is exceedingly rare before 10 years of age. However multiple odontogenic keratocysts found in children are often reflective of nevoid basal cell carcinoma syndrome. Here is a case report which documents multiple jaw cysts involving both the jaws, in three siblings of ages 10, 13 and 17 years with negative parental history. All three reported cases were free of any systemic involvement. As odontogenic keratocyst spreads through bone marrow, destruction is more before any clinical manifestation. Therefore, early detection and intervention are essential in preventing extensive destruction. PMID:23505078

Connectivity disruption sparks explosive epidemic spreading.

PubMed

Böttcher, L; Woolley-Meza, O; Goles, E; Helbing, D; Herrmann, H J

2016-04-01

We investigate the spread of an infection or other malfunction of cascading nature when a system component can recover only if it remains reachable from a functioning central component. We consider the susceptible-infected-susceptible model, typical of mathematical epidemiology, on a network. Infection spreads from infected to healthy nodes, with the addition that infected nodes can only recover when they remain connected to a predefined central node, through a path that contains only healthy nodes. In this system, clusters of infected nodes will absorb their noninfected interior because no path exists between the central node and encapsulated nodes. This gives rise to the simultaneous infection of multiple nodes. Interestingly, the system converges to only one of two stationary states: either the whole population is healthy or it becomes completely infected. This simultaneous cluster infection can give rise to discontinuous jumps of different sizes in the number of failed nodes. Larger jumps emerge at lower infection rates. The network topology has an important effect on the nature of the transition: we observed hysteresis for networks with dominating local interactions. Our model shows how local spread can abruptly turn uncontrollable when it disrupts connectivity at a larger spatial scale.

Efficient determination of vehicle emission factors by fuel use category using on-road measurements: downward trends on Los Angeles freight corridor I-710

PubMed Central

Hudda, N.; Fruin, S.; Delfino, R. J.; Sioutas, C.

2013-01-01

To evaluate the success of vehicle emissions regulations, trends in both fleet-wide average emissions as well as high-emitter emissions are needed, but it is challenging to capture the full spread of vehicle emission factors (EFs) with chassis dynamometer or tunnel studies, and remote sensing studies cannot evaluate particulate compounds. We developed an alternative method that links real-time on-road pollutant measurements from a mobile platform with real-time traffic data, and allows efficient calculation of both the average and the spread of EFs for light-duty gasoline-powered vehicles (LDG) and heavy-duty diesel-powered vehicles (HDD). This is the first study in California to report EFs under a full range of real-world driving conditions on multiple freeways. Fleet average LDG EFs were in agreement with most recent studies and an order of magnitude lower than observed HDD EFs. HDD EFs reflected the relatively rapid decreases in diesel emissions that have recently occurred in Los Angeles/California, and on I-710, a primary route used for goods movement and a focus of additional truck fleet turnover incentives, HDD EFs were often lower than on other freeways. When freeway emission rates (ER) were quantified as the product of EF and vehicle miles traveled (VMT) per time per mile of freeway, despite a twoto three-fold difference in HDD fractions between freeways, ERs were found to be generally similar in magnitude. Higher LDG VMT on low HDD fraction freeways largely offset the difference. Therefore, the conventional assumption that free ways with the highest HDD fractions are significantly worse sources of total emissions in Los Angeles may no longer be true. PMID:24244208

Efficient determination of vehicle emission factors by fuel use category using on-road measurements: downward trends on Los Angeles freight corridor I-710.

PubMed

Hudda, N; Fruin, S; Delfino, R J; Sioutas, C

2013-01-11

To evaluate the success of vehicle emissions regulations, trends in both fleet-wide average emissions as well as high-emitter emissions are needed, but it is challenging to capture the full spread of vehicle emission factors (EFs) with chassis dynamometer or tunnel studies, and remote sensing studies cannot evaluate particulate compounds. We developed an alternative method that links real-time on-road pollutant measurements from a mobile platform with real-time traffic data, and allows efficient calculation of both the average and the spread of EFs for light-duty gasoline-powered vehicles (LDG) and heavy-duty diesel-powered vehicles (HDD). This is the first study in California to report EFs under a full range of real-world driving conditions on multiple freeways. Fleet average LDG EFs were in agreement with most recent studies and an order of magnitude lower than observed HDD EFs. HDD EFs reflected the relatively rapid decreases in diesel emissions that have recently occurred in Los Angeles/California, and on I-710, a primary route used for goods movement and a focus of additional truck fleet turnover incentives, HDD EFs were often lower than on other freeways. When freeway emission rates (ER) were quantified as the product of EF and vehicle miles traveled (VMT) per time per mile of freeway, despite a twoto three-fold difference in HDD fractions between freeways, ERs were found to be generally similar in magnitude. Higher LDG VMT on low HDD fraction freeways largely offset the difference. Therefore, the conventional assumption that free ways with the highest HDD fractions are significantly worse sources of total emissions in Los Angeles may no longer be true.