Error-rate performance analysis of incremental decode-and-forward opportunistic relaying

KAUST Repository

Tourki, Kamel

2011-06-01

In this paper, we investigate an incremental opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we consider regenerative relaying in which the decision to cooperate is based on a signal-to-noise ratio (SNR) threshold and takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive a closed-form expression for the end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation based on the exact probability density function (PDF) of each hop. Furthermore, we evaluate the asymptotic error performance and the diversity order is deduced. We show that performance simulation results coincide with our analytical results. © 2011 IEEE.

Toward distributed relay selection for opportunistic amplify-and-forward transmission

KAUST Repository

Tourki, Kamel

2011-05-01

Opportunistic relaying in cooperative communication depends on careful relay selection. However the traditional centralized method used for opportunistic Amplify-and-Forward (OAF) protocols requires precise measurements of channel state information (CSI) at the destination (CSI-OAF). In this paper, we propose a distributed relay selection framework for opportunistic AF (D-OAF) cooperative communications and offer an accurate performance analysis based on exact statistics of the local signalto- noise ratios of the best relay. Furthermore, we validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures, and we compare our new results with their CSI-based counterparts. © 2011 IEEE.

Benefits and performance of ATLAS approaches to utilizing opportunistic resources

CERN Document Server

Filip\\v{c}i\\v{c}, Andrej; The ATLAS collaboration

2016-01-01

ATLAS has been extensively exploring possibilities of using computing resources extending beyond conventional grid sites in the WLCG fabric to deliver as many computing cycles as possible and thereby enhance the significance of the Monte-Carlo samples to deliver better physics results. The difficulties of using such opportunistic resources come from architectural differences such as unavailability of grid services, the absence of network connectivity on worker nodes or inability to use standard authorization protocols. Nevertheless, ATLAS has been extremely successful in running production payloads on a variety of sites, thanks largely to the job execution workflow design in which the job assignment, input data provisioning and execution steps are clearly separated and can be offloaded to custom services. To transparently include the opportunistic sites in the ATLAS central production system, several models with supporting services have been developed to mimic the functionality of a full WLCG site. Some are e...

Capacity of Wireless Ad Hoc Networks with Opportunistic Collaborative Communications

Directory of Open Access Journals (Sweden)

Simeone O

2007-01-01

Full Text Available Optimal multihop routing in ad hoc networks requires the exchange of control messages at the MAC and network layer in order to set up the (centralized optimization problem. Distributed opportunistic space-time collaboration (OST is a valid alternative that avoids this drawback by enabling opportunistic cooperation with the source at the physical layer. In this paper, the performance of OST is investigated. It is shown analytically that opportunistic collaboration outperforms (centralized optimal multihop in case spatial reuse (i.e., the simultaneous transmission of more than one data stream is not allowed by the transmission protocol. Conversely, in case spatial reuse is possible, the relative performance between the two protocols has to be studied case by case in terms of the corresponding capacity regions, given the topology and the physical parameters of network at hand. Simulation results confirm that opportunistic collaborative communication is a promising paradigm for wireless ad hoc networks that deserves further investigation.

Capacity of Wireless Ad Hoc Networks with Opportunistic Collaborative Communications

Directory of Open Access Journals (Sweden)

O. Simeone

2007-03-01

Full Text Available Optimal multihop routing in ad hoc networks requires the exchange of control messages at the MAC and network layer in order to set up the (centralized optimization problem. Distributed opportunistic space-time collaboration (OST is a valid alternative that avoids this drawback by enabling opportunistic cooperation with the source at the physical layer. In this paper, the performance of OST is investigated. It is shown analytically that opportunistic collaboration outperforms (centralized optimal multihop in case spatial reuse (i.e., the simultaneous transmission of more than one data stream is not allowed by the transmission protocol. Conversely, in case spatial reuse is possible, the relative performance between the two protocols has to be studied case by case in terms of the corresponding capacity regions, given the topology and the physical parameters of network at hand. Simulation results confirm that opportunistic collaborative communication is a promising paradigm for wireless ad hoc networks that deserves further investigation.

Performance of an opportunistic multi-user cognitive network with multiple primary users

KAUST Repository

Khan, Fahd Ahmed

2014-04-01

Consider a multi-user underlay cognitive network where multiple cognitive users, having limited peak transmit power, concurrently share the spectrum with a primary network with multiple users. The channel between the secondary network is assumed to have independent but not identical Nakagami-m fading. The interference channel between the secondary users and the primary users is assumed to have Rayleigh fading. The uplink scenario is considered where a single secondary user is selected for transmission. This opportunistic selection depends on the transmission channel power gain and the interference channel power gain as well as the power allocation policy adopted at the users. Exact closed form expressions for the momentgenerating function, outage performance and the symbol-error-rate performance are derived. The outage performance is also studied in the asymptotic regimes and the generalized diversity gain of this scheduling scheme is derived. Numerical results corroborate the derived analytical results.

Evaluation of Opportunistic Routing Algorithms on Opportunistic Mobile Sensor Networks with Infrastructure Assistance

NARCIS (Netherlands)

Le Viet Duc, L Duc; Scholten, Johan; Havinga, Paul J.M.

2012-01-01

Recently the increasing number of sensors integrated in smartphones, especially the iPhone and Android phones, has motivated the development of routing algorithms for Opportunistic Mobile Sensor Networks (OppMSNs). Although there are many existing opportunistic routing algorithms, researchers still

Performance of an opportunistic multi-user cognitive network with multiple primary users

KAUST Repository

Khan, Fahd Ahmed; Tourki, Kamel; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

2014-01-01

for transmission. This opportunistic selection depends on the transmission channel power gain and the interference channel power gain as well as the power allocation policy adopted at the users. Exact closed form expressions for the momentgenerating function

Effect of threshold quantization in opportunistic splitting algorithm

KAUST Repository

Nam, Haewoon; Alouini, Mohamed-Slim

2011-01-01

This paper discusses algorithms to find the optimal threshold and also investigates the impact of threshold quantization on the scheduling outage performance of the opportunistic splitting scheduling algorithm. Since this algorithm aims at finding

Performance of systematic and non-systematic ('opportunistic') screening mammography: a comparative study from Denmark

DEFF Research Database (Denmark)

Bihrmann, Kristine; Jensen, Allan; Olsen, Anne Helene

2008-01-01

screening were calculated. RESULTS: Defining BI-RADS(trade mark) 4-5 as a positive screening outcome, the overall sensitivity of opportunistic screening was 33.6% and the specificity was 99.1%. Using BI-RADS(trade mark) 3-5 as positive, the sensitivity was 37.4% and the specificity was 97.9%. Organized...... screening (which was not categorized according to BI-RADS(trade mark)) had an overall sensitivity of 67.2% and a specificity of 98.4%. CONCLUSION: Our study showed a considerably higher sensitivity in organized screening than in opportunistic screening, while the specificity was fairly similar in the two...

Alternative Opportunistic Alert Diffusion to Support Infrastructure Failure during Disasters

Directory of Open Access Journals (Sweden)

Farouk Mezghani

2017-10-01

Full Text Available Opportunistic communications present a promising solution for disaster network recovery in emergency situations such as hurricanes, earthquakes, and floods, where infrastructure might be destroyed. Some recent works in the literature have proposed opportunistic-based disaster recovery solutions, but they have omitted the consideration of mobile devices that come with different network technologies and various initial energy levels. This work presents COPE, an energy-aware Cooperative OPportunistic alErt diffusion scheme for trapped survivors to use during disaster scenarios to report their position and ease their rescue operation. It aims to maintain mobile devices functional for as long as possible for maximum network coverage until reaching proximate rescuers. COPE deals with mobile devices that come with an assortment of networks and aims to perform systematic network interface selection. Furthermore, it considers mobile devices with various energy levels and allows low-energy nodes to hold their charge for longer time with the support of high-energy nodes. A proof-of-concept implementation has been performed to study the doability and efficiency of COPE, and to highlight the lessons learned.

Stimulating Creativity Through Opportunistic Software Development

NARCIS (Netherlands)

Z. Obrenovic; D. Gasevic; A. P. W. Eliëns (Anton)

2008-01-01

htmlabstractUsing opportunistic software development principles in computer engineering education encourages students to be creative and to develop solutions that cross the boundaries of diverse technologies. A framework for opportunistic software development education helps to create a space in

Stimulating creativity through opportunistic software development

NARCIS (Netherlands)

Obrenovic, Z.; Gasevic, D.; Eliëns, A.

2008-01-01

Using opportunistic software development principles in computer engineering education encourages students to be creative and to develop solutions that cross the boundaries of diverse technologies. A framework for opportunistic software development education helps to create a space in which students

A P2P Query Algorithm for Opportunistic Networks Utilizing betweenness Centrality Forwarding

Directory of Open Access Journals (Sweden)

Jianwei Niu

2013-01-01

Full Text Available With the proliferation of high-end mobile devices that feature wireless interfaces, many promising applications are enabled in opportunistic networks. In contrary to traditional networks, opportunistic networks utilize the mobility of nodes to relay messages in a store-carry-forward paradigm. Thus, the relay process in opportunistic networks faces several practical challenges in terms of delay and delivery rate. In this paper, we propose a novel P2P Query algorithm, namely Betweenness Centrality Forwarding (PQBCF, for opportunistic networking. PQBCF adopts a forwarding metric called Betweenness Centrality (BC, which is borrowed from social network, to quantify the active degree of nodes in the networks. In PQBCF, nodes with a higher BC are preferable to serve as relays, leading to higher query success rate and lower query delay. A comparison with the state-of-the-art algorithms reveals that PQBCF can provide better performance on both the query success Ratio and query delay, and approaches the performance of Epidemic Routing (ER with much less resource consumption.

Opportunistic Sensing in Wireless Sensor Networks

NARCIS (Netherlands)

Scholten, Johan; Bakker, Pascal

Opportunistic sensing systems consist of changing constellations of wireless sensor nodes that, for a limited amount of time, work together to achieve a common goal. Such constellations are self-organizing and come into being spontaneously. This paper presents an opportunistic sensing system to

Opportunistic resource usage in CMS

International Nuclear Information System (INIS)

Kreuzer, Peter; Hufnagel, Dirk; Dykstra, D; Gutsche, O; Tadel, M; Sfiligoi, I; Letts, J; Wuerthwein, F; McCrea, A; Bockelman, B; Fajardo, E; Linares, L; Wagner, R; Konstantinov, P; Blumenfeld, B; Bradley, D

2014-01-01

CMS is using a tiered setup of dedicated computing resources provided by sites distributed over the world and organized in WLCG. These sites pledge resources to CMS and are preparing them especially for CMS to run the experiment's applications. But there are more resources available opportunistically both on the GRID and in local university and research clusters which can be used for CMS applications. We will present CMS' strategy to use opportunistic resources and prepare them dynamically to run CMS applications. CMS is able to run its applications on resources that can be reached through the GRID, through EC2 compliant cloud interfaces. Even resources that can be used through ssh login nodes can be harnessed. All of these usage modes are integrated transparently into the GlideIn WMS submission infrastructure, which is the basis of CMS' opportunistic resource usage strategy. Technologies like Parrot to mount the software distribution via CVMFS and xrootd for access to data and simulation samples via the WAN are used and will be described. We will summarize the experience with opportunistic resource usage and give an outlook for the restart of LHC data taking in 2015.

Optimising social information by game theory and ant colony method to enhance routing protocol in opportunistic networks

Directory of Open Access Journals (Sweden)

Chander Prabha

2016-09-01

Full Text Available The data loss and disconnection of nodes are frequent in the opportunistic networks. The social information plays an important role in reducing the data loss because it depends on the connectivity of nodes. The appropriate selection of next hop based on social information is critical for improving the performance of routing in opportunistic networks. The frequent disconnection problem is overcome by optimising the social information with Ant Colony Optimization method which depends on the topology of opportunistic network. The proposed protocol is examined thoroughly via analysis and simulation in order to assess their performance in comparison with other social based routing protocols in opportunistic network under various parameters settings.

Performance analysis of an opportunistic multi-user cognitive network with multiple primary users

KAUST Repository

Khan, Fahd Ahmed; Tourki, Kamel; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

2014-01-01

constraint is imposed on the secondary network in addition to the limited peak transmit power of each SU. The uplink scenario is considered where a single SU is selected for transmission. This opportunistic selection depends on the transmission channel power

Opportunistic Infections and Complications in Human Immunodeficiency Virus-1-Infected Children: Correlation with immune status

Directory of Open Access Journals (Sweden)

Jaivinder Yadav

2014-10-01

Full Text Available Objectives: The aim of this study was to ascertain the correlation between various opportunistic infections and complications in human immunodeficiency virus (HIV-1-infected children and the immune status of these patients, evaluated by absolute cluster of differentiation 4 (CD4 count and CD4 percentage. Methods: This study was conducted from January 2009 to June 2010 at the Antiretroviral Treatment Centre of the Pt. B.D. Sharma Post Graduate Institute of Medical Sciences, a tertiary care hospital in Rohtak, Haryana, in northern India. A total of 20 HIV-1-infected children aged 4–57 months were studied. Demographic and baseline investigations were performed prior to the start of highly active antiretroviral therapy (HAART. A fixed-dose combination of HAART was given based on the patient’s weight. Baseline investigations were repeated after six months of HAART. Results: There was a significant increase in the patients’ haemoglobin, weight, height and CD4 count after six months of HAART. Significant improvements (P <0.05 were also noted in the patients’ immune status, graded according to the World Health Organization. Conclusion: This study observed that the severity and frequency of opportunistic complications in paediatric patients with HIV-1 increased with a fall in the CD4 count. The treatment of opportunistic infections, along with antiretroviral therapy, may lead to both clinical and immunological recovery as well as a decreased incidence of future opportunistic infections. The CD4 count may give treating physicians an initial idea about the immune status of each child and could also be used as a biological marker of HAART efficacy. Patient compliance must be ensured during HAART as this is a key factor in improving outcomes.

Improving Network Performance with Affinity based Mobility Model in Opportunistic Network

OpenAIRE

Suvadip Batabyal; Parama Bhaumik

2012-01-01

Opportunistic network is a type of Delay Tolerant Network which is characterized by intermittent connectivity amongst the nodes and communication largely depends upon the mobility of the participating nodes. The network being highly dynamic, traditional MANET protocols cannot be applied and the nodes must adhere to store-carry-forward mechanism. Nodes do not have the information about the network topology, number of participating nodes and the location of the destination node. Hence, message ...

Exploiting opportunistic resources for ATLAS with ARC CE and the Event Service

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00226583; The ATLAS collaboration; Filipčič, Andrej; Guan, Wen; Tsulaia, Vakhtang; Walker, Rodney; Wenaus, Torre

2017-01-01

With ever-greater computing needs and fixed budgets, big scientific experiments are turning to opportunistic resources as a means to add much-needed extra computing power. These resources can be very different in design from the resources that comprise the Grid computing of most experiments, therefore exploiting these resources requires a change in strategy for the experiment. The resources may be highly restrictive in what can be run or in connections to the outside world, or tolerate opportunistic usage only on condition that tasks may be terminated without warning. The ARC CE with its non-intrusive architecture is designed to integrate resources such as High Performance Computing (HPC) systems into a computing Grid. The ATLAS experiment developed the Event Service primarily to address the issue of jobs that can be terminated at any point when opportunistic resources are needed by someone else. This paper describes the integration of these two systems in order to exploit opportunistic resources for ATLAS in...

Exploiting Opportunistic Resources for ATLAS with ARC CE and the Event Service

CERN Document Server

Cameron, David; The ATLAS collaboration

2016-01-01

With ever-greater computing needs and fixed budgets, big scientific experiments are turning to opportunistic resources as a means to add much-needed extra computing power. These resources can be very different in design from the resources that comprise the Grid computing of most experiments, therefore exploiting these resources requires a change in strategy for the experiment. The resources may be highly restrictive in what can be run or in connections to the outside world, or tolerate opportunistic usage only on condition that tasks may be terminated without warning. The ARC CE with its non-intrusive architecture is designed to integrate resources such as High Performance Computing (HPC) systems into a computing Grid. The ATLAS experiment developed the Event Service primarily to address the issue of jobs that can be terminated at any point when opportunistic resources are needed by someone else. This paper describes the integration of these two systems in order to exploit opportunistic resources for ATLAS in...

Distance-Based Opportunistic Mobile Data Offloading.

Science.gov (United States)

Lu, Xiaofeng; Lio, Pietro; Hui, Pan

2016-06-15

Cellular network data traffic can be offload onto opportunistic networks. This paper proposes a Distance-based Opportunistic Publish/Subscribe (DOPS) content dissemination model, which is composed of three layers: application layer, decision-making layer and network layer. When a user wants new content, he/she subscribes on a subscribing server. Users having the contents decide whether to deliver the contents to the subscriber based on the distance information. If in the meantime a content owner has traveled further in the immediate past time than the distance between the owner and the subscriber, the content owner will send the content to the subscriber through opportunistic routing. Simulations provide an evaluation of the data traffic offloading efficiency of DOPS.

Opportunistic spectrum access in cognitive radio based on channel switching

KAUST Repository

Gaaloul, Fakhreddine; Yang, Hongchuan; Radaydeh, Redha Mahmoud Mesleh; Alouini, Mohamed-Slim

2012-01-01

This paper investigates the performance of a cognitive radio transceiver that can monitor multiple channels and opportunistically use any one of them should it be available. In our work, we propose and compare two different opportunistic channel access schemes. The first scheme applies when the secondary user (SU) has access to only one channel. The second scheme applies when the SU has access to multiple channels but can at a given time monitor and access only one channel. Two switching strategies, namely the switch and examine and the switch and stay strategies, are proposed. For these proposed access schemes, we investigate their performance by deriving the analytical expression of the novel metric of the average access duration and the average waiting time and based on these two metrics a time average SU throughput formula is proposed to predict the performance of the secondary cognitive system. © 2012 ICST.

Distance-Based Opportunistic Mobile Data Offloading

Directory of Open Access Journals (Sweden)

Xiaofeng Lu

2016-06-01

Full Text Available Cellular network data traffic can be offload onto opportunistic networks. This paper proposes a Distance-based Opportunistic Publish/Subscribe (DOPS content dissemination model, which is composed of three layers: application layer, decision-making layer and network layer. When a user wants new content, he/she subscribes on a subscribing server. Users having the contents decide whether to deliver the contents to the subscriber based on the distance information. If in the meantime a content owner has traveled further in the immediate past time than the distance between the owner and the subscriber, the content owner will send the content to the subscriber through opportunistic routing. Simulations provide an evaluation of the data traffic offloading efficiency of DOPS.

Opportunistic quantum network coding based on quantum teleportation

Science.gov (United States)

Shang, Tao; Du, Gang; Liu, Jian-wei

2016-04-01

It seems impossible to endow opportunistic characteristic to quantum network on the basis that quantum channel cannot be overheard without disturbance. In this paper, we propose an opportunistic quantum network coding scheme by taking full advantage of channel characteristic of quantum teleportation. Concretely, it utilizes quantum channel for secure transmission of quantum states and can detect eavesdroppers by means of quantum channel verification. What is more, it utilizes classical channel for both opportunistic listening to neighbor states and opportunistic coding by broadcasting measurement outcome. Analysis results show that our scheme can reduce the times of transmissions over classical channels for relay nodes and can effectively defend against classical passive attack and quantum active attack.

Social-aware data dissemination in opportunistic mobile social networks

Science.gov (United States)

Yang, Yibo; Zhao, Honglin; Ma, Jinlong; Han, Xiaowei

Opportunistic Mobile Social Networks (OMSNs), formed by mobile users with social relationships and characteristics, enhance spontaneous communication among users that opportunistically encounter each other. Such networks can be exploited to improve the performance of data forwarding. Discovering optimal relay nodes is one of the important issues for efficient data propagation in OMSNs. Although traditional centrality definitions to identify the nodes features in network, they cannot identify effectively the influential nodes for data dissemination in OMSNs. Existing protocols take advantage of spatial contact frequency and social characteristics to enhance transmission performance. However, existing protocols have not fully exploited the benefits of the relations and the effects between geographical information, social features and user interests. In this paper, we first evaluate these three characteristics of users and design a routing protocol called Geo-Social-Interest (GSI) protocol to select optimal relay nodes. We compare the performance of GSI using real INFOCOM06 data sets. The experiment results demonstrate that GSI overperforms the other protocols with highest data delivery ratio and low communication overhead.

Opportunistic Carrier Sensing for Energy-Efficient Information Retrieval in Sensor Networks

Directory of Open Access Journals (Sweden)

Zhao Qing

2005-01-01

Full Text Available We consider distributed information retrieval for sensor networks with cluster heads or mobile access points. The performance metric used in the design is energy efficiency defined as the ratio of the average number of bits reliably retrieved by the access point to the total amount of energy consumed. A distributed opportunistic transmission protocol is proposed using a combination of carrier sensing and backoff strategy that incorporates channel state information (CSI of individual sensors. By selecting a set of sensors with the best channel states to transmit, the proposed protocol achieves the upper bound on energy efficiency when the signal propagation delay is negligible. For networks with substantial propagation delays, a backoff function optimized for energy efficiency is proposed. The design of this backoff function utilizes properties of extreme statistics and is shown to have mild performance loss in practical scenarios. We also demonstrate that opportunistic strategies that use CSI may not be optimal when channel acquisition at individual sensors consumes substantial energy. We show further that there is an optimal sensor density for which the opportunistic information retrieval is the most energy efficient. This observation leads to the design of the optimal sensor duty cycle.

Non-Orthogonal Opportunistic Beamforming: Performance Analysis and Implementation

KAUST Repository

Xia, Minghua

2012-04-01

Aiming to achieve the sum-rate capacity in multi-user multi-antenna systems where $N_t$ antennas are implemented at the transmitter, opportunistic beamforming (OBF) generates~$N_t$ orthonormal beams and serves $N_t$ users during each channel use, which results in high scheduling delay over the users, especially in densely populated networks. Non-orthogonal OBF with more than~$N_t$ transmit beams can be exploited to serve more users simultaneously and further decrease scheduling delay. However, the inter-beam interference will inevitably deteriorate the sum-rate. Therefore, there is a tradeoff between sum-rate and scheduling delay for non-orthogonal OBF. In this context, system performance and implementation of non-orthogonal OBF with $N>N_t$ beams are investigated in this paper. Specifically, it is analytically shown that non-orthogonal OBF is an interference-limited system as the number of users $K \\\\to \\\\infty$. When the inter-beam interference reaches its minimum for fixed $N_t$ and~$N$, the sum-rate scales as $N\\\\ln\\\\left(\\\\frac{N}{N-N_t}\\ ight)$ and it degrades monotonically with the number of beams $N$ for fixed $N_t$. On the contrary, the average scheduling delay is shown to scale as $\\\\frac{1}{N}K\\\\ln{K}$ channel uses and it improves monotonically with $N$. Furthermore, two practical non-orthogonal beamforming schemes are explicitly constructed and they are demonstrated to yield the minimum inter-beam interference for fixed $N_t$ and $N$. This study reveals that, if user traffic is light and one user can be successfully served within a single transmission, non-orthogonal OBF can be applied to obtain lower worst-case delay among the users. On the other hand, if user traffic is heavy, non-orthogonal OBF is inferior to orthogonal OBF in terms of sum-rate and packet delay.

Opportunistic infection of HIV/AIDS patients in West Papua

Science.gov (United States)

Witaningrum, A. M.; Khairunisa, S. Q.; Yunifiar, M. Q.; Bramanthi, R.; Rachman, B. E.; Nasronudin

2018-03-01

Human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) had a major impact on health problemin Indonesia. HIV type 1 (HIV-1) epidemic is currently infected with HIV viruses developing rapidly in Indonesia.Papua provinces have the highest prevalence rate of human immunodeficiency virus type 1 (HIV-1) infection in Indonesia; however, data on opportunistic infection of HIV-1 are limited. The study using medical records as a research sample was conducted among HIV patients from January 2013 - December 2014 in Sele be Solu hospital among 49 patients. Opportunistic infections commonly occur in HIV-infected patients. The aim of the study was to know theprevalence of opportunistic infection among HIV positive patients in West Papua. Forty-nine HIV-1 patients were collected in Sele be Solu Hospital, West Papua.Opportunistic infection was identified such as tuberculosis, tuberculosis Pulmo, tuberculosis and candidiasis, candidiasis and diarrhea. The clinical sign appeared in HIV infected patients such as itchy, cough and loss weight. The prevalence of opportunistic infection indicated the necessity of monitoring the opportunistic infection of HIV/AIDS patients in Indonesia.

Switch Based Opportunistic Spectrum Access for General Primary User Traffic Model

KAUST Repository

Gaaloul, Fakhreddine

2012-06-18

This letter studies cognitive radio transceiver that can opportunistically use the available channels of primary user (PU). Specifically, we investigate and compare two different opportunistic channel access schemes. The first scheme applies when the secondary user (SU) has access to only one channel. The second scheme, based on channel switching mechanism, applies when the SU has access to multiple channels but can at a given time monitor and access only one channel. For these access schemes, we derive the exact analytical results for the novel performance metrics of average access time and average waiting time under general PU traffic models.

Switch Based Opportunistic Spectrum Access for General Primary User Traffic Model

KAUST Repository

Gaaloul, Fakhreddine; Alouini, Mohamed-Slim; Radaydeh, Redha M.; Yang, Hong-Chuan

2012-01-01

This letter studies cognitive radio transceiver that can opportunistically use the available channels of primary user (PU). Specifically, we investigate and compare two different opportunistic channel access schemes. The first scheme applies when the secondary user (SU) has access to only one channel. The second scheme, based on channel switching mechanism, applies when the SU has access to multiple channels but can at a given time monitor and access only one channel. For these access schemes, we derive the exact analytical results for the novel performance metrics of average access time and average waiting time under general PU traffic models.

Iterative group splitting algorithm for opportunistic scheduling systems

KAUST Repository

Nam, Haewoon; Alouini, Mohamed-Slim

2014-01-01

An efficient feedback algorithm for opportunistic scheduling systems based on iterative group splitting is proposed in this paper. Similar to the opportunistic splitting algorithm, the proposed algorithm adjusts (or lowers) the feedback threshold

Efficient scheduling request algorithm for opportunistic wireless access

KAUST Repository

Nam, Haewoon; Alouini, Mohamed-Slim

2011-01-01

An efficient scheduling request algorithm for opportunistic wireless access based on user grouping is proposed in this paper. Similar to the well-known opportunistic splitting algorithm, the proposed algorithm initially adjusts (or lowers

Exploiting opportunistic resources for ATLAS with ARC CE and the Event Service

Science.gov (United States)

Cameron, D.; Filipčič, A.; Guan, W.; Tsulaia, V.; Walker, R.; Wenaus, T.; ATLAS Collaboration

2017-10-01

With ever-greater computing needs and fixed budgets, big scientific experiments are turning to opportunistic resources as a means to add much-needed extra computing power. These resources can be very different in design from those that comprise the Grid computing of most experiments, therefore exploiting them requires a change in strategy for the experiment. They may be highly restrictive in what can be run or in connections to the outside world, or tolerate opportunistic usage only on condition that tasks may be terminated without warning. The Advanced Resource Connector Computing Element (ARC CE) with its nonintrusive architecture is designed to integrate resources such as High Performance Computing (HPC) systems into a computing Grid. The ATLAS experiment developed the ATLAS Event Service (AES) primarily to address the issue of jobs that can be terminated at any point when opportunistic computing capacity is needed by someone else. This paper describes the integration of these two systems in order to exploit opportunistic resources for ATLAS in a restrictive environment. In addition to the technical details, results from deployment of this solution in the SuperMUC HPC centre in Munich are shown.

Opportunistic Music

OpenAIRE

Hachet , Martin; Kian , Arash; Berthaut , Florent; Franco , Jean-Sébastien; Desainte-Catherine , Myriam

2009-01-01

International audience; While mixed reality has inspired the development of many new musical instruments, few approaches explore the potential of mobile setups. We present a new musical interaction concept, called "opportunistic music". It allows musicians to recreate a hardware musical controller using any objects of their immediate environment. This approach benefits from the physical properties of real objects for controlling music. Our prototype is based on a stereo-vision tracking system...

Economic transactions, opportunistic behavior and protective mechanisms

DEFF Research Database (Denmark)

Koch, Carsten Allan

Whenever actors participate in transactions they expose themselves to risks of various kinds. Some of these risks are attributable to events outside the control of the participants and are unavoidable. Others originate in, or are aggrevated by, opportunistic actions undertaken by contract partners...... and other co-operators. This paper is concerned with the latter type of risk and the protection against it. Six protective mechanisms, which may serve as safeguards against opportunistic behavior, are presented and discussed. Special attention is paid to reputation effects. It is noted that such effects may...... account for the lack of opportunistic behavior with which networks are often credited. No protective mechanism is, however, effective under all circumstances....

Opportunistic transmitter selection for selfless overlay cognitive radios

KAUST Repository

Shaqfeh, Mohammad

2013-11-01

We propose an opportunistic strategy to grant channel access to the primary and secondary transmitters in causal selfless overlay cognitive radios over block-fading channels. The secondary transmitter helps the primary transmitter by relaying the primary messages opportunistically, aided by a buffer to store the primary messages temporarily. The optimal channel-aware transmitter- selection strategy is the solution of the maximization of the average secondary rate under the average primary rate requirement and the buffer stability constraints. Numerical results demonstrate the gains of the proposed opportunistic selection strategy. © 2013 IEEE.

Performance analysis of an opportunistic multi-user cognitive network with multiple primary users

KAUST Repository

Khan, Fahd Ahmed

2014-03-01

Consider a multi-user underlay cognitive network where multiple cognitive users concurrently share the spectrum with a primary network with multiple users. The channel between the secondary network is assumed to have independent but not identical Nakagami-m fading. The interference channel between the secondary users (SUs) and the primary users is assumed to have Rayleigh fading. A power allocation based on the instantaneous channel state information is derived when a peak interference power constraint is imposed on the secondary network in addition to the limited peak transmit power of each SU. The uplink scenario is considered where a single SU is selected for transmission. This opportunistic selection depends on the transmission channel power gain and the interference channel power gain as well as the power allocation policy adopted at the users. Exact closed form expressions for the moment-generating function, outage performance, symbol error rate performance, and the ergodic capacity are derived. Numerical results corroborate the derived analytical results. The performance is also studied in the asymptotic regimes, and the generalized diversity gain of this scheduling scheme is derived. It is shown that when the interference channel is deeply faded and the peak transmit power constraint is relaxed, the scheduling scheme achieves full diversity and that increasing the number of primary users does not impact the diversity order. © 2014 John Wiley & Sons, Ltd.

Path Diversity Improved Opportunistic Routing for Underwater Sensor Networks.

Science.gov (United States)

Bai, Weigang; Wang, Haiyan; He, Ke; Zhao, Ruiqin

2018-04-23

The packets carried along a pre-defined route in underwater sensor networks are very vulnerble. Node mobility or intermittent channel availability easily leads to unreachable routing. Opportunistic routing has been proven to be a promising paradigm to design routing protocols for underwater sensor networks. It takes advantage of the broadcast nature of the wireless medium to combat packet losses and selects potential paths on the fly. Finding an appropriate forwarding candidate set is a key issue in opportunistic routing. Many existing solutions ignore the impact of candidates location distribution on packet forwarding. In this paper, a path diversity improved candidate selection strategy is applied in opportunistic routing to improve packet forwarding efficiency. It not only maximizes the packet forwarding advancements but also takes the candidate’s location distribution into account. Based on this strategy, we propose two effective routing protocols: position improved candidates selection (PICS) and position random candidates selection (PRCS). PICS employs two-hop neighbor information to make routing decisions. PRCS only uses one-hop neighbor information. Simulation results show that both PICS and PRCS can significantly improve network performance when compared with the previous solutions, in terms of packet delivery ratio, average energy consumption and end-to-end delay.

Path Diversity Improved Opportunistic Routing for Underwater Sensor Networks

Directory of Open Access Journals (Sweden)

Weigang Bai

2018-04-01

Full Text Available The packets carried along a pre-defined route in underwater sensor networks are very vulnerble. Node mobility or intermittent channel availability easily leads to unreachable routing. Opportunistic routing has been proven to be a promising paradigm to design routing protocols for underwater sensor networks. It takes advantage of the broadcast nature of the wireless medium to combat packet losses and selects potential paths on the fly. Finding an appropriate forwarding candidate set is a key issue in opportunistic routing. Many existing solutions ignore the impact of candidates location distribution on packet forwarding. In this paper, a path diversity improved candidate selection strategy is applied in opportunistic routing to improve packet forwarding efficiency. It not only maximizes the packet forwarding advancements but also takes the candidate’s location distribution into account. Based on this strategy, we propose two effective routing protocols: position improved candidates selection (PICS and position random candidates selection (PRCS. PICS employs two-hop neighbor information to make routing decisions. PRCS only uses one-hop neighbor information. Simulation results show that both PICS and PRCS can significantly improve network performance when compared with the previous solutions, in terms of packet delivery ratio, average energy consumption and end-to-end delay.

Channel access delay and buffer distribution of two-user opportunistic scheduling schemes in wireless networks

KAUST Repository

Hossain, Md Jahangir

2010-07-01

In our earlier works, we proposed rate adaptive hierarchical modulation-assisted two-best user opportunistic scheduling (TBS) and hybrid two-user scheduling (HTS) schemes. The proposed schemes are innovative in the sense that they include a second user in the transmission opportunistically using hierarchical modulations. As such the frequency of information access of the users increases without any degradation of the system spectral efficiency (SSE) compared to the classical opportunistic scheduling scheme. In this paper, we analyze channel access delay of an incoming packet at the base station (BS) buffer when our proposed TBS and HTS schemes are employed at the BS. Specifically, using a queuing analytic model we derive channel access delay as well as buffer distribution of the packets that wait at BS buffer for down-link (DL) transmission. We compare performance of the TBS and HTS schemes with that of the classical single user opportunistic schemes namely, absolute carrier-to-noise ratio (CNR)-based single user scheduling (ASS) and normalized CNR-based single user scheduling (NSS). For an independent and identically distributed (i.i.d.) fading environment, our proposed scheme can improve packet\\'s access delay performance compared to the ASS. Selected numerical results in an independent but non-identically distributed (i.n.d.) fading environment show that our proposed HTS achieves overall good channel access delay performance. © 2010 IEEE.

Beyond Traditional DTN Routing: Social Networks for Opportunistic Communication

OpenAIRE

Schurgot, Mary R.; Comaniciu, Cristina; Jaffrès-Runser, Katia

2011-01-01

This article examines the evolution of routing protocols for intermittently connected ad hoc networks and discusses the trend toward social-based routing protocols. A survey of current routing solutions is presented, where routing protocols for opportunistic networks are classified based on the network graph employed. The need to capture performance tradeoffs from a multi-objective perspective is highlighted.

Performance Analysis of Cell-Phone Worm Spreading in Cellular Networks through Opportunistic Communications

Directory of Open Access Journals (Sweden)

YAHUI, W.

2012-05-01

Full Text Available Worms spreading directly between cell-phones over short-range radio (Bluetooth, WiFi, etc. are increasing rapidly. Communication by these technologies is opportunistic and has very close relation with the social characteristics of the phone carriers. In this paper, we try to evaluate the impact of different characteristics on the spreading performance of worms. On the other hand, the behaviors of worms may have certain impact, too. For example, worms may make phones be completely dysfunctional and these phones can be seen as killed. We study the impact of the killing speed. Using the Markov model, we propose some theoretical models to evaluate the spreading performance in different cases. Simulation results show the accuracy of our models. Numerical results show that if users do not believe the data coming from others easily, the worms may bring less damage. Surprisingly, if the users are more willing to install the anti-virus software, the worms may bring bigger damage when the software becomes to be outdated with high probability. Though the worms can bring big damage on the network temporarily by killing phones rapidly, numerical results show that this behavior may decrease the total damage in the long time. Therefore, killing nodes more rapidly may be not optimal for worms.

Node-Dependence-Based Dynamic Incentive Algorithm in Opportunistic Networks

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Ruiyun Yu

2014-01-01

Full Text Available Opportunistic networks lack end-to-end paths between source nodes and destination nodes, so the communications are mainly carried out by the “store-carry-forward” strategy. Selfish behaviors of rejecting packet relay requests will severely worsen the network performance. Incentive is an efficient way to reduce selfish behaviors and hence improves the reliability and robustness of the networks. In this paper, we propose the node-dependence-based dynamic gaming incentive (NDI algorithm, which exploits the dynamic repeated gaming to motivate nodes relaying packets for other nodes. The NDI algorithm presents a mechanism of tolerating selfish behaviors of nodes. Reward and punishment methods are also designed based on the node dependence degree. Simulation results show that the NDI algorithm is effective in increasing the delivery ratio and decreasing average latency when there are a lot of selfish nodes in the opportunistic networks.

Iterative group splitting algorithm for opportunistic scheduling systems

KAUST Repository

Nam, Haewoon

2014-05-01

An efficient feedback algorithm for opportunistic scheduling systems based on iterative group splitting is proposed in this paper. Similar to the opportunistic splitting algorithm, the proposed algorithm adjusts (or lowers) the feedback threshold during a guard period if no user sends a feedback. However, when a feedback collision occurs at any point of time, the proposed algorithm no longer updates the threshold but narrows down the user search space by dividing the users into multiple groups iteratively, whereas the opportunistic splitting algorithm keeps adjusting the threshold until a single user is found. Since the threshold is only updated when no user sends a feedback, it is shown that the proposed algorithm significantly alleviates the signaling overhead for the threshold distribution to the users by the scheduler. More importantly, the proposed algorithm requires a less number of mini-slots than the opportunistic splitting algorithm to make a user selection with a given level of scheduling outage probability or provides a higher ergodic capacity given a certain number of mini-slots. © 2013 IEEE.

Alleviate Cellular Congestion Through Opportunistic Trough Filling

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Yichuan Wang

2014-04-01

Full Text Available The demand for cellular data service has been skyrocketing since the debut of data-intensive smart phones and touchpads. However, not all data are created equal. Many popular applications on mobile devices, such as email synchronization and social network updates, are delay tolerant. In addition, cellular load varies significantly in both large and small time scales. To alleviate network congestion and improve network performance, we present a set of opportunistic trough filling schemes that leverage the time-variation of network congestion and delay-tolerance of certain traffic in this paper. We consider average delay, deadline, and clearance time as the performance metrics. Simulation results show promising performance improvement over the standard schemes. The work shed lights on addressing the pressing issue of cellular overload.

Science and Technology Teachers' Views of Primary School Science and Technology Curriculum

Science.gov (United States)

Yildiz-Duban, Nil

2013-01-01

This phenomenographic study attempts to explicit science and technology teachers' views of primary school science and technology curriculum. Participants of the study were selected through opportunistic sampling and consisted of 30 science and technology teachers teaching in primary schools in Afyonkarahisar, Turkey. Data were collected through an…

Node Load Balance Multi-flow Opportunistic Routing in Wireless Mesh Networks

Directory of Open Access Journals (Sweden)

Wang Tao

2014-04-01

Full Text Available Opportunistic routing (OR has been proposed to improve the performance of wireless networks by exploiting the multi-user diversity and broadcast nature of the wireless medium. It involves multiple candidate forwarders to relay packets every hop. The existing OR doesn’t take account of the traffic load and load balance, therefore some nodes may be overloaded while the others may not, leading to network performance decline. In this paper, we focus on opportunities routing selection with node load balance which is described as a convex optimization problem. To solve the problem, by combining primal-dual and sub-gradient methods, a fully distributed Node load balance Multi-flow Opportunistic Routing algorithm (NMOR is proposed. With node load balance constraint, NMOR allocates the flow rate iteratively and the rate allocation decides the candidate forwarder selection of opportunities routing. The simulation results show that NMOR algorithm improves 100 %, 62 % of the aggregative throughput than ETX and EAX, respectively.

Opportunistic mammography screening provides effective detection rates in a limited resource healthcare system.

Science.gov (United States)

Teh, Yew-Ching; Tan, Gie-Hooi; Taib, Nur Aishah; Rahmat, Kartini; Westerhout, Caroline Judy; Fadzli, Farhana; See, Mee-Hoong; Jamaris, Suniza; Yip, Cheng-Har

2015-05-15

Breast cancer is the leading cause of cancer deaths in women world-wide. In low and middle income countries, where there are no population-based mammographic screening programmes, late presentation is common, and because of inadequate access to optimal treatment, survival rates are poor. Mammographic screening is well-studied in high-income countries in western populations, and because it has been shown to reduce breast cancer mortality, it has become part of the healthcare systems in such countries. However the performance of mammographic screening in a developing country is largely unknown. This study aims to evaluate the performance of mammographic screening in Malaysia, a middle income country, and to compare the stage and surgical treatment of screen-detected and symptomatic breast cancer. A retrospective review of 2510 mammograms performed from Jan to Dec 2010 in a tertiary medical centre is carried out. The three groups identified are the routine (opportunistic) screening group, the targeted (high risk) screening group and the diagnostic group. The performance indicators of each group is calculated, and stage at presentation and treatment between the screening and diagnostic group is analyzed. The cancer detection rate in the opportunistic screening group, targeted screening group, and the symptomatic group is 0.5 %, 1.25 % and 26 % respectively. The proportion of ductal carcinoma in situ is 23.1 % in the two screening groups compared to only 2.5 % in the diagnostic group. Among the opportunistic screening group, the cancer detection rate was 0.2 % in women below 50 years old compared to 0.65 % in women 50 years and above. The performance indicators are within international standards. Early-staged breast cancer (Stage 0-2) were 84.6 % in the screening groups compared to 61.1 % in the diagnostic group. From the results, in a setting with resource constraints, targeted screening of high risk individuals will give a higher yield, and if more resources are

On the Capacity of Hybrid Wireless Networks with Opportunistic Routing

Directory of Open Access Journals (Sweden)

Le Tan

2010-01-01

Full Text Available This paper studies the capacity of hybrid wireless networks with opportunistic routing (OR. We first extend the opportunistic routing algorithm to exploit high-speed data transmissions in infrastructure network through base stations. We then develop linear programming models to calculate the end-to-end throughput bounds from multiple source nodes to single as well as multiple destination nodes. The developed models are applied to study several hybrid wireless network examples. Through case studies, we investigate several factors that have significant impacts on the hybrid wireless network capacity under opportunistic routing, such as node transmission range, density and distribution pattern of base stations (BTs, and number of wireless channels on wireless nodes and base stations. Our numerical results demonstrate that opportunistic routing could achieve much higher throughput on both ad hoc and hybrid networks than traditional unicast routing (UR. Moreover, opportunistic routing can efficiently utilize base stations and achieve significantly higher throughput gains in hybrid wireless networks than in pure ad hoc networks especially with multiple-channel base stations.

Location-Aided Reliable Routing for Opportunistic Networks

Institute of Scientific and Technical Information of China (English)

Yong Yang; Zhi Ren; Jibi Li

2012-01-01

In our study, we investigate the problem of location-based routing in opportunistic networks. Due to the uncertainty of end-to-end paths between sources and destinations, the classical location-based ad hoc routing protocols cannot adapt to the environment of opportunistic networks, which leads to the decrease of the delivery rate of data. To address it, we propose in this paper a novel location-aided routing protocol which is suitable for opportunistic networks. In our protocol, a node can send location information on demand by using prediction mechanism, and when sending a data packet, the node chooses multiple neighbors which are closer to the destination as next hops. If the candidate neighbors do not exist, the node carries the data till it meets a proper neighbor or the destination. Theoretical analysis and simulation results show that our proposed protocol outperforms DREAM (Distance Routing Effect Protocol Mobility) and one of its improved versions, BFDREAM (Boundary Forwarding DREAM), in terms of the delivery rate and overhead.

On the performance of two-way multiuser mixed RF/FSO relay networks with opportunistic scheduling & asymmetric channel gains

KAUST Repository

Al-Eryani, Yasser F.; Salhab, Anas M.; Zummo, Salam A.; Alouini, Mohamed-Slim

2017-01-01

In this paper, the performance of two-way relaying (TWR) multiuser mixed radio frequency/free space optical (RF/FSO) relay networks with opportunistic user scheduling and asymmetric channel fading is studied. First, closed-form expressions for the exact outage probability, asymptotic (high signal-to-noise ration (SNR)) outage probability, and average ergodic channel capacity are derived assuming heterodyne detection (HD) scheme. Additionally, impacts of several system parameters including number of users, pointing errors, and atmospheric turbulence conditions on the overall network performance are investigated. All the theoretical results are validated by Monte-Carlo simulations. The results show that the TWR scheme almost doubles the network ergodic capacity compared to that of one-way relaying (OWR) scheme with the same outage performance. Additionally, the overall diversity order of the network is shown to be affected not only by the number of users, but it is also a function of the pointing error and atmospheric turbulence conditions.

On the performance of two-way multiuser mixed RF/FSO relay networks with opportunistic scheduling & asymmetric channel gains

KAUST Repository

Al-Eryani, Yasser F.

2017-07-20

In this paper, the performance of two-way relaying (TWR) multiuser mixed radio frequency/free space optical (RF/FSO) relay networks with opportunistic user scheduling and asymmetric channel fading is studied. First, closed-form expressions for the exact outage probability, asymptotic (high signal-to-noise ration (SNR)) outage probability, and average ergodic channel capacity are derived assuming heterodyne detection (HD) scheme. Additionally, impacts of several system parameters including number of users, pointing errors, and atmospheric turbulence conditions on the overall network performance are investigated. All the theoretical results are validated by Monte-Carlo simulations. The results show that the TWR scheme almost doubles the network ergodic capacity compared to that of one-way relaying (OWR) scheme with the same outage performance. Additionally, the overall diversity order of the network is shown to be affected not only by the number of users, but it is also a function of the pointing error and atmospheric turbulence conditions.

An Opportunistic Routing Mechanism Combined with Long-Term and Short-Term Metrics for WMN

Directory of Open Access Journals (Sweden)

Weifeng Sun

2014-01-01

Full Text Available WMN (wireless mesh network is a useful wireless multihop network with tremendous research value. The routing strategy decides the performance of network and the quality of transmission. A good routing algorithm will use the whole bandwidth of network and assure the quality of service of traffic. Since the routing metric ETX (expected transmission count does not assure good quality of wireless links, to improve the routing performance, an opportunistic routing mechanism combined with long-term and short-term metrics for WMN based on OLSR (optimized link state routing and ETX is proposed in this paper. This mechanism always chooses the highest throughput links to improve the performance of routing over WMN and then reduces the energy consumption of mesh routers. The simulations and analyses show that the opportunistic routing mechanism is better than the mechanism with the metric of ETX.

An opportunistic routing mechanism combined with long-term and short-term metrics for WMN.

Science.gov (United States)

Sun, Weifeng; Wang, Haotian; Piao, Xianglan; Qiu, Tie

2014-01-01

WMN (wireless mesh network) is a useful wireless multihop network with tremendous research value. The routing strategy decides the performance of network and the quality of transmission. A good routing algorithm will use the whole bandwidth of network and assure the quality of service of traffic. Since the routing metric ETX (expected transmission count) does not assure good quality of wireless links, to improve the routing performance, an opportunistic routing mechanism combined with long-term and short-term metrics for WMN based on OLSR (optimized link state routing) and ETX is proposed in this paper. This mechanism always chooses the highest throughput links to improve the performance of routing over WMN and then reduces the energy consumption of mesh routers. The simulations and analyses show that the opportunistic routing mechanism is better than the mechanism with the metric of ETX.

The Impact of Message Replication on the Performance of Opportunistic Networks for Sensed Data Collection

Directory of Open Access Journals (Sweden)

Tekenate E. Amah

2017-11-01

Full Text Available Opportunistic networks (OppNets provide a scalable solution for collecting delay‑tolerant data from sensors for their respective gateways. Portable handheld user devices contribute significantly to the scalability of OppNets since their number increases according to user population and they closely follow human movement patterns. Hence, OppNets for sensed data collection are characterised by high node population and degrees of spatial locality inherent to user movement. We study the impact of these characteristics on the performance of existing OppNet message replication techniques. Our findings reveal that the existing replication techniques are not specifically designed to cope with these characteristics. This raises concerns regarding excessive message transmission overhead and throughput degradations due to resource constraints and technological limitations associated with portable handheld user devices. Based on concepts derived from the study, we suggest design guidelines to augment existing message replication techniques. We also follow our design guidelines to propose a message replication technique, namely Locality Aware Replication (LARep. Simulation results show that LARep achieves better network performance under high node population and degrees of spatial locality as compared with existing techniques.

Delay and cost performance analysis of the diffie-hellman key exchange protocol in opportunistic mobile networks

Science.gov (United States)

Soelistijanto, B.; Muliadi, V.

2018-03-01

Diffie-Hellman (DH) provides an efficient key exchange system by reducing the number of cryptographic keys distributed in the network. In this method, a node broadcasts a single public key to all nodes in the network, and in turn each peer uses this key to establish a shared secret key which then can be utilized to encrypt and decrypt traffic between the peer and the given node. In this paper, we evaluate the key transfer delay and cost performance of DH in opportunistic mobile networks, a specific scenario of MANETs where complete end-to-end paths rarely exist between sources and destinations; consequently, the end-to-end delays in these networks are much greater than typical MANETs. Simulation results, driven by a random node movement model and real human mobility traces, showed that DH outperforms a typical key distribution scheme based on the RSA algorithm in terms of key transfer delay, measured by average key convergence time; however, DH performs as well as the benchmark in terms of key transfer cost, evaluated by total key (copies) forwards.

Cooperative Opportunistic Pressure Based Routing for Underwater Wireless Sensor Networks

Directory of Open Access Journals (Sweden)

Nadeem Javaid

2017-03-01

Full Text Available In this paper, three opportunistic pressure based routing techniques for underwater wireless sensor networks (UWSNs are proposed. The first one is the cooperative opportunistic pressure based routing protocol (Co-Hydrocast, second technique is the improved Hydrocast (improved-Hydrocast, and third one is the cooperative improved Hydrocast (Co-improved Hydrocast. In order to minimize lengthy routing paths between the source and the destination and to avoid void holes at the sparse networks, sensor nodes are deployed at different strategic locations. The deployment of sensor nodes at strategic locations assure the maximum monitoring of the network field. To conserve the energy consumption and minimize the number of hops, greedy algorithm is used to transmit data packets from the source to the destination. Moreover, the opportunistic routing is also exploited to avoid void regions by making backward transmissions to find reliable path towards the destination in the network. The relay cooperation mechanism is used for reliable data packet delivery, when signal to noise ratio (SNR of the received signal is not within the predefined threshold then the maximal ratio combining (MRC is used as a diversity technique to improve the SNR of the received signals at the destination. Extensive simulations validate that our schemes perform better in terms of packet delivery ratio and energy consumption than the existing technique; Hydrocast.

Cooperative Opportunistic Pressure Based Routing for Underwater Wireless Sensor Networks.

Science.gov (United States)

Javaid, Nadeem; Muhammad; Sher, Arshad; Abdul, Wadood; Niaz, Iftikhar Azim; Almogren, Ahmad; Alamri, Atif

2017-03-19

In this paper, three opportunistic pressure based routing techniques for underwater wireless sensor networks (UWSNs) are proposed. The first one is the cooperative opportunistic pressure based routing protocol (Co-Hydrocast), second technique is the improved Hydrocast (improved-Hydrocast), and third one is the cooperative improved Hydrocast (Co-improved Hydrocast). In order to minimize lengthy routing paths between the source and the destination and to avoid void holes at the sparse networks, sensor nodes are deployed at different strategic locations. The deployment of sensor nodes at strategic locations assure the maximum monitoring of the network field. To conserve the energy consumption and minimize the number of hops, greedy algorithm is used to transmit data packets from the source to the destination. Moreover, the opportunistic routing is also exploited to avoid void regions by making backward transmissions to find reliable path towards the destination in the network. The relay cooperation mechanism is used for reliable data packet delivery, when signal to noise ratio (SNR) of the received signal is not within the predefined threshold then the maximal ratio combining (MRC) is used as a diversity technique to improve the SNR of the received signals at the destination. Extensive simulations validate that our schemes perform better in terms of packet delivery ratio and energy consumption than the existing technique; Hydrocast.

A Comparative Study of Novel Opportunistic Routing Protocols in Mobile Ad Hoc Networks

OpenAIRE

R. Poonkuzhali; M. Y. Sanavullah; M. R. Gurupriya

2014-01-01

Opportunistic routing is used, where the network has the features like dynamic topology changes and intermittent network connectivity. In Delay tolerant network or Disruption tolerant network opportunistic forwarding technique is widely used. The key idea of opportunistic routing is selecting forwarding nodes to forward data packets and coordination among these nodes to avoid duplicate transmissions. This paper gives the analysis of pros and cons of various opportunistic ...

Opportunistic infection manifestation of HIV-AIDS patients in Airlangga university hospital Surabaya

Science.gov (United States)

Asmarawati, T. P.; Putranti, A.; Rachman, B. E.; Hadi, U.; Nasronudin

2018-03-01

Opportunistic infections are common in HIV-infected patients especially those who progress to acquired immunodeficiency syndrome. There are many factors involved in the prevalence of opportunistic infections. We investigated the patterns of opportunistic infection in HIV-infected patients admitted to Airlangga University Hospital Surabaya. This study was an observational study, conducted in adults patients with HIV infection from January 2016 to September 2017. Data collected from the medical records of the patients. The number of samples in this study was 58. The mean age was 42.9 years, mostly male. Most patients admitted were in clinical stadium III or IV. Heterosexual transmission is a common risk factor in patients. The most prevalent opportunistic infections found in patients were oral candidiasis (58.6%), followed by pulmonary tuberculosis (41.4%) and pneumonia/PCP (41.4%). Other infections found were toxoplasmosis, chronic diarrhea, cytomegalovirus, meningitis TB, hepatitis C, amoebiasis, and cerebritis. Opportunistic infections occurred more often in age≥40 years and increased as clinical stadium get worse. From the results, we conclude that oral candidiasis and pulmonary tuberculosis were the most common opportunistic infections found in Airlangga University Hospital. The pattern of opportunistic infections in this study could help the hospital to set priorities related to the management of patients.

Opportunistic Adaptive Transmission for Network Coding Using Nonbinary LDPC Codes

Directory of Open Access Journals (Sweden)

Cocco Giuseppe

2010-01-01

Full Text Available Network coding allows to exploit spatial diversity naturally present in mobile wireless networks and can be seen as an example of cooperative communication at the link layer and above. Such promising technique needs to rely on a suitable physical layer in order to achieve its best performance. In this paper, we present an opportunistic packet scheduling method based on physical layer considerations. We extend channel adaptation proposed for the broadcast phase of asymmetric two-way bidirectional relaying to a generic number of sinks and apply it to a network context. The method consists of adapting the information rate for each receiving node according to its channel status and independently of the other nodes. In this way, a higher network throughput can be achieved at the expense of a slightly higher complexity at the transmitter. This configuration allows to perform rate adaptation while fully preserving the benefits of channel and network coding. We carry out an information theoretical analysis of such approach and of that typically used in network coding. Numerical results based on nonbinary LDPC codes confirm the effectiveness of our approach with respect to previously proposed opportunistic scheduling techniques.

[New approaches to oral cavity opportunistic microbiota study].

Science.gov (United States)

Tets, G V; Vikina, D S; Vecherkovskaia, M F; Domorad, A A; Kharlamova, V V; Tets, V V

2013-01-01

Identification of some bacteria of the oral microbiota in humans including opportunistic pathogens capable of causing infections of various locations is a challenging problem for dentistry. Lack of knowledge on oral microbiota is the result of the absence of appropriate culture technique for isolation of pure cultures of those bacteria. The paper presents the study on mixed oral microbial biofilms with isolation and identification of insufficiently explored or still unknown aerobic opportunistic bacteria.

Cooperative HARQ with Poisson Interference and Opportunistic Routing

KAUST Repository

Kaveh, Mostafa

2014-01-06

This presentation considers reliable transmission of data from a source to a destination, aided cooperatively by wireless relays selected opportunistically and utilizing hybrid forward error correction/detection, and automatic repeat request (Hybrid ARQ, or HARQ). Specifically, we present a performance analysis of the cooperative HARQ protocol in a wireless adhoc multihop network employing spatial ALOHA. We model the nodes in such a network by a homogeneous 2-D Poisson point process. We study the tradeoff between the per-hop rate, spatial density and range of transmissions inherent in the network by optimizing the transport capacity with respect to the network design parameters, HARQ coding rate and medium access probability. We obtain an approximate analytic expression for the expected progress of opportunistic routing and optimize the capacity approximation by convex optimization. By way of numerical results, we show that the network design parameters obtained by optimizing the analytic approximation of transport capacity closely follows that of Monte Carlo based exact transport capacity optimization. As a result of the analysis, we argue that the optimal HARQ coding rate and medium access probability are independent of the node density in the network.

Lower Bound of Energy-Latency Tradeoff of Opportunistic Routing in Multihop Networks

Directory of Open Access Journals (Sweden)

Gorce Jean-Marie

2011-01-01

Full Text Available Opportunistic networking aims at exploiting sporadic radio links to improve the connectivity of multihop networks and to foster data transmissions. The broadcast nature of wireless channels is an important feature that can be exploited to improve transmissions by using several potential receivers. Opportunistic relaying is thus the first brick for opportunistic networking. However, the advantage of opportunistic relaying may be degraded due to energy increase related to having multiple active receivers. This paper proposes a thorough analysis of opportunistic relaying efficiency under different realistic radio channel conditions. The study is intended to find the best tradeoff between two objectives: energy and latency minimizations, with a hard reliability constraint. We derive an optimal bound, namely, the Pareto front of the related optimization problem, which offers a good insight into the benefits of opportunistic routings compared with classical multihop routing schemes. Meanwhile, the lower bound provides a framework to optimize the parameters at the physical layer, MAC layer, and routing layer from the viewpoint of cross layer during the design or planning phase of a network.

Game Theory in Wireless Ad-Hoc Opportunistic Radios

OpenAIRE

Mumtaz, Shahid; Gameiro, Atilio

2010-01-01

Emerging research in game theory based power control applied to ad hoc opportunist networks shows much promise to help understand the complex interactions between OR nodes in this highly dynamic and distributed environment. Also, the employment of game theory in modeling dynamic situations for opportunist ad hoc networks where OR nodes have incomplete information has led to the application of largely unexplored games such as games of imperfect monitoring. Ad hoc security using game theory is ...

Contributing opportunistic resources to the grid with HTCondor-CE-Bosco

Science.gov (United States)

Weitzel, Derek; Bockelman, Brian

2017-10-01

The HTCondor-CE [1] is the primary Compute Element (CE) software for the Open Science Grid. While it offers many advantages for large sites, for smaller, WLCG Tier-3 sites or opportunistic clusters, it can be a difficult task to install, configure, and maintain the HTCondor-CE. Installing a CE typically involves understanding several pieces of software, installing hundreds of packages on a dedicated node, updating several configuration files, and implementing grid authentication mechanisms. On the other hand, accessing remote clusters from personal computers has been dramatically improved with Bosco: site admins only need to setup SSH public key authentication and appropriate accounts on a login host. In this paper, we take a new approach with the HTCondor-CE-Bosco, a CE which combines the flexibility and reliability of the HTCondor-CE with the easy-to-install Bosco. The administrators of the opportunistic resource are not required to install any software: only SSH access and a user account are required from the host site. The OSG can then run the grid-specific portions from a central location. This provides a new, more centralized, model for running grid services, which complements the traditional distributed model. We will show the architecture of a HTCondor-CE-Bosco enabled site, as well as feedback from multiple sites that have deployed it.

Exact outage analysis of incremental decode-and-forward opportunistic relaying

KAUST Repository

Tourki, Kamel; Yang, Hongchuan; Alouini, Mohamed-Slim

2010-01-01

In this paper, we investigate a dual-hop decode-andforward opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we derive exact closed-form expression for the outage probability based on the exact statistics of each hop. Furthermore, we perform asymptotic analysis and we deduce the diversity order of the scheme. We validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures. © 2010 IEEE.

Exact outage analysis of incremental decode-and-forward opportunistic relaying

KAUST Repository

Tourki, Kamel

2010-11-01

In this paper, we investigate a dual-hop decode-andforward opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we derive exact closed-form expression for the outage probability based on the exact statistics of each hop. Furthermore, we perform asymptotic analysis and we deduce the diversity order of the scheme. We validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures. © 2010 IEEE.

Low-Feedback Opportunistic Scheduling Schemes for Wireless Networks with Heterogenous Users

KAUST Repository

Rashid, Faraan

2012-07-01

Efficient implementation of resource sharing strategies in a multi-user wireless environment can improve the performance of a network significantly. In this thesis we study various scheduling strategies for wireless networks and handle the problem of opportunistically scheduling transmissions using channel aware schemes. First we propose a scheme that can handle users with asymmetric channel conditions and is opportunistic in the sense that it exploits the multi-user diversity of the network. The scheme requires the users to have a priori knowledge of their channel distributions. The associated overhead is limited meaning it offers reduced feedback load, that does not scale with the increasing number of users. The main technique used to shrink the feedback load is the contention based distributed implementation of a splitting algorithm that does not require explicit feedback to the scheduler from every user. The users find the best among themselves, in a distributed manner, while requiring just a ternary broadcast feedback from the scheduler at the end of each mini-slot. In addition, it can also handle fairness constraints in time and throughput to various degrees. Next we propose another opportunistic scheduler that offers most of the benefits of the previously proposed scheme but is more practical because it can also handle heterogenous users whose channel distributions are unknown. This new scheme actually reduces the complexity and is also more robust for changing traffic patterns. Finally we extend both these schemes to the scenario where there are fixed thresholds, this enables us to handle opportunistic scheduling in practical systems that can only transmit over finite number of discrete rates with the additional benefit that full feedback session, even from the selected user, is never required.

Efficient scheduling request algorithm for opportunistic wireless access

KAUST Repository

Nam, Haewoon

2011-08-01

An efficient scheduling request algorithm for opportunistic wireless access based on user grouping is proposed in this paper. Similar to the well-known opportunistic splitting algorithm, the proposed algorithm initially adjusts (or lowers) the threshold during a guard period if no user sends a scheduling request. However, if multiple users make requests simultaneously and therefore a collision occurs, the proposed algorithm no longer updates the threshold but narrows down the user search space by splitting the users into multiple groups iteratively, whereas the opportunistic splitting algorithm keeps adjusting the threshold until a single user is found. Since the threshold is only updated when no user sends a request, it is shown that the proposed algorithm significantly alleviates the burden of the signaling for the threshold distribution to the users by the scheduler. More importantly, the proposed algorithm requires a less number of mini-slots to make a user selection given a certain scheduling outage probability. © 2011 IEEE.

Location Prediction-Based Data Dissemination Using Swarm Intelligence in Opportunistic Cognitive Networks

Directory of Open Access Journals (Sweden)

Jie Li

2014-01-01

Full Text Available Swarm intelligence is widely used in the application of communication networks. In this paper we adopt a biologically inspired strategy to investigate the data dissemination problem in the opportunistic cognitive networks (OCNs. We model the system as a centralized and distributed hybrid system including a location prediction server and a pervasive environment deploying the large-scale human-centric devices. To exploit such environment, data gathering and dissemination are fundamentally based on the contact opportunities. To tackle the lack of contemporaneous end-to-end connectivity in opportunistic networks, we apply ant colony optimization as a cognitive heuristic technology to formulate a self-adaptive dissemination-based routing scheme in opportunistic cognitive networks. This routing strategy has attempted to find the most appropriate nodes conveying messages to the destination node based on the location prediction information and intimacy between nodes, which uses the online unsupervised learning on geographical locations and the biologically inspired algorithm on the relationship of nodes to estimate the delivery probability. Extensive simulation is carried out on the real-world traces to evaluate the accuracy of the location prediction and the proposed scheme in terms of transmission cost, delivery ratio, average hops, and delivery latency, which achieves better routing performances compared to the typical routing schemes in OCNs.

PERFORMANCE OF OPPORTUNISTIC SPECTRUM ACCESS WITH SENSING ERROR IN COGNITIVE RADIO AD HOC NETWORKS

Directory of Open Access Journals (Sweden)

N. ARMI

2012-04-01

Full Text Available Sensing in opportunistic spectrum access (OSA has a responsibility to detect the available channel by performing binary hypothesis as busy or idle states. If channel is busy, secondary user (SU cannot access and refrain from data transmission. SU is allowed to access when primary user (PU does not use it (idle states. However, channel is sensed on imperfect communication link. Fading, noise and any obstacles existed can cause sensing errors in PU signal detection. False alarm detects idle states as a busy channel while miss-identification detects busy states as an idle channel. False detection makes SU refrain from transmission and reduces number of bits transmitted. On the other hand, miss-identification causes SU collide to PU transmission. This paper study the performance of OSA based on the greedy approach with sensing errors by the restriction of maximum collision probability allowed (collision threshold by PU network. The throughput of SU and spectrum capacity metric is used to evaluate OSA performance and make comparisons to those ones without sensing error as function of number of slot based on the greedy approach. The relations between throughput and signal to noise ratio (SNR with different collision probability as well as false detection with different SNR are presented. According to the obtained results show that CR users can gain the reward from the previous slot for both of with and without sensing errors. It is indicated by the throughput improvement as slot number increases. However, sensing on imperfect channel with sensing errors can degrade the throughput performance. Subsequently, the throughput of SU and spectrum capacity improves by increasing maximum collision probability allowed by PU network as well. Due to frequent collision with PU, the throughput of SU and spectrum capacity decreases at certain value of collision threshold. Computer simulation is used to evaluate and validate these works.

Special issue Oceans and Humans Health: the ecology of marine opportunists.

Science.gov (United States)

Burge, Colleen A; Kim, Catherine J S; Lyles, Jillian M; Harvell, C Drew

2013-05-01

Opportunistic marine pathogens, like opportunistic terrestrial pathogens, are ubiquitous in the environment (waters, sediments, and organisms) and only cause disease in immune-compromised or stressed hosts. In this review, we discuss four host-pathogen interactions within the marine environment that are typically considered opportunistic: sea fan coral-fungus, eelgrass-Labyrinthula zosterae, sea fan-Labyrinthulomycetes, and hard clam-Quahog Parasite Unknown with particular focus on disease ecology, parasite pathology, host response, and known associated environmental conditions. Disease is a natural part of all ecosystems; however, in some cases, a shift in the balance between the host, pathogen, and the environment may lead to epizootics in natural or cultured populations. In marine systems, host-microbe interactions are less understood than their terrestrial counterparts. The biological and physical changes to the world's oceans, coupled with other anthropogenic influences, will likely lead to more opportunistic diseases in the marine environment.

Outage analysis of opportunistic decode-and-forward relaying

KAUST Repository

Tourki, Kamel

2010-09-01

In this paper, we investigate a dual-hop opportunistic decode-and-forward relaying scheme where the source may or not be able to communicate directly with the destination. We first derive statistics based on exact probability density function (PDF) of each hop. Then, the PDFs are used to determine closed-form outage probability expression for a transmission rate R. Furthermore, we evaluate the asymptotic outage performance and the diversity order is deduced. Unlike existing works where the analysis focused on high signal-to-noise ratio (SNR) regime, such results are important to enable the designers to take decisions regarding practical systems that operate at low SNR regime. We show that performance simulation results coincide with our analytical results under practical assumption of unbalanced hops. © 2010 IEEE.

An Overlapping Communities Detection Algorithm via Maxing Modularity in Opportunistic Networks

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Gao Zhi-Peng

2016-01-01

Full Text Available Community detection in opportunistic networks has been a significant and hot issue, which is used to understand characteristics of networks through analyzing structure of it. Community is used to represent a group of nodes in a network where nodes inside the community have more internal connections than external connections. However, most of the existing community detection algorithms focus on binary networks or disjoint community detection. In this paper, we propose a novel algorithm via maxing modularity of communities (MMCto find overlapping community structure in opportunistic networks. It utilizes contact history of nodes to calculate the relation intensity between nodes. It finds nodes with high relation intensity as the initial community and extend the community with nodes of higher belong degree. The algorithm achieves a rapid and efficient overlapping community detection method by maxing the modularity of community continuously. The experiments prove that MMC is effective for uncovering overlapping communities and it achieves better performance than COPRA and Conductance.

Optimal Caching in Multicast 5G Networks with Opportunistic Spectrum Access

KAUST Repository

Emara, Mostafa

2018-01-15

Cache-enabled small base station (SBS) densification is foreseen as a key component of 5G cellular networks. This architecture enables storing popular files at the network edge (i.e., SBS caches), which empowers local communication and alleviates traffic congestions at the core/backhaul network. This paper develops a mathematical framework, based on stochastic geometry, to characterize the hit probability of a cache-enabled multicast 5G network with SBS multi-channel capabilities and opportunistic spectrum access. To this end, we first derive the hit probability by characterizing opportunistic spectrum access success probabilities, service distance distributions, and coverage probabilities. The optimal caching distribution to maximize the hit probability is then computed. The performance and trade-offs of the derived optimal caching distributions are then assessed and compared with two widely employed caching distribution schemes, namely uniform and Zipf caching, through numerical results and extensive simulations. It is shown that the Zipf caching almost optimal only in scenarios with large number of available channels and large cache sizes.

Retinitis due to opportunistic infections in Iranian HIV infected patients.

Directory of Open Access Journals (Sweden)

Ali Abdollahi

2013-10-01

Full Text Available We tried to evaluate prevalence and characteristics of Iranian HIV infected patients with retinitis due to opportunistic infections. In this cross sectional study, we evaluated 106 HIV infected patients via indirect ophthalmoscopy and slit lamp examination by 90 lens to find retinitis cases. General information and results of ophthalmologic examination were analyzed. Prevalence of retinitis due to opportunistic infections was 6.6%: cytomegalovirus (CMV retinitis 1.88%, toxoplasmosis retinochoroiditis 1.88% and tuberculosis chorioretinitis 2.83%. CD4 count was higher than 50 cell/µlit in both cases with CMV retinitis. Along with increasing survival in the HIV infected patients, the prevalence of complications such as ocular manifestation due to opportunistic infections are increasing and must be more considered.

Opportunistic breast cancer early detection in Tyrol, Austria 1996-2004

International Nuclear Information System (INIS)

Frede, Thomas E.

2005-01-01

Purpose: Evaluate the need for a mammography-screening program for Tyrol, as recently proposed in an OeBIG feasibility study commissioned by the Austrian Ministry for Health and Women, in view of the already existing organized opportunistic screening. Materials and methods: This author has examined the state of breast cancer early detection and diagnosis in Tyrol. A comprehensive review of all available data and results based on 3340 primary biopsy recommendations between 1996 and 2004 at our breast centre was performed. Results: Early detection has been improved by organizing the existing opportunistic screening through a true team approach, incorporating not only the clinic's specialties, but also the private radiologists and referring physicians. In 2004, our centre made the definitive diagnosis in 230 (67.6%) of the about 340 primary breast cancer cases occurring yearly in Tyrol with 62.2% being discovered by routine examination and 74.3% stemming from second opinion examinations. About 92.4% of our primary biopsies are performed minimally invasive with an overall 42.9% (1375 of 3205 cases) malignancy rate. Pathological TNM-staging was obtained in over 95% of women under 70 years of age. On average 55.3% (62.0% in 2004) of all discovered cancers were TNM-stage 1 or better lesions (76.2% in our routine patients). With an overall participation of about 75% of our target group (women over 34 years), it is women under the age of 50 years, who most consistently follow our recommendations, resulting in an above average rate of 58.5% TNM-stage 1 and better lesions for all discovered breast cancers (routine and symptomatic) in this group. Conclusions: Opportunistic screening with a true team approach, combined with minimally invasive diagnosis and a strive for excellence have resulted in improved diagnosis, ever expanding patient and referring physician acceptance and an increase of positive prognostic factors, which eclipses the results of any published international

Government Spending Cycles: Ideological or Opportunistic?

NARCIS (Netherlands)

H.P. van Dalen (Hendrik); O.H. Swank (Otto)

1996-01-01

textabstractands. The time series analysis, covering the period 1953–1993, allows for different types of government spending. In general, spending is inspired by ideological and opportunistic motives: all government expenditure categories show an upward drift during election times and the partisan

Who needs the assumption of opportunistic behavior? Transaction cost economics does not!

DEFF Research Database (Denmark)

Koch, Carsten Allan

2000-01-01

The assumption of opportunistic behavior, familiar from transaction cost economics, has been and remains highly controversial. But opportunistic behavior, albeit undoubtedly an extremely important form of motivation, is not a necessary condition for the contractual problems studied by transaction...

Adaptive Opportunistic Cooperative Control Mechanism Based on Combination Forecasting and Multilevel Sensing Technology of Sensors for Mobile Internet of Things

Directory of Open Access Journals (Sweden)

Yong Jin

2014-01-01

Full Text Available In mobile Internet of Things, there are many challenges, including sensing technology of sensors, how and when to join cooperative transmission, and how to select the cooperative sensors. To address these problems, we studied the combination forecasting based on the multilevel sensing technology of sensors, building upon which we proposed the adaptive opportunistic cooperative control mechanism based on the threshold values such as activity probability, distance, transmitting power, and number of relay sensors, in consideration of signal to noise ratio and outage probability. More importantly, the relay sensors would do self-test real time in order to judge whether to join the cooperative transmission, for maintaining the optimal cooperative transmission state with high performance. The mathematical analyses results show that the proposed adaptive opportunistic cooperative control approach could perform better in terms of throughput ratio, packet error rate and delay, and energy efficiency, compared with the direct transmission and opportunistic cooperative approaches.

ABORt: Acknowledgement-Based Opportunistic Routing Protocol for High Data Rate Multichannel WSNs

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Hamadoun Tall

2017-10-01

Full Text Available The ease of deployment and the auto-configuration capabilities of Wireless Sensor Networks (WSNs make them very attractive in different domains like environmental, home automation or heath care applications. The use of multichannel communications in WSNs helps to improve the overall performance of the network. However, in heavy traffic scenarios, routing protocols should be adapted to allow load balancing and to avoid losing data packets due to congestion and queue overflow. In this paper, we present an Acknowledgement-Based Opportunistic Routing (ABORt protocol designed for high data rate multichannel WSNs. It is a low overhead protocol that does not rely on synchronization for control traffic exchange during the operational phase of the network. ABORt is an opportunistic protocol that relies on link layer acknowledgements to disseminate routing metrics, which helps to reduce overhead. The performance of ABORt is evaluated using the Cooja simulator and the obtained results show that ABORt has a high packet delivery ratio with reduced packet end-to-end delay compared to two single channel routing protocols and two multichannel routing protocols that use number of hops and expected transmission count as routing metrics.

Feasibility of opportunistic osteoporosis screening in routine contrast-enhanced multi detector computed tomography (MDCT) using texture analysis.

Science.gov (United States)

Mookiah, M R K; Rohrmeier, A; Dieckmeyer, M; Mei, K; Kopp, F K; Noel, P B; Kirschke, J S; Baum, T; Subburaj, K

2018-04-01

This study investigated the feasibility of opportunistic osteoporosis screening in routine contrast-enhanced MDCT exams using texture analysis. The results showed an acceptable reproducibility of texture features, and these features could discriminate healthy/osteoporotic fracture cohort with an accuracy of 83%. This aim of this study is to investigate the feasibility of opportunistic osteoporosis screening in routine contrast-enhanced MDCT exams using texture analysis. We performed texture analysis at the spine in routine MDCT exams and investigated the effect of intravenous contrast medium (IVCM) (n = 7), slice thickness (n = 7), the long-term reproducibility (n = 9), and the ability to differentiate healthy/osteoporotic fracture cohort (n = 9 age and gender matched pairs). Eight texture features were extracted using gray level co-occurrence matrix (GLCM). The independent sample t test was used to rank the features of healthy/fracture cohort and classification was performed using support vector machine (SVM). The results revealed significant correlations between texture parameters derived from MDCT scans with and without IVCM (r up to 0.91) slice thickness of 1 mm versus 2 and 3 mm (r up to 0.96) and scan-rescan (r up to 0.59). The performance of the SVM classifier was evaluated using 10-fold cross-validation and revealed an average classification accuracy of 83%. Opportunistic osteoporosis screening at the spine using specific texture parameters (energy, entropy, and homogeneity) and SVM can be performed in routine contrast-enhanced MDCT exams.

Reduced feedback opportunistic and layered random beamforming for MIMO-OFDMA systems

OpenAIRE

Han, C; Nicolaou, M; Doufexi, A; Armour, SMD

2007-01-01

This paper considers a number of techniques employed in opportunistic and layered random beamforming OFDMA schemes that aim to reduce the feedback required to perform scheduling whilst also minimising the throughput degradations resulting from this reduced throughput (due to the lack of full CSI at the Base Station (BS). Frequency response correlation among subcarriers can be exploited to group adjacent subcarriers into clusters which can then be treated as a single unit for feedback purposes...

Towards A New Opportunistic IoT Network Architecture for Wildlife Monitoring System

NARCIS (Netherlands)

Ayele, Eyuel Debebe; Meratnia, Nirvana; Havinga, Paul J.M.

In this paper we introduce an opportunistic dual radio IoT network architecture for wildlife monitoring systems (WMS). Since data processing consumes less energy than transmitting the raw data, the proposed architecture leverages opportunistic mobile networks in a fixed LPWAN IoT network

A graph model for opportunistic network coding

KAUST Repository

Sorour, Sameh; Aboutoraby, Neda; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

2015-01-01

© 2015 IEEE. Recent advancements in graph-based analysis and solutions of instantly decodable network coding (IDNC) trigger the interest to extend them to more complicated opportunistic network coding (ONC) scenarios, with limited increase

MOSDEN: A Scalable Mobile Collaborative Platform for Opportunistic Sensing Applications

Directory of Open Access Journals (Sweden)

Prem Prakash Jayaraman

2014-05-01

Full Text Available Mobile smartphones along with embedded sensors have become an efficient enabler for various mobile applications including opportunistic sensing. The hi-tech advances in smartphones are opening up a world of possibilities. This paper proposes a mobile collaborative platform called MOSDEN that enables and supports opportunistic sensing at run time. MOSDEN captures and shares sensor data acrossmultiple apps, smartphones and users. MOSDEN supports the emerging trend of separating sensors from application-specific processing, storing and sharing. MOSDEN promotes reuse and re-purposing of sensor data hence reducing the efforts in developing novel opportunistic sensing applications. MOSDEN has been implemented on Android-based smartphones and tablets. Experimental evaluations validate the scalability and energy efficiency of MOSDEN and its suitability towards real world applications. The results of evaluation and lessons learned are presented and discussed in this paper.

A graph model for opportunistic network coding

KAUST Repository

Sorour, Sameh

2015-08-12

© 2015 IEEE. Recent advancements in graph-based analysis and solutions of instantly decodable network coding (IDNC) trigger the interest to extend them to more complicated opportunistic network coding (ONC) scenarios, with limited increase in complexity. In this paper, we design a simple IDNC-like graph model for a specific subclass of ONC, by introducing a more generalized definition of its vertices and the notion of vertex aggregation in order to represent the storage of non-instantly-decodable packets in ONC. Based on this representation, we determine the set of pairwise vertex adjacency conditions that can populate this graph with edges so as to guarantee decodability or aggregation for the vertices of each clique in this graph. We then develop the algorithmic procedures that can be applied on the designed graph model to optimize any performance metric for this ONC subclass. A case study on reducing the completion time shows that the proposed framework improves on the performance of IDNC and gets very close to the optimal performance.

Security-Reliability Trade-Off Analysis for Multiuser SIMO Mixed RF/FSO Relay Networks With Opportunistic User Scheduling

KAUST Repository

El-Malek, Ahmed H. Abd; Salhab, Anas M.; Zummo, Salam A.; Alouini, Mohamed-Slim

2016-01-01

In this paper, we study the performance of multiuser single-input multiple-output mixed radio frequency (RF)/free space optical (FSO) relay network with opportunistic user scheduling. The considered system includes multiple users, one amplify

Opportunistic Error Correction for WLAN Applications

NARCIS (Netherlands)

Shao, X.; Schiphorst, Roelof; Slump, Cornelis H.

2008-01-01

The current error correction layer of IEEE 802.11a WLAN is designed for worst case scenarios, which often do not apply. In this paper, we propose a new opportunistic error correction layer based on Fountain codes and a resolution adaptive ADC. The key part in the new proposed system is that only

Performative Social Science and Psychology

Directory of Open Access Journals (Sweden)

Mary Gergen

2010-11-01

Full Text Available This article presents an overview of "Performative Social Science," which is defined as the deployment of different forms of artistic performance in the execution of a scientific project. Such forms may include art, theater, poetry, music, dance, photography, fiction writing, and multi-media applications. Performative research practices are in their developmental stage, with most of the major work appearing in the last two decades. Frequently based on a social constructionist metatheory, supporters reject a realist, or mapping view of representation, and explore varieties of expressive forms for constructing worlds relevant to the social sciences. The performative orientation often relies on a dramaturgical approach that encompasses value-laden, emotionally charged topics and presentations. Social scientists invested in social justice issues and political perspectives have been especially drawn to this approach. Performative social science invites productive collaborations among various disciplinary fields and between the sciences and arts. URN: http://nbn-resolving.de/urn:nbn:de:0114-fqs1101119

Accurate outage analysis of incremental decode-and-forward opportunistic relaying

KAUST Repository

Tourki, Kamel; Yang, Hongchuan; Alouini, Mohamed-Slim

2011-01-01

In this paper, we investigate a dual-hop decode-and-forward opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. We first derive the exact statistics of received signal-to-noise (SNR) over each hop with co-located relays, in terms of probability density function (PDF). Then, the PDFs are used to determine very accurate closed-form expression for the outage probability for a transmission rate R. Furthermore, we perform asymptotic analysis and we deduce the diversity order of the scheme. We validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures. © 2011 IEEE.

Accurate outage analysis of incremental decode-and-forward opportunistic relaying

KAUST Repository

Tourki, Kamel

2011-04-01

In this paper, we investigate a dual-hop decode-and-forward opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. We first derive the exact statistics of received signal-to-noise (SNR) over each hop with co-located relays, in terms of probability density function (PDF). Then, the PDFs are used to determine very accurate closed-form expression for the outage probability for a transmission rate R. Furthermore, we perform asymptotic analysis and we deduce the diversity order of the scheme. We validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures. © 2011 IEEE.

Opportunistic pathology-based screening for diabetes

Science.gov (United States)

Simpson, Aaron J; Krowka, Renata; Kerrigan, Jennifer L; Southcott, Emma K; Wilson, J Dennis; Potter, Julia M; Nolan, Christopher J; Hickman, Peter E

2013-01-01

Objective To determine the potential of opportunistic glycated haemoglobin (HbA1c) testing of pathology samples to detect previously unknown diabetes. Design Pathology samples from participants collected for other reasons and suitable for HbA1c testing were utilised for opportunistic diabetes screening. HbA1c was measured with a Biorad Variant II turbo analyser and HbA1c levels of ≥6.5% (48 mmol/mol) were considered diagnostic for diabetes. Confirmation of previously unknown diabetes status was obtained by a review of hospital medical records and phone calls to general practitioners. Setting Hospital pathology laboratory receiving samples from hospital-based and community-based (CB) settings. Participants Participants were identified based on the blood sample collection location in the CB, emergency department (ED) and inpatient (IP) groups. Exclusions pretesting were made based on the electronic patient history of: age <18 years, previous diabetes diagnosis, query for diabetes status in the past 12 months, evidence of pregnancy and sample collected postsurgery or transfusion. Only one sample per individual participant was tested. Results Of the 22 396 blood samples collected, 4505 (1142 CB, 1113 ED, 2250 IP) were tested of which 327 (7.3%) had HbA1c levels ≥6.5% (48 mmol/mol). Of these 120 (2.7%) were determined to have previously unknown diabetes (11 (1%) CB, 21 (1.9%) ED, 88 (3.9%) IP). The prevalence of previously unknown diabetes was substantially higher (5.4%) in hospital-based (ED and IP) participants aged over 54 years. Conclusions Opportunistic testing of referred pathology samples can be an effective method of screening for diabetes, especially in hospital-based and older persons. PMID:24065696

Joint opportunistic scheduling and network coding for bidirectional relay channel

KAUST Repository

Shaqfeh, Mohammad

2013-07-01

In this paper, we consider a two-way communication system in which two users communicate with each other through an intermediate relay over block-fading channels. We investigate the optimal opportunistic scheduling scheme in order to maximize the long-term average transmission rate in the system assuming symmetric information flow between the two users. Based on the channel state information, the scheduler decides that either one of the users transmits to the relay, or the relay transmits to a single user or broadcasts to both users a combined version of the two users\\' transmitted information by using linear network coding. We obtain the optimal scheduling scheme by using the Lagrangian dual problem. Furthermore, in order to characterize the gains of network coding and opportunistic scheduling, we compare the achievable rate of the system versus suboptimal schemes in which the gains of network coding and opportunistic scheduling are partially exploited. © 2013 IEEE.

Recognizing and Conducting Opportunistic Experiments in Education: A Guide for Policymakers and Researchers. REL 2014-037

Science.gov (United States)

Resch, Alexandra; Berk, Jillian; Akers, Lauren

2014-01-01

An opportunistic experiment is a type of randomized controlled trial that studies the effects of a planned intervention or policy change with minimal added disruption and cost. This guide defines opportunistic experiments and provides examples, discusses issues to consider when identifying potential opportunistic experiments, and outlines the…

The Long-Term Effectiveness and Cost Effectiveness of Organized versus Opportunistic Screening for Breast Cancer in Austria.

Science.gov (United States)

Schiller-Fruehwirth, Irmgard; Jahn, Beate; Einzinger, Patrick; Zauner, Günther; Urach, Christoph; Siebert, Uwe

2017-09-01

In 2014, Austrian health authorities implemented an organized breast cancer screening program. Until then, there has been a long-standing tradition of opportunistic screening. To evaluate the cost-effectiveness of organized screening compared with opportunistic screening, as well as to identify factors influencing the clinical and economic outcomes. We developed and validated an individual-level state-transition model and assessed the health outcomes and costs of organized and opportunistic screening for 40-year-old asymptomatic women. The base-case analysis compared a scenario involving organized biennial screening with a scenario reflecting opportunistic screening practice for an average-risk woman aged 45 to 69 years. We applied an annual discount rate of 3% and estimated the incremental cost-effectiveness ratio in terms of the cost (2012 euros) per life-year gained (LYG) from a health care perspective. Deterministic and probabilistic sensitivity analyses were performed to assess uncertainty. Compared with opportunistic screening, an organized program yielded on average additional 0.0118 undiscounted life-years (i.e., 4.3 days) and cost savings of €41 per woman. In the base-case analysis, the incremental cost-effectiveness ratio of organized screening was approximately €20,000 per LYG compared with no screening. Assuming a willingness-to-pay threshold of €50,000 per LYG, there was a 70% probability that organized screening would be considered cost-effective. The attendance rate, but not the test accuracy of mammography, was an influential factor for the cost-effectiveness. The decision to adopt organized screening is likely an efficient use of limited health care resources in Austria. Copyright © 2017 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Cooperative HARQ with Poisson Interference and Opportunistic Routing

KAUST Repository

Kaveh, Mostafa; Rajana, Aomgh

2014-01-01

This presentation considers reliable transmission of data from a source to a destination, aided cooperatively by wireless relays selected opportunistically and utilizing hybrid forward error correction/detection, and automatic repeat request (Hybrid

Research of opportunistic behavior in the market of non-standard products

Directory of Open Access Journals (Sweden)

Natalya Sergeyevna Grigoryeva

2015-03-01

Full Text Available Objective to study the characteristic features of opportunistic behavior in the markets of complex products not subject to standardization by the example of rendering services during constructionandassembling operations. Methods analysis synthesis collection and description of empirical data. Results a significant amount of theoretical material has been analyzed budgets of constructionandassembling operations have been analyzed normative documents have been studied. A poll of quantity surveyors supervisors of constructionandassembling operations consumers of services and works have been carried out. The differences were revealed in the kinds of opportunistic behavior in the nonstandard products markets compared to the standard products markets the results of those surveys were presented in the earlier works by the author. Scientific novelty it has been shown that in case of individual elaboration of each project due to the uniqueness of the result of economic activity as a single complex the opportunistic behavior has such prerequisites as high costs for measurements and control of the quantity and quality of the rendered services and used materials lack of professional competencies of the consumers in the sphere of activity of the producer. Practical value the key provisions and conclusions of the article can be used in the scientific and educational activity when viewing the issues of opportunistic revelations between economic subjects. nbsp

Noisy mean field game model for malware propagation in opportunistic networks

KAUST Repository

Tembine, Hamidou

2012-01-01

In this paper we present analytical mean field techniques that can be used to better understand the behavior of malware propagation in opportunistic large networks. We develop a modeling methodology based on stochastic mean field optimal control that is able to capture many aspects of the problem, especially the impact of the control and heterogeneity of the system on the spreading characteristics of malware. The stochastic large process characterizing the evolution of the total number of infected nodes is examined with a noisy mean field limit and compared to a deterministic one. The stochastic nature of the wireless environment make stochastic approaches more realistic for such types of networks. By introducing control strategies, we show that the fraction of infected nodes can be maintained below some threshold. In contrast to most of the existing results on mean field propagation models which focus on deterministic equations, we show that the mean field limit is stochastic if the second moment of the number of object transitions per time slot is unbounded with the size of the system. This allows us to compare one path of the fraction of infected nodes with the stochastic trajectory of its mean field limit. In order to take into account the heterogeneity of opportunistic networks, the analysis is extended to multiple types of nodes. Our numerical results show that the heterogeneity can help to stabilize the system. We verify the results through simulation showing how to obtain useful approximations in the case of very large systems. © 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering.

Migration and opportunistic feeding increase PCB accumulation in Arctic seabirds.

Science.gov (United States)

Baert, J M; Janssen, C R; Borgå, K; De Laender, F

2013-10-15

It is widely accepted that body concentrations of persistent organic pollutants (POPs) tend to increase with trophic level (TL). Yet, little attention has been paid to the causes in the underlying differences in POP body concentrations between species occupying similar TLs. In this paper we use two modeling approaches to quantify the importance of migration and opportunistic feeding, relative to that of trophic level, in explaining interspecific differences in polychlorinated biphenyl (PCB) body concentrations between 6 Arctic seabird species breeding in the Barents Sea: Little Auk (Alle alle), Black Guillemot (Cepphus grylle), Brünnich's Guillemot (Uria lomvia), Common Eider (Somateria mollissima), Black-legged Kittiwake (Rissa tridactyla), and Glaucous Gull (Larus hyperboreus). As a first approach, we use additive models to analyze two independent data sets (n = 470 and n = 726). We demonstrate that migration, opportunistic feeding, and TL significantly (p < 0.001) increase PCB body concentrations by a factor 3.61-4.10, 2.66-20.95, and 2.38-2.41, respectively. Our second approach, using a mechanistic bioaccumulation model, confirmed these positive effects on the body burdens but suggested lower effects of migration, opportunistic feeding, and TL (1.55, 2.39, and 2.38) than did our statistical analysis. These two independent approaches demonstrate that the effects of migration and opportunistic feeding on seabird body burdens can be similar to that of an increase of one TL and should therefore be accounted for in future analyses.

Opportunistic transmitter selection for selfless overlay cognitive radios

KAUST Repository

Shaqfeh, Mohammad; Zafar, Ammar; Alnuweiri, Hussein M.; Alouini, Mohamed-Slim

2013-01-01

We propose an opportunistic strategy to grant channel access to the primary and secondary transmitters in causal selfless overlay cognitive radios over block-fading channels. The secondary transmitter helps the primary transmitter by relaying

Joint Network Coding and Opportunistic Scheduling for the Bidirectional Relay Channel

KAUST Repository

Shaqfeh, Mohammad

2013-05-27

In this paper, we consider a two-way communication system in which two users communicate with each other through an intermediate relay over block-fading channels. We investigate the optimal opportunistic scheduling scheme in order to maximize the long-term average transmission rate in the system assuming symmetric information flow between the two users. Based on the channel state information, the scheduler decides that either one of the users transmits to the relay, or the relay transmits to a single user or broadcasts to both users a combined version of the two users’ transmitted information by using linear network coding. We obtain the optimal scheduling scheme by using the Lagrangian dual problem. Furthermore, in order to characterize the gains of network coding and opportunistic scheduling, we compare the achievable rate of the system versus suboptimal schemes in which the gains of network coding and opportunistic scheduling are partially exploited.

Joint Network Coding and Opportunistic Scheduling for the Bidirectional Relay Channel

KAUST Repository

Shaqfeh, Mohammad; Alnuweiri, Hussein; Alouini, Mohamed-Slim; Zafar, Ammar

2013-01-01

In this paper, we consider a two-way communication system in which two users communicate with each other through an intermediate relay over block-fading channels. We investigate the optimal opportunistic scheduling scheme in order to maximize the long-term average transmission rate in the system assuming symmetric information flow between the two users. Based on the channel state information, the scheduler decides that either one of the users transmits to the relay, or the relay transmits to a single user or broadcasts to both users a combined version of the two users’ transmitted information by using linear network coding. We obtain the optimal scheduling scheme by using the Lagrangian dual problem. Furthermore, in order to characterize the gains of network coding and opportunistic scheduling, we compare the achievable rate of the system versus suboptimal schemes in which the gains of network coding and opportunistic scheduling are partially exploited.

Opportunistic or event-driven maintenance at the Stanford Linear Accelerator Center

International Nuclear Information System (INIS)

Allen, C.W.; Anderson, S.; Erickson, R.; Linebarger, W.; Sheppard, J.C.; Stanek, M.

1997-03-01

The Stanford Linear Accelerator Center (SLAC) uses a maintenance management philosophy that is best described as opportunistic or event-driven. Opportunistic maintenance can be defined as a systematic method of collecting, investigating, pre-planning, and publishing a set of proposed maintenance tasks and acting on them when there is an unscheduled failure or repair ''opportunity''. Opportunistic maintenance can be thought of as a modification of the run-to-fail maintenance management philosophy. This maintenance plan was adopted and developed to improve the overall availability of SLAC's linear accelerator, beam delivery systems, and associated controls, power systems, and utilities. In the late 1980's, as the technical complexity of the accelerator facility increased, variations on a conventional maintenance plan were used with mixed results. These variations typically included some type of regular periodic interruption to operations. The periodic shutdowns and unscheduled failures were additive and resulted in unsatisfactory availability. Maintenance issues are evaluated in a daily meeting that includes the accelerator managers, maintenance supervisors and managers, safety office personnel, program managers, and accelerator operators. Lists of pending maintenance tasks are made available to the general SLAC population by a World Wide Web site on a local internet. A conventional information system which pre-dates the WWW site is still being used to provide paper copies to groups that are not yet integrated into the WWW system. The local internet provides real time maintenance information, allowing people throughout the facility to track progress on tasks with essentially real-time status updates. With the introduction of opportunistic maintenance, the accelerator's availability has been measurably better. This paper will discuss processes, rolls and responsibilities of key maintenance groups, and management tools developed to support opportunistic maintenance

Keeping pace with criminals: An extended study of designing patrol allocation against adaptive opportunistic criminals

OpenAIRE

Zhang, Chao; Gholami, Shahrzad; Kar, Debarun; Sinha, Arunesh; Jain, Manish; Goyal, Ripple; Tambe, Milind

2016-01-01

Game theoretic approaches have recently been used to model the deterrence effect of patrol officers’ assignments on opportunistic crimes in urban areas. One major challenge in this domain is modeling the behavior of opportunistic criminals. Compared to strategic attackers (such as terrorists) who execute a well-laid out plan, opportunistic criminals are less strategic in planning attacks and more flexible in executing well-laid plans based on their knowledge of patrol officers’ assignments. I...

Opportunistic tri-band carrier aggregation in licensed spectrum for multi-operator 5G hetnet

Science.gov (United States)

Maksymuk, Taras; Kyryk, Maryan; Klymash, Mykhailo; Jo, Minho; Romaniuk, Ryszard; Kotyra, Andrzej; Zhanpeisova, Aizhan; Kozbekova, Ainur

2017-08-01

Increasing capacity of mobile networks is a real challenge due to rapid increasing of traffic demands and spectrum scarcity. Carrier aggregation technology is aimed to increase the user data rate by combining the throughput of few spectrum bands, even if they are not physically collocated. Utilization of unlicensed Wi-Fi 5 GHz band for mobile transmission opens new perspectives for carrier aggregation due to vast amount of spectrum range, which can be available for aggregation to supplement data rates for end users. There are many solutions proposed to enable mobile data transmission in unlicensed band without disturbing interference for the existing Wi-Fi users. The paper presents a new approach for opportunistic carrier aggregation in licensed and unlicensed band for multi-operator 5G network. It allows multiple network operators to utilize unlicensed spectrum opportunistically if it is not currently used by Wi-Fi or other mobile network operators. Performance of the proposed approach has been simulated in case of two competing operators. Simulation results reveal that applying the proposed method ensures achieving satisfactory performance of carrier aggregation for the case of two network operators.

Partial QoS-Aware Opportunistic Relay Selection Over Two-Hop Channels: End-to-End Performance Under Spectrum-Sharing Requirements

KAUST Repository

Yuli Yang,

2014-10-01

In this paper, we propose a partial quality-of-service (QoS)-oriented relay selection scheme with a decode-and-forward (DF) relaying protocol, to reduce the feedback amount required for relay selection. In the proposed scheme, the activated relay is the one with the maximum signal-to-noise power ratio (SNR) in the second hop among those whose packet loss rates (PLRs) in the first hop achieve a predetermined QoS level. For the purpose of evaluating the performance of the proposed scheme, we exploit it with transmission constraints imposed on the transmit power budget and interference to other users. By analyzing the statistics of received SNRs in the first and second hops, we obtain the end-to-end PLR of this scheme in closed form under the considered scenario. Moreover, to compare the proposed scheme with popular relay selection schemes, we also derive the closed-form PLR expressions for partial relay selection (PRS) and opportunistic relay selection (ORS) criteria in the same scenario under study. Illustrative numerical results demonstrate the accuracy of our derivations and substantiate that the proposed relay selection scheme is a promising alternative with respect to the tradeoff between performance and complexity.

Optimality of Multichannel Myopic Sensing in the Presence of Sensing Error for Opportunistic Spectrum Access

Directory of Open Access Journals (Sweden)

Xiaofeng Jiang

2013-01-01

Full Text Available The optimization problem for the performance of opportunistic spectrum access is considered in this study. A user, with the limited sensing capacity, has opportunistic access to a communication system with multiple channels. The user can only choose several channels to sense and decides whether to access these channels based on the sensing information in each time slot. Meanwhile, the presence of sensing error is considered. A reward is obtained when the user accesses a channel. The objective is to maximize the expected (discounted or average reward accrued over an infinite horizon. This problem can be formulated as a partially observable Markov decision process. This study shows the optimality of the simple and robust myopic policy which focuses on maximizing the immediate reward. The results show that the myopic policy is optimal in the case of practical interest.

Diagnostic mode and tumor stage of breast cancers in the setting of opportunistic screening

International Nuclear Information System (INIS)

Graf, O.; Hopf, G.; Obermayer, M.; Fruehwald, F.; Scheurecker, A.; Kramer, J.

2006-01-01

Purpose: To analyze data at the time of diagnosis of breast cancer in three radiology practices in Austria in the setting of opportunistic screening. Materials and methods: In 529 women (ages 31 - 89, mean age 61.1) with breast cancer, the mode of diagnosis (detected clinically or by opportunistic screening), the local tumor stages, and intervals between screening examinations were assessed. Results: In 33.6% (178 of 529) of the cases, the breast cancer was detected clinically, and in 66.4% (351 of 529) of the cases, the cancer was detected by opportunistic screening. Cancers in prognostically favorable stages (in situ carcinomas, pT1 a, pT1 b, pT1c) were detected by opportunistic screening in 79.9% of the cases. The clinically detected cancers were in locally advanced stages (pT2, pT3) in 58.4% of the cases. In the majority of clinically detected cases (75%), the women had never had a mammogram before or had not had a recent one. In 13% of the cases detected by opportunistic screening, diagnosis was made during the first exam, in 40% of the cases, the period since the last mammogram was less than 24 months, and in 47% of the cases, this period was greater than 24 months. Conclusion: In our patients the majority of breast cancers were detected in early stages by opportunistic screening. The use of an organized system with exams at regular intervals may further reduce the number of advanced cancers. (orig.)

Pattern of gastrointestinal opportunistic infections among HIV ...

African Journals Online (AJOL)

Twenty-two per cent (22%) of these had mixed parasitosis of cryptosporidium and hookworm. There was no significant association of CD4 cells count with intestinal parasitosis. x2 = 5.286 and p=0.259. However marital status was significantly associated with gastrointestinal opportunistic parasitosis with x2 of 12.693, ...

Pathogenic and opportunistic microorganisms in caves

Directory of Open Access Journals (Sweden)

Sanchez-Moral Sergio

2010-01-01

Full Text Available With today’s leisure tourism, the frequency of visits to many caves makes it necessary to know about possible potentially pathogenic microorganisms in caves, determine their reservoirs, and inform the public about the consequences of such visits. Our data reveal that caves could be a potential danger to visitors because of the presence of opportunistic microorganisms, whose existence and possible development in humans is currently unknown.

Chest x-ray findings of opportunistic infections

International Nuclear Information System (INIS)

Lee, Yul; Jeon, Suk Chul; Lim, Jeong Ki; Park, Jae Hyung; Kim, Chu Wan

1983-01-01

The chest x-ray findings of 20 cases of pulmonary opportunistic infection were analyzed according to causative agents. The results were as follows: 1. Final diagnoses of 20 cases of opportunistic infections were tuberculosis in 6 cases, pneumocystis carinii pneumonia in 5 cases, bacterial infection in 7 cases, and fungal infection in 2 cases. 2. The underlying diseases were leukemia in 6 cases, kidney transplantation in 6 cases, lymphoma in 3 cases, nephrotic syndrome in 1 case, nasopharyngeal cancer in 1 case, multiple myeloma in 1 case, agranulocytosis in 1 case, and hypogammaglobulinemia in 1 case. 3. In tuberculosis, all the 6 cases showed severe manifestations such as military tuberculosis, tuberculous pneumonia, moderately advanced tuberculosis and tuberculous pericarditis. 4. In pneumocystis carinii pneumonia, the most frequent findings were bilateral alveolar densities and peripheral field of the lung was saved in most cases. 5. In 2 cases of fungal infections bilateral multiple cavity nodules were noted. 6. In cases of bacterial infection there was more cases of gram negative infection than gram positive and 2 cases of pseudomonas revealed bilateral multiple cavitary nodules

Isolation of Cryptococcus neoformans and other opportunistic fungi from pigeon droppings.

Science.gov (United States)

Soltani, Maryam; Bayat, Mansour; Hashemi, Seyed J; Zia, Mohammadali; Pestechian, Nader

2013-01-01

Invasive fungal infections cause considerable morbidity and mortality in immunocompromised hosts. Pigeon droppings could especially be a potential carrier in the spread of pathogenic yeasts and mold fungi into the environment. The objective of this study was to isolation of Cryptococcus neoformans and other opportunistic fungi from pigeon droppings. One hundred twenty samples of pigeon droppings were suspended 1:10 in saline solution and then cultured. Identification of C. neoformans was performed on bird seed agar, presence of a capsule on India ink preparation, urease production on urea agar medium and RapID yeast plus system. The identification of candida species was based on micro-morphological analysis on corn meal-Tween 80 agar, RapID yeast plus system and growth in CHROMagar candida. The identification of other fungi was based on macromorphologic, microscopic, biochemical and physiological characteristics. The highest frequency of yeasts and mold fungi were observed in Candida albicans 6.6% and Penicillium spp. 25%. The frequency rate of C. neoformans isolation was 2.5%. Several types of fungi are present in pigeon droppings that can spread in environment and transmit to children and elderly as well as immunocompromised patients who are at increased risk of contracting opportunistic diseases.

Isolation of Cryptococcus neoformans and other opportunistic fungi from pigeon droppings

Directory of Open Access Journals (Sweden)

Maryam Soltani

2013-01-01

Full Text Available Background: Invasive fungal infections cause considerable morbidity and mortality in immunocompromised hosts. Pigeon droppings could especially be a potential carrier in the spread of pathogenic yeasts and mold fungi into the environment. The objective of this study was to isolation of Cryptococcus neoformans and other opportunistic fungi from pigeon droppings. Materials and Methods: One hundred twenty samples of pigeon droppings were suspended 1:10 in saline solution and then cultured. Identification of C. neoformans was performed on bird seed agar, presence of a capsule on India ink preparation, urease production on urea agar medium and RapID yeast plus system. The identification of candida species was based on micro-morphological analysis on corn meal-Tween 80 agar, RapID yeast plus system and growth in CHROMagar candida. The identification of other fungi was based on macromorphologic, microscopic, biochemical and physiological characteristics. Results: The highest frequency of yeasts and mold fungi were observed in Candida albicans 6.6% and Penicillium spp. 25%. The frequency rate of C. neoformans isolation was 2.5%. Conclusion: Several types of fungi are present in pigeon droppings that can spread in environment and transmit to children and elderly as well as immunocompromised patients who are at increased risk of contracting opportunistic diseases.

[Acceptability and feasibility among primary care doctors of the opportunistic search for HIV in Health Care centers in Spain].

Science.gov (United States)

Puentes Torres, Rafael Carlos; Aguado Taberné, Cristina; Pérula de Torres, Luis Ángel; Espejo Espejo, José; Castro Fernández, Cristina; Fransi Galiana, Luis

2017-12-01

To evaluate the acceptability and feasibility of the opportunistic search of HIV according to primary care doctors' experience. To set up the profile of the physician involved in this study. Observational, transversal study. Primary Care Centers of the National Health System. General practitioners and residents who participated in VIH-AP study to measure the acceptability of HIV opportunistic search by patients. Self-filling survey to collect data on age, sex, teaching skills, amount of years dedicated to research, time working with the same quota of patients, acceptability and feasibility of opportunistic HIV search. A total of 197 physicians with a mean age of 45.2±9.7 (SD) years. 18.8% were under 36years old, 70.1% were women and 62.4% had teaching skills. 55.8% worked in towns with a population over 100,000 inhabitants and the mean of years working with the same quota of patients was 6.4±6.6. 91.9% (95%CI: 88.1-98.7) of them considered the opportunistic search of HIV acceptable and 89.3% (95%CI: 85.0-93.6), feasible to perform. The multivariate analysis showed positive relation between the acceptability/feasibility and teaching skills (OR: 2.74; 95%CI: 1.16-6.49). The acceptance of the screening by patients was 93.1% and this was positively related to how long the doctor had worked with the same quota, teaching skills and the amount of years dedicated to research. HIV opportunistic search is an acceptable and feasible method for primary care professionals. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

Analytical evaluation of adaptive-modulation-based opportunistic cognitive radio in nakagami-m fading channels

KAUST Repository

Chen, Yunfei; Alouini, Mohamed-Slim; Tang, Liang; Khan, Fahdahmed

2012-01-01

The performance of adaptive modulation for cognitive radio with opportunistic access is analyzed by considering the effects of spectrum sensing, primary user (PU) traffic, and time delay for Nakagami- m fading channels. Both the adaptive continuous rate scheme and the adaptive discrete rate scheme are considered. Numerical examples are presented to quantify the effects of spectrum sensing, PU traffic, and time delay for different system parameters. © 1967-2012 IEEE.

Analytical evaluation of adaptive-modulation-based opportunistic cognitive radio in nakagami-m fading channels

KAUST Repository

Chen, Yunfei

2012-09-01

The performance of adaptive modulation for cognitive radio with opportunistic access is analyzed by considering the effects of spectrum sensing, primary user (PU) traffic, and time delay for Nakagami- m fading channels. Both the adaptive continuous rate scheme and the adaptive discrete rate scheme are considered. Numerical examples are presented to quantify the effects of spectrum sensing, PU traffic, and time delay for different system parameters. © 1967-2012 IEEE.

Fluconazole resistant opportunistic oro-pharyngeal candida and non ...

African Journals Online (AJOL)

Background: Oro-Pharyngeal Candidiasis (OPC) continues to be considered the most common opportunistic fungal disease in HIV/AIDS patients globally. Azole antifungal agent has become important in the treatment of mucosal candidiasis in HIV patients. Presently, antifungal drug resistance is fast becoming a major ...

Relationship between lactobacilli and opportunistic bacterial pathogens associated with vaginitis.

Science.gov (United States)

Razzak, Mohammad Sabri A; Al-Charrakh, Alaa H; Al-Greitty, Bara Hamid

2011-04-01

Vaginitis, is an infectious inflammation of the vaginal mucosa, which sometimes involves the vulva. The balance of the vaginal flora is maintained by the Lactobacilli and its protective and probiotic role in treating and preventing vaginal infection by producing antagonizing compounds which are regarded as safe for humans. The aim of this study was to evaluate the protective role of Lactobacilli against common bacterial opportunistic pathogens in vaginitis and study the effects of some antibiotics on Lactobacilli isolates. In this study (110) vaginal swabs were obtained from women suffering from vaginitis who admitted to Babylon Hospital of Maternity and Paediatrics in Babylon province, Iraq. The study involved the role of intrauterine device among married women with vaginitis and also involved isolation of opportunistic bacterial isolates among pregnant and non pregnant women. This study also involved studying probiotic role of Lactobacilli by production of some defense factors like hydrogen peroxide, bacteriocin, and lactic acid. Results revealed that a total of 130 bacterial isolates were obtained. Intrauterine device was a predisposing factor for vaginitis. The most common opportunistic bacterial isolates were Staphylococcus aureus, Escherichia coli, Streptococcus agalactiae, and Klebsiella pneumoniae. All Lactobacilli were hydrogen peroxide producers while some isolates were bacteriocin producers that inhibited some of opportunistic pathogens (S. aureus, E. coli). Lactobacilli were sensitive to erythromycin while 93.3% of them were resistant to ciprofloxacin and (40%, 53.3%) of them were resistant to amoxicillin and gentamycin respectively. Results revealed that there was an inverse relationship between Lactobacilli presence and organisms causing vaginitis. This may be attributed to the production of defense factors by Lactobacilli. The types of antibiotics used to treat vaginitis must be very selective in order not to kill the beneficial bacteria

Full-Duplex opportunistic relay selection in future spectrum-sharing networks

KAUST Repository

Khafagy, Mohammad Galal; Alouini, Mohamed-Slim; Aï ssa, Sonia

2015-01-01

We propose and analyze the performance of full-duplex relay selection in primary/secondary spectrum-sharing networks. Contrary to half-duplex relaying, full-duplex relaying (FDR) enables simultaneous listening/forwarding at the secondary relay, thereby allowing for a higher spectral efficiency. However, since the source and relay simultaneously transmit in FDR, their superimposed signal at the primary receiver should now satisfy the existing interference constraint which can considerably limit the secondary network throughput. In this regard, relay selection can offer an adequate solution to boost the secondary throughput while satisfying the imposed interference limit. We first analyze the performance of opportunistic relay selection among a cluster of full-duplex decode-and-forward relays with self-interference by deriving the exact cumulative distribution function of its end-to-end signal-to-noise ratio. Second, we evaluate the end-to-end performance of relay selection with interference constraints due to the presence of a primary receiver. Finally, the presented exact theoretical findings are verified by numerical simulations.

Full-Duplex opportunistic relay selection in future spectrum-sharing networks

KAUST Repository

Khafagy, Mohammad Galal

2015-06-01

We propose and analyze the performance of full-duplex relay selection in primary/secondary spectrum-sharing networks. Contrary to half-duplex relaying, full-duplex relaying (FDR) enables simultaneous listening/forwarding at the secondary relay, thereby allowing for a higher spectral efficiency. However, since the source and relay simultaneously transmit in FDR, their superimposed signal at the primary receiver should now satisfy the existing interference constraint which can considerably limit the secondary network throughput. In this regard, relay selection can offer an adequate solution to boost the secondary throughput while satisfying the imposed interference limit. We first analyze the performance of opportunistic relay selection among a cluster of full-duplex decode-and-forward relays with self-interference by deriving the exact cumulative distribution function of its end-to-end signal-to-noise ratio. Second, we evaluate the end-to-end performance of relay selection with interference constraints due to the presence of a primary receiver. Finally, the presented exact theoretical findings are verified by numerical simulations.

Optimizing Cooperative Cognitive Radio Networks with Opportunistic Access

KAUST Repository

Zafar, Ammar; Alouini, Mohamed-Slim; Chen, Yunfei; Radaydeh, Redha M.

2012-01-01

Optimal resource allocation for cooperative cognitive radio networks with opportunistic access to the licensed spectrum is studied. Resource allocation is based on minimizing the symbol error rate at the receiver. Both the cases of all-participate relaying and selective relaying are considered. The objective function is derived and the constraints are detailed for both scenarios. It is then shown that the objective functions and the constraints are nonlinear and nonconvex functions of the parameters of interest, that is, source and relay powers, symbol time, and sensing time. Therefore, it is difficult to obtain closed-form solutions for the optimal resource allocation. The optimization problem is then solved using numerical techniques. Numerical results show that the all-participate system provides better performance than its selection counterpart, at the cost of greater resources. © 2012 Ammar Zafar et al.

Optimizing Cooperative Cognitive Radio Networks with Opportunistic Access

KAUST Repository

Zafar, Ammar

2012-09-16

Optimal resource allocation for cooperative cognitive radio networks with opportunistic access to the licensed spectrum is studied. Resource allocation is based on minimizing the symbol error rate at the receiver. Both the cases of all-participate relaying and selective relaying are considered. The objective function is derived and the constraints are detailed for both scenarios. It is then shown that the objective functions and the constraints are nonlinear and nonconvex functions of the parameters of interest, that is, source and relay powers, symbol time, and sensing time. Therefore, it is difficult to obtain closed-form solutions for the optimal resource allocation. The optimization problem is then solved using numerical techniques. Numerical results show that the all-participate system provides better performance than its selection counterpart, at the cost of greater resources. © 2012 Ammar Zafar et al.

Lung Infections in Systemic Rheumatic Disease: Focus on Opportunistic Infections.

Science.gov (United States)

Di Franco, Manuela; Lucchino, Bruno; Spaziante, Martina; Iannuccelli, Cristina; Valesini, Guido; Iaiani, Giancarlo

2017-01-29

Systemic rheumatic diseases have significant morbidity and mortality, due in large part to concurrent infections. The lung has been reported among the most frequent sites of infection in patients with rheumatic disease, who are susceptible to developing pneumonia sustained both by common pathogens and by opportunistic microorganisms. Patients with rheumatic disease show a peculiar vulnerability to infectious complications. This is due in part to intrinsic disease-related immune dysregulation and in part to the immunosuppressive treatments. Several therapeutic agents have been associated to a wide spectrum of infections, complicating the management of rheumatic diseases. This review discusses the most frequent pulmonary infections encountered in rheumatic diseases, focusing on opportunistic agents, consequent diagnostic challenges and appropriate therapeutic strategies.

Loss of competition in the outside host environment generates outbreaks of environmental opportunist pathogens.

Directory of Open Access Journals (Sweden)

Jani Anttila

Full Text Available Environmentally transmitted pathogens face ecological interactions (e.g., competition, predation, parasitism in the outside-host environment and host immune system during infection. Despite the ubiquitousness of environmental opportunist pathogens, traditional epidemiology focuses on obligatory pathogens incapable of environmental growth. Here we ask how competitive interactions in the outside-host environment affect the dynamics of an opportunist pathogen. We present a model coupling the classical SI and Lotka-Volterra competition models. In this model we compare a linear infectivity response and a sigmoidal infectivity response. An important assumption is that pathogen virulence is traded off with competitive ability in the environment. Removing this trade-off easily results in host extinction. The sigmoidal response is associated with catastrophic appearances of disease outbreaks when outside-host species richness, or overall competition pressure, decreases. This indicates that alleviating outside-host competition with antibacterial substances that also target the competitors can have unexpected outcomes by providing benefits for opportunist pathogens. These findings may help in developing alternative ways of controlling environmental opportunist pathogens.

Plancton: an opportunistic distributed computing project based on Docker containers

Science.gov (United States)

Concas, Matteo; Berzano, Dario; Bagnasco, Stefano; Lusso, Stefano; Masera, Massimo; Puccio, Maximiliano; Vallero, Sara

2017-10-01

The computing power of most modern commodity computers is far from being fully exploited by standard usage patterns. In this work we describe the development and setup of a virtual computing cluster based on Docker containers used as worker nodes. The facility is based on Plancton: a lightweight fire-and-forget background service. Plancton spawns and controls a local pool of Docker containers on a host with free resources, by constantly monitoring its CPU utilisation. It is designed to release the resources allocated opportunistically, whenever another demanding task is run by the host user, according to configurable policies. This is attained by killing a number of running containers. One of the advantages of a thin virtualization layer such as Linux containers is that they can be started almost instantly upon request. We will show how fast the start-up and disposal of containers eventually enables us to implement an opportunistic cluster based on Plancton daemons without a central control node, where the spawned Docker containers behave as job pilots. Finally, we will show how Plancton was configured to run up to 10 000 concurrent opportunistic jobs on the ALICE High-Level Trigger facility, by giving a considerable advantage in terms of management compared to virtual machines.

Cooperative Cloud Service Aware Mobile Internet Coverage Connectivity Guarantee Protocol Based on Sensor Opportunistic Coverage Mechanism

Directory of Open Access Journals (Sweden)

Qin Qin

2015-01-01

Full Text Available In order to improve the Internet coverage ratio and provide connectivity guarantee, based on sensor opportunistic coverage mechanism and cooperative cloud service, we proposed the coverage connectivity guarantee protocol for mobile Internet. In this scheme, based on the opportunistic covering rules, the network coverage algorithm of high reliability and real-time security was achieved by using the opportunity of sensor nodes and the Internet mobile node. Then, the cloud service business support platform is created based on the Internet application service management capabilities and wireless sensor network communication service capabilities, which is the architecture of the cloud support layer. The cooperative cloud service aware model was proposed. Finally, we proposed the mobile Internet coverage connectivity guarantee protocol. The results of experiments demonstrate that the proposed algorithm has excellent performance, in terms of the security of the Internet and the stability, as well as coverage connectivity ability.

Computed tomography in opportunistic lung infections

International Nuclear Information System (INIS)

Hartelius, H.

1988-01-01

Chest radiography in two teenage boys, one with Wiscott-Aldrich's syndrome and one with acute lymphatic leucemia in remission showed increased interstitial pattern. In both computed tomography (CT) of the lungs showed heavy interstitial pneumonia, rather different in appearance but in both cases equal to the CT findings in opportunistic lung infections known from immunoincompetent patients with for instance pneumocystis carinii and/or cytomegalo virus infections. In both patients the CT findings led to lung biopsy establishing the etiologic agent. (orig.)

Opportunistic Beacon Networks: Information Dissemination via Wireless Network Identifiers

NARCIS (Netherlands)

Türkes, Okan; Scholten, Johan; Havinga, Paul J.M.

2016-01-01

This paper presents OBN, a universal opportunistic ad hoc networking model particularly intended for smart mobile devices. It enables fast and lightweight data dissemination in wireless community networks through the utilization of universally-available wireless network identifiers. As a ubiquitous

Mathematical Modeling and Analysis Methodology for Opportunistic Routing in Wireless Multihop Networks

Directory of Open Access Journals (Sweden)

Wang Dongyang

2015-01-01

Full Text Available Modeling the forwarding feature and analyzing the performance theoretically for opportunistic routing in wireless multihop network are of great challenge. To address this issue, a generalized geometric distribution (GGD is firstly proposed. Based on the GGD, the forwarding probability between any two forwarding candidates could be calculated and it can be proved that the successful delivery rate after several transmissions of forwarding candidates is irrelevant to the priority rule. Then, a discrete-time queuing model is proposed to analyze mean end-to-end delay (MED of a regular opportunistic routing with the knowledge of the forwarding probability. By deriving the steady-state joint generating function of the queue length distribution, MED for directly connected networks and some special cases of nondirectly connected networks could be ultimately determined. Besides, an approximation approach is proposed to assess MED for the general cases in the nondirectly connected networks. By comparing with a large number of simulation results, the rationality of the analysis is validated. Both the analysis and simulation results show that MED varies with the number of forwarding candidates, especially when it comes to connected networks; MED increases more rapidly than that in nondirectly connected networks with the increase of the number of forwarding candidates.

Opportunistic Sensor Data Collection with Bluetooth Low Energy.

Science.gov (United States)

Aguilar, Sergio; Vidal, Rafael; Gomez, Carles

2017-01-23

Bluetooth Low Energy (BLE) has gained very high momentum, as witnessed by its widespread presence in smartphones, wearables and other consumer electronics devices. This fact can be leveraged to carry out opportunistic sensor data collection (OSDC) in scenarios where a sensor node cannot communicate with infrastructure nodes. In such cases, a mobile entity (e.g., a pedestrian or a vehicle) equipped with a BLE-enabled device can collect the data obtained by the sensor node when both are within direct communication range. In this paper, we characterize, both analytically and experimentally, the performance and trade-offs of BLE as a technology for OSDC, for the two main identified approaches, and considering the impact of its most crucial configuration parameters. Results show that a BLE sensor node running on a coin cell battery can achieve a lifetime beyond one year while transferring around 10 Mbit/day, in realistic OSDC scenarios.

AFSC/NMML: Cook Inlet Beluga Opportunistic Sightings, 1975 to 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — As a part of National Marine Fisheries Service (NMFS) management of the endangered Cook Inlet beluga whale population, a database of opportunistic beluga whale...

Towards Opportunistic Data Dissemination in Mobile Phone Sensor Networks

NARCIS (Netherlands)

Le Viet Duc, L Duc; Scholten, Johan; Havinga, Paul J.M.

Recently, there has been a growing interest within the research community in developing opportunistic routing protocols. Many schemes have been proposed; however, they differ greatly in assumptions and in type of network for which they are evaluated. As a result, researchers have an ambiguous

A non-digging zoobenthivorous fish attracts two opportunistic predatory fish associates

Directory of Open Access Journals (Sweden)

Cristina Sazima

Full Text Available Following behaviour among reef fishes involves mostly a digging nuclear species while foraging, which attracts opportunistic followers preying on the exposed organisms. The flying gurnard Dactylopterus volitans preys on benthic animals, mostly crustaceans and small fishes, scratching and probing the bottom with the inner rays of its pectoral fins. We recorded the flying gurnard being followed by two opportunistic predators, the yellow jack Caranx bartholomaei and the coney Cephalopholis fulva at Fernando de Noronha, off northeast Brazil. Albeit not actually digging the substrate, the flying gurnard acts as a nuclear species by exploring algae tufts and by its wandering near the boulders and ledges, disturbing and flushing out hidden animals which thus become available to predation.

Exploiting volatile opportunistic computing resources with Lobster

Science.gov (United States)

Woodard, Anna; Wolf, Matthias; Mueller, Charles; Tovar, Ben; Donnelly, Patrick; Hurtado Anampa, Kenyi; Brenner, Paul; Lannon, Kevin; Hildreth, Mike; Thain, Douglas

2015-12-01

Analysis of high energy physics experiments using the Compact Muon Solenoid (CMS) at the Large Hadron Collider (LHC) can be limited by availability of computing resources. As a joint effort involving computer scientists and CMS physicists at Notre Dame, we have developed an opportunistic workflow management tool, Lobster, to harvest available cycles from university campus computing pools. Lobster consists of a management server, file server, and worker processes which can be submitted to any available computing resource without requiring root access. Lobster makes use of the Work Queue system to perform task management, while the CMS specific software environment is provided via CVMFS and Parrot. Data is handled via Chirp and Hadoop for local data storage and XrootD for access to the CMS wide-area data federation. An extensive set of monitoring and diagnostic tools have been developed to facilitate system optimisation. We have tested Lobster using the 20 000-core cluster at Notre Dame, achieving approximately 8-10k tasks running simultaneously, sustaining approximately 9 Gbit/s of input data and 340 Mbit/s of output data.

Guidelines for the naming of genes, gene products, and mutants in the opportunistic protists.

Science.gov (United States)

Limper, Andrew H; Weiss, Louis M

2011-01-01

The opportunistic protists encompass a wide diversity of organisms including Pneumocystis, Toxoplasma, cryptosporidia, microsporidia, and related genera. Recent advances in the molecular biology and cellular biochemistry of these organisms have led to the identification of an ever growing numbers of key genes and their cognate proteins. Until now, these molecules have not been designated using any consistent nomenclature system, leading to considerable confusion. The participants of the 11th International Workshop on Opportunistic Protists met on August 3, 2010 to reach consensus of a nomenclature system for genes, gene products, and mutants in the opportunistic protists. The following summary reports the consensus agreement to move toward a unified nomenclature system for these organisms. The system is adapted from that used for Saccharomyces cerevisiae. © 2011 The Author(s). Journal of Eukaryotic Microbiology © 2011 International Society of Protistologists.

Opportunistic Sensor Data Collection with Bluetooth Low Energy

Directory of Open Access Journals (Sweden)

Sergio Aguilar

2017-01-01

Full Text Available Bluetooth Low Energy (BLE has gained very high momentum, as witnessed by its widespread presence in smartphones, wearables and other consumer electronics devices. This fact can be leveraged to carry out opportunistic sensor data collection (OSDC in scenarios where a sensor node cannot communicate with infrastructure nodes. In such cases, a mobile entity (e.g., a pedestrian or a vehicle equipped with a BLE-enabled device can collect the data obtained by the sensor node when both are within direct communication range. In this paper, we characterize, both analytically and experimentally, the performance and trade-offs of BLE as a technology for OSDC, for the two main identified approaches, and considering the impact of its most crucial configuration parameters. Results show that a BLE sensor node running on a coin cell battery can achieve a lifetime beyond one year while transferring around 10 Mbit/day, in realistic OSDC scenarios.

Effect of threshold quantization in opportunistic splitting algorithm

KAUST Repository

Nam, Haewoon

2011-12-01

This paper discusses algorithms to find the optimal threshold and also investigates the impact of threshold quantization on the scheduling outage performance of the opportunistic splitting scheduling algorithm. Since this algorithm aims at finding the user with the highest channel quality within the minimal number of mini-slots by adjusting the threshold every mini-slot, optimizing the threshold is of paramount importance. Hence, in this paper we first discuss how to compute the optimal threshold along with two tight approximations for the optimal threshold. Closed-form expressions are provided for those approximations for simple calculations. Then, we consider linear quantization of the threshold to take the limited number of bits for signaling messages in practical systems into consideration. Due to the limited granularity for the quantized threshold value, an irreducible scheduling outage floor is observed. The numerical results show that the two approximations offer lower scheduling outage probability floors compared to the conventional algorithm when the threshold is quantized. © 2006 IEEE.

Development of a simple screening tool for opportunistic COPD case finding in primary care in Latin America: The PUMA study.

Science.gov (United States)

López Varela, Maria Victorina; Montes de Oca, Maria; Rey, Alejandra; Casas, Alejandro; Stirbulov, Roberto; Di Boscio, Valentina

2016-10-01

Opportunistic chronic obstructive pulmonary disease (COPD) case finding approaches for high-risk individuals with or without symptoms is a feasible option for disease identification. PUMA is an opportunistic case finding study conducted in primary care setting of Argentina, Colombia, Venezuela and Uruguay. The objectives were to measure COPD prevalence in an at-risk population visiting primary care for any reason, to assess the yield of this opportunistic approach and the accuracy of a score developed to detect COPD. Subjects attending routine primary care visits, ≥40 years of age, current or former smokers or exposed to biomass smoke, completed a questionnaire and performed spirometry. COPD was defined as post-bronchodilator (post-BD) forced expiratory volume in 1 s (FEV1 )/forced vital capacity (FVC) 50 years, heavy smokers (>30 pack-years), with dyspnoea, and having prior spirometry. A simple score and a weighted score constructed using the following predictive factors: gender, age, pack-years smoking, dyspnoea, sputum, cough and spirometry, had a mean accuracy for detecting COPD (post-BD FEV1 /FVC tool to select subjects for spirometry in primary care. © 2016 Asian Pacific Society of Respirology.

The 13th International Workshops on Opportunistic Protists (IWOP13).

Science.gov (United States)

Calderon, Enrique J; Cushion, Melanie T; Xiao, Lihua; Lorenzo-Morales, Jacob; Matos, Olga; Kaneshiro, Edna S; Weiss, Louis M

2015-01-01

The 13th International Workshops on Opportunistic Protists (IWOP-13) was held November 13-15, 2014 in Seville, Spain. The objectives of the IWOP meetings are to: (1) serve as a forum for exchange of new information among active researchers concerning the basic biology, molecular genetics, immunology, biochemistry, pathogenesis, drug development, therapy, and epidemiology of these immunodeficiency-associated pathogenic eukaryotic microorganisms that are seen in patients with AIDS and; (2) to foster the entry of new and young investigators into these underserved research areas. The IWOP meeting focuses on opportunistic protists; e.g. the free-living amoebae, Pneumocystis, Cryptosporidium, Toxoplasma, the Microsporidia, and kinetoplastid flagellates. This conference represents the major conference which brings together research groups working on these opportunistic pathogens. Progress has been achieved on understanding the biology of these pathogenic organisms, their involvement in disease causation in both immune deficient and immune competent hosts and is providing important insights into these emerging and reemerging pathogens. A continuing concern of the participants is the ongoing loss of scientific expertise and diversity in this research community. This decline is due to the small size of these research communities and an ongoing lack of understanding by the broader scientific community of the challenges and limitations faced by researchers working on these organisms, which makes these research communities very sensitive to declines in research funding. © 2015 The Author(s) Journal of Eukaryotic Microbiology © 2015 International Society of Protistologists.

Performance in grade 12 mathematics and science predicts student nurses' performance in first year science modules at a university in the Western Cape.

Science.gov (United States)

Mthimunye, Katlego D T; Daniels, Felicity M

2017-10-26

The demand for highly qualified and skilled nurses is increasing in South Africa as well as around the world. Having a background in science can create a significant advantage for students wishing to enrol for an undergraduate nursing qualification because nursing as profession is grounded in scientific evidence. The aim of this study was to investigate the predictive validity of grade 12 mathematics and science on the academic performance of first year student nurses in science modules. A quantitative research method using a cross-sectional predictive design was employed in this study. The participants included first year Bachelor of Nursing students enrolled at a university in the Western Cape, South Africa. Descriptive and inferential statistics were performed to analyse the data by using the IBM Statistical Package for Social Sciences versions 24. Descriptive analysis of all variables was performed as well as the Spearman's rank correlation test to describe the relationship among the study variables. Standard multiple linear regressions analysis was performed to determine the predictive validity of grade 12 mathematics and science on the academic performance of first year student nurses in science modules. The results of this study showed that grade 12 physical science is not a significant predictor (p > 0.062) of performance in first year science modules. The multiple linear regression revealed that grade 12 mathematics and life science grades explained 37.1% to 38.1% (R2 = 0.381 and adj R2 = 0.371) of the variation in the first year science grade distributions. Based on the results of the study it is evident that performance in grade 12 mathematics (β = 2.997) and life science (β = 3.175) subjects is a significant predictor (p < 0.001) of the performance in first year science modules for student nurses at the university identified for this study.

SPRINT-SELF: Social-Based Routing and Selfish Node Detection in Opportunistic Networks

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Radu Ioan Ciobanu

2015-01-01

Full Text Available Since mobile devices nowadays have become ubiquitous, several types of networks formed over such devices have been proposed. One such approach is represented by opportunistic networking, which is based on a store-carry-and-forward paradigm, where nodes store data and carry it until they reach a suitable node for forwarding. The problem in such networks is how to decide what the next hop will be, since nodes do not have a global view of the network. We propose using the social network information of a node when performing routing, since a node is more likely to encounter members of its own social community than other nodes. In addition, we approximate a node’s contact as a Poisson distribution and show that we can predict its future behavior based on the contact history. Furthermore, since opportunistic network nodes may be selfish, we improve our solution by adding a selfish node detection and avoidance mechanism, which can help reduce the number of unnecessary messages sent in the network, and thus avoid congestion and decrease battery consumption. We show that our algorithm outperforms existing solutions such as BUBBLE Rap and Epidemic in terms of delivery cost and hit rate, as well as the rate of congestion introduced in the network, by testing in various realistic scenarios.

Mobile opportunistic networks architectures, protocols and applications

CERN Document Server

Denko, Mieso K

2011-01-01

Widespread availability of pervasive and mobile devices coupled with recent advances in networking technologies make opportunistic networks one of the most promising communication technologies for a growing number of future mobile applications. Covering the basics as well as advanced concepts, this book introduces state-of-the-art research findings, technologies, tools, and innovations. Prominent researchers from academia and industry report on communication architectures, network algorithms and protocols, emerging applications, experimental studies, simulation tools, implementation test beds,

Totally opportunistic routing algorithm (TORA) for underwater wireless sensor network

Science.gov (United States)

Hashim, Fazirulhisyam; Rasid, Mohd Fadlee A.; Othman, Mohamed

2018-01-01

Underwater Wireless Sensor Network (UWSN) has emerged as promising networking techniques to monitor and explore oceans. Research on acoustic communication has been conducted for decades, but had focused mostly on issues related to physical layer such as high latency, low bandwidth, and high bit error. However, data gathering process is still severely limited in UWSN due to channel impairment. One way to improve data collection in UWSN is the design of routing protocol. Opportunistic Routing (OR) is an emerging technique that has the ability to improve the performance of wireless network, notably acoustic network. In this paper, we propose an anycast, geographical and totally opportunistic routing algorithm for UWSN, called TORA. Our proposed scheme is designed to avoid horizontal transmission, reduce end to end delay, overcome the problem of void nodes and maximize throughput and energy efficiency. We use TOA (Time of Arrival) and range based equation to localize nodes recursively within a network. Once nodes are localized, their location coordinates and residual energy are used as a matrix to select the best available forwarder. All data packets may or may not be acknowledged based on the status of sender and receiver. Thus, the number of acknowledgments for a particular data packet may vary from zero to 2-hop. Extensive simulations were performed to evaluate the performance of the proposed scheme for high network traffic load under very sparse and very dense network scenarios. Simulation results show that TORA significantly improves the network performance when compared to some relevant existing routing protocols, such as VBF, HHVBF, VAPR, and H2DAB, for energy consumption, packet delivery ratio, average end-to-end delay, average hop-count and propagation deviation factor. TORA reduces energy consumption by an average of 35% of VBF, 40% of HH-VBF, 15% of VAPR, and 29% of H2DAB, whereas the packet delivery ratio has been improved by an average of 43% of VBF, 26

Totally opportunistic routing algorithm (TORA) for underwater wireless sensor network.

Science.gov (United States)

Rahman, Ziaur; Hashim, Fazirulhisyam; Rasid, Mohd Fadlee A; Othman, Mohamed

2018-01-01

Underwater Wireless Sensor Network (UWSN) has emerged as promising networking techniques to monitor and explore oceans. Research on acoustic communication has been conducted for decades, but had focused mostly on issues related to physical layer such as high latency, low bandwidth, and high bit error. However, data gathering process is still severely limited in UWSN due to channel impairment. One way to improve data collection in UWSN is the design of routing protocol. Opportunistic Routing (OR) is an emerging technique that has the ability to improve the performance of wireless network, notably acoustic network. In this paper, we propose an anycast, geographical and totally opportunistic routing algorithm for UWSN, called TORA. Our proposed scheme is designed to avoid horizontal transmission, reduce end to end delay, overcome the problem of void nodes and maximize throughput and energy efficiency. We use TOA (Time of Arrival) and range based equation to localize nodes recursively within a network. Once nodes are localized, their location coordinates and residual energy are used as a matrix to select the best available forwarder. All data packets may or may not be acknowledged based on the status of sender and receiver. Thus, the number of acknowledgments for a particular data packet may vary from zero to 2-hop. Extensive simulations were performed to evaluate the performance of the proposed scheme for high network traffic load under very sparse and very dense network scenarios. Simulation results show that TORA significantly improves the network performance when compared to some relevant existing routing protocols, such as VBF, HHVBF, VAPR, and H2DAB, for energy consumption, packet delivery ratio, average end-to-end delay, average hop-count and propagation deviation factor. TORA reduces energy consumption by an average of 35% of VBF, 40% of HH-VBF, 15% of VAPR, and 29% of H2DAB, whereas the packet delivery ratio has been improved by an average of 43% of VBF, 26

Public policy and regulatory implications for the implementation of Opportunistic Cloud Computing Services for Enterprises

DEFF Research Database (Denmark)

Kuada, Eric; Olesen, Henning; Henten, Anders

2012-01-01

Opportunistic Cloud Computing Services (OCCS) is a social network approach to the provisioning and management of cloud computing services for enterprises. This paper discusses how public policy and regulations will impact on OCCS implementation. We rely on documented publicly available government...... and corporate policies on the adoption of cloud computing services and deduce the impact of these policies on their adoption of opportunistic cloud computing services. We conclude that there are regulatory challenges on data protection that raises issues for cloud computing adoption in general; and the lack...... of a single globally accepted data protection standard poses some challenges for very successful implementation of OCCS for companies. However, the direction of current public and corporate policies on cloud computing make a good case for them to try out opportunistic cloud computing services....

AIRBORNE HYPERSPECTRAL IDENTIFICATION OF INVASIVE AND OPPORTUNISTIC WETLANDS PLANT SPECIES

Science.gov (United States)

Coastal wetlands are among the most fragmented and disturbed ecosystems and the Great Lakes are no exception. One possible result is the observed increase in the presence and dominance of invasive and other opportunistic plant species, such as the common reed (Phragmites australi...

HIV-associated opportunistic fungal infections: a guide to using the ...

African Journals Online (AJOL)

This review aims to provide a guide for clinicians to using the clinical microbiology laboratory for management of common HIV-associated opportunistic fungal infections, e.g. mucosal candidiasis, cryptococcosis, Pneumocystis jirovecii pneumonia (PCP), histoplasmosis, etc. Laboratory tests provide valuable guidance at ...

Genome-Wide Screen for Saccharomyces cerevisiae Genes Contributing to Opportunistic Pathogenicity in an Invertebrate Model Host

Directory of Open Access Journals (Sweden)

Sujal S. Phadke

2018-01-01

Full Text Available Environmental opportunistic pathogens can exploit vulnerable hosts through expression of traits selected for in their natural environments. Pathogenicity is itself a complicated trait underpinned by multiple complex traits, such as thermotolerance, morphology, and stress response. The baker’s yeast, Saccharomyces cerevisiae, is a species with broad environmental tolerance that has been increasingly reported as an opportunistic pathogen of humans. Here we leveraged the genetic resources available in yeast and a model insect species, the greater waxmoth Galleria mellonella, to provide a genome-wide analysis of pathogenicity factors. Using serial passaging experiments of genetically marked wild-type strains, a hybrid strain was identified as the most fit genotype across all replicates. To dissect the genetic basis for pathogenicity in the hybrid isolate, bulk segregant analysis was performed which revealed eight quantitative trait loci significantly differing between the two bulks with alleles from both parents contributing to pathogenicity. A second passaging experiment with a library of deletion mutants for most yeast genes identified a large number of mutations whose relative fitness differed in vivo vs. in vitro, including mutations in genes controlling cell wall integrity, mitochondrial function, and tyrosine metabolism. Yeast is presumably subjected to a massive assault by the innate insect immune system that leads to melanization of the host and to a large bottleneck in yeast population size. Our data support that resistance to the innate immune response of the insect is key to survival in the host and identifies shared genetic mechanisms between S. cerevisiae and other opportunistic fungal pathogens.

Cook Inlet Beluga Opportunistic Sightings, 1975 to 2015 (NCEI Accession 0142326)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — As a part of National Marine Fisheries Service (NMFS) management of the endangered Cook Inlet beluga whale population, a database of opportunistic beluga whale...

Analysis of the association opportunistic infections with c-reactive protein focus toxoplasma, cytomegalovirus, rubella,and hepatitis in human immunodeficiency virus

Science.gov (United States)

Khadijah, K. H.; Ferica, K.; Katu, S.; Halim, R.; Mubin, A. H.

2018-03-01

Opportunistic infections occur more often severe in people with HIV. C-reactive protein is known to have a prognostic value in HIV and those with HIV-related opportunistic infections. High level of CRP will increase therisk of infection toxoplasma, CMV, rubella,and hepatitis in HIV.Analyzing association of opportunistic infections toxoplasma, CMV, rubella,and hepatitis with the level of CRP in HIV, a cross-sectional analytic study wasduring January-July 2017 on both outpatientand inpatient HIV subjects at Wahidin Sudirohusodo Hospital, Makassar. Each HIV patient is categorized into agroup of opportunistic infections: toxoplasma, CMV, rubella, hepatitis. CRP levels will be assessed in each group, defined by normal values 0.05).

A concept for performance management for Federal science programs

Science.gov (United States)

Whalen, Kevin G.

2017-11-06

The demonstration of clear linkages between planning, funding, outcomes, and performance management has created unique challenges for U.S. Federal science programs. An approach is presented here that characterizes science program strategic objectives by one of five “activity types”: (1) knowledge discovery, (2) knowledge development and delivery, (3) science support, (4) inventory and monitoring, and (5) knowledge synthesis and assessment. The activity types relate to performance measurement tools for tracking outcomes of research funded under the objective. The result is a multi-time scale, integrated performance measure that tracks individual performance metrics synthetically while also measuring progress toward long-term outcomes. Tracking performance on individual metrics provides explicit linkages to root causes of potentially suboptimal performance and captures both internal and external program drivers, such as customer relations and science support for managers. Functionally connecting strategic planning objectives with performance measurement tools is a practical approach for publicly funded science agencies that links planning, outcomes, and performance management—an enterprise that has created unique challenges for public-sector research and development programs.

Graduate performance of science education department in implementing conservation-based science teaching

Science.gov (United States)

Parmin; Savitri, E. N.; Amalia, A. V.; Pratama, M. R.

2018-04-01

This study aims to measure the performance of graduates in implementing conservation-based science teaching. The study employed a qualitative method by collecting the self-assessment data from alumni and the performance assessment from the headmasters of schools where the graduates are currently teaching. There are nine indicators of conservation insight examined in this study. The study concluded that the 78 alumni, who have become teachers when the study was conducted, perform well in implementing conservative science lessons.

Plumbing of hospital premises is a reservoir for opportunistically pathogenic microorganisms: a review.

Science.gov (United States)

Williams, Margaret M; Armbruster, Catherine R; Arduino, Matthew J

2013-01-01

Several bacterial species that are natural inhabitants of potable water distribution system biofilms are opportunistic pathogens important to sensitive patients in healthcare facilities. Waterborne healthcare-associated infections (HAI) may occur during the many uses of potable water in the healthcare environment. Prevention of infection is made more challenging by lack of data on infection rate and gaps in understanding of the ecology, virulence, and infectious dose of these opportunistic pathogens. Some healthcare facilities have been successful in reducing infections by following current water safety guidelines. This review describes several infections, and remediation steps that have been implemented to reduce waterborne HAIs.

Influence of Physical Activities to Science Performance

Directory of Open Access Journals (Sweden)

RS Wilson DR. Constantino

2017-11-01

Full Text Available This study explored the physical activities of fifth and sixth graders that projected correlations to science performance and how these physical activities may be utilized for classroom purposes in the context of science-related play activities. Descriptive survey correlational design directed the data collection and analysis of the physical activities of purposively selected 133 fifth and sixth graders. Primarily, the study used a researcher-developed and validated instrument (Physical Activity Questionnaire [PAQ], and standard instruments: Philippine National Physical Activity Guide (PNPAG and General Physical Activity Questionnaire (GPAQ. The latter classified the physical activities into five domains which directed the interpretation of the participants‟ responses. The Pearson-r Moment of Correlation described the level of correlation of the frequency of engagement to physical activities (limited to local and localized activities and the science grade of the respondents. Results show that each of the physical activity domains showed specific correlations to science performance of the respondents. For further research, enrichment of the relationship of the physical activities and the science performance may focus on possible moderating variables like economic status, and time allotment for physical activities.

Spectrum Of Opportunistic Infections In Aids Cases In A Tertiary Care Hospital In Nepal

Directory of Open Access Journals (Sweden)

Hari Shanker Joshi

2006-12-01

Full Text Available A retrospective study was carried out, 404 clinically suspected cases attending AIDS clinic at Manipal Teaching Hospital, Pokhara, Nepal to assess an occurance of opportunistic infections in AIDS cases. Study reveals that Tuberculosis (60%, Cryptospridiosis (13.33% and candidasis (11.11% are the predominant opportunistic infection in HIV/AIDS patients in the Pokharo village. Next common pathogen was found an ubiquitous yeast. Candida obtained from skin, oral cavity, oesophagus, sputum and stool. The least common documented documented infection was pneumocystis carini pneumonia (2.22%.

A Cross-Layer Optimized Opportunistic Routing Scheme for Loss-and-Delay Sensitive WSNs

Science.gov (United States)

Xu, Xin; Yuan, Minjiao; Liu, Xiao; Cai, Zhiping; Wang, Tian

2018-01-01

In wireless sensor networks (WSNs), communication links are typically error-prone and unreliable, so providing reliable and timely data routing for loss- and delay-sensitive applications in WSNs it is a challenge issue. Additionally, with specific thresholds in practical applications, the loss and delay sensitivity implies requirements for high reliability and low delay. Opportunistic Routing (OR) has been well studied in WSNs to improve reliability for error-prone and unreliable wireless communication links where the transmission power is assumed to be identical in the whole network. In this paper, a Cross-layer Optimized Opportunistic Routing (COOR) scheme is proposed to improve the communication link reliability and reduce delay for loss-and-delay sensitive WSNs. The main contribution of the COOR scheme is making full use of the remaining energy in networks to increase the transmission power of most nodes, which will provide a higher communication reliability or further transmission distance. Two optimization strategies referred to as COOR(R) and COOR(P) of the COOR scheme are proposed to improve network performance. In the case of increasing the transmission power, the COOR(R) strategy chooses a node that has a higher communication reliability with same distance in comparison to the traditional opportunistic routing when selecting the next hop candidate node. Since the reliability of data transmission is improved, the delay of the data reaching the sink is reduced by shortening the time of communication between candidate nodes. On the other hand, the COOR(P) strategy prefers a node that has the same communication reliability with longer distance. As a result, network performance can be improved for the following reasons: (a) the delay is reduced as fewer hops are needed while the packet reaches the sink in longer transmission distance circumstances; (b) the reliability can be improved since it is the product of the reliability of every hop of the routing path

A Cross-Layer Optimized Opportunistic Routing Scheme for Loss-and-Delay Sensitive WSNs.

Science.gov (United States)

Xu, Xin; Yuan, Minjiao; Liu, Xiao; Liu, Anfeng; Xiong, Neal N; Cai, Zhiping; Wang, Tian

2018-05-03

In wireless sensor networks (WSNs), communication links are typically error-prone and unreliable, so providing reliable and timely data routing for loss- and delay-sensitive applications in WSNs it is a challenge issue. Additionally, with specific thresholds in practical applications, the loss and delay sensitivity implies requirements for high reliability and low delay. Opportunistic Routing (OR) has been well studied in WSNs to improve reliability for error-prone and unreliable wireless communication links where the transmission power is assumed to be identical in the whole network. In this paper, a Cross-layer Optimized Opportunistic Routing (COOR) scheme is proposed to improve the communication link reliability and reduce delay for loss-and-delay sensitive WSNs. The main contribution of the COOR scheme is making full use of the remaining energy in networks to increase the transmission power of most nodes, which will provide a higher communication reliability or further transmission distance. Two optimization strategies referred to as COOR(R) and COOR(P) of the COOR scheme are proposed to improve network performance. In the case of increasing the transmission power, the COOR(R) strategy chooses a node that has a higher communication reliability with same distance in comparison to the traditional opportunistic routing when selecting the next hop candidate node. Since the reliability of data transmission is improved, the delay of the data reaching the sink is reduced by shortening the time of communication between candidate nodes. On the other hand, the COOR(P) strategy prefers a node that has the same communication reliability with longer distance. As a result, network performance can be improved for the following reasons: (a) the delay is reduced as fewer hops are needed while the packet reaches the sink in longer transmission distance circumstances; (b) the reliability can be improved since it is the product of the reliability of every hop of the routing path

A Cross-Layer Optimized Opportunistic Routing Scheme for Loss-and-Delay Sensitive WSNs

Directory of Open Access Journals (Sweden)

Xin Xu

2018-05-01

Full Text Available In wireless sensor networks (WSNs, communication links are typically error-prone and unreliable, so providing reliable and timely data routing for loss- and delay-sensitive applications in WSNs it is a challenge issue. Additionally, with specific thresholds in practical applications, the loss and delay sensitivity implies requirements for high reliability and low delay. Opportunistic Routing (OR has been well studied in WSNs to improve reliability for error-prone and unreliable wireless communication links where the transmission power is assumed to be identical in the whole network. In this paper, a Cross-layer Optimized Opportunistic Routing (COOR scheme is proposed to improve the communication link reliability and reduce delay for loss-and-delay sensitive WSNs. The main contribution of the COOR scheme is making full use of the remaining energy in networks to increase the transmission power of most nodes, which will provide a higher communication reliability or further transmission distance. Two optimization strategies referred to as COOR(R and COOR(P of the COOR scheme are proposed to improve network performance. In the case of increasing the transmission power, the COOR(R strategy chooses a node that has a higher communication reliability with same distance in comparison to the traditional opportunistic routing when selecting the next hop candidate node. Since the reliability of data transmission is improved, the delay of the data reaching the sink is reduced by shortening the time of communication between candidate nodes. On the other hand, the COOR(P strategy prefers a node that has the same communication reliability with longer distance. As a result, network performance can be improved for the following reasons: (a the delay is reduced as fewer hops are needed while the packet reaches the sink in longer transmission distance circumstances; (b the reliability can be improved since it is the product of the reliability of every hop of the

Do managers act opportunistically towards the end of their career?

NARCIS (Netherlands)

Kabir, Rezaul; Li, Hao; Veld-Merkoulova, Yulia

2018-01-01

As managers approach retirement, their career horizons become shorter and they might start to behave opportunistically by taking a more risk-averse and short-term orientation. Long-term risky investments, such as research and development, can suffer the most from this problem as their payoff comes

Sinabro: A Smartphone-Integrated Opportunistic Electrocardiogram Monitoring System

OpenAIRE

Sungjun Kwon; Dongseok Lee; Jeehoon Kim; Youngki Lee; Seungwoo Kang; Sangwon Seo; Kwangsuk Park

2016-01-01

In our preliminary study, we proposed a smartphone-integrated, unobtrusive electrocardiogram (ECG) monitoring system, Sinabro, which monitors a user?s ECG opportunistically during daily smartphone use without explicit user intervention. The proposed system also monitors ECG-derived features, such as heart rate (HR) and heart rate variability (HRV), to support the pervasive healthcare apps for smartphones based on the user?s high-level contexts, such as stress and affective state levels. In th...

Opportunistic maintenance considering non-homogenous opportunity arrivals and stochastic opportunity durations

International Nuclear Information System (INIS)

Truong Ba, H.; Cholette, M.E.; Borghesani, P.; Zhou, Y.; Ma, L.

2017-01-01

Many systems and manufacturing processes undergo intermittent operation due to external factors (e.g. weather, low market prices), offering opportunities to conduct maintenance with reduced production losses. Making use of appropriate opportunities can thus lead to significant reduction in the total cost of maintenance and improvement in productivity. In this paper, an opportunistic maintenance (OM) model is developed considering two critical properties of real world opportunities: (i) non-homogeneous opportunity arrivals and (ii) stochastic opportunity duration. The model enables exploiting downtime cost savings from “partial” opportunities (stops shorter than the required maintenance time) thus extending the potential benefit of OM. The criteria for accepting maintenance opportunities are found by minimizing the single-cycle total cost. A closed form expression of the single-cycle total cost is derived for a given PM/OM policy and then a Genetic Algorithm is used to solve the optimization problem. Numerical results are presented to assess the benefit of opportunistic maintenance and the marginal benefit of considering partial opportunities. Results indicate that significant savings can be achieved by considering OM. Moreover, it is shown that the novel consideration of partial opportunities significantly increase the benefit of OM. - Highlights: • Opportunistic and time-based preventive maintenance jointly optimized. • Non-homogeneous opportunity arrivals and stochastic durations considered. • “Partial” opportunities considered for the first time. • Opportunity duration thresholds used as a decision criterion. • Numerical study conducted to evaluate benefit of optimized policy.

Science learning motivation as correlate of students’ academic performances

Directory of Open Access Journals (Sweden)

Nhorvien Jay P. Libao

2016-09-01

Full Text Available This study was designed to analyze the relationship  of students’ learning motivation and their academic performances in science. The study made use of 21 junior and senior Biological Science students to conclude on the formulated research problems. The respondents had a good to very good motivation in learning science. In general, the extent of their motivation do not vary across their sex, age, and curriculum year. Moreover, the respondents had good academic performances in science. Aptly, extrinsic motivation was found to be related with their academic performances among the indicators of motivations in learning science.

Opportunistic error correction for mimo-ofdm: from theory to practice

NARCIS (Netherlands)

Shao, X.; Slump, Cornelis H.

Opportunistic error correction based on fountain codes is especially designed for the MIMOOFDM system. The key point of this new method is the tradeoff between the code rate of error correcting codes and the number of sub-carriers in the channel vector to be discarded. By transmitting one

Novel Opportunistic Network Routing Based on Social Rank for Device-to-Device Communication

Directory of Open Access Journals (Sweden)

Tong Wang

2017-01-01

Full Text Available In recent years, there has been dramatic proliferation of research concerned with fifth-generation (5G mobile communication networks, among which device-to-device (D2D communication is one of the key technologies. Due to the intermittent connection of nodes, the D2D network topology may be disconnected frequently, which will lead to failure in transmission of large data files. In opportunistic networks, in case of encountering nodes which never meet before a flood message blindly to cause tremendous network overhead, a novel opportunistic network routing protocol based on social rank and intermeeting time (SRIT is proposed in this paper. An improved utility approach applied in utility replication based on encounter durations and intermeeting time is put forward to enhance the routing efficiency. Meanwhile, in order to select better candidate nodes in the network, a social graph among people is established when they socially relate to each other in social rank replication. The results under the scenario show an advantage of the proposed opportunistic network routing based on social rank and intermeeting time (SRIT over the compared algorithms in terms of delivery ratio, average delivery latency, and overhead ratio.

Trust Management System for Opportunistic Cloud Services

DEFF Research Database (Denmark)

Kuada, Eric

2013-01-01

We have over the past three years been working on the feasibility of Opportunistic Cloud Services (OCS) for enterprises. OCS is about enterprises strategically contributing and utilizing spare IT resources as cloud services. One of the major challenges that such a platform faces is data security...... and trust management issues. This paper presents a trust management system for OCS platforms. It models the concept of trust and applies it to OCS platforms. The trust model and the trust management system are verified through the simulation of the computation of the trust values with Infrastructure...

The 12th International Workshops on Opportunistic Protists (IWOP-12).

Science.gov (United States)

Weiss, Louis M; Cushion, Melanie T; Didier, Elizabeth; Xiao, Lihua; Marciano-Cabral, Francine; Sinai, Anthony P; Matos, Olga; Calderon, Enrique J; Kaneshiro, Edna S

2013-01-01

The 12th International Workshops on Opportunistic Protists (IWOP-12) was held in August 2012 in Tarrytown, New York. The objectives of the IWOP meetings are to: (1) serve as a forum for exchange of new information among active researchers concerning the basic biology, molecular genetics, immunology, biochemistry, pathogenesis, drug development, therapy, and epidemiology of these immunodeficiency-associated pathogenic eukaryotic microorganisms that are seen in patients with AIDS and (2) foster the entry of new and young investigators into these underserved research areas. The IWOP meeting focuses on opportunistic protists, e.g. the free-living amoebae, Pneumocystis, Cryptosporidium, Toxoplasma, the Microsporidia, and kinetoplastid flagellates. This conference represents the major conference that brings together research groups working on these opportunistic pathogens. Slow but steady progress is being achieved on understanding the biology of these pathogenic organisms, their involvement in disease causation in both immune-deficient and immune-competent hosts, and is providing critical insights into these emerging and reemerging pathogens. This IWOP meeting demonstrated the importance of newly developed genomic level information for many of these pathogens and how analysis of such large data sets is providing key insights into the basic biology of these organisms. A great concern is the loss of scientific expertise and diversity in the research community due to the ongoing decline in research funding. This loss of researchers is due to the small size of many of these research communities and a lack of appreciation by the larger scientific community concerning the state of art and challenges faced by researchers working on these organisms. © 2013 The Author(s) Journal of Eukaryotic Microbiology © 2013 International Society of Protistologists.

Two-user opportunistic scheduling using hierarchical modulations in wireless networks with heterogenous average link gains

KAUST Repository

Hossain, Md Jahangir

2010-03-01

Our contribution, in this paper, is two-fold. First, we analyze the performance of a hierarchical modulation-assisted two-best user opportunistic scheduling (TBS) scheme, which was proposed by the authors, in a fading environment where different users have different average link gains. Specifically, we present a new expression for the spectral efficiency (SE) of the users and using this expression, we compare the degrees of fairness (DOF) of the TBS scheme with that of classical single user opportunistic scheduling schemes, namely, absolute carrier-to-noise ratio (CNR) based single-best user scheduling (SBS) and normalized CNR based proportional fair scheduling (PFS) schemes. The second contribution is that we propose a new hybrid two-user opportunistic scheduling (HTS) scheme based on our earlier proposed TBS scheme. This HTS scheme selects the first user based on the largest absolute CNR value among all the users while the second user is selected based on the ratios of the absolute CNRs to the corresponding average CNRs of the remaining users. The total transmission rate i.e., the constellation size is selected according to the absolute CNR of the first best user. The total transmission rate is then allocated among these selected users by joint consideration of their absolute CNRs and allocated number of information bit(s) are transmitted to them using hierarchical modulations. Numerical results are presented for a fading environment where different users experience independent but non-identical (i.n.d.) channel fading. These selected numerical results show that the proposed HTS scheme can considerably increase the system\\'s fairness without any degradation of the link spectral efficiency (LSE) i.e., the multiuser diversity gain compared to the classical SBS scheme. These results also show that the proposed HTS scheme has a lower fairness in comparison to the PFS scheme which suffers from a considerable degradation in LSE. © 2010 IEEE.

Beginning science teachers' performances: Assessment in times of reform

Science.gov (United States)

Budzinsky, Fie K.

2000-10-01

The current reform in science education and the research on effective teaching and student learning have reinforced the importance of teacher competency. To better measure performances in the teaching of science, performance assessment has been added to Connecticut's licensure process for beginning science teachers. Teaching portfolios are used to document teaching and learning over time. Portfolios, however, are not without problems. One of the major concerns with the portfolio assessment process is its subjectivity. Assessors may not have opportunities to ask clarifying or follow-up questions to enhance the interpretation of a teacher's performance. In addition, portfolios often contain components based on self-documentation, which are subjective. Furthermore, the use of portfolios raises test equity issues. These concerns present challenges for persons in charge of establishing the validity of a portfolio-based licensure process. In high-stakes decision processes, such as teaching licensure, the validity of the assessment instruments must be studied. The primary purpose of this study was to explore the criterion-related validity of the Connecticut State Department of Education's Beginning Science Teaching Portfolio by comparing the interpretations of performances from science teaching portfolios to those derived from another assessment method, the Expert Science Teaching Educational and Evaluation Model, (ESTEEM). The analysis of correlations between the Beginning Science Teaching Portfolio and ESTEEM instrument scores was the primary method for establishing support for validity. The results indicated moderate correlations between all Beginning Science Teaching Portfolio and ESTEEM category and total variables. Multiple regression was used to examine whether differences existed in beginning science teachers' performances based on gender, poverty group, school level, and science discipline taught. None of these variables significantly contributed to the

Methodological approaches for monitoring opportunistic pathogens in premise plumbing: A review.

Science.gov (United States)

Wang, Hong; Bédard, Emilie; Prévost, Michèle; Camper, Anne K; Hill, Vincent R; Pruden, Amy

2017-06-15

Opportunistic premise (i.e., building) plumbing pathogens (OPPPs, e.g., Legionella pneumophila, Mycobacterium avium complex, Pseudomonas aeruginosa, Acanthamoeba, and Naegleria fowleri) are a significant and growing source of disease. Because OPPPs establish and grow as part of the native drinking water microbiota, they do not correspond to fecal indicators, presenting a major challenge to standard drinking water monitoring practices. Further, different OPPPs present distinct requirements for sampling, preservation, and analysis, creating an impediment to their parallel detection. The aim of this critical review is to evaluate the state of the science of monitoring OPPPs and identify a path forward for their parallel detection and quantification in a manner commensurate with the need for reliable data that is informative to risk assessment and mitigation. Water and biofilm sampling procedures, as well as factors influencing sample representativeness and detection sensitivity, are critically evaluated with respect to the five representative bacterial and amoebal OPPPs noted above. Available culturing and molecular approaches are discussed in terms of their advantages, limitations, and applicability. Knowledge gaps and research needs towards standardized approaches are identified. Copyright © 2017 Elsevier Ltd. All rights reserved.

Science learning motivation as correlate of students’ academic performances

OpenAIRE

Libao, Nhorvien Jay P.; Sagun, Jessie John B.; Tamangan, Elvira A.; Pattalitan, Agaton P.; Dupa, Maria Elena D.; Bautista, Romiro Gordo

2016-01-01

This study was designed to analyze the relationship of students’ learning motivation and their academic performances in science. The study made use of 21 junior and senior Biological Science students to conclude on the formulated research problems. The respondents had a good to very good motivation in learning science. In general, the extent of their motivation do not vary across their sex, age, and curriculum year. Moreover, the respondents had good academic performances in science. Aptly, e...

Gender and practical skill performance in science

Science.gov (United States)

Lock, Roger

The performance of 18 boys and 18 girls on four problem-solving tasks set in science contexts was compared. The tasks were administered in a one-to-one testing situation and assessments were made by direct observation, questioning, and by using written records. The tasks were valid and reliable, and the samples of boys and girls were matched for ability and curriculum background. Past studies have identified gender differences in performance on science tasks; however, this study found little evidence to support these findings. Few significant differences in performance were found. No gender differences were detected in observation, reporting, or planning skills, and there was no differential performance on the use of scientific language. Girls performed less well in relation to self-reliance, and performance differences on the interpretation skill approached significance with boys' performance superior.

An Arrival and Departure Time Predictor for Scheduling Communication in Opportunistic IoT

Science.gov (United States)

Pozza, Riccardo; Georgoulas, Stylianos; Moessner, Klaus; Nati, Michele; Gluhak, Alexander; Krco, Srdjan

2016-01-01

In this article, an Arrival and Departure Time Predictor (ADTP) for scheduling communication in opportunistic Internet of Things (IoT) is presented. The proposed algorithm learns about temporal patterns of encounters between IoT devices and predicts future arrival and departure times, therefore future contact durations. By relying on such predictions, a neighbour discovery scheduler is proposed, capable of jointly optimizing discovery latency and power consumption in order to maximize communication time when contacts are expected with high probability and, at the same time, saving power when contacts are expected with low probability. A comprehensive performance evaluation with different sets of synthetic and real world traces shows that ADTP performs favourably with respect to previous state of the art. This prediction framework opens opportunities for transmission planners and schedulers optimizing not only neighbour discovery, but the entire communication process. PMID:27827909

An Arrival and Departure Time Predictor for Scheduling Communication in Opportunistic IoT.

Science.gov (United States)

Pozza, Riccardo; Georgoulas, Stylianos; Moessner, Klaus; Nati, Michele; Gluhak, Alexander; Krco, Srdjan

2016-11-04

In this article, an Arrival and Departure Time Predictor (ADTP) for scheduling communication in opportunistic Internet of Things (IoT) is presented. The proposed algorithm learns about temporal patterns of encounters between IoT devices and predicts future arrival and departure times, therefore future contact durations. By relying on such predictions, a neighbour discovery scheduler is proposed, capable of jointly optimizing discovery latency and power consumption in order to maximize communication time when contacts are expected with high probability and, at the same time, saving power when contacts are expected with low probability. A comprehensive performance evaluation with different sets of synthetic and real world traces shows that ADTP performs favourably with respect to previous state of the art. This prediction framework opens opportunities for transmission planners and schedulers optimizing not only neighbour discovery, but the entire communication process.

Hopping control channel MAC protocol for opportunistic spectrum access networks

Institute of Scientific and Technical Information of China (English)

FU Jing-tuan; JI Hong; MAO Xu

2010-01-01

Opportunistic spectrum access （OSA） is considered as a promising approach to mitigate spectrum scarcity by allowing unlicensed users to exploit spectrum opportunities in licensed frequency bands. Derived from the existing channel-hopping multiple access （CHMA） protocol,we introduce a hopping control channel medium access control （MAC） protocol in the context of OSA networks. In our proposed protocol,all nodes in the network follow a common channel-hopping sequence; every frequency channel can be used as control channel and data channel. Considering primary users＇ occupancy of the channel,we use a primary user （PU） detection model to calculate the channel availability for unlicensed users＇ access. Then,a discrete Markov chain analytical model is applied to describe the channel states and deduce the system throughput. Through simulation,we present numerical results to demonstrate the throughput performance of our protocol and thus validate our work.

The PERFORM project: using performing arts to increase engagement and understanding of science.

Science.gov (United States)

James, Jon

2017-04-01

This commentary describes some of the current challenges for science education in the UK and how an EU educational project (PERFORM) is seeking to use performing arts to engage young people with science, its values and the processes of research. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Friend-to-friend short message service with opportunistic Wi-Fi beacons

NARCIS (Netherlands)

Türkes, Okan; Scholten, Johan; Havinga, Paul J.M.

2016-01-01

This study introduces Oppline, an ad hoc opportunistic short message service that can be collaboratively used by everyone who has a smart mobile device. The data exchange method of Oppline is built on top of the universal Wi-Fi standard, thus expedites platform-independent integration of related

Prevalence of opportunistic intestinal parasitic infection among HIV infected patients who are taking antiretroviral treatment at Jimma Health Center, Jimma, Ethiopia.

Science.gov (United States)

Zeynudin, A; Hemalatha, K; Kannan, S

2013-02-01

One of the major health problems among HIV sero-positive patients are superimposed infections due to the deficient immunity. Furthermore, intestinal parasitic (IP) infections, which are also one of the basic health problems in tropical regions, are common in these patients. Infection by opportunistic pathogens, including various forms of intestinal parasites has been the hall mark of HIV since the beginning of the epidemic. To study the prevalence of opportunistic intestinal parasitic infection among HIV patients who are taking antiretroviral treatment (ART) in Jimma, Ethiopia. Patient samples were diagnosed by examination of single stool specimen which was examined as fresh wet mounts, formal-ether concentration technique and modified Ziehl-Neelsen staining technique. Data was obtained from 91 study subjects selected by convenience sampling method. The overall prevalence of intestinal parasitic infections was found to be 39.56%. Eight types of intestinal parasites was identified, the most dominant being, Ascaris lumbricoides, 21.67%, Entamoeba histolytica, 15% and Cryptosporidium parvum 13.33%. The prevalence of opportunistic parasite was 15.38%, the prevalence of non-opportunistic parasite was 20.87% and the prevalence of both opportunistic and non opportunistic was 3.29%. The study indicated that intestinal parasites were still a problem in the study area. Data also showed that among the predisposing factors, habit of hand washing before meal, usage of latrine and duration after treatment was statistically associated with intestinal parasitic infections.

Microbiological characterization of aquatic microbiomes targeting taxonomical marker genes and antibiotic resistance genes of opportunistic bacteria.

Science.gov (United States)

Alexander, Johannes; Bollmann, Anna; Seitz, Wolfram; Schwartz, Thomas

2015-04-15

The dissemination of medically relevant antibiotic resistance genes (ARGs) (blaVIM-1, vanA, ampC, ermB, and mecA) and opportunistic bacteria (Enterococcus faecium/faecalis, Pseudomonas aeruginosa, Enterobacteriaceae, Staphylococcus aureus, and CNS) was determined in different anthropogenically influenced aquatic habitats in a selected region of Germany. Over a period of two years, four differently sized wastewater treatment plants (WWTPs) with and without clinical influence, three surface waters, four rain overflow basins, and three groundwater sites were analyzed by quantitative Polymerase Chain Reaction (qPCR). Results were calculated in cell equivalents per 100 ng of total DNA extracted from water samples and per 100 mL sample volume, which seems to underestimate the abundance of antibiotic resistance and opportunistic bacteria. High abundances of opportunistic bacteria and ARG were quantified in clinical wastewaters and influents of the adjacent WWTP. The removal capacities of WWTP were up to 99% for some, but not all investigated bacteria. The abundances of most ARG targets were found to be increased in the bacterial population after conventional wastewater treatment. As a consequence, downstream surface water and also some groundwater compartments displayed high abundances of all four ARGs. It became obvious that the dynamics of the ARG differed from the fate of the opportunistic bacteria. This underlines the necessity of an advanced microbial characterization of anthropogenically influenced environments. Copyright © 2015 Elsevier B.V. All rights reserved.

Position statement on opportunistic genomic screening from the Association of Genetic Nurses and Counsellors (UK and Ireland)

OpenAIRE

Middleton, Anna; Patch, Chris; Wiggins, Jennifer; Barnes, Kathy; Crawford, Gill; Benjamin, Caroline; Bruce, Anita

2014-01-01

The American College of Medical Genetics and Genomics released recommendations for reporting incidental findings (IFs) in clinical exome and genome sequencing. These suggest ‘opportunistic genomic screening' should be available to both adults and children each time a sequence is done and would be undertaken without seeking preferences from the patient first. Should opportunistic genomic screening be implemented in the United Kingdom, the Association of Genetic Nurses and Counsellors (AGNC), w...

An Ad-Hoc Opportunistic Dissemination Protocol for Smartphone-based Participatory Traffic Monitoring

NARCIS (Netherlands)

Türkes, Okan; Seraj, Fatjon; Scholten, Johan; Meratnia, Nirvana; Havinga, Paul J.M.

2015-01-01

This study introduces an ad-hoc opportunistic data dissemination protocol, called VADISS, that facilitates participatory traffic monitoring applications with smartphones. As a ubiquitous alternative to existing vehicular networking methods, VADISS uses the default WiFi interfaces universally adopted

Opportunistic esophagitis in AIDS: Radiographic diagnosis

International Nuclear Information System (INIS)

Levine, M.S.; Woldenberg, R.; Herlinger, H.; Laufer, I.

1987-01-01

Between 1983 and 1986, 35 of 90 patients with acquired immunodeficiency syndrome (AIDS) had double-contrast esophagograms to rule out opportunistic esophagitis. The radiographs were reviewed without knowledge of the clinical or endoscopic findings. Candida esophagitis was diagnosed radiographically in 17 patients who had varying degrees of plaque formation and viral esophagitis in three who had discrete ulcers without plaques. All three patients with viral esophagitis (herpes in 2 and cytomegalo virus in one) and 15 of 17 with Candida esophagitis had endoscopic and/or clinical corroboration of the radiographic diagnosis. Thus, the authors' experience suggests that fungal and viral esophagitis can often be differentiated on double-contrast esophagography, so that appropriate antifungal or antiviral therapy can be instituted without need for endoscopic intervention

The Open Science Grid

Energy Technology Data Exchange (ETDEWEB)

Pordes, Ruth; /Fermilab; Kramer, Bill; Olson, Doug; / /LBL, Berkeley; Livny, Miron; Roy, Alain; /Wisconsin U., Madison; Avery, Paul; /Florida U.; Blackburn, Kent; /Caltech; Wenaus, Torre; /Brookhaven; Wurthwein, Frank; /UC, San Diego; Gardner, Rob; Wilde, Mike; /Chicago U. /Indiana U.

2007-06-01

The Open Science Grid (OSG) provides a distributed facility where the Consortium members provide guaranteed and opportunistic access to shared computing and storage resources. OSG provides support for and evolution of the infrastructure through activities that cover operations, security, software, troubleshooting, addition of new capabilities, and support for existing and engagement with new communities. The OSG SciDAC-2 project provides specific activities to manage and evolve the distributed infrastructure and support its use. The innovative aspects of the project are the maintenance and performance of a collaborative (shared & common) petascale national facility over tens of autonomous computing sites, for many hundreds of users, transferring terabytes of data a day, executing tens of thousands of jobs a day, and providing robust and usable resources for scientific groups of all types and sizes. More information can be found at the OSG web site: www.opensciencegrid.org.

Outage Probability versus Fairness Trade-off in Opportunistic Relay Selection with Outdated CSI

Directory of Open Access Journals (Sweden)

Vicario JoseLopez

2009-01-01

Full Text Available We analyze the existing trade-offs in terms of system performance versus fairness of a cooperative system based on opportunistic relay selection (ORS and with outdated channel state information (CSI. In particular, system performance is analytically evaluated in terms of outage probability, and the fairness behavior is assessed based on the power consumption at the different relays. In order to improve the fairness behavior of ORS while keeping the selection diversity gain, we propose a relay selection mechanism where the relay with the highest normalized signal-to-noise ratio (SNR is selected for relaying the source's information. The proposed strategy is compared with existing relay selection strategies by adopting a novel graphical representation inspired by expected profit versus risk plots used in modern portfolio theory. As shown in the paper, this strategy allows operating the system in more favorable points of the outage versus fairness region.

Impact of Texas high school science teacher credentials on student performance in high school science

Science.gov (United States)

George, Anna Ray Bayless

A study was conducted to determine the relationship between the credentials held by science teachers who taught at a school that administered the Science Texas Assessment on Knowledge and Skills (Science TAKS), the state standardized exam in science, at grade 11 and student performance on a state standardized exam in science administered in grade 11. Years of teaching experience, teacher certification type(s), highest degree level held, teacher and school demographic information, and the percentage of students who met the passing standard on the Science TAKS were obtained through a public records request to the Texas Education Agency (TEA) and the State Board for Educator Certification (SBEC). Analysis was performed through the use of canonical correlation analysis and multiple linear regression analysis. The results of the multiple linear regression analysis indicate that a larger percentage of students met the passing standard on the Science TAKS state attended schools in which a large portion of the high school science teachers held post baccalaureate degrees, elementary and physical science certifications, and had 11-20 years of teaching experience.

Keeping Pace with Criminals: An Extended Study of Designing Patrol Allocation against Adaptive Opportunistic Criminals

Directory of Open Access Journals (Sweden)

Chao Zhang

2016-06-01

Full Text Available Game theoretic approaches have recently been used to model the deterrence effect of patrol officers’ assignments on opportunistic crimes in urban areas. One major challenge in this domain is modeling the behavior of opportunistic criminals. Compared to strategic attackers (such as terrorists who execute a well-laid out plan, opportunistic criminals are less strategic in planning attacks and more flexible in executing well-laid plans based on their knowledge of patrol officers’ assignments. In this paper, we aim to design an optimal police patrolling strategy against opportunistic criminals in urban areas. Our approach is comprised by two major parts: learning a model of the opportunistic criminal (and how he or she responds to patrols and then planning optimal patrols against this learned model. The planning part, by using information about how criminals responds to patrols, takes into account the strategic game interaction between the police and criminals. In more detail, first, we propose two categories of models for modeling opportunistic crimes. The first category of models learns the relationship between defender strategy and crime distribution as a Markov chain. The second category of models represents the interaction of criminals and patrol officers as a Dynamic Bayesian Network (DBN with the number of criminals as the unobserved hidden states. To this end, we: (i apply standard algorithms, such as Expectation Maximization (EM, to learn the parameters of the DBN; (ii modify the DBN representation that allows for a compact representation of the model, resulting in better learning accuracy and the increased speed of learning of the EM algorithm when used for the modified DBN. These modifications exploit the structure of the problem and use independence assumptions to factorize the large joint probability distributions. Next, we propose an iterative learning and planning mechanism that periodically updates the adversary model. We

Cocoon: A lightweight opportunistic networking middleware for community-oriented smart mobile applications

NARCIS (Netherlands)

Türkes, Okan; Scholten, Johan; Havinga, Paul J.M.

2016-01-01

Modern society is surrounded by an ample spectrum of smart mobile devices. This ubiquity forms a high potential for community-oriented opportunistic ad hoc networking applications. Nevertheless, today’s smart mobile devices such as smartphones, tablets, and wristbands are still onerous to

[Experimental interaction of halophilic prokaryotes and opportunistic bacteria in brine].

Science.gov (United States)

Selivanova, E A; Nemtseva, N V

2013-01-01

Study the effect of extremely halophilic archaea and moderately halophilic bacteria on preservation of opportunistic bacteria in brine. 17 strains of moderately halophilic bacteria and 2 strains of extremely halophilic archaea were isolated from continental hypersaline lake Razval of Sol-Iletsk area of Orenburg Region. Identification of pure cultures of prokaryotes was carried out taking into account their phenotype properties and based on determination of 16S RNA gene sequence. The effect of halophilic prokaryote on elimination of Escherichia coli from brine was evaluated during co-cultivation. Antagonistic activity of cell extracts of the studied microorganisms was evaluated by photometric method. A more prolonged preservation of an E. coli strain in brine in the presence of live cells of extremely halophilic archaea Halorubrum tebenquichense and moderately halophilic bacteria Marinococcus halophilus was established. Extracts of cells of extremely halophilic archaea and moderately halophilic bacteria on the contrary displayed antagonistic activity. The protective effect of live cells of halophilic prokaryotes and antagonistic activity of their cell extracts change the period of conservation of opportunistic bacteria in brine that regulates inter-microbial interactions and changes the period of self-purification that reflects the sanitary condition of a hypersaline water body.

Executive summary: Prevention and treatment of opportunistic infections and other coinfections in HIV-infected patients: May 2015.

Science.gov (United States)

Iribarren, José Antonio; Rubio, Rafael; Aguirrebengoa, Koldo; Arribas, Jose Ramón; Baraia-Etxaburu, Josu; Gutiérrez, Félix; Lopez Bernaldo de Quirós, Juan Carlos; Losa, Juan Emilio; Miró, José Ma; Moreno, Santiago; Pérez Molina, José; Podzamczer, Daniel; Pulido, Federico; Riera, Melchor; Rivero, Antonio; Sanz Moreno, José; Amador, Concha; Antela, Antonio; Arazo, Piedad; Arrizabalaga, Julio; Bachiller, Pablo; Barros, Carlos; Berenguer, Juan; Caylá, Joan; Domingo, Pere; Estrada, Vicente; Knobel, Hernando; Locutura, Jaime; López Aldeguer, José; Llibre, Josep Ma; Lozano, Fernando; Mallolas, Josep; Malmierca, Eduardo; Miralles, Celia; Miralles, Pilar; Muñoz, Agustín; Ocampo, Agustín; Olalla, Julián; Pérez, Inés; Pérez Elías, Ma Jesús; Pérez Arellano, José Luis; Portilla, Joaquín; Ribera, Esteban; Rodríguez, Francisco; Santín, Miguel; Sanz Sanz, Jesús; Téllez, Ma Jesús; Torralba, Miguel; Valencia, Eulalia; Von Wichmann, Miguel Angel

2016-10-01

Opportunistic infections continue to be a cause of morbidity and mortality in HIV-infected patients. They often arise because of severe immunosuppression resulting from poor adherence to antiretroviral therapy, failure of antiretroviral therapy, or unawareness of HIV infection by patients whose first clinical manifestation of AIDS is an opportunistic infection. The present article is an executive summary of the document that updates the previous recommendations on the prevention and treatment of opportunistic infections in HIV-infected patients, namely, infections by parasites, fungi, viruses, mycobacteria, and bacteria, as well as imported infections. The article also addresses immune reconstitution inflammatory syndrome. This document is intended for all professionals who work in clinical practice in the field of HIV infection. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Instructional practices and science performance of 10 top-performing regions in PISA 2015

Science.gov (United States)

Lau, Kwok-chi; Lam, Terence Yuk-ping

2017-10-01

This study analysed 10 top-performing regions in PISA 2015 on their science performances and instructional practices. The regions include Singapore, Japan, Estonia, Taipei, Finland, Macao, Canada, Hong Kong, China and Korea. The science performances of the 10 regions and their teaching practices are described and compared. The construct of enquiry-based instruction as developed in PISA 2015 is revised into two new constructs using factor analysis. Then, the relationships of the teaching practices with science performance are analysed using hierarchical linear modelling. Adaptive instruction, teacher-directed instruction and interactive application are found positively associated with performance in all regions, while investigation and perceived feedback are all negative. The regions except Japan and Korea tend to have a high frequency of teacher-directed instruction facilitated by more or less authoritative class discussion in class. A fair amount of practical work is done, but not many of them are investigations. The cultural influences on teaching practices are discussed on how an amalgam of didactic and constructivist pedagogy is created by the Western progressive educational philosophy meeting the Confucian culture. The reasons for investigation's negative association with performance are also explored.

Value of 67Ga scintigraphy in primary diagnosis and follow-up of opportunistic pneumonias in patients with AIDS

International Nuclear Information System (INIS)

Tatsch, K.; Knesewitsch, P.; Kirsch, C.M.; Kueffer, G.; Doerner, G.; Moser, E.; Matuschke, A.; Bogner, J.; Goebel, F.D.

1988-01-01

Opportunistic pneumonias are a life-threatening complication in patients with AIDS. Early diagnosis and therapy is necessary to improve prognosis. This study was designed to assess the value of 67 Ga scintigraphy in the primary detection and follow-up of these special pneumonias. 67 Ga scintigraphy was performed in 40 patients: 10 normal controls and 30 HIV-positive patients with AIDS or AIDS-related complex (ARC). 67 Ga scan results were compared with current chest radiographs and the results of pathogen detection. The evaluation of positive scans was based on a quantification of the pulmonary uptake, expressed as a pulmonary/soft-tissue uptake ratio. Only 8/30 patients had a normal scan, 22/30 showed diffuse (13/22) or focal (9/22) increases of pulmonary uptake. In 7/8 patients with normal scans the chest radiograph was negative as well. The one patient with negative scan but positive chest radiograph had pulmonary Kaposi's sarcoma. In 11/22 patients the 67 Ga scan and chest radiograph were positive simultaneously. In the other 11/22 patients with positive scans chest radiographs were initially negative but showed pathology in 5 cases within 1-2 weeks. The reason for positive scans in most cases was an opportunistic lung infection; other forms of pneumonia were only observed in two cases. The defined uptake ratio demonstrated to be a highly sensitive parameter for monitoring pneumonia and the effects of therapy in follow-up studies. In conclusion, quantitative 67 Ga scintigraphy proved to be a reliable and highly sensitive method for primary detection and follow-up of opportunistic pneumonias in patients with AIDS. (orig.) [de

Ethiopian Journal of Health Sciences - Vol 28, No 2 (2018)

African Journals Online (AJOL)

Ethiopian Journal of Health Sciences - Vol 28, No 2 (2018). Journal Home > Archives > Vol 28, No 2 (2018). Log in or Register to get access to full text downloads. ... Prevalence of opportunistic intestinal parasites and associated factors among HIV patients while receiving ART at Arba Minch Hospital in southern Ethiopia: a ...

Radio-science performance analysis software

Science.gov (United States)

Morabito, D. D.; Asmar, S. W.

1995-02-01

The Radio Science Systems Group (RSSG) provides various support functions for several flight project radio-science teams. Among these support functions are uplink and sequence planning, real-time operations monitoring and support, data validation, archiving and distribution functions, and data processing and analysis. This article describes the support functions that encompass radio-science data performance analysis. The primary tool used by the RSSG to fulfill this support function is the STBLTY program set. STBLTY is used to reconstruct observable frequencies and calculate model frequencies, frequency residuals, frequency stability in terms of Allan deviation, reconstructed phase, frequency and phase power spectral density, and frequency drift rates. In the case of one-way data, using an ultrastable oscillator (USO) as a frequency reference, the program set computes the spacecraft transmitted frequency and maintains a database containing the in-flight history of the USO measurements. The program set also produces graphical displays. Some examples and discussions on operating the program set on Galileo and Ulysses data will be presented.

Specialized or opportunistic-how does the high mountain endemic butterfly Erebia nivalis survive in its extreme habitats?

Science.gov (United States)

Ehl, Stefan; Dalstein, Vivian; Tull, Fabienne; Gros, Patrick; Schmitt, Thomas

2018-02-01

High mountain ecosystems are a challenge for the survival of animal and plant species, which have to evolve specific adaptations to cope with the prevailing extreme conditions. The strategies to survive may reach from opportunistic to highly adapted traits. One species successfully surviving under these conditions is the here studied butterfly Erebia nivalis. In a mark-release-recapture study performed in the Hohe Tauern National Park (Austria) from 22 July to 26 August 2013, we marked 1386 individuals and recaptured 342 of these. For each capture event, we recorded the exact point of capture and various other traits (wing conditions, behavior, nectar sources). The population showed a partial protandrous demography with the minority of males emerging prior to the females, but the majority being synchronized with them. Males and females differed significantly in their behavior with males being more flight active and females nectaring and resting more. Both sexes showed preferences for the same plant species as nectar sources, but this specialization apparently is the result of a rapid individual adaptation to the locally available flowers. Estimates of the realized dispersal distances predicted a comparatively high amount of long-distance flights, especially for females. Therefore, the adaptation of Erebia nivalis to the unpredictable high mountain conditions might be a mixture of opportunism and specialized traits. © 2016 Institute of Zoology, Chinese Academy of Sciences.

What Kills Science in School?: Lessons from Pre-Service Teachers' Responses to Urban children's Science Inquiries.

Science.gov (United States)

Matusov, Eugene

2018-06-01

This opportunistic case-study highlights striking differences in 6 urban children's and 12 preservice suburban middle-class teachers' perception of science and discuss consequences of science education and beyond. I found that all of the interviewed urban children demonstrated scientific inquiries and interests outside of the school science education that can be characterized by diverse simultaneous discourses from diverse practices, i.e., "heterodiscoursia" (Matusov in Culture & Psychology, 17(1), 99-119, 2011b), despite their diverse, positive and negative, attitudes toward school science. In contrast to the urban children's mixed attitudes to science, the preservice teachers view science negatively. They could not see science inquiries in the videotaped interviews of the urban children. There seemed to be many reasons for that. One of the possible reasons for that was that the preservice teachers tried to purify the science practice. Another reason was that they did not see a necessity to be interested and engaged in the curriculum that they are going to teach in future. The pedagogical consequences and remedies are discussed.

Opportunistic Screening for Exposure to Bullying in the Pediatric Emergency Department.

Science.gov (United States)

Seltzer, Marlene; Menoch, Margaret; Chen, Charity

2017-01-01

To assess opportunistic screening for exposure to bullying in the pediatric emergency department (ED), an anonymous survey inquiring about exposure to physical, verbal, social, and cyber bullying behaviors was given to ED patients 5 to 18 years old. The survey asked about being the recipient, perpetrator, and/or witness of bullying; the frequency of exposure; liking school; missing school; and presenting complaint. Either the child or parent could complete the survey. A total of 909 surveys were analyzed. Exposure was 78.7%. A greater proportion of females reported being victims and witnesses. Youth who reported being both victims and witnesses represented the largest group, with witness-only the second largest. Parents reported less cyber-bullying and witness status to all types of bullying. For children who did not like school, there was a significant difference in exposure versus nonexposure. There was no association with presenting complaint. Opportunistic screening for bullying exposure in pediatric ED patients warrants consideration as it may increase detection of preclinical status and clinical sequelae.

Opportunistic Energy-Aware Amplify-and-Forward Cooperative Systems with Imperfect CSI

KAUST Repository

Amin, Osama

2015-07-29

Recently, much attention has been paid to the green design of wireless communication systems using energy efficiency (EE) metrics that should capture all energy consumption sources to deliver the required data. In this paper, we design an energyefficient relay assisted communication system based on estimated channel state information (CSI). It employs amplify-andforward relaying and switches between different communication schemes, which are known as direct-transmission, two-hop and cooperative-transmission schemes, using the estimated CSI in order to maximize the EE. Two estimation strategies are assumed, namely disintegrated channel estimation and cascaded channel estimation. To formulate an accurate EE metric for the proposed opportunistic amplify-and-forward system, the channel estimation cost is reflected on the EE metric by including its impact in the signal-to-noise ratio term and in the energy consumption during the channels estimation phase. Based on the formulated EE metric, we propose an adaptive power allocation algorithm to maximize the EE of the proposed opportunistic amplify-andforward system with channel estimation. Furthermore, we study the impact of the estimation parameters on the proposed system via simulation examples.

Opportunistic relaying in multipath and slow fading channel: Relay selection and optimal relay selection period

KAUST Repository

Sungjoon Park,

2011-11-01

In this paper we present opportunistic relay communication strategies of decode and forward relaying. The channel that we are considering includes pathloss, shadowing, and fast fading effects. We find a simple outage probability formula for opportunistic relaying in the channel, and validate the results by comparing it with the exact outage probability. Also, we suggest a new relay selection algorithm that incorporates shadowing. We consider a protocol of broadcasting the channel gain of the previously selected relay. This saves resources in slow fading channel by reducing collisions in relay selection. We further investigate the optimal relay selection period to maximize the throughput while avoiding selection overhead. © 2011 IEEE.

Increased breast cancer screening and downstaging in Colombian women: A randomized trial of opportunistic breast-screening.

Science.gov (United States)

Murillo, Raúl; Díaz, Sandra; Perry, Fernando; Poveda, César; Piñeros, Marion; Sánchez, Oswaldo; Buitrago, Lina; Gamboa, Oscar; Lozano, Teófilo; Yu, Hsiang; Wang, Ching-Yun; Duggan, Catherine; Thomas, David B; Anderson, Benjamin O

2016-02-01

The lack of breast cancer screening in low and middle-income countries results in later stage diagnosis and worsened outcomes for women. A cluster randomized trial was performed in Bogotá, Colombia between 2008 and 2012 to evaluate effects of opportunistic breast cancer screening. Thirteen clinics were randomized to an intervention arm and 13 to a control arm. Physicians in intervention clinics were instructed to perform clinical breast examination on all women aged 50-69 years attending clinics for non-breast health issues, and then refer them for mammographic screening. Physicians in control clinics were not explicitly instructed to perform breast screening or mammography referrals, but could do so if they thought it indicated ("usual care"). Women were followed for 2-years postrandomization. 7,436 women were enrolled and 7,419 (99.8%) screened in intervention clinics, versus 8,419 enrolled and 1,108 (13.1%) screened in control clinics. Incidence ratios (IR) of early, advanced and all breast cancers were 2.9 (95% CI 1.1-9.2), 1.0 (0.3-3.5) and 1.9 (0.9-4.1) in the first (screening) year of the trial, and the cumulative IR for all breast cancers converged to 1.4 (0.7-2.8) by the end of follow-up (Year 2). Eighteen (69.2%) of 26 women with early stage disease had breast conservation surgery (BCS) versus 6 (42.5%) of 14 women with late-stage disease (p = 0.02). Fifteen (68.2%) of 22 women with breast cancer in the intervention group had BCS versus nine (50.0%) of 18 women in the control group (p = 0.34). Well-designed opportunistic clinic-based breast cancer screening programs may be useful for early breast cancer detection in LMICs. © 2015 The Authors. Published by Wiley Periodicals, Inc. on behalf of UICC.

Phylogenetic Analysis and Antimicrobial Profiles of Cultured Emerging Opportunistic Pathogens (Phyla Actinobacteria and Proteobacteria) Identified in Hot Springs.

Science.gov (United States)

Jardine, Jocelyn Leonie; Abia, Akebe Luther King; Mavumengwana, Vuyo; Ubomba-Jaswa, Eunice

2017-09-15

Hot spring water may harbour emerging waterborne opportunistic pathogens that can cause infections in humans. We have investigated the diversity and antimicrobial resistance of culturable emerging and opportunistic bacterial pathogens, in water and sediment of hot springs located in Limpopo, South Africa. Aerobic bacteria were cultured and identified using 16S ribosomal DNA (rDNA) gene sequencing. The presence of Legionella spp. was investigated using real-time polymerase chain reaction. Isolates were tested for resistance to ten antibiotics representing six different classes: β-lactam (carbenicillin), aminoglycosides (gentamycin, kanamycin, streptomycin), tetracycline, amphenicols (chloramphenicol, ceftriaxone), sulphonamides (co-trimoxazole) and quinolones (nalidixic acid, norfloxacin). Gram-positive Kocuria sp. and Arthrobacter sp. and gram-negative Cupriavidus sp., Ralstonia sp., Cronobacter sp., Tepidimonas sp., Hafnia sp. and Sphingomonas sp. were isolated, all recognised as emerging food-borne pathogens. Legionella spp. was not detected throughout the study. Isolates of Kocuria , Arthrobacter and Hafnia and an unknown species of the class Gammaproteobacteria were resistant to two antibiotics in different combinations of carbenicillin, ceftriaxone, nalidixic acid and chloramphenicol. Cronobacter sp. was sensitive to all ten antibiotics. This study suggests that hot springs are potential reservoirs for emerging opportunistic pathogens, including multiple antibiotic resistant strains, and highlights the presence of unknown populations of emerging and potential waterborne opportunistic pathogens in the environment.

Interactions between the tropical sea anemone Aiptasia pallida and Serratia marcescens, an opportunistic pathogen of corals.

Science.gov (United States)

Krediet, Cory J; Meyer, Julie L; Gimbrone, Nicholas; Yanong, Roy; Berzins, Ilze; Alagely, Ali; Castro, Herman; Ritchie, Kim B; Paul, Valerie J; Teplitski, Max

2014-06-01

Coral reefs are under increasing stress caused by global and local environmental changes, which are thought to increase the susceptibility of corals to opportunistic pathogens. In the absence of an easily culturable model animal, the understanding of the mechanisms of disease progression in corals remains fairly limited. In the present study, we tested the susceptibility of the tropical sea anemone Aiptasia pallida to an opportunistic coral pathogen (Serratia marcescens). A. pallida was susceptible to S. marcescens PDL100 and responded to this opportunistic coral pathogen with darkening of the tissues and retraction of tentacles, followed by complete disintegration of polyp tissues. Histological observations revealed loss of zooxanthellae and structural changes in eosinophilic granular cells in response to pathogen infection. A screen of S. marcescens mutants identified a motility and tetrathionate reductase mutants as defective in virulence in the A. pallida infection model. In co-infections with the wild-type strain, the tetrathionate reductase mutant was less fit within the surface mucopolysaccharide layer of the host coral Acropora palmata. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Asymmetric competition prevents the outbreak of an opportunistic species after coral reef degradation.

Science.gov (United States)

González-Rivero, Manuel; Bozec, Yves-Marie; Chollett, Iliana; Ferrari, Renata; Schönberg, Christine H L; Mumby, Peter J

2016-05-01

Disturbance releases space and allows the growth of opportunistic species, excluded by the old stands, with a potential to alter community dynamics. In coral reefs, abundances of fast-growing, and disturbance-tolerant sponges are expected to increase and dominate as space becomes available following acute coral mortality events. Yet, an increase in abundance of these opportunistic species has been reported in only a few studies, suggesting certain mechanisms may be acting to regulate sponge populations. To gain insights into mechanisms of population control, we simulated the dynamics of the common reef-excavating sponge Cliona tenuis in the Caribbean using an individual-based model. An orthogonal hypothesis testing approach was used, where four candidate mechanisms-algal competition, stock-recruitment limitation, whole and partial mortality-were incorporated sequentially into the model and the results were tested against independent field observations taken over a decade in Belize, Central America. We found that releasing space after coral mortality can promote C. tenuis outbreaks, but such outbreaks can be curtailed by macroalgal competition. The asymmetrical competitive superiority of macroalgae, given by their capacity to pre-empt space and outcompete with the sponge in a size-dependant fashion, supports their capacity to steal the opportunity from other opportunists. While multiple system stages can be expected in coral reefs following intense perturbation macroalgae may prevent the growth of other space-occupiers, such as bioeroding sponges, under low grazing pressure.

EpSoc: Social-Based Epidemic-Based Routing Protocol in Opportunistic Mobile Social Network

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Halikul Lenando

2018-01-01

Full Text Available In opportunistic networks, the nature of intermittent and disruptive connections degrades the efficiency of routing. Epidemic routing protocol is used as a benchmark for most of routing protocols in opportunistic mobile social networks (OMSNs due to its high message delivery and latency. However, Epidemic incurs high cost in terms of overhead and hop count. In this paper, we propose a hybrid routing protocol called EpSoc which utilizes the Epidemic routing forwarding strategy and exploits an important social feature, that is, degree centrality. Two techniques are used in EpSoc. Messages’ TTL is adjusted based on the degree centrality of nodes, and the message blocking mechanism is used to control replication. Simulation results show that EpSoc increases the delivery ratio and decreases the overhead ratio, the average latency, and the hop counts as compared to Epidemic and Bubble Rap.

Buffer Management and Hybrid Probability Choice Routing for Packet Delivery in Opportunistic Networks

Directory of Open Access Journals (Sweden)

Daru Pan

2012-01-01

Full Text Available Due to the features of long connection delays, frequent network partitions, and topology unsteadiness, the design of opportunistic networks faces the challenge of how to effectively deliver data based only on occasional encountering of nodes, where the conventional routing schemes do not work properly. This paper proposes a hybrid probability choice routing protocol with buffer management for opportunistic networks. A delivery probability function is set up based on continuous encounter duration time, which is used for selecting a better node to relay packets. By combining the buffer management utility and the delivery probability, a total utility is used to decide whether the packet should be kept in the buffer or be directly transmitted to the encountering node. Simulation results show that the proposed routing outperforms the existing one in terms of the delivery rate and the average delay.

The Opportunistic House for Tehran: A Design Prototype

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Sara Khorshidifard

2015-12-01

Full Text Available This article is an advocacy research for Tehran, promoting an implication of architectural design as a tool for citizen empowerment and positive environmental change. In the article, I am offering a fresh look at Tehran’s housing problems by speculating an “opportunistic house” typology as a residential style that would serve much more than just shelter. I am making a case for a new house prototype that applies socially-equitable solutions in design. My study finds applications and significance beyond plain housing design and, mainly, onto the design of ad hoc urban public realm spaces. This is in accord with my overarching mission of supporting new way of thinking about, and ultimately offering, welcoming, safe, and energized places for Tehran’s citizens. These will additionally have important implications for inhospitable public spaces worldwide. This research is grounded in my prior, multidisciplinary doctoral studies. The article itself is an initial step in my ongoing research design, of helping to build and revitalize a wide range of urban communities by nurturing their relationship to their built and natural environments. The article is a discussion around the following questions. How can housing design inventions empower citizens? In what manner can design offer progressive living place options whose services go beyond shelter needs? Particularly, in what ways can domestic spaces be designed to also embody other-than-living capacities, for example, for new kinds of public spaces? And eventually, what could a prototype of the opportunistic house look like in the context of a city like Tehran? The article is structured to first present a brief survey of how Tehran house forms and functions have developed historically, with more emphasis on their current state. It will then offer examples of opportunistic uses of domestic spaces in Tehran. This notion is communicated through narrative analysis and photographic vignettes from a few

Danish General Practitioners' Use of Prostate-Specific Antigen in Opportunistic Screening for Prostate Cancer

DEFF Research Database (Denmark)

Jessen, Kasper; Søndergaard, Jens; Larsen, Pia Veldt

2013-01-01

Background. The use of prostate-specific antigen test has markedly increased in Danish general practice in the last decade. Despite the national guidelines advice against PSA screening, opportunistic screening is supposed to be the primary reason for this increased number of PSA tests performed....... Aims. Based on the increase in the amount of PSA conducted, we aimed to analyse how GPs in Denmark use the PSA test. Methods. A self-administrated questionnaire concerning symptomatic and asymptomatic patient cases was developed based on the national and international guidelines and the extensive...... literature review, and an in-depth interview conducted with a GP was performed. Results. None of the GPs would do a PSA measurement for an asymptomatic 76-year-old man. For asymptomatic 55- and 42-year-old men, respectively, 21.9% and 18.6% of GPs would measure PSA. Patient request and concern could...

REMOTE DETENTION OF INVASIVE AND OPPORTUNISTIC PLANT SPECIES IN GREAT LAKES COASTAL WETLANDS

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Invasive and opportunistic plant species have been associated with wetland disturbance. Increases in the abundance of plant species such as common reed (Phragmites australis) in coastal Great Lakes wetlands are hypothesized to occur with shifts toward drier hydrologic regimes, fr...

The Opportunistic Pathogen Serratia marcescens Utilizes Type VI Secretion To Target Bacterial Competitors ▿†

Science.gov (United States)

Murdoch, Sarah L.; Trunk, Katharina; English, Grant; Fritsch, Maximilian J.; Pourkarimi, Ehsan; Coulthurst, Sarah J.

2011-01-01

The type VI secretion system (T6SS) is the most recently described and least understood of the protein secretion systems of Gram-negative bacteria. It is widely distributed and has been implicated in the virulence of various pathogens, but its mechanism and exact mode of action remain to be defined. Additionally there have been several very recent reports that some T6SSs can target bacteria rather than eukaryotic cells. Serratia marcescens is an opportunistic enteric pathogen, a class of bacteria responsible for a significant proportion of hospital-acquired infections. We describe the identification of a functional T6SS in S. marcescens strain Db10, the first report of type VI secretion by an opportunist enteric bacterium. The T6SS of S. marcescens Db10 is active, with secretion of Hcp to the culture medium readily detected, and is expressed constitutively under normal growth conditions from a large transcriptional unit. Expression of the T6SS genes did not appear to be dependent on the integrity of the T6SS. The S. marcescens Db10 T6SS is not required for virulence in three nonmammalian virulence models. It does, however, exhibit dramatic antibacterial killing activity against several other bacterial species and is required for S. marcescens to persist in a mixed culture with another opportunist pathogen, Enterobacter cloacae. Importantly, this antibacterial killing activity is highly strain specific, with the S. marcescens Db10 T6SS being highly effective against another strain of S. marcescens with a very similar and active T6SS. We conclude that type VI secretion plays a crucial role in the competitiveness, and thus indirectly the virulence, of S. marcescens and other opportunistic bacterial pathogens. PMID:21890705

Science Learning Motivation as Correlate of Students' Academic Performances

Science.gov (United States)

Libao, Nhorvien Jay P.; Sagun, Jessie John B.; Tamangan, Elvira A.; Pattalitan, Agaton P., Jr.; Dupa, Maria Elena D.; Bautista, Romiro G.

2016-01-01

This study was designed to analyze the relationship of students' learning motivation and their academic performances in science. The study made use of 21 junior and senior Biological Science students to conclude on the formulated research problems. The respondents had a good to very good motivation in learning science. In general, the extent of…

Opportunistic Pathogens and Microbial Communities and Their Associations with Sediment Physical Parameters in Drinking Water Storage Tank Sediments

Science.gov (United States)

Qin, Ke; Struewing, Ian; Domingo, Jorge Santo; Lytle, Darren

2017-01-01

The occurrence and densities of opportunistic pathogens (OPs), the microbial community structure, and their associations with sediment elements from eight water storage tanks in Ohio, West Virginia, and Texas were investigated. The elemental composition of sediments was measured through X-ray fluorescence (XRF) spectra. The occurrence and densities of OPs and amoeba hosts (i.e., Legionella spp. and L. pneumophila, Mycobacterium spp., P. aeruginosa, V. vermiformis, Acanthamoeba spp.) were determined using genus- or species-specific qPCR assays. Microbial community analysis was performed using next generation sequencing on the Illumina Miseq platform. Mycobacterium spp. were most frequently detected in the sediments and water samples (88% and 88%), followed by Legionella spp. (50% and 50%), Acanthamoeba spp. (63% and 13%), V. vermiformis (50% and 25%), and P. aeruginosa (0 and 50%) by qPCR method. Comamonadaceae (22.8%), Sphingomonadaceae (10.3%), and Oxalobacteraceae (10.1%) were the most dominant families by sequencing method. Microbial communities in water samples were mostly separated with those in sediment samples, suggesting differences of communities between two matrices even in the same location. There were associations of OPs with microbial communities. Both OPs and microbial community structures were positively associated with some elements (Al and K) in sediments mainly from pipe material corrosions. Opportunistic pathogens presented in both water and sediments, and the latter could act as a reservoir of microbial contamination. There appears to be an association between potential opportunistic pathogens and microbial community structures. These microbial communities may be influenced by constituents within storage tank sediments. The results imply that compositions of microbial community and elements may influence and indicate microbial water quality and pipeline corrosion, and that these constituents may be important for optimal storage tank management

Nocardia – Opportunistic chest infection in elderly: A case report

OpenAIRE

Sanyal, Kaushik; Sabanathan, Kanagasabesan

2008-01-01

In this rare case a non-immunocompromised patient with old Tuberculosis on low dose of steroids presents with opportunistic infection of a weakly aerobic gram positive acid fast, filamentous bacteria called Nocardia. An 80 year old non-smoking white female presented with cough, shortness of breath and purulent sputum. Initial antibiotics given were not helpful. Later microbial diagnosis was Nocardia in sputum sample which was uncommon in a non-immunocompromised. She responded to co-trimoxazol...

Relationship between lactobacilli and opportunistic bacterial pathogens associated with vaginitis

OpenAIRE

Razzak, Mohammad Sabri A.; Al-Charrakh, Alaa H.; AL-Greitty, Bara Hamid

2011-01-01

Background: Vaginitis, is an infectious inflammation of the vaginal mucosa, which sometimes involves the vulva. The balance of the vaginal flora is maintained by the Lactobacilli and its protective and probiotic role in treating and preventing vaginal infection by producing antagonizing compounds which are regarded as safe for humans. Aim: The aim of this study was to evaluate the protective role of Lactobacilli against common bacterial opportunistic pathogens in vaginitis and study the effec...

How Pre-Service Teachers' Understand and Perform Science Process Skills

Science.gov (United States)

Chabalengula, Vivien Mweene; Mumba, Frackson; Mbewe, Simeon

2012-01-01

This study explored pre-service teachers' conceptual understanding and performance on science process skills. A sample comprised 91 elementary pre-service teachers at a university in the Midwest of the USA. Participants were enrolled in two science education courses; introductory science teaching methods course and advanced science methods course.…

Towards New Antifolates Targeting Eukaryotic Opportunistic Infections

Energy Technology Data Exchange (ETDEWEB)

Liu, J.; Bolstad, D; Bolstad, E; Wright, D; Anderson, A

2009-01-01

Trimethoprim, an antifolate commonly prescribed in combination with sulfamethoxazole, potently inhibits several prokaryotic species of dihydrofolate reductase (DHFR). However, several eukaryotic pathogenic organisms are resistant to trimethoprim, preventing its effective use as a therapeutic for those infections. We have been building a program to reengineer trimethoprim to more potently and selectively inhibit eukaryotic species of DHFR as a viable strategy for new drug discovery targeting several opportunistic pathogens. We have developed a series of compounds that exhibit potent and selective inhibition of DHFR from the parasitic protozoa Cryptosporidium and Toxoplasma as well as the fungus Candida glabrata. A comparison of the structures of DHFR from the fungal species Candida glabrata and Pneumocystis suggests that the compounds may also potently inhibit Pneumocystis DHFR.

Occurrence of Opportunistic Pathogens Legionella pneumophila and non-tuberculous mycobacteria in hospital plumbing systems

Science.gov (United States)

Occurrence of Opportunistic Pathogens Legionella pneumophila and non-tuberculous mycobacteria in hospital plumbing systems Jill Hoelle, Michael Coughlin, Elizabeth Sotkiewicz, Jingrang Lu, Stacy Pfaller, Mark Rodgers, and Hodon Ryu U.S. Environmental Protection Agency, Cincinnati...

High Performance Computing in Science and Engineering '14

CERN Document Server

Kröner, Dietmar; Resch, Michael

2015-01-01

This book presents the state-of-the-art in supercomputer simulation. It includes the latest findings from leading researchers using systems from the High Performance Computing Center Stuttgart (HLRS). The reports cover all fields of computational science and engineering ranging from CFD to computational physics and from chemistry to computer science with a special emphasis on industrially relevant applications. Presenting findings of one of Europe’s leading systems, this volume covers a wide variety of applications that deliver a high level of sustained performance. The book covers the main methods in high-performance computing. Its outstanding results in achieving the best performance for production codes are of particular interest for both scientists and   engineers. The book comes with a wealth of color illustrations and tables of results.  

Barriers and facilitators to opportunistic chronic kidney disease screening by general practice nurses.

Science.gov (United States)

Sinclair, Peter M; Day, Jenny; Levett-Jones, Tracy; Kable, Ashley

2017-10-01

Opportunistic screening in general practice (GP) is a cost-effective and viable approach to the early identification of chronic kidney disease (CKD). This study sought to identify the barriers and facilitators to CKD screening practices of GP nurses working in a regional area of New South Wales, Australia. An eight-item elicitation questionnaire informed by the Theory of Planned Behaviour was administered to a convenience sample of 26 GP nurses. Participants identified that the advantages of CKD screening were its early detection and treatment, the reduction of disease burden, and the opportunity to increase awareness and provide disease prevention education. These positive attitudinal beliefs were offset by negative beliefs about the impost of opportunistic screening on nursing time, particularly when there were other competing clinical priorities. Participants reported that practice doctors were wary of the financial costs associated with additional non-claimable services and believed that unfunded services, regardless of patient benefit, were difficult to justify in a private business environment. Screening was enabled in GP settings with existing screening protocols or initiatives, and when patients presented with known risk factors. Barriers to screening were more frequently described and illustrated a strong focus on financial aspects of GP. Without reimbursement through the Medicare Benefits Scheme, screening was not considered an economical use of nursing time. Other competing and billable clinical services took precedence. The findings of this study can be used to inform the development and evaluation of interventions that target opportunistic CKD screening in the GP setting. © 2016 Asian Pacific Society of Nephrology.

Performance Assessment as a Diagnostic Tool for Science Teachers

Science.gov (United States)

Kruit, Patricia; Oostdam, Ron; van den Berg, Ed; Schuitema, Jaap

2018-04-01

Information on students' development of science skills is essential for teachers to evaluate and improve their own education, as well as to provide adequate support and feedback to the learning process of individual students. The present study explores and discusses the use of performance assessments as a diagnostic tool for formative assessment to inform teachers and guide instruction of science skills in primary education. Three performance assessments were administered to more than 400 students in grades 5 and 6 of primary education. Students performed small experiments using real materials while following the different steps of the empirical cycle. The mutual relationship between the three performance assessments is examined to provide evidence for the value of performance assessments as useful tools for formative evaluation. Differences in response patterns are discussed, and the diagnostic value of performance assessments is illustrated with examples of individual student performances. Findings show that the performance assessments were difficult for grades 5 and 6 students but that much individual variation exists regarding the different steps of the empirical cycle. Evaluation of scores as well as a more substantive analysis of students' responses provided insight into typical errors that students make. It is concluded that performance assessments can be used as a diagnostic tool for monitoring students' skill performance as well as to support teachers in evaluating and improving their science lessons.

Evaluation of two novel barcodes for species recognition of opportunistic pathogens in Fusarium.

NARCIS (Netherlands)

de Hoog, S.; van Diepeningen, A.D.

2015-01-01

The genus Fusarium includes more than 200 species of which 73 have been isolated from human infections. Fusarium species are opportunistic human pathogens with variable aetiology. Species determination is best made with the combined phylogeny of protein-coding genes such as elongation factor (TEF1),

Regrowth of potential opportunistic pathogens and algae in reclaimed-water distribution systems.

Science.gov (United States)

Jjemba, Patrick K; Weinrich, Lauren A; Cheng, Wei; Giraldo, Eugenio; Lechevallier, Mark W

2010-07-01

A study of the quality of reclaimed water in treated effluent, after storage, and at three points in the distribution system of four plants in California, Florida, Massachusetts, and New York was conducted for 1 year. The plants had different treatment processes (conventional versus membrane bioreactor), production capacities, and methods for storage of the water, and the intended end uses of the water were different. The analysis focused on the occurrence of indicator bacteria (heterotrophic bacteria, coliforms, Escherichia coli, and enterococci) and opportunistic pathogens (Aeromonas spp., enteropathogenic E. coli O157:H7, Legionella spp., Mycobacterium spp., and Pseudomonas spp.), as well as algae. Using immunological methods, E. coli O157:H7 was detected in the effluent of only one system, but it was not detected at the sampling points, suggesting that its survival in the system was poor. Although all of the treatment systems effectively reduced the levels of bacteria in the effluent, bacteria regrew in the reservoir and distribution systems because of the loss of residual disinfectant and high assimilable organic carbon levels. In the systems with open reservoirs, algal growth reduced the water quality by increasing the turbidity and accumulating at the end of the distribution system. Opportunistic pathogens, notably Aeromonas, Legionella, Mycobacterium, and Pseudomonas, occurred more frequently than indicator bacteria (enterococci, coliforms, and E. coli). The Mycobacterium spp. were very diverse and occurred most frequently in membrane bioreactor systems, and Mycobacterium cookii was identified more often than the other species. The public health risk associated with these opportunistic pathogens in reclaimed water is unknown. Collectively, our results show the need to develop best management practices for reclaimed water to control bacterial regrowth and degradation of water before it is utilized at the point of use.

Opportunistic screening for osteoporosis on routine computed tomography? An external validation study

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Buckens, Constantinus F. [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Universitair Medisch Centrum Utrecht, Department of Radiology, Utrecht (Netherlands); Dijkhuis, Gawein; Jong, Pim A. de [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Keizer, Bart de [University Medical Center Utrecht, Department of Nuclear Medicine, Utrecht (Netherlands); Verhaar, Harald J. [University Medical Center Utrecht, Department of Geriatric Medicine, Utrecht (Netherlands)

2015-07-15

Opportunistic screening for osteoporosis using computed tomography (CT) examinations that happen to visualise the spine can be used to identify patients with osteoporosis. We sought to verify the diagnostic performance of vertebral Hounsfield unit (HU) measurements on routine CT examinations for diagnosing osteoporosis in a separate, external population. Consecutive patients who underwent a CT examination of the chest or abdomen and had also received a dual-energy X-ray absorptiometry (DXA) test were retrospectively included. CTs were evaluated for vertebral fractures and vertebral attenuation (density) values were measured. Diagnostic performance measures and the area under the receiver operator characteristics curve (AUC) for diagnosing osteoporosis were calculated. Three hundred and two patients with a mean age of 57.9 years were included, of which 82 (27 %) had osteoporosis according to DXA and 65 (22 %) had vertebral fractures. The diagnostic performance for vertebral HU measurements was modest, with a maximal AUC of 0.74 (0.68 - 0.80). At that optimal threshold the sensitivity was 62 % (51 - 72 %) and the specificity was 79 % (74 - 84 %). We confirmed that simple trabecular vertebral density measurements on routine CT contain diagnostic information related to bone mineral density as measured by DXA, albeit with substantially lower diagnostic accuracy than previously reported. (orig.)

Opportunistic screening for osteoporosis on routine computed tomography? An external validation study

International Nuclear Information System (INIS)

Buckens, Constantinus F.; Dijkhuis, Gawein; Jong, Pim A. de; Keizer, Bart de; Verhaar, Harald J.

2015-01-01

Opportunistic screening for osteoporosis using computed tomography (CT) examinations that happen to visualise the spine can be used to identify patients with osteoporosis. We sought to verify the diagnostic performance of vertebral Hounsfield unit (HU) measurements on routine CT examinations for diagnosing osteoporosis in a separate, external population. Consecutive patients who underwent a CT examination of the chest or abdomen and had also received a dual-energy X-ray absorptiometry (DXA) test were retrospectively included. CTs were evaluated for vertebral fractures and vertebral attenuation (density) values were measured. Diagnostic performance measures and the area under the receiver operator characteristics curve (AUC) for diagnosing osteoporosis were calculated. Three hundred and two patients with a mean age of 57.9 years were included, of which 82 (27 %) had osteoporosis according to DXA and 65 (22 %) had vertebral fractures. The diagnostic performance for vertebral HU measurements was modest, with a maximal AUC of 0.74 (0.68 - 0.80). At that optimal threshold the sensitivity was 62 % (51 - 72 %) and the specificity was 79 % (74 - 84 %). We confirmed that simple trabecular vertebral density measurements on routine CT contain diagnostic information related to bone mineral density as measured by DXA, albeit with substantially lower diagnostic accuracy than previously reported. (orig.)

Heavy Metal Distribution in Opportunistic Beach Nourishment: A Case Study in Greece

Directory of Open Access Journals (Sweden)

Spyros Foteinis

2013-01-01

Full Text Available The existence and distribution of persistent pollutants, such as heavy metals, in coastal sediment used for opportunistic beach nourishment, is a problem that has not received much attention. Here, we assessed the coastal sediments in one restoration project for the occurrence and distribution of heavy metals, by utilizing an Energy Dispersive X-Ray Fluorescence (EDXRF system. Heavy metal point sources included (i the effluents of small industries (tanneries, (ii wastewater treatment plant effluents, and (iii paint and oil scraps from substandard ship maintenance activities that take place on ports breakwaters. A few neighboring beaches were found to have similar heavy metal concentrations, with mean values of Cu, Zn, and Pb ranging from 80 to 130, 15 to 25, and 25 to 40 mg/kg, respectively. Existing legislation regarding dredging activities in Greece appears insufficient for sustainable and environmentally friendly nourishment. We conclude that before opportunistic beach restoration projects materialize with material borrowed from ports and harbors the quality of the dredged material needs to be assessed.

Position statement on opportunistic genomic screening from the Association of Genetic Nurses and Counsellors (UK and Ireland).

Science.gov (United States)

Middleton, Anna; Patch, Chris; Wiggins, Jennifer; Barnes, Kathy; Crawford, Gill; Benjamin, Caroline; Bruce, Anita

2014-08-01

The American College of Medical Genetics and Genomics released recommendations for reporting incidental findings (IFs) in clinical exome and genome sequencing. These suggest 'opportunistic genomic screening' should be available to both adults and children each time a sequence is done and would be undertaken without seeking preferences from the patient first. Should opportunistic genomic screening be implemented in the United Kingdom, the Association of Genetic Nurses and Counsellors (AGNC), which represents British and Irish genetic counsellors and nurses, feels strongly that the following must be considered (see article for complete list): (1) Following appropriate genetic counselling, patients should be allowed to consent to or opt out of opportunistic genomic screening. (2) If true IFs are discovered the AGNC are guided by the report from the Joint Committee on Medical Genetics about the sharing of genetic testing results. (3) Children should not be routinely tested for adult-onset conditions. (4) The formation of a list of variants should involve a representative from the AGNC as well as a patient support group. (5) The variants should be for serious or life-threatening conditions for which there are treatments or preventative strategies available. (6) There needs to be robust evidence that the benefits of opportunistic screening outweigh the potential harms. (7) The clinical validity and utility of variants should be known. (8) There must be a quality assurance framework that operates to International standards for laboratory testing. (9) Psychosocial research is urgently needed in this area to understand the impact on patients.

The Impact of Agricultural Science Education on Performance in a Biology Course

Science.gov (United States)

Ernest, Byron L.

The lack of student achievement in science is often cited in U.S. educational reports. At the study site, low student achievement in science has been an ongoing concern for administrators. The purpose of this mixed methods study was to investigate the impact of agricultural science education on student performance in a Biology course. Vygotsky's constructivist theory and Gardner's multiple intelligences theory provided the framework for the study. The quantitative research question examined the relationship between the completion of Fundamentals of Agriculture Science and Business course and student performance in Biology I. Teacher perceptions and experiences regarding the integration of science and agricultural curriculum and traditional science curriculum were examined qualitatively. A sequential explanatory design was employed using 3 years of data collected from 486 high school students and interviews with 10 teachers. Point-biserial correlation and chi square tests revealed statistically significant relationships between whether or not students completed Fundamentals of Agriculture Science and Business and Biology I course performance, as measured by the end of course assessment and the course grade. In the qualitative sequence, typological and inductive data analyses were applied to the interview data, and themes of student impact and teacher experience emerged. Social change implications may be possible through improved science education for students in this program. Agriculture science courses may be used to facilitate learning of complex science concepts, designing teacher collaboration and professional development for teaching science in a relevant context, and resultant improved student performance in science.

Life science students' attitudes, interest, and performance in introductory physics for life sciences: An exploratory study

Science.gov (United States)

Crouch, Catherine H.; Wisittanawat, Panchompoo; Cai, Ming; Renninger, K. Ann

2018-06-01

In response to national calls for improved physical sciences education for students pursuing careers in the life sciences and medicine, reformed introductory physics for life sciences (IPLS) courses are being developed. This exploratory study is among the first to assess the effect of an IPLS course on students' attitudes, interest, and performance. The IPLS course studied was the second semester of introductory physics, following a standard first semester course, allowing the outcomes of the same students in a standard course and in an IPLS course to be compared. In the IPLS course, each physics topic was introduced and elaborated in the context of a life science example, and developing students' skills in applying physics to life science situations was an explicitly stated course goal. Items from the Colorado Learning about Science Survey were used to assess change in students' attitudes toward and their interest in physics. Whereas the same students' attitudes declined during the standard first semester course, we found that students' attitudes toward physics hold steady or improve in the IPLS course. In particular, students with low initial interest in physics displayed greater increases in both attitudes and interest during the IPLS course than in the preceding standard course. We also find that in the IPLS course, students' interest in the life science examples is a better predictor of their performance than their pre-IPLS interest in physics. Our work suggests that the life science examples in the IPLS course can support the development of student interest in physics and positively influence their performance.

Life science students’ attitudes, interest, and performance in introductory physics for life sciences: An exploratory study

Directory of Open Access Journals (Sweden)

Catherine H. Crouch

2018-03-01

Full Text Available In response to national calls for improved physical sciences education for students pursuing careers in the life sciences and medicine, reformed introductory physics for life sciences (IPLS courses are being developed. This exploratory study is among the first to assess the effect of an IPLS course on students’ attitudes, interest, and performance. The IPLS course studied was the second semester of introductory physics, following a standard first semester course, allowing the outcomes of the same students in a standard course and in an IPLS course to be compared. In the IPLS course, each physics topic was introduced and elaborated in the context of a life science example, and developing students’ skills in applying physics to life science situations was an explicitly stated course goal. Items from the Colorado Learning about Science Survey were used to assess change in students’ attitudes toward and their interest in physics. Whereas the same students’ attitudes declined during the standard first semester course, we found that students’ attitudes toward physics hold steady or improve in the IPLS course. In particular, students with low initial interest in physics displayed greater increases in both attitudes and interest during the IPLS course than in the preceding standard course. We also find that in the IPLS course, students’ interest in the life science examples is a better predictor of their performance than their pre-IPLS interest in physics. Our work suggests that the life science examples in the IPLS course can support the development of student interest in physics and positively influence their performance.

A Novel Cooperative Opportunistic Routing Scheme for Underwater Sensor Networks.

Science.gov (United States)

Ghoreyshi, Seyed Mohammad; Shahrabi, Alireza; Boutaleb, Tuleen

2016-02-26

Increasing attention has recently been devoted to underwater sensor networks (UWSNs) because of their capabilities in the ocean monitoring and resource discovery. UWSNs are faced with different challenges, the most notable of which is perhaps how to efficiently deliver packets taking into account all of the constraints of the available acoustic communication channel. The opportunistic routing provides a reliable solution with the aid of intermediate nodes' collaboration to relay a packet toward the destination. In this paper, we propose a new routing protocol, called opportunistic void avoidance routing (OVAR), to address the void problem and also the energy-reliability trade-off in the forwarding set selection. OVAR takes advantage of distributed beaconing, constructs the adjacency graph at each hop and selects a forwarding set that holds the best trade-off between reliability and energy efficiency. The unique features of OVAR in selecting the candidate nodes in the vicinity of each other leads to the resolution of the hidden node problem. OVAR is also able to select the forwarding set in any direction from the sender, which increases its flexibility to bypass any kind of void area with the minimum deviation from the optimal path. The results of our extensive simulation study show that OVAR outperforms other protocols in terms of the packet delivery ratio, energy consumption, end-to-end delay, hop count and traversed distance.

The 14th International Workshops on Opportunistic Protists (IWOP 14).

Science.gov (United States)

Cushion, Melanie T; Limper, Andrew H; Porollo, Aleksey; Saper, Vivian E; Sinai, Anthony P; Weiss, Louis M

2018-05-03

The 14th International Workshops on Opportunistic Protists (IWOP-14) was held August 10-12, 2017 in Cincinnati, OH, USA. The IWOP meetings focus on opportunistic protists (OIs); for example, free-living amoebae, Pneumocystis spp., Cryptosporidium spp., Toxoplasma, the Microsporidia, and kinetoplastid flagellates. The highlights of Pneumocystis spp. research included the reports of primary homothallism for mating; a potential requirement for sexual replication in its life cycle; a new antigen on the surface of small asci; roles for CLRs, Dectin-1, and Mincle in host responses; and identification of MSG families and mechanisms used for surface variation. Studies of Cryptosporidia spp. included comparative genomics, a new cryopreservation method; the role of mucin in attachment and invasion, and epidemiological surveys illustrating species diversity in animals. One of the five identified proteins in the polar tube of Microsporidia, PTP4, was shown to play a role in host infection. Zebrafish were used as a low cost vertebrate animal model for an evaluation of potential anti-toxoplasma drugs. Folk medicine compounds with anti-toxoplasma activity were presented, and reports on the chronic toxoplasma infection provided evidence for increased tractability for the study of this difficult life cycle stage. Escape from the parasitophorus vacuole and cell cycle regulation were the topics of the study in the acute phase. © 2018 International Society of Protistologists.

Percolation-theoretic bounds on the cache size of nodes in mobile opportunistic networks.

Science.gov (United States)

Yuan, Peiyan; Wu, Honghai; Zhao, Xiaoyan; Dong, Zhengnan

2017-07-18

The node buffer size has a large influence on the performance of Mobile Opportunistic Networks (MONs). This is mainly because each node should temporarily cache packets to deal with the intermittently connected links. In this paper, we study fundamental bounds on node buffer size below which the network system can not achieve the expected performance such as the transmission delay and packet delivery ratio. Given the condition that each link has the same probability p to be active in the next time slot when the link is inactive and q to be inactive when the link is active, there exists a critical value p c from a percolation perspective. If p > p c , the network is in the supercritical case, where we found that there is an achievable upper bound on the buffer size of nodes, independent of the inactive probability q. When p network is in the subcritical case, and there exists a closed-form solution for buffer occupation, which is independent of the size of the network.

The Effects of Motivation on Student Performance on Science Assessments

Science.gov (United States)

Glenn, Tina Heard

Academic achievement of public school students in the United States has significantly fallen behind other countries. Students' lack of knowledge of, or interest in, basic science and math has led to fewer graduates of science, technology, engineering, and math-related fields (STEM), a factor that may affect their career success and will certainly affect the numbers in the workforce who are prepared for some STEM jobs. Drawing from self-determination theory and achievement theory, the purpose of this correlational study was to determine whether there were significant relationships between high school academic performance in science classes, motivations (self-efficacy, self-regulation, and intrinsic and extrinsic goal orientation), and academic performance in an introductory online college biology class. Data were obtained at 2 points in time from a convenience multiethnic sample of adult male ( n =16) and female (n = 49) community college students in the southeast United States. Correlational analyses indicated no statistically significant relationships for intrinsic or extrinsic goal orientation, self-efficacy, or self-regulation with high school science mean-GPA nor college biology final course grade. However, high school academic performance in science classes significantly predicted college performance in an entry-level online biology class. The implications of positive social change include knowledge useful for educational institutions to explore additional factors that may motivate students to enroll in science courses, potentially leading to an increase in scientific knowledge and STEM careers.

Sadhana | Indian Academy of Sciences

Indian Academy of Sciences (India)

Position based opportunistic routing (POR) is a stateless, robust, and reliable geographic routing protocol in Mobile AdHoc NETwork (MANET). The opportunistic routing embraces broadcast property of wireless channels and utilizes it for opportunistic forwarding. Both the malicious node behavior and the backupnodes' ...

Distributed opportunistic spectrum sharing in cognitive radio networks

KAUST Repository

Hawa, Mohammed

2016-05-19

In cases where the licensed radio spectrum is underutilized, cognitive radio technology enables cognitive devices to sense and then dynamically access this scarce resource making the most out of it. In this work, we introduce a simple and intuitive, yet powerful and efficient, technique that allows opportunistic channel access in cognitive radio systems in a completely distributed fashion. Our proposed method achieves very high values of spectrum utilization and throughput. It also minimizes interference between cognitive base stations and the primary users licensed to use the spectrum. The algorithm responds quickly and efficiently to variations in the network parameters and also achieves a high degree of fairness between cognitive base stations. © 2016 John Wiley & Sons, Ltd.

Opportunistic relaying in multipath and slow fading channel: Relay selection and optimal relay selection period

KAUST Repository

Sungjoon Park,; Stark, Wayne E.

2011-01-01

In this paper we present opportunistic relay communication strategies of decode and forward relaying. The channel that we are considering includes pathloss, shadowing, and fast fading effects. We find a simple outage probability formula

SURVEY OF HOUSE RAT INTESTINAL PARASITES FROM SURABAYA DISTRICT, EAST JAVA, INDONESIA THAT CAN CAUSE OPPORTUNISTIC INFECTIONS IN HUMANS.

Science.gov (United States)

Prasetyo, R H

2016-03-01

The purpose of this study was to investigate the prevalence of house rat zoonotic intestinal parasites from Surabaya District, East Java, Indonesia that have the potential to cause opportunistic infection in humans. House rat fecal samples were collected from an area of Surabaya District with a dense rat population during May 2015. Intestinal parasites were detected microscopically using direct smear of feces stained with Lugol's iodine and modified Ziehl-Neelsen stains. The fecal samples were also cultured for Strongyloides stercoralis. Ninety-eight house rat fecal samples were examined. The potential opportunistic infection parasite densities found in those samples were Strongyloides stercoralis in 53%, Hymenolepis nana in 42%, Cryptosporidium spp in 33%, and Blastocystis spp in 6%. This is the first report of this kind in Surabaya District. Measures need to be taken to control the house rat population in the study area to reduce the risk of the public health problem. Keywords: zoonotic intestinal parasites, opportunistic infection, house rat, densely populated area, Indonesia

Opportunistically collected data reveal habitat selection by migrating Whooping Cranes in the U.S. Northern Plains

Science.gov (United States)

Niemuth, Neil D.; Ryba, Adam J.; Pearse, Aaron T.; Kvas, Susan M.; Brandt, David; Wangler, Brian; Austin, Jane; Carlisle, Martha J.

2018-01-01

The Whooping Crane (Grus americana) is a federally endangered species in the United States and Canada that relies on wetland, grassland, and cropland habitat during its long migration between wintering grounds in coastal Texas, USA, and breeding sites in Alberta and Northwest Territories, Canada. We combined opportunistic Whooping Crane sightings with landscape data to identify correlates of Whooping Crane occurrence along the migration corridor in North Dakota and South Dakota, USA. Whooping Cranes selected landscapes characterized by diverse wetland communities and upland foraging opportunities. Model performance substantially improved when variables related to detection were included, emphasizing the importance of accounting for biases associated with detection and reporting of birds in opportunistic datasets. We created a predictive map showing relative probability of occurrence across the study region by applying our model to GIS data layers; validation using independent, unbiased locations from birds equipped with platform transmitting terminals indicated that our final model adequately predicted habitat use by migrant Whooping Cranes. The probability map demonstrated that existing conservation efforts have protected much top-tier Whooping Crane habitat, especially in the portions of North Dakota and South Dakota that lie east of the Missouri River. Our results can support species recovery by informing prioritization for acquisition and restoration of landscapes that provide safe roosting and foraging habitats. Our results can also guide the siting of structures such as wind towers and electrical transmission and distribution lines, which pose a strike and mortality risk to migrating Whooping Cranes.

Epidemiology and Ecology of Opportunistic Premise Plumbing Pathogens: Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa

Science.gov (United States)

BACKGROUND: Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa are opportunistic premise plumbing pathogens (OPPPs) that persist and grow in household plumbing, habitats they share with humans. Infections caused by these OPPPs involve individuals with preexis...

Opportunistic Beamforming with Wireless Powered 1-bit Feedback Through Rectenna Array

OpenAIRE

Krikidis, Ioannis

2015-01-01

This letter deals with the opportunistic beamforming (OBF) scheme for multi-antenna downlink with spatial randomness. In contrast to conventional OBF, the terminals return only 1-bit feedback, which is powered by wireless power transfer through a rectenna array. We study two fundamental topologies for the combination of the rectenna elements; the direct-current combiner and the radio-frequency combiner. The beam outage probability is derived in closed form for both combination schemes, by usi...

DIRECTIONAL OPPORTUNISTIC MECHANISM IN CLUSTER MESSAGE CRITICALITY LEVEL BASED ZIGBEE ROUTING

OpenAIRE

B.Rajeshkanna *1, Dr.M.Anitha 2

2018-01-01

The cluster message criticality level based zigbee routing(CMCLZOR) has been proposed for routing the cluster messages in wireless smart energy home area networks. It employs zigbee opportunistic shortcut tree routing(ZOSTR) and AODV individually for routing normal messages and highly critical messages respectively. ZOSTR allows the receiving nodes to compete for forwarding a packet with the priority of left-over hops rather than stating single next hop node like unicast protocols. Since it h...

Leadership in Mobile Technology: An Opportunity for Family and Consumer Sciences Teacher Educators

Science.gov (United States)

Godfrey, Roxie V.; Duke, Sandra E.

2014-01-01

A stroll across campus reveals that students are plugged into mobile technology. They never have to break stride in their social connectivity as they pursue an education.Where does the family and consumer sciences (FCS) teacher educator fit into this opportunistic scenario? From its inception, FCS has been at the forefront in the application of…

Enabling opportunistic resources for CMS Computing Operations

Energy Technology Data Exchange (ETDEWEB)

Hufnagel, Dick [Fermilab

2015-11-19

With the increased pressure on computing brought by the higher energy and luminosity from the LHC in Run 2, CMS Computing Operations expects to require the ability to utilize “opportunistic” resources — resources not owned by, or a priori configured for CMS — to meet peak demands. In addition to our dedicated resources we look to add computing resources from non CMS grids, cloud resources, and national supercomputing centers. CMS uses the HTCondor/glideinWMS job submission infrastructure for all its batch processing, so such resources will need to be transparently integrated into its glideinWMS pool. Bosco and parrot wrappers are used to enable access and bring the CMS environment into these non CMS resources. Here we describe our strategy to supplement our native capabilities with opportunistic resources and our experience so far using them.

Understanding Fear of Opportunism in Global Prize-Based Science Contests: Evidence for Gender and Age Differences.

Science.gov (United States)

Acar, Oguz Ali; van den Ende, Jan

2015-01-01

Global prize-based science contests have great potential for tapping into diverse knowledge on a global scale and overcoming important scientific challenges. A necessary step for knowledge to be utilized in these contests is for that knowledge to be disclosed. Knowledge disclosure, however, is paradoxical in nature: in order for the value of knowledge to be assessed, inventors must disclose their knowledge, but then the person who receives that knowledge does so at no cost and may use it opportunistically. This risk of potential opportunistic behavior in turn makes the inventor fearful of disclosing knowledge, and this is a major psychological barrier to knowledge disclosure. In this project, we investigated this fear of opportunism in global prize-based science contests by surveying 630 contest participants in the InnoCentive online platform for science contests. We found that participants in these science contests experience fear of opportunism to varying degrees, and that women and older participants have significantly less fear of disclosing their scientific knowledge. Our findings highlight the importance of taking differences in such fears into account when designing global prize-based contests so that the potential of the contests for reaching solutions to important and challenging problems can be used more effectively.

Understanding Fear of Opportunism in Global Prize-Based Science Contests: Evidence for Gender and Age Differences.

Directory of Open Access Journals (Sweden)

Oguz Ali Acar

Full Text Available Global prize-based science contests have great potential for tapping into diverse knowledge on a global scale and overcoming important scientific challenges. A necessary step for knowledge to be utilized in these contests is for that knowledge to be disclosed. Knowledge disclosure, however, is paradoxical in nature: in order for the value of knowledge to be assessed, inventors must disclose their knowledge, but then the person who receives that knowledge does so at no cost and may use it opportunistically. This risk of potential opportunistic behavior in turn makes the inventor fearful of disclosing knowledge, and this is a major psychological barrier to knowledge disclosure. In this project, we investigated this fear of opportunism in global prize-based science contests by surveying 630 contest participants in the InnoCentive online platform for science contests. We found that participants in these science contests experience fear of opportunism to varying degrees, and that women and older participants have significantly less fear of disclosing their scientific knowledge. Our findings highlight the importance of taking differences in such fears into account when designing global prize-based contests so that the potential of the contests for reaching solutions to important and challenging problems can be used more effectively.

The OSG Open Facility: an on-ramp for opportunistic scientific computing

Science.gov (United States)

Jayatilaka, B.; Levshina, T.; Sehgal, C.; Gardner, R.; Rynge, M.; Würthwein, F.

2017-10-01

The Open Science Grid (OSG) is a large, robust computing grid that started primarily as a collection of sites associated with large HEP experiments such as ATLAS, CDF, CMS, and DZero, but has evolved in recent years to a much larger user and resource platform. In addition to meeting the US LHC community’s computational needs, the OSG continues to be one of the largest providers of distributed high-throughput computing (DHTC) to researchers from a wide variety of disciplines via the OSG Open Facility. The Open Facility consists of OSG resources that are available opportunistically to users other than resource owners and their collaborators. In the past two years, the Open Facility has doubled its annual throughput to over 200 million wall hours. More than half of these resources are used by over 100 individual researchers from over 60 institutions in fields such as biology, medicine, math, economics, and many others. Over 10% of these individual users utilized in excess of 1 million computational hours each in the past year. The largest source of these cycles is temporary unused capacity at institutions affiliated with US LHC computational sites. An increasing fraction, however, comes from university HPC clusters and large national infrastructure supercomputers offering unused capacity. Such expansions have allowed the OSG to provide ample computational resources to both individual researchers and small groups as well as sizable international science collaborations such as LIGO, AMS, IceCube, and sPHENIX. Opening up access to the Fermilab FabrIc for Frontier Experiments (FIFE) project has also allowed experiments such as mu2e and NOvA to make substantial use of Open Facility resources, the former with over 40 million wall hours in a year. We present how this expansion was accomplished as well as future plans for keeping the OSG Open Facility at the forefront of enabling scientific research by way of DHTC.

The OSG Open Facility: An On-Ramp for Opportunistic Scientific Computing

Energy Technology Data Exchange (ETDEWEB)

Jayatilaka, B. [Fermilab; Levshina, T. [Fermilab; Sehgal, C. [Fermilab; Gardner, R. [Chicago U.; Rynge, M. [USC - ISI, Marina del Rey; Würthwein, F. [UC, San Diego

2017-11-22

The Open Science Grid (OSG) is a large, robust computing grid that started primarily as a collection of sites associated with large HEP experiments such as ATLAS, CDF, CMS, and DZero, but has evolved in recent years to a much larger user and resource platform. In addition to meeting the US LHC community’s computational needs, the OSG continues to be one of the largest providers of distributed high-throughput computing (DHTC) to researchers from a wide variety of disciplines via the OSG Open Facility. The Open Facility consists of OSG resources that are available opportunistically to users other than resource owners and their collaborators. In the past two years, the Open Facility has doubled its annual throughput to over 200 million wall hours. More than half of these resources are used by over 100 individual researchers from over 60 institutions in fields such as biology, medicine, math, economics, and many others. Over 10% of these individual users utilized in excess of 1 million computational hours each in the past year. The largest source of these cycles is temporary unused capacity at institutions affiliated with US LHC computational sites. An increasing fraction, however, comes from university HPC clusters and large national infrastructure supercomputers offering unused capacity. Such expansions have allowed the OSG to provide ample computational resources to both individual researchers and small groups as well as sizable international science collaborations such as LIGO, AMS, IceCube, and sPHENIX. Opening up access to the Fermilab FabrIc for Frontier Experiments (FIFE) project has also allowed experiments such as mu2e and NOvA to make substantial use of Open Facility resources, the former with over 40 million wall hours in a year. We present how this expansion was accomplished as well as future plans for keeping the OSG Open Facility at the forefront of enabling scientific research by way of DHTC.

Channel access delay and buffer distribution of two-user opportunistic scheduling schemes in wireless networks

KAUST Repository

Hossain, Md Jahangir; Alouini, Mohamed-Slim; Bhargava, Vijay K.

2010-01-01

In our earlier works, we proposed rate adaptive hierarchical modulation-assisted two-best user opportunistic scheduling (TBS) and hybrid two-user scheduling (HTS) schemes. The proposed schemes are innovative in the sense that they include a second

The presence of opportunistic pathogens, Legionella spp., L. pneumophila and Mycobacterium avium complex, in South Australian reuse water distribution pipelines.

Science.gov (United States)

Whiley, H; Keegan, A; Fallowfield, H; Bentham, R

2015-06-01

Water reuse has become increasingly important for sustainable water management. Currently, its application is primarily constrained by the potential health risks. Presently there is limited knowledge regarding the presence and fate of opportunistic pathogens along reuse water distribution pipelines. In this study opportunistic human pathogens Legionella spp., L. pneumophila and Mycobacterium avium complex were detected using real-time polymerase chain reaction along two South Australian reuse water distribution pipelines at maximum concentrations of 10⁵, 10³ and 10⁵ copies/mL, respectively. During the summer period of sampling the concentration of all three organisms significantly increased (P < 0.05) along the pipeline, suggesting multiplication and hence viability. No seasonality in the decrease in chlorine residual along the pipelines was observed. This suggests that the combination of reduced chlorine residual and increased water temperature promoted the presence of these opportunistic pathogens.

Opportunistic Nonorthogonal Packet Scheduling in Fixed Broadband Wireless Access Networks

Directory of Open Access Journals (Sweden)

Ahmed Mohamed H

2006-01-01

Full Text Available In order to mitigate high cochannel interference resulting from dense channel reuse, the interference management issues are often considered as essential part of scheduling schemes in fixed broadband wireless access (FBWA networks. To that end, a series of literature has been published recently, in which a group of base stations forms an interferer group (downlink transmissions from each base station become dominant interference for the users in other in-group base stations, and the scheduling scheme deployed in the group allows only one base station to transmit at a time. As a result of time orthogonality in transmissions, the dominant cochannel interferers are prevented, and hence the packet error rate can be improved. However, prohibiting concurrent transmissions in these orthogonal schemes introduces throughput penalty as well as higher end-to-end packet delay which might not be desirable for real-time services. In this paper, we utilize opportunistic nonorthogonality among the in-group transmissions whenever possible and propose a novel transmission scheduling scheme for FBWA networks. The proposed scheme, in contrast to the proactive interference avoidance techniques, strives for the improvements in delay and throughput efficiency. To facilitate opportunistic nonorthogonal transmissions in the interferer group, estimation of signal-to-interference-plus-noise ratio (SINR is required at the scheduler. We have observed from simulations that the proposed scheme outperforms the reference orthogonal scheme in terms of spectral efficiency, mean packet delay, and packet dropping rate.

Proof-of-Concept System for Opportunistic Spectrum Access in Multi-user Decentralized Networks

Directory of Open Access Journals (Sweden)

Sumit J. Darak

2016-09-01

Full Text Available Poor utilization of an electromagnetic spectrum and ever increasing demand for spectrum have led to surge of interests in opportunistic spectrum access (OSA based paradigms like cognitive radio and unlicensed LTE. In OSA for decentralized networks, frequency band selection from wideband spectrum is a challenging task since secondary users (SUs do not share any information with each other. In this paper, a new decision making policy (DMP has been proposed for OSA in the multi-user decentralized networks. First contribution is an accurate characterization of frequency bands using Bayes-UCB algorithm. Then, a novel SU orthogonization scheme using Bayes-UCB algorithm is proposed replacing randomization based scheme. At the end, USRP testbed has been developed for analyzing the performance of DMPs using real radio signals. Experimental results show that the proposed DMP offers significant improvement in spectrum utilization, fewer subband switching and collisions compared to other DMPs.

Regrowth of Potential Opportunistic Pathogens and Algae in Reclaimed-Water Distribution Systems ▿

Science.gov (United States)

Jjemba, Patrick K.; Weinrich, Lauren A.; Cheng, Wei; Giraldo, Eugenio; LeChevallier, Mark W.

2010-01-01

A study of the quality of reclaimed water in treated effluent, after storage, and at three points in the distribution system of four plants in California, Florida, Massachusetts, and New York was conducted for 1 year. The plants had different treatment processes (conventional versus membrane bioreactor), production capacities, and methods for storage of the water, and the intended end uses of the water were different. The analysis focused on the occurrence of indicator bacteria (heterotrophic bacteria, coliforms, Escherichia coli, and enterococci) and opportunistic pathogens (Aeromonas spp., enteropathogenic E. coli O157:H7, Legionella spp., Mycobacterium spp., and Pseudomonas spp.), as well as algae. Using immunological methods, E. coli O157:H7 was detected in the effluent of only one system, but it was not detected at the sampling points, suggesting that its survival in the system was poor. Although all of the treatment systems effectively reduced the levels of bacteria in the effluent, bacteria regrew in the reservoir and distribution systems because of the loss of residual disinfectant and high assimilable organic carbon levels. In the systems with open reservoirs, algal growth reduced the water quality by increasing the turbidity and accumulating at the end of the distribution system. Opportunistic pathogens, notably Aeromonas, Legionella, Mycobacterium, and Pseudomonas, occurred more frequently than indicator bacteria (enterococci, coliforms, and E. coli). The Mycobacterium spp. were very diverse and occurred most frequently in membrane bioreactor systems, and Mycobacterium cookii was identified more often than the other species. The public health risk associated with these opportunistic pathogens in reclaimed water is unknown. Collectively, our results show the need to develop best management practices for reclaimed water to control bacterial regrowth and degradation of water before it is utilized at the point of use. PMID:20453149

PlayNCool: Opportunistic Network Coding for Local Optimization of Routing in Wireless Mesh Networks

DEFF Research Database (Denmark)

Pahlevani, Peyman; Roetter, Daniel Enrique Lucani; Pedersen, Morten Videbæk

2013-01-01

This paper introduces PlayNCool, an opportunistic protocol with local optimization based on network coding to increase the throughput of a wireless mesh network (WMN). PlayNCool aims to enhance current routing protocols by (i) allowing random linear network coding transmissions end-to-end, (ii) r...

Draft genome sequences of two opportunistic pathogenic strains of Staphylococcus cohnii isolated from human patients.

Science.gov (United States)

Mendoza-Olazarán, Soraya; Garcia-Mazcorro, José F; Morfín-Otero, Rayo; Villarreal-Treviño, Licet; Camacho-Ortiz, Adrián; Rodríguez-Noriega, Eduardo; Bocanegra-Ibarias, Paola; Maldonado-Garza, Héctor J; Dowd, Scot E; Garza-González, Elvira

2017-01-01

Herein, we report the draft-genome sequences and annotation of two opportunistic pathogenic strains of Staphylococcus cohnii isolated from humans. One strain (SC-57) was isolated from blood from a male patient in May 2006 and the other (SC-532) from a catheter from a male patient in June 2006. Similar to other genomes of Staphylococcus species, most genes (42%) of both strains are involved in metabolism of amino acids and derivatives, carbohydrates and proteins. Eighty (4%) genes are involved in virulence, disease, and defense and both species show phenotypic low biofilm production and evidence of increased antibiotic resistance associated to biofilm production. From both isolates, a new Staphylococcal Cassette Chromosome mec was detected: mec class A, ccr type 1. This is the first report of whole genome sequences of opportunistic S. cohnii isolated from human patients.

Opportunistic and other intestinal parasites among HIV/AIDS patients attending Gambi higher clinic in Bahir Dar city, North West Ethiopia.

Science.gov (United States)

Alemu, Abebe; Shiferaw, Yitayal; Getnet, Gebeyaw; Yalew, Aregaw; Addis, Zelalem

2011-08-01

To determine the magnitude of opportunistic and non-opportunistic intestinal parasitic infections among HIV/AIDS patients in Bahir Dar. Cross-sectional study was conducted among HIV/AIDS patients attending Gambi higher clinic from April1-May 30, 2009. Convenient sampling technique was employed to identify the study subjects and hence a total of 248 subjects were included. A pre-tested structured questionnaire was used to collect socio-demographic data of patients. Stool samples were examined by direct saline, iodine wet mount, formol-ether sedimentation concentration and modified Ziehl-Neelsen staining technique. Out of 248 enrolled in the study, 171(69.0%) (90 males and 81 females) were infected with one or more intestinal parasites. The highest rate of intestinal parasites were observed among HIV/AIDS patients (80.3%, 151/188), and the infection rate of HIV negative individuals was 33.3% (20/60). Cryptosporidum parvum (43.6%), Isospora belli (15.5%) and Blastocystis hominis (10.5%) were opportunistic parasites that were found only in HIV/AIDS patients. Opportunistic parasite infections are common health problem among HIV/AIDS patients in the study area. Therefore, early detection and treatment of these parasites are important to improve the quality of life of HIV/AIDS patients. Copyright © 2011 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

Performance data from the ZEPLIN-III second science run

International Nuclear Information System (INIS)

Majewski, P; Edwards, B; Kalmus, G E; Lindote, A; Solovov, V N; Chepel, V; DeViveiros, L; Lopes, M I; Akimov, D Yu; Belov, V A; Burenkov, A A; Kobyakin, A S; Kovalenko, A G; Araújo, H M; Currie, A; Horn, M; Lebedenko, V N; Barnes, E J; Ghag, C; Hollingsworth, A

2012-01-01

ZEPLIN-III is a two-phase xenon direct dark matter experiment located at the Boulby Mine (U.K.). After its first science run in 2008 it was upgraded with: an array of low background photomultipliers, a new anti-coincidence detector system with plastic scintillator and an improved calibration system. After 319 days of data taking the second science run ended in May 2011. In this paper we describe the instrument performance with emphasis on the position and energy reconstruction algorithm and summarise the final science results.

Opportunistic MSPA Demonstration #1: Final Report

Science.gov (United States)

Abraham, D. S.; Finley, S. G.; Heckman, D. P.; Lay, N. E.; Lush, C. M.; MacNeal, B. E.

2015-02-01

The Opportunistic Multiple Spacecraft Per Antenna (OMSPA) concept seeks to provide smallsat missions with a low-attributed-aperture-fee technique for obtaining routine downlink in a manner that is very low cost to the Deep Space Network (DSN). Unlike traditional MSPA in which the number of spacecraft that can be supported is limited by the number of available receivers, OMSPA makes use of a digital recorder at each station that is capable of capturing IF signals from every spacecraft in the antenna beam within the frequency bands of interest. When smallsat missions see one or more opportunities to intercept the traditionally scheduled antenna beam of a "host" spacecraft, they can transmit open loop during those opportunities. Via a secure Internet site, the smallsat mission operators can then retrieve relevant portions of the digital recording for subsequent demodulation and decoding or subscribe to a service that does it for them. The demonstration discussed in this article was intended to provide prospective smallsat users and the DSN, as the prospective service provider, with demonstrable proof that the OMSPA concept is, in fact, an operationally viable means for obtaining routine downlink telemetry. To do this, the demonstration began by treating Mars Odyssey as a "smallsat" and Mars Reconnaissance Orbiter (MRO) as the "host" spacecraft. Using a specially created Beam Intercept Planning System (BIPS) and a DSN 7-Day Schedule Cross-Comparison (7-DSC) tool, opportunities were identified when Mars Odyssey would be transmitting while in MRO's ground antenna beam. Existing Very Long Baseline Interferometry (VLBI) Science Receivers (VSRs) were used to record the Mars Odyssey downlink telemetry during these opportunities. The recordings were played back to a secure server outside the Flight Operations Network firewall, but inside the JPL firewall. The demonstration team's signal processing personnel retrieved the recordings from this secure server and downloaded them

Prediction Approach of Critical Node Based on Multiple Attribute Decision Making for Opportunistic Sensor Networks

Directory of Open Access Journals (Sweden)

Qifan Chen

2016-01-01

Full Text Available Predicting critical nodes of Opportunistic Sensor Network (OSN can help us not only to improve network performance but also to decrease the cost in network maintenance. However, existing ways of predicting critical nodes in static network are not suitable for OSN. In this paper, the conceptions of critical nodes, region contribution, and cut-vertex in multiregion OSN are defined. We propose an approach to predict critical node for OSN, which is based on multiple attribute decision making (MADM. It takes RC to present the dependence of regions on Ferry nodes. TOPSIS algorithm is employed to find out Ferry node with maximum comprehensive contribution, which is a critical node. The experimental results show that, in different scenarios, this approach can predict the critical nodes of OSN better.

Performative Social Science: A Consideration of Skills, Purpose and Context

Directory of Open Access Journals (Sweden)

Brian Roberts

2008-05-01

Full Text Available This article reviews recent work applying a notion of "performance" in the study and representation of lives. It tries to clarify some of the issues involved—including the meaning of "performance"—and "performative"—the range of possible approaches (e.g., in addition to drama—other arts and the relationship between "subjects", "researcher" and "audience". An immediate concern is the nature of the researcher—as having the necessary skills and abilities or knowledge involved in "performance" (in researching, writing, recording and representing, as engaged (to some extent in "artistic" endeavour, and moving between a number of "roles" and social relations in "performing" with/to others (the "researched" group, audience and society. An important issue for social science in crossing or bridging the social science-arts, in taking up "performative approaches", is "What remains distinctive about the social science if it becomes involved with performance approaches?" As a source for comparison (and inspiration, some brief reference will be made to the work of KANDINSKY—who moved across disciplinary boundaries and artistic practices—as ethnographer, painter, teacher, designer, theorist and poet. Finally, perhaps, there is a deeper "turn" indicated by the "turn to performance" in the study of lives, a more "complete" portrait of the individual as an active, communicative and sensual being. URN: urn:nbn:de:0114-fqs0802588

Performance Determinants in Physical Sciences for ODL ...

African Journals Online (AJOL)

Identifying performance determinants in physical science subjects for students studying through open and distance learning modes in higher learning institutions requires wider range of intuition than it is for conventional institutions. Using data from The Open University of Tanzania, this paper has unearthed some of the ...

BLESSED with Opportunistic Beacons: A Lightweight Data Dissemination Model for Smart Mobile Ad-Hoc Networks

NARCIS (Netherlands)

Türkes, Okan; Scholten, Johan; Havinga, Paul J.M.

2015-01-01

This paper introduces BLESSED, a universal opportunistic ad hoc networking model intended for smart mobile devices. It enables fast and lightweight data dissemination in wireless community networks through the complementary utilization of the IEEE 802.11 and Bluetooth Low Energy standards. As a

Opportunistic Beamforming with Wireless Powered 1-bit Feedback Through Rectenna Array

Science.gov (United States)

Krikidis, Ioannis

2015-11-01

This letter deals with the opportunistic beamforming (OBF) scheme for multi-antenna downlink with spatial randomness. In contrast to conventional OBF, the terminals return only 1-bit feedback, which is powered by wireless power transfer through a rectenna array. We study two fundamental topologies for the combination of the rectenna elements; the direct-current combiner and the radio-frequency combiner. The beam outage probability is derived in closed form for both combination schemes, by using high order statistics and stochastic geometry.

Larval habitat choice in still water and flume flows by the opportunistic bivalve Mulinia lateralis

Science.gov (United States)

Grassle, Judith P.; Snelgrove, Paul V. R.; Butman, Cheryl Ann

Competent pediveligers of the coot clam Mulinia lateralis (Say) clearly preferred an organically-rich mud over abiotic glass beads in 24-h flume experiments, and often demonstrated the same choice in still-water experiments. We hypothesize that peediveligers with characteristic helical swimming paths above the bottom can exercise habitat choice in both still water nad flow, but that the limited swimming ambits of physiologically older periveligers require near-bottom flows to move the larvae between sediment patches so that they can exercise habitat choice. Although M. lateralis larvae are planktotrophic, their ability to delay metamorphosis in the absence of a preferred sediment cue is limited to about five days, a shorter time than the lecithotrophi larvae of the opportunistic polychaete species, Capitella spp. I and II. Field distributions of all three opportunistic species may result, at least in part, from active habitat selection for high-organic sediments by settling larvae.

High Performance Computing in Science and Engineering '15 : Transactions of the High Performance Computing Center

CERN Document Server

Kröner, Dietmar; Resch, Michael

2016-01-01

This book presents the state-of-the-art in supercomputer simulation. It includes the latest findings from leading researchers using systems from the High Performance Computing Center Stuttgart (HLRS) in 2015. The reports cover all fields of computational science and engineering ranging from CFD to computational physics and from chemistry to computer science with a special emphasis on industrially relevant applications. Presenting findings of one of Europe’s leading systems, this volume covers a wide variety of applications that deliver a high level of sustained performance. The book covers the main methods in high-performance computing. Its outstanding results in achieving the best performance for production codes are of particular interest for both scientists and engineers. The book comes with a wealth of color illustrations and tables of results.

High Performance Computing in Science and Engineering '17 : Transactions of the High Performance Computing Center

CERN Document Server

Kröner, Dietmar; Resch, Michael; HLRS 2017

2018-01-01

This book presents the state-of-the-art in supercomputer simulation. It includes the latest findings from leading researchers using systems from the High Performance Computing Center Stuttgart (HLRS) in 2017. The reports cover all fields of computational science and engineering ranging from CFD to computational physics and from chemistry to computer science with a special emphasis on industrially relevant applications. Presenting findings of one of Europe’s leading systems, this volume covers a wide variety of applications that deliver a high level of sustained performance.The book covers the main methods in high-performance computing. Its outstanding results in achieving the best performance for production codes are of particular interest for both scientists and engineers. The book comes with a wealth of color illustrations and tables of results.

Dynamics of T-cell subsets and their relationship with oral and systemic opportunistic infections in HIV/AIDS patients during the first year of HAART in Guangxi, China.

Science.gov (United States)

Zhang, Linlin; Huang, Yuxiao; Liu, Zhenmin; Liu, Wei; Qin, Qi; Tao, Renchuan

2015-07-01

To analyze the dynamic changes in Th1, Th2, Tc1, and Tc2 of HIV/AIDS patients during the first year of highly active antiretroviral therapy (HAART) and to explore their relationship with oral and systemic opportunistic infections, a cohort study was carried out among HIV/AIDS patients in Guangxi, China. Ninety HIV/AIDS patients and 30 healthy controls (HC) were included. The enrolled HIV/AIDS patients were examined at baseline and after 3, 6, and 12 months of HAART. On each visit, oral and systemic opportunistic infections were recorded, oral Candida load and plasma viral load (VL) were counted, differential T-cell counts and flow cytometric analysis of T-cell subsets were performed. During the first year of HAART, the total number of opportunistic infections decreased steadily with the change in oral candidiasis (OC) most representatively. A significant Th1→Th2 switch (Th1/Th2 ratio 0.23 ± 0.12, HC 1.45 ± 0.38) and slight Tc1→Tc2 shift (Tc1/Tc2 ratio 0.93 ± 0.29, HC 1.13 ± 0.33) were found at baseline, and both received slow mitigation after HAART. LgCFU and clinical OC were correlated positively with both LgVL and clinical stage (P Candida load could be useful clinical markers in the evaluation of HIV/AIDS patients. Th1 may play an important role against oral and systemic opportunistic infections. Tc1 and Tc2 both showed positive roles in the control of viremia without HAART. J. Med. Virol. 87:1158-1167, 2015. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

Effect of oral hygiene interventions on opportunistic pathogens in patients after stroke.

Science.gov (United States)

Lam, Otto L T; McMillan, Anne S; Samaranayake, Lakshman P; Li, Leonard S W; McGrath, Colman

2013-02-01

Despite the role of the oral cavity as a reservoir of opportunistic pathogens for infection in patients following stroke, the evaluation of the effects of oral hygiene interventions has been largely neglected. This randomized clinical trial included 102 patients undergoing hospital-based rehabilitation for stroke. Patients were randomized to one of 3 groups: oral hygiene instruction (OHI) only; OHI and 0.2% chlorhexidine mouth rinse twice daily; or OHI, 0.2% chlorhexidine mouth rinse twice daily, and assisted brushing twice weekly. Oral samples were obtained at baseline and after 3 weeks for detection of Staphylococcus aureus, aerobic and facultatively anaerobic gram-negative bacilli, and yeasts. Almost three-quarters (72.8%) of the patients harbored oral anaerobic gram-negative bacilli at baseline, and more than half had detectable S aureus (56.8%) and yeasts (59.3%). Percentage frequencies and viable counts of pathogens remained relatively stable during the course of the clinical trial, and no significant differences were observed among the 3 patient groups. In our study cohort, there was no significant difference in the effectiveness of the 3 different oral hygiene interventions on the prevalence or viable counts of oral opportunistic pathogens. Copyright © 2013 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Hiding in Fresh Fruits and Vegetables: Opportunistic Pathogens May Cross Geographical Barriers

Directory of Open Access Journals (Sweden)

Zahra S. Al-Kharousi

2016-01-01

Full Text Available Different microbial groups of the microbiome of fresh produce can have diverse effects on human health. This study was aimed at identifying some microbial communities of fresh produce by analyzing 105 samples of imported fresh fruits and vegetables originated from different countries in the world including local samples (Oman for aerobic plate count and the counts of Enterobacteriaceae, Enterococcus, and Staphylococcus aureus. The isolated bacteria were identified by molecular (PCR and biochemical methods (VITEK 2. Enterobacteriaceae occurred in 60% of fruits and 91% of vegetables. Enterococcus was isolated from 20% of fruits and 42% of vegetables. E. coli and S. aureus were isolated from 22% and 7% of vegetables, respectively. Ninety-seven bacteria comprising 21 species were similarly identified by VITEK 2 and PCR to species level. E. coli, Klebsiella pneumoniae, Enterococcus casseliflavus, and Enterobacter cloacae were the most abundant species; many are known as opportunistic pathogens which may raise concern to improve the microbial quality of fresh produce. Phylogenetic trees showed no relationship between clustering of the isolates based on the 16S rRNA gene and the original countries of fresh produce. Intercountry passage of opportunistic pathogens in fresh produce cannot be ruled out, which requires better management.

Science Identity's Influence on Community College Students' Engagement, Persistence, and Performance in Biology

Science.gov (United States)

Riccitelli, Melinda

In the United States (U.S.), student engagement, persistence, and academic performance levels in college science, technology, engineering, and mathematics (STEM) programs have been unsatisfactory over the last decade. Low student engagement, persistence, and academic performance in STEM disciplines have been identified as major obstacles to U.S. economic goals and U.S. science education objectives. The central and salient science identity a college student claims can influence his engagement, persistence, and academic achievement in college science. While science identity studies have been conducted on four-year college populations there is a gap in the literature concerning community college students' science identity and science performance. The purpose of this quantitative correlational study was to examine the relationship between community college students claimed science identities and engagement, persistence, and academic performance. A census sample of 264 community college students enrolled in biology during the summer of 2015 was used to study this relationship. Science identity and engagement levels were calculated using the Science Identity Centrality Scale and the Biology Motivation Questionnaire II, respectively. Persistence and final grade data were collected from institutional and instructor records. Engagement significantly correlated to, r =.534, p = .01, and varied by science identity, p < .001. Percent final grade also varied by science identity (p < .005), but this relationship was weaker (r = .208, p = .01). Results for science identity and engagement and final grade were consistent with the identity literature. Persistence did not vary by science identity in this student sample (chi2 =2.815, p = .421). This result was inconsistent with the literature on science identity and persistence. Quantitative results from this study present a mixed picture of science identity status at the community college level. It is suggested, based on the findings

Two-user opportunistic scheduling using hierarchical modulations in wireless networks with heterogenous average link gains

KAUST Repository

Hossain, Md Jahangir; Alouini, Mohamed-Slim; Bhargava, Vijay K.

2010-01-01

-user opportunistic scheduling (HTS) scheme based on our earlier proposed TBS scheme. This HTS scheme selects the first user based on the largest absolute CNR value among all the users while the second user is selected based on the ratios of the absolute CNRs

Evidence-based consensus on opportunistic infections in inflammatory bowel disease (republication

Directory of Open Access Journals (Sweden)

2018-04-01

Full Text Available Inflammatory bowel disease (IBD patients are a high-risk population for opportunistic infections. The IBD group of the Chinese Society of Gastroenterology of the Chinese Medical Association organized an expert group to discuss and develop this consensus opinion. This consensus opinion referenced clinical study results from China and other countries to provide guidance for clinical practices. Eight major topics, including cytomegalovirus infection, Epstein-Barr virus infection, viral hepatitis, bacterial infection, Mycobacterium tuberculosis infection, fungal infection, parasitic infection, and vaccines were introduced in this article.

Anthropogenic disturbance can determine the magnitude of opportunistic species responses on marine urban infrastructures.

Science.gov (United States)

Airoldi, Laura; Bulleri, Fabio

2011-01-01

Coastal landscapes are being transformed as a consequence of the increasing demand for infrastructures to sustain residential, commercial and tourist activities. Thus, intertidal and shallow marine habitats are largely being replaced by a variety of artificial substrata (e.g. breakwaters, seawalls, jetties). Understanding the ecological functioning of these artificial habitats is key to planning their design and management, in order to minimise their impacts and to improve their potential to contribute to marine biodiversity and ecosystem functioning. Nonetheless, little effort has been made to assess the role of human disturbances in shaping the structure of assemblages on marine artificial infrastructures. We tested the hypothesis that some negative impacts associated with the expansion of opportunistic and invasive species on urban infrastructures can be related to the severe human disturbances that are typical of these environments, such as those from maintenance and renovation works. Maintenance caused a marked decrease in the cover of dominant space occupiers, such as mussels and oysters, and a significant enhancement of opportunistic and invasive forms, such as biofilm and macroalgae. These effects were particularly pronounced on sheltered substrata compared to exposed substrata. Experimental application of the disturbance in winter reduced the magnitude of the impacts compared to application in spring or summer. We use these results to identify possible management strategies to inform the improvement of the ecological value of artificial marine infrastructures. We demonstrate that some of the impacts of globally expanding marine urban infrastructures, such as those related to the spread of opportunistic, and invasive species could be mitigated through ecologically-driven planning and management of long-term maintenance of these structures. Impact mitigation is a possible outcome of policies that consider the ecological features of built infrastructures and

Anthropogenic disturbance can determine the magnitude of opportunistic species responses on marine urban infrastructures.

Directory of Open Access Journals (Sweden)

Laura Airoldi

Full Text Available BACKGROUND: Coastal landscapes are being transformed as a consequence of the increasing demand for infrastructures to sustain residential, commercial and tourist activities. Thus, intertidal and shallow marine habitats are largely being replaced by a variety of artificial substrata (e.g. breakwaters, seawalls, jetties. Understanding the ecological functioning of these artificial habitats is key to planning their design and management, in order to minimise their impacts and to improve their potential to contribute to marine biodiversity and ecosystem functioning. Nonetheless, little effort has been made to assess the role of human disturbances in shaping the structure of assemblages on marine artificial infrastructures. We tested the hypothesis that some negative impacts associated with the expansion of opportunistic and invasive species on urban infrastructures can be related to the severe human disturbances that are typical of these environments, such as those from maintenance and renovation works. METHODOLOGY/PRINCIPAL FINDINGS: Maintenance caused a marked decrease in the cover of dominant space occupiers, such as mussels and oysters, and a significant enhancement of opportunistic and invasive forms, such as biofilm and macroalgae. These effects were particularly pronounced on sheltered substrata compared to exposed substrata. Experimental application of the disturbance in winter reduced the magnitude of the impacts compared to application in spring or summer. We use these results to identify possible management strategies to inform the improvement of the ecological value of artificial marine infrastructures. CONCLUSIONS/SIGNIFICANCE: We demonstrate that some of the impacts of globally expanding marine urban infrastructures, such as those related to the spread of opportunistic, and invasive species could be mitigated through ecologically-driven planning and management of long-term maintenance of these structures. Impact mitigation is a

Yield of opportunistic targeted screening for type 2 diabetes in primary care: the diabscreen study.

NARCIS (Netherlands)

Klein Woolthuis, E.P.; Grauw, W.J.C. de; Gerwen, W.H.E.M. van; Hoogen, H.J.M. van den; Lisdonk, E.H. van de; Metsemakers, J.F.M.; Weel, C. van

2009-01-01

PURPOSE: In screening for type 2 diabetes, guidelines recommend targeting high-risk individuals. Our objectives were to assess the yield of opportunistic targeted screening for type 2 diabetes in primary care and to assess the diagnostic value of various risk factors. METHODS: In 11 family practices

Allelopathic interactions between the opportunistic species Ulva prolifera and the native macroalga Gracilaria lichvoides.

Directory of Open Access Journals (Sweden)

Dong Xu

Full Text Available Allelopathy, one type of direct plant competition, can be a potent mechanism through which plant communities are structured. The aim of this study was to determine whether allelopathic interactions occur between the opportunistic green tide-forming species Ulva prolifera and the native macroalga Gracilaria lichvoides, both of which were collected from the coastline of East China sea. In laboratory experiments, the presence of G. lichvoides at 1.25 g wet weight L(-1 significantly inhibited growth and photosynthesis of U. prolifera at concentrations of 1.25, 2.50, and 3.75 g wet weight L(-1 (p0.05. Culture medium experiments further confirmed that some allelochemicals may be released by both of the tested macroalgae, and these could account for the observed physiological inhibition of growth and photosynthesis. Moreover, the native macroalgae G. lichvoides was a stronger competitor than the opportunistic species U. prolifera. Collectively, the results of the present study represent a significant advance in exploring ecological questions about the effects of green tide blooms on the macroalgal community.

OPPORTUNISTIC ASPERGILLUS PATHOGENS MEASURED IN HOME AND HOSPITAL TAP WATER BY MOLD SPECIFIC QUANTITATIVE PCR (MSQPCR)

Science.gov (United States)

Opportunistic fungal pathogens are a concern because of the increasing number of immunocompromised patients. The goal of this research was to test a simple extraction method and rapid quantitative PCR (QPCR) measurement of the occurrence of potential pathogens, Aspergillus fumiga...

High Performance Networks for High Impact Science

Energy Technology Data Exchange (ETDEWEB)

Scott, Mary A.; Bair, Raymond A.

2003-02-13

This workshop was the first major activity in developing a strategic plan for high-performance networking in the Office of Science. Held August 13 through 15, 2002, it brought together a selection of end users, especially representing the emerging, high-visibility initiatives, and network visionaries to identify opportunities and begin defining the path forward.

Service time analysis of secondary packet transmission with opportunistic channel access

KAUST Repository

Usman, Muneer; Yang, Hongchuan; Alouini, Mohamed-Slim

2014-01-01

Cognitive radio transceiver can opportunistically access the underutilized channels of primary systems for new wireless services. The secondary transmission may be interrupted by the primary user's transmission. To facilitate the delay analysis of such secondary packet transmission, we study the resulting extended delivery time for a fixed-size secondary packet that includes both transmission time and waiting time. In particular we derive the exact distribution functions of extended delivery time of secondary transmission for both continuous sensing and periodic sensing cases. Selected numerical results are presented for illustrating the mathematical formulation.

Service time analysis of secondary packet transmission with opportunistic channel access

KAUST Repository

Usman, Muneer

2014-09-01

Cognitive radio transceiver can opportunistically access the underutilized channels of primary systems for new wireless services. The secondary transmission may be interrupted by the primary user\\'s transmission. To facilitate the delay analysis of such secondary packet transmission, we study the resulting extended delivery time for a fixed-size secondary packet that includes both transmission time and waiting time. In particular we derive the exact distribution functions of extended delivery time of secondary transmission for both continuous sensing and periodic sensing cases. Selected numerical results are presented for illustrating the mathematical formulation.

Basic Pharmaceutical Sciences Examination as a Predictor of Student Performance during Clinical Training.

Science.gov (United States)

Fassett, William E.; Campbell, William H.

1984-01-01

A comparison of Basic Pharmaceutical Sciences Examination (BPSE) results with student performance evaluations in core clerkships, institutional and community externships, didactic and clinical courses, and related basic science coursework revealed the BPSE does not predict student performance during clinical instruction. (MSE)

The Impacts of Control Mechanism in Strategic Alliance on Alliance Performance: From the Perspective of Boundary Dilemma

Institute of Scientific and Technical Information of China (English)

SHEN Hao; XIE En; WANG Dong

2016-01-01

In order to solve the problem of boundary dilemma in the strategic alliance,this paper firstly examines the impact of the control mechanism in the strategic alliance on the coordinative efficiency and opportunistic risks of the alliance,and then it tests the different impacts of coordinative efficiency and opportunistic risks on the performances of the alliance members.The empirical results indicate that the formal contract control can efficiently resolve the problem of opportunistic risks in the boundary dilemma,so as to improve the performance of the alliance members;whereas the informal social control including relation control and information technology control can efficiently solve the problem of coordinative efficiency in the boundary dilemma,so as to improve the performance of the alliance members.These findings can enrich and extend existing literature in strategic alliance management and provide significant empirical evidences and theoretical supports for the strategic alliance members to resolve boundary dilemma and further enhance alliance cooperative performance.

Opportunistic testing versus organized prostate-specific antigen screening: outcome after 18 years in the Göteborg randomized population-based prostate cancer screening trial.

Science.gov (United States)

Arnsrud Godtman, Rebecka; Holmberg, Erik; Lilja, Hans; Stranne, Johan; Hugosson, Jonas

2015-09-01

It has been shown that organized screening decreases prostate cancer (PC) mortality, but the effect of opportunistic screening is largely unknown. To compare the ability to reduce PC mortality and the risk of overdiagnosis between organized and opportunistic screening. The Göteborg screening study invited 10 000 randomly selected men for prostate-specific antigen (PSA) testing every 2 yr since 1995, with a prostate biopsy recommended for men with PSA ≥2.5 ng/ml. The control group of 10 000 men not invited has been exposed to a previously reported increased rate of opportunistic PSA testing. Both groups were followed until December 31, 2012. Observed cumulative PC incidence and mortality rates in both groups were calculated using the actuarial method. Using historical data from 1990-1994 (pre-PSA era), we calculated expected PC incidence and mortality rates in the absence of any PSA testing. The number needed to invite (NNI) and the number needed to diagnose (NND) were calculated by comparing the expected versus observed incidence and mortality rates. At 18 yr, 1396 men were diagnosed with PC and 79 men died of PC in the screening group, compared to 962 and 122, respectively, in the control group. In the screening group, the observed cumulative PC incidence/mortality was 16%/0.98% compared to expected values of 6.8%/1.7%. The corresponding values for the control group were 11%/1.5% and 6.9%/1.7%. Organized screening was associated with an absolute PC-specific mortality reduction of 0.72% (95% confidence interval [CI] 0.50-0.94%) and relative risk reduction of 42% (95% CI 28-54%). There was an absolute reduction in PC deaths of 0.20% (95% CI -0.06% to 0.47%) and a relative risk reduction of 12% (95% CI -5 to 26%) associated with opportunistic PSA testing. NNI and NND were 139 (95% CI 107-200) and 13 for organized biennial screening and 493 (95% CI 213- -1563) and 23 for opportunistic screening. The extent of opportunistic screening could not be measured

Sinabro: A Smartphone-Integrated Opportunistic Electrocardiogram Monitoring System.

Science.gov (United States)

Kwon, Sungjun; Lee, Dongseok; Kim, Jeehoon; Lee, Youngki; Kang, Seungwoo; Seo, Sangwon; Park, Kwangsuk

2016-03-11

In our preliminary study, we proposed a smartphone-integrated, unobtrusive electrocardiogram (ECG) monitoring system, Sinabro, which monitors a user's ECG opportunistically during daily smartphone use without explicit user intervention. The proposed system also monitors ECG-derived features, such as heart rate (HR) and heart rate variability (HRV), to support the pervasive healthcare apps for smartphones based on the user's high-level contexts, such as stress and affective state levels. In this study, we have extended the Sinabro system by: (1) upgrading the sensor device; (2) improving the feature extraction process; and (3) evaluating extensions of the system. We evaluated these extensions with a good set of algorithm parameters that were suggested based on empirical analyses. The results showed that the system could capture ECG reliably and extract highly accurate ECG-derived features with a reasonable rate of data drop during the user's daily smartphone use.

Sinabro: A Smartphone-Integrated Opportunistic Electrocardiogram Monitoring System

Directory of Open Access Journals (Sweden)

Sungjun Kwon

2016-03-01

Full Text Available In our preliminary study, we proposed a smartphone-integrated, unobtrusive electrocardiogram (ECG monitoring system, Sinabro, which monitors a user’s ECG opportunistically during daily smartphone use without explicit user intervention. The proposed system also monitors ECG-derived features, such as heart rate (HR and heart rate variability (HRV, to support the pervasive healthcare apps for smartphones based on the user’s high-level contexts, such as stress and affective state levels. In this study, we have extended the Sinabro system by: (1 upgrading the sensor device; (2 improving the feature extraction process; and (3 evaluating extensions of the system. We evaluated these extensions with a good set of algorithm parameters that were suggested based on empirical analyses. The results showed that the system could capture ECG reliably and extract highly accurate ECG-derived features with a reasonable rate of data drop during the user’s daily smartphone use.

Opportunistic and other intestinal parasitic infections in AIDS patients, HIV seropositive healthy carriers and HIV seronegative individuals in southwest Ethiopia.

Science.gov (United States)

Mariam, Zelalem T; Abebe, Gemeda; Mulu, Andargachew

2008-12-01

Human Immunodeficiency Virus (HIV) infection leads to acquired immunodeficiency syndrome (AIDS) and major causes of morbidity and mortality of such patients are opportunistic infections caused by viral, bacterial, fungal and parasitic pathogens. To determine the magnitude of opportunistic and non-opportunistic intestinal parasitic infections among AIDS patients and HIV positive carrier individuals. Cross-sectional study was conducted among AIDS patients, HIV positive healthy carriers and HIV negative individuals in Jimma University Hospital, Mother Theresa Missionary Charity Centre, Medan Acts Projects and Mekdim HIV positive persons and AIDS orphans' national association from January to May, 2004. Convenient sampling technique was employed to identify the study subjects and hence a total of 160 subjects were included. A pre-tested structured questionnaire was used to collect socio-demographic data of the patients. Stool samples were examined by direct saline, iodine wet mount, formol-ether sedimentation concentration, oocyst concentration and modified Ziehl-Neelsen staining technique. Out of 160 persons enrolled in this study 100 (62.5%) (i.e. 65 male and 35 female) were infected with one or more intestinal parasites. The highest rate 36 (69.2%) of intestinal parasites were observed among HIV/AIDS patients, followed by HIV positive healthy carriers 35 (61.4%) of and HIV negative individuals (29 (56.9%). Isospora belli 2 (3.9%), Cryptosporidum parvum 8 (15.4%), Strongyloides stercoralis 6 (11.5%) and Blastocystis 2 (3.9%) were found only in HIV/AIDS groups I. belli, C. parvum, S. stercoralis and Blastocystis are the major opportunistic intestinal parasites observed in HIV/AIDS patients. Therefore, early detection and treatment of these parasites are important to improve the quality of life of HIV/AIDS patients with diarrhoea.

Opportunistic pathogens and elements of the resistome that are common in bottled mineral water support the need for continuous surveillance.

Directory of Open Access Journals (Sweden)

Maria Fernanda Falcone-Dias

Full Text Available Several differences concerning bacterial species, opportunistic pathogens, elements of the resistome as well as variations concerning the CFU/mL counts were identified in some of the five most marketed bottled mineral water from Araraquara city, São Paulo, Brazil. Two out of five brands tested were confirmed as potential source of opportunistic pathogens, including Mycobacterium gordonae, Ralstonia picketti and Burkholderia cepacia complex (Bcc. A total of one hundred and six isolates were recovered from four of these bottled mineral water brands. Betaproteobacteria was predominant followed by Alphaproteobacteria, Gammaproteobacteria and Firmicutes. Ninety percent of the bacteria isolated demonstrated resistance to seventeen of the nineteen antimicrobials tested. These antimicrobials included eight different classes, including 3rd and 4th generation cephalosporins, carbapenems and fluoroquinolones. Multidrug resistant bacteria were detected for fifty-nine percent of isolates in three water brands at counts up to 103 CFU/ml. Of major concern, the two bottled mineral water harboring opportunistic pathogens were also source of elements of the resistome that could be directly transferred to humans. All these differences found among brands highlight the need for continuous bacteriological surveillance of bottled mineral water.

Opportunistic pathogens and elements of the resistome that are common in bottled mineral water support the need for continuous surveillance.

Science.gov (United States)

Falcone-Dias, Maria Fernanda; Centrón, Daniela; Pavan, Fernando; Moura, Adriana Candido da Silva; Naveca, Felipe Gomes; de Souza, Victor Costa; Farache Filho, Adalberto; Leite, Clarice Queico Fujimura

2015-01-01

Several differences concerning bacterial species, opportunistic pathogens, elements of the resistome as well as variations concerning the CFU/mL counts were identified in some of the five most marketed bottled mineral water from Araraquara city, São Paulo, Brazil. Two out of five brands tested were confirmed as potential source of opportunistic pathogens, including Mycobacterium gordonae, Ralstonia picketti and Burkholderia cepacia complex (Bcc). A total of one hundred and six isolates were recovered from four of these bottled mineral water brands. Betaproteobacteria was predominant followed by Alphaproteobacteria, Gammaproteobacteria and Firmicutes. Ninety percent of the bacteria isolated demonstrated resistance to seventeen of the nineteen antimicrobials tested. These antimicrobials included eight different classes, including 3rd and 4th generation cephalosporins, carbapenems and fluoroquinolones. Multidrug resistant bacteria were detected for fifty-nine percent of isolates in three water brands at counts up to 103 CFU/ml. Of major concern, the two bottled mineral water harboring opportunistic pathogens were also source of elements of the resistome that could be directly transferred to humans. All these differences found among brands highlight the need for continuous bacteriological surveillance of bottled mineral water.

Multiresistant opportunistic pathogenic bacteria isolated from polluted rivers and first detection of nontuberculous mycobacteria in the Algerian aquatic environment.

Science.gov (United States)

Djouadi, Lydia Neïla; Selama, Okba; Abderrahmani, Ahmed; Bouanane-Darenfed, Amel; Abdellaziz, Lamia; Amziane, Meriam; Fardeau, Marie-Laure; Nateche, Farida

2017-08-01

Opportunistic infections constitute a major challenge for modern medicine mainly because the involved bacteria are usually multiresistant to antibiotics. Most of these bacteria possess remarkable ability to adapt to various ecosystems, including those exposed to anthropogenic activities. This study isolated and identified 21 multiresistant opportunistic bacteria from two polluted rivers, located in Algiers. Cadmium, lead, and copper concentrations were determined for both water samples to evaluate heavy metal pollution. High prevalence of Enterobacteria and non-fermentative Gram-negative rods was found and a nontuberculous Mycobacterium (NTM) strain was isolated. To the best of our knowledge, this is the first detection of NTM in the Algerian environment. The strains were tested for their resistance against 34 antibiotics and 8 heavy metals. Multiple antibiotics and heavy metals resistance was observed in all isolates. The two most resistant strains, identified as Acinetobacter sp. and Citrobacter freundii, were submitted to plasmid curing to determine if resistance genes were plasmid or chromosome encoded. Citrobacter freundii strain P18 showed a high molecular weight plasmid which seems to code for resistance to zinc, lead, and tetracycline, at the same time. These findings strongly suggest that anthropized environments constitute a reservoir for multiresistant opportunistic bacteria and for circulating resistance genes.

High performance computing in science and engineering Garching/Munich 2016

Energy Technology Data Exchange (ETDEWEB)

Wagner, Siegfried; Bode, Arndt; Bruechle, Helmut; Brehm, Matthias (eds.)

2016-11-01

Computer simulations are the well-established third pillar of natural sciences along with theory and experimentation. Particularly high performance computing is growing fast and constantly demands more and more powerful machines. To keep pace with this development, in spring 2015, the Leibniz Supercomputing Centre installed the high performance computing system SuperMUC Phase 2, only three years after the inauguration of its sibling SuperMUC Phase 1. Thereby, the compute capabilities were more than doubled. This book covers the time-frame June 2014 until June 2016. Readers will find many examples of outstanding research in the more than 130 projects that are covered in this book, with each one of these projects using at least 4 million core-hours on SuperMUC. The largest scientific communities using SuperMUC in the last two years were computational fluid dynamics simulations, chemistry and material sciences, astrophysics, and life sciences.

Mycological assessment of sediments in Ligurian beaches in the Northwestern Mediterranean: pathogens and opportunistic pathogens.

Science.gov (United States)

Salvo, Vanessa-Sarah; Fabiano, Mauro

2007-05-01

Sediments of five Ligurian beaches in compliance with European Union bathing water regulations were studied based on the characteristics of the fungal assemblage during the tourism season. Among the 179 taxa of filamentous fungi isolated, 120 were opportunistic pathogens, such as Acremonium sp., and the genus Penicillium was also present as the pathogenic species P. citrinum. Furthermore, 5% of the total filamentous fungi belonged to the dermatophyte genus Microsporum, whose species can cause mycoses. Beach sediments showed elevated densities of opportunistic pathogens, of pathogenic filamentous fungi, and of yeasts during the tourism season. Although monitoring of beach sediments for microbiological contamination is not mandatory, and disease transmission from sediments has not yet been demonstrated, our study suggests that beach sediments may act as a reservoir of potential pathogens, including fungi. In addition, the mycoflora displayed high sensitivity to critical environmental situations in the beaches studied. Therefore, the fungal community can be a useful tool for assessing the quality of sandy beaches in terms of sanitary and environmental quality.

Specialized Fungal Parasites and Opportunistic Fungi in Gardens of Attine Ants

Directory of Open Access Journals (Sweden)

Fernando C. Pagnocca

2012-01-01

Full Text Available Ants in the tribe Attini (Hymenoptera: Formicidae comprise about 230 described species that share the same characteristic: all coevolved in an ancient mutualism with basidiomycetous fungi cultivated for food. In this paper we focused on fungi other than the mutualistic cultivar and their roles in the attine ant symbiosis. Specialized fungal parasites in the genus Escovopsis negatively impact the fungus gardens. Many fungal parasites may have small impacts on the ants' fungal colony when the colony is balanced, but then may opportunistically shift to having large impacts if the ants' colony becomes unbalanced.

New resource allocation scheme for cognitive relay networks with opportunistic access

KAUST Repository

Zafar, Ammar

2012-06-01

In this paper, a new resource allocation scheme to minimize Symbol Error rate (SER) for relay assisted cognitive radio networks is studied. A cognitive relay network with amplify-and-forward (AF) fixed gain relays and opportunistic access to the licensed spectrum is considered. The SER objective function and the optimization constraints are derived first. The resource allocation algorithm is then derived using the Langrangian multiplier method. Closed form expressions are derived for the source and relay powers and, symbol time. Analytical results show that the optimal power allocation follows an extended water-filling solution. © 2012 IEEE.

Strategic Innovation for Business Performance: The Art and Science of Transformation

Directory of Open Access Journals (Sweden)

Harold Schroeder

2013-09-01

Full Text Available Despite the well-documented association between innovation and business performance, many organizations struggle in their attempts to become successful innovators. This article discusses a recommended “art and science of transformation” approach to help companies improve their innovation performance through effective organizational change. The approach is focused on four key factors: culture, collaboration, strategy, and systems. Examples are drawn from a review of previous research to demonstrate successful innovation practice using similar approaches, and examples of less successful practice are included to highlight ways in which an "art and science" approach can help overcome the difficulties often faced. The article concludes with some practical, step-by-step guidance based on the art and science of transformation framework.

Magnitude of opportunistic infections and associated factors in HIV-infected adults on antiretroviral therapy in eastern Ethiopia

Directory of Open Access Journals (Sweden)

Mitiku H

2015-05-01

Full Text Available Habtamu Mitiku, Fitsum Weldegebreal, Zelalem Teklemariam Haramaya University, College of Health and Medical Sciences, Department of Medical Laboratory Sciences, Harar, Ethiopia Purpose: The aim of this study was to assess the prevalence of opportunistic infections (OIs and associated factors among HIV-infected adults on anti-retroviral therapy (ART in Hiwot Fana Specialized University Hospital, Eastern Ethiopia. Patients and methods: A hospital-based retrospective study was conducted in 358 HIV-infected adult patients on ART from April to June 2014. Data were collected through review of clinical records. The data was entered and analyzed by using SPSS version 16.0. Univariate and multivariate analyses were performed to determine the association of each independent variable with occurrence of OIs. A 95% confidence interval (CI and P-value less than 0.05 were considered as significant association. Results: A total of 358 patients were included in the study, in which majority (68.4% were females. The mean age of patients was 34 (standard deviation [SD] ±9.8 years. The overall of prevalence of OIs among HIV/AIDS patients on ART was 48%. The highest prevalent rates of OIs observed were tuberculosis (TB (21.23%, followed by Herpes zoster (11.2% and oral candidiasis (9.5%. Baseline CD4 cell count <200 cells/mm3 (adjusted odds ratio [AOR] =1.645, 95% CI =2.187, 3.983, baseline World Health Organization (WHO clinical stage III (AOR =2.801, 95% CI =1.958, 7.165 and IV (AOR =3.856; 95% CI =2.691, 10.390, and not using prophylaxis (AOR =1.912, 95% CI =1.444, 3.824 were found to have strong association with acquisition of OIs. Conclusion: There was a high prevalence of OIs observed in this study. Baselines CD4 count of <200 cells/mm3, advanced WHO clinical stages, and not using prophylaxis were found to be predictors of OIs. Interventions were aimed at promoting early HIV testing and enrollment of HIV-infected individuals into ART services needed before CD4

Reforming High School Science for Low-Performing Students Using Inquiry Methods and Communities of Practice

Science.gov (United States)

Bolden, Marsha Gail

Some schools fall short of the high demand to increase science scores on state exams because low-performing students enter high school unprepared for high school science. Low-performing students are not successful in high school for many reasons. However, using inquiry methods have improved students' understanding of science concepts. The purpose of this qualitative research study was to investigate the teachers' lived experiences with using inquiry methods to motivate low-performing high school science students in an inquiry-based program called Xtreem Science. Fifteen teachers were selected from the Xtreem Science program, a program designed to assist teachers in motivating struggling science students. The research questions involved understanding (a) teachers' experiences in using inquiry methods, (b) challenges teachers face in using inquiry methods, and (c) how teachers describe student's response to inquiry methods. Strategy of data collection and analysis included capturing and understanding the teachers' feelings, perceptions, and attitudes in their lived experience of teaching using inquiry method and their experience in motivating struggling students. Analysis of interview responses revealed teachers had some good experiences with inquiry and expressed that inquiry impacted their teaching style and approach to topics, and students felt that using inquiry methods impacted student learning for the better. Inquiry gave low-performing students opportunities to catch up and learn information that moved them to the next level of science courses. Implications for positive social change include providing teachers and school district leaders with information to help improve performance of the low performing science students.

Opportunistic splitting for scheduling using a score-based approach

KAUST Repository

Rashid, Faraan

2012-06-01

We consider the problem of scheduling a user in a multi-user wireless environment in a distributed manner. The opportunistic splitting algorithm is applied to find the best group of users without reporting the channel state information to the centralized scheduler. The users find the best among themselves while requiring just a ternary feedback from the common receiver at the end of each mini-slot. The original splitting algorithm is modified to handle users with asymmetric channel conditions. We use a score-based approach with the splitting algorithm to introduce time and throughput fairness while exploiting the multi-user diversity of the network. Analytical and simulation results are given to show that the modified score-based splitting algorithm works well as a fair scheduling scheme with good spectral efficiency and reduced feedback. © 2012 IEEE.

Gender performance in an out-of-school science context

Science.gov (United States)

Silfver, Eva

2018-03-01

This article examines how school students perform gender during a visit to a science centre where they programme Lego cars. The focus is on how students relate to each other—how they talk and what they do. Theoretically, the article draws on the `heterosexual matrix' and a Foucauldian understanding of how power and knowledge are tightly interwoven and that discursive practices regulate people's possible positions and ways of being in different situations and contexts. The analysis is primarily based on video data from the science centre and a number of student interviews. The article gives several examples of how stereotypical gender performances are maintained but also challenged. This is important knowledge, because if we want to challenge norms, we first need to see them and understand how they are reproduced.

Differential Performance by English Language Learners on an Inquiry-Based Science Assessment

Science.gov (United States)

Turkan, Sultan; Liu, Ou Lydia

2012-10-01

The performance of English language learners (ELLs) has been a concern given the rapidly changing demographics in US K-12 education. This study aimed to examine whether students' English language status has an impact on their inquiry science performance. Differential item functioning (DIF) analysis was conducted with regard to ELL status on an inquiry-based science assessment, using a multifaceted Rasch DIF model. A total of 1,396 seventh- and eighth-grade students took the science test, including 313 ELL students. The results showed that, overall, non-ELLs significantly outperformed ELLs. Of the four items that showed DIF, three favored non-ELLs while one favored ELLs. The item that favored ELLs provided a graphic representation of a science concept within a family context. There is some evidence that constructed-response items may help ELLs articulate scientific reasoning using their own words. Assessment developers and teachers should pay attention to the possible interaction between linguistic challenges and science content when designing assessment for and providing instruction to ELLs.

Performance in the Science Fiction and Fantasy Writing Workshop

OpenAIRE

Angus, Tiffani

2017-01-01

This paper looks at the dynamic of science fiction and fantasy (SFF) writing workshop critique groups. Because of the nature of SFF as a fandom group, critiques and feedback in writing workshops—in this case, affinity groups with the same goal—can cross the line from participation to performance; group members tend to perform depending on their levels of cultural literacy and impostor syndrome, both of which influence fans working to become published writers. The performance can have positive...

Effective Social Relationship Measurement and Cluster Based Routing in Mobile Opportunistic Networks.

Science.gov (United States)

Zeng, Feng; Zhao, Nan; Li, Wenjia

2017-05-12

In mobile opportunistic networks, the social relationship among nodes has an important impact on data transmission efficiency. Motivated by the strong share ability of "circles of friends" in communication networks such as Facebook, Twitter, Wechat and so on, we take a real-life example to show that social relationships among nodes consist of explicit and implicit parts. The explicit part comes from direct contact among nodes, and the implicit part can be measured through the "circles of friends". We present the definitions of explicit and implicit social relationships between two nodes, adaptive weights of explicit and implicit parts are given according to the contact feature of nodes, and the distributed mechanism is designed to construct the "circles of friends" of nodes, which is used for the calculation of the implicit part of social relationship between nodes. Based on effective measurement of social relationships, we propose a social-based clustering and routing scheme, in which each node selects the nodes with close social relationships to form a local cluster, and the self-control method is used to keep all cluster members always having close relationships with each other. A cluster-based message forwarding mechanism is designed for opportunistic routing, in which each node only forwards the copy of the message to nodes with the destination node as a member of the local cluster. Simulation results show that the proposed social-based clustering and routing outperforms the other classic routing algorithms.

Does Formative Assessment Improve Student Learning and Performance in Soil Science?

Science.gov (United States)

Kopittke, Peter M.; Wehr, J. Bernhard; Menzies, Neal W.

2012-01-01

Soil science students are required to apply knowledge from a range of disciplines to unfamiliar scenarios to solve complex problems. To encourage deep learning (with student performance an indicator of learning), a formative assessment exercise was introduced to a second-year soil science subject. For the formative assessment exercise, students…

Activation and coagulation biomarkers are independent predictors of the development of opportunistic disease in patients with HIV infection

DEFF Research Database (Denmark)

Rodger, Alison J; Fox, Zoe; Lundgren, Jens

2009-01-01

BACKGROUND: Activation and coagulation biomarkers were measured within the Strategies for Management of Antiretroviral Therapy (SMART) trial. Their associations with opportunistic disease (OD) in human immunodeficiency virus (HIV)-positive patients were examined. METHODS: Inflammatory (high-sensi...

Trends in overall opportunistic illnesses, Pneumocystis carinii pneumonia, cerebral toxoplasmosis and Mycobacterium avium complex incidence rates over the 30 years of the HIV epidemic: a systematic review

Directory of Open Access Journals (Sweden)

Lara Coelho

2014-03-01

Conclusions: Opportunistic illnesses remain an important public health problem. To better guide health policies in low/middle-income settings, multicenter cohort studies should be encouraged. Studies from Brazil are urgently needed to assess the current burden of opportunistic illnesses in our population and to support the planning of HIV/AIDS health care services organization.

Members of native coral microbiota inhibit glycosidases and thwart colonization of coral mucus by an opportunistic pathogen.

Science.gov (United States)

Krediet, Cory J; Ritchie, Kim B; Alagely, Ali; Teplitski, Max

2013-05-01

The outcome of the interactions between native commensal microorganisms and opportunistic pathogens is crucial to the health of the coral holobiont. During the establishment within the coral surface mucus layer, opportunistic pathogens, including a white pox pathogen Serratia marcescens PDL100, compete with native bacteria for available nutrients. Both commensals and pathogens employ glycosidases and N-acetyl-glucosaminidase to utilize components of coral mucus. This study tested the hypothesis that specific glycosidases were critical for the growth of S. marcescens on mucus and that their inhibition by native coral microbiota reduces fitness of the pathogen. Consistent with this hypothesis, a S. marcescens transposon mutant with reduced glycosidase and N-acetyl-glucosaminidase activities was unable to compete with the wild type on the mucus of the host coral Acropora palmata, although it was at least as competitive as the wild type on a minimal medium with glycerol and casamino acids. Virulence of the mutant was modestly reduced in the Aiptasia model. A survey revealed that ∼8% of culturable coral commensal bacteria have the ability to inhibit glycosidases in the pathogen. A small molecular weight, ethanol-soluble substance(s) produced by the coral commensal Exiguobacterium sp. was capable of the inhibition of the induction of catabolic enzymes in S. marcescens. This inhibition was in part responsible for the 10-100-fold reduction in the ability of the pathogen to grow on coral mucus. These results provide insight into potential mechanisms of commensal interference with early colonization and infection behaviors in opportunistic pathogens and highlight an important function for the native microbiota in coral health.

An analysis of high-performing science students' preparation for collegiate science courses

Science.gov (United States)

Walter, Karen

This mixed-method study surveyed first year high-performing science students who participated in high-level courses such as International Baccalaureate (IB), Advanced Placement (AP), and honors science courses in high school to determine their perception of preparation for academic success at the collegiate level. The study used 52 students from an honors college campus and surveyed the students and their professors. The students reported that they felt better prepared for academic success at the collegiate level by taking these courses in high school (pstudent GPA with honors science courses (n=55 and Pearson's r=-0.336), while AP courses (n=47 and Pearson's r=0.0016) and IB courses (n=17 and Pearson's r=-0.2716) demonstrated no correlation between perception of preparation and GPA. Students reported various themes that helped or hindered their perception of academic success once at the collegiate level. Those themes that reportedly helped students were preparedness, different types of learning, and teacher qualities. Students reported in a post-hoc experience that more lab time, rigorous coursework, better teachers, and better study techniques helped prepare them for academic success at the collegiate level. Students further reported on qualities of teachers and teaching that helped foster their academic abilities at the collegiate level, including teacher knowledge, caring, teaching style, and expectations. Some reasons for taking high-level science courses in high school include boosting GPA, college credit, challenge, and getting into better colleges.

Science ethics education part II: changes in attitude toward scientific fraud among medical researchers after a short course in science ethics.

Science.gov (United States)

Vuckovic-Dekic, L; Gavrilovic, D; Kezic, I; Bogdanovic, G; Brkic, S

2012-01-01

To determine the impact of the short science ethics courses on the knowledge of basic principles of responsible conduct of research (RCR), and on the attitude toward scientific fraud among young biomedical researchers. A total of 361 attendees of the course on science ethics answered a specially designed anonymous multiple- choice questionnaire before and after a one-day course in science ethics. The educational course consisted of 10 lectures: 1) Good scientific practice - basic principles; 2) Publication ethics; 3) Scientific fraud - fabrication, falsification, plagiarism; 4) Conflict of interests; 5) Underpublishing; 6) Mentorship; 7) Authorship; 8) Coauthorship; 9) False authorship; 10) Good scientific practice - ethical codex of science. In comparison to their answers before the course, a significantly higher (pscience ethics as sufficient after the course was completed. That the wrongdoers deserve severe punishment for all types of scientific fraud, including false authorship, thought significantly (pscience ethics had a great impact on the attendees, enlarging their knowledge of responsible conduct of research and changing their previous, somewhat opportunistic, behavior regarding the reluctance to react publicly and punish the wrongdoers.

The Impact of Data-Based Science Instruction on Standardized Test Performance

Science.gov (United States)

Herrington, Tia W.

Increased teacher accountability efforts have resulted in the use of data to improve student achievement. This study addressed teachers' inconsistent use of data-driven instruction in middle school science. Evidence of the impact of data-based instruction on student achievement and school and district practices has been well documented by researchers. In science, less information has been available on teachers' use of data for classroom instruction. Drawing on data-driven decision making theory, the purpose of this study was to examine whether data-based instruction impacted performance on the science Criterion Referenced Competency Test (CRCT) and to explore the factors that impeded its use by a purposeful sample of 12 science teachers at a data-driven school. The research questions addressed in this study included understanding: (a) the association between student performance on the science portion of the CRCT and data-driven instruction professional development, (b) middle school science teachers' perception of the usefulness of data, and (c) the factors that hindered the use of data for science instruction. This study employed a mixed methods sequential explanatory design. Data collected included 8th grade CRCT data, survey responses, and individual teacher interviews. A chi-square test revealed no improvement in the CRCT scores following the implementation of professional development on data-driven instruction (chi 2 (1) = .183, p = .67). Results from surveys and interviews revealed that teachers used data to inform their instruction, indicating time as the major hindrance to their use. Implications for social change include the development of lesson plans that will empower science teachers to deliver data-based instruction and students to achieve identified academic goals.

Public storage for the Open Science Grid

International Nuclear Information System (INIS)

Levshina, T; Guru, A

2014-01-01

The Open Science Grid infrastructure doesn't provide efficient means to manage public storage offered by participating sites. A Virtual Organization that relies on opportunistic storage has difficulties finding appropriate storage, verifying its availability, and monitoring its utilization. The involvement of the production manager, site administrators and VO support personnel is required to allocate or rescind storage space. One of the main requirements for Public Storage implementation is that it should use SRM or GridFTP protocols to access the Storage Elements provided by the OSG Sites and not put any additional burden on sites. By policy, no new services related to Public Storage can be installed and run on OSG sites. Opportunistic users also have difficulties in accessing the OSG Storage Elements during the execution of jobs. A typical users' data management workflow includes pre-staging common data on sites before a job's execution, then storing for a subsequent download to a local institution the output data produced by a job on a worker node. When the amount of data is significant, the only means to temporarily store the data is to upload it to one of the Storage Elements. In order to do that, a user's job should be aware of the storage location, availability, and free space. After a successful data upload, users must somehow keep track of the data's location for future access. In this presentation we propose solutions for storage management and data handling issues in the OSG. We are investigating the feasibility of using the integrated Rule-Oriented Data System developed at RENCI as a front-end service to the OSG SEs. The current architecture, state of deployment and performance test results will be discussed. We will also provide examples of current usage of the system by beta-users.

Public storage for the Open Science Grid

Science.gov (United States)

Levshina, T.; Guru, A.

2014-06-01

The Open Science Grid infrastructure doesn't provide efficient means to manage public storage offered by participating sites. A Virtual Organization that relies on opportunistic storage has difficulties finding appropriate storage, verifying its availability, and monitoring its utilization. The involvement of the production manager, site administrators and VO support personnel is required to allocate or rescind storage space. One of the main requirements for Public Storage implementation is that it should use SRM or GridFTP protocols to access the Storage Elements provided by the OSG Sites and not put any additional burden on sites. By policy, no new services related to Public Storage can be installed and run on OSG sites. Opportunistic users also have difficulties in accessing the OSG Storage Elements during the execution of jobs. A typical users' data management workflow includes pre-staging common data on sites before a job's execution, then storing for a subsequent download to a local institution the output data produced by a job on a worker node. When the amount of data is significant, the only means to temporarily store the data is to upload it to one of the Storage Elements. In order to do that, a user's job should be aware of the storage location, availability, and free space. After a successful data upload, users must somehow keep track of the data's location for future access. In this presentation we propose solutions for storage management and data handling issues in the OSG. We are investigating the feasibility of using the integrated Rule-Oriented Data System developed at RENCI as a front-end service to the OSG SEs. The current architecture, state of deployment and performance test results will be discussed. We will also provide examples of current usage of the system by beta-users.

Reduction rules-based search algorithm for opportunistic replacement strategy of multiple life-limited parts

Directory of Open Access Journals (Sweden)

Xuyun FU

2018-01-01

Full Text Available The opportunistic replacement of multiple Life-Limited Parts (LLPs is a problem widely existing in industry. The replacement strategy of LLPs has a great impact on the total maintenance cost to a lot of equipment. This article focuses on finding a quick and effective algorithm for this problem. To improve the algorithm efficiency, six reduction rules are suggested from the perspectives of solution feasibility, determination of the replacement of LLPs, determination of the maintenance occasion and solution optimality. Based on these six reduction rules, a search algorithm is proposed. This search algorithm can identify one or several optimal solutions. A numerical experiment shows that these six reduction rules are effective, and the time consumed by the algorithm is less than 38 s if the total life of equipment is shorter than 55000 and the number of LLPs is less than 11. A specific case shows that the algorithm can obtain optimal solutions which are much better than the result of the traditional method in 10 s, and it can provide support for determining to-be-replaced LLPs when determining the maintenance workscope of an aircraft engine. Therefore, the algorithm is applicable to engineering applications concerning opportunistic replacement of multiple LLPs in aircraft engines.

Pacific CRYSTAL Project: Explicit Literacy Instruction Embedded in Middle School Science Classrooms

Science.gov (United States)

Anthony, Robert J.; Tippett, Christine D.; Yore, Larry D.

2010-01-01

Science literacy leading to fuller and informed participation in the public debate about science, technology, society, and environmental (STSE) issues that produce justified decisions and sustainable actions is the shared and central goal of the Pacific CRYSTAL Project. There is broad agreement by science education researchers that learners need to be able to construct and interpret specific scientific discourses and texts to be literate in science. We view these capabilities as components in the fundamental sense of science literacy and as interactive and synergetic to the derived sense of science literacy, which refers to having general knowledge about concepts, principles, and methods of science. This article reports on preliminary findings from Years 1, 2, and 3 of the 5-year Pacific CRYSTAL project that aims to identify, develop, and embed explicit literacy instruction in science programs to achieve both senses of science literacy. A community-based, opportunistic, engineering research and development approach has been utilized to identify problems and concerns and to design instructional solutions for teaching middle school (Grades 6, 7, and 8) science. Initial data indicate (a) opportunities in programs for embedding literacy instruction and tasks; (b) difficulties generalist teachers have with new science curricula; (c) difficulties specialist science teachers have with literacy activities, strategies, genre, and writing-to-learn science tasks; and (d) potential literacy activities (vocabulary, reading comprehension, visual literacy, genre, and writing tasks) for middle school science. Preinstruction student assessments indicate a range of challenges in achieving effective learning in science and the need for extensive teacher support to achieve the project’s goals. Postinstructional assessments indicate positive changes in students’ ability to perform target reading and writing tasks. Qualitative data indicate teachers’ desire for external direction

The art and science of selecting graduate students in the biomedical sciences: Performance in doctoral study of the foundational sciences.

Science.gov (United States)

Park, Hee-Young; Berkowitz, Oren; Symes, Karen; Dasgupta, Shoumita

2018-01-01

The goal of this study was to investigate associations between admissions criteria and performance in Ph.D. programs at Boston University School of Medicine. The initial phase of this project examined student performance in the classroom component of a newly established curriculum named "Foundations in Biomedical Sciences (FiBS)". Quantitative measures including undergraduate grade point average (GPA), graduate record examination (GRE; a standardized, computer-based test) scores for the verbal (assessment of test takers' ability to analyze, evaluate, and synthesize information and concepts provided in writing) and quantitative (assessment of test takers' problem-solving ability) components of the examination, previous research experience, and competitiveness of previous research institution were used in the study. These criteria were compared with competencies in the program defined as students who pass the curriculum as well as students categorized as High Performers. These data indicated that there is a significant positive correlation between FiBS performance and undergraduate GPA, GRE scores, and competitiveness of undergraduate institution. No significant correlations were found between FiBS performance and research background. By taking a data-driven approach to examine admissions and performance, we hope to refine our admissions criteria to facilitate an unbiased approach to recruitment of students in the life sciences and to share our strategy to support similar goals at other institutions.

Twenty-five years of sport performance research in the Journal of Sports Sciences.

Science.gov (United States)

Nevill, Alan; Atkinson, Greg; Hughes, Mike

2008-02-15

In this historical review covering the past 25 years, we reflect on the content of manuscripts relevant to the Sport Performance section of the Journal of Sports Sciences. Due to the wide diversity of sport performance research, the remit of the Sport Performance section has been broad and includes mathematical and statistical evaluation of competitive sports performances, match- and notation-analysis, talent identification, training and selection or team organization. In addition, due to the academic interests of its section editors, they adopted a quality-assurance role for the Sport Performance section, invariably communicated through key editorials that subsequently shaped the editorial policy of the Journal. Key high-impact manuscripts are discussed, providing readers with some insight into what might lead an article to become a citation "classic". Finally, landmark articles in the areas of "science and football" and "notation analysis" are highlighted, providing further insight into how such articles have contributed to the development of sport performance research in general and the Journal of Sports Sciences in particular.

Investigation of Effect of Different Run-Time Distributions on Smartnet Performance

National Research Council Canada - National Science Library

Armstrong, Robert

1997-01-01

This thesis investigates, using in-line simulation, the effect of non-deterministic runtime distributions on the performance of SmartNet's schedule execution using the Opportunistic Load Balancing (OLB...

Sadhana | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Sadhana. A RAJESH. Articles written in Sadhana. Volume 41 Issue 11 November 2016 pp 1261-1274. Context sensitive trust based geographic opportunistic routing in mobile ad hoc networks · A RAJESH N MOHAN KUMAR · More Details Abstract Fulltext PDF. Position based opportunistic routing (POR) is ...

Sadhana | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Sadhana. N MOHAN KUMAR. Articles written in Sadhana. Volume 41 Issue 11 November 2016 pp 1261-1274. Context sensitive trust based geographic opportunistic routing in mobile ad hoc networks · A RAJESH N MOHAN KUMAR · More Details Abstract Fulltext PDF. Position based opportunistic routing ...

Ethnopharmacological surveys and pharmacological studies of plants used in traditional medicine in the treatment of HIV/AIDS opportunistic diseases in Gabon.

Science.gov (United States)

Tchouya, Guy Raymond Feuya; Souza, Alain; Tchouankeu, Jean Claude; Yala, Jean-Fabrice; Boukandou, Marlaine; Foundikou, Hibrahim; Obiang, Giresse Delphang Nguema; Boyom, Fabrice Fekam; Mabika, Rolande Mabika; Menkem, Elisabeth Zeuko'o; Ndinteh, Derek Tantoh; Lebibi, Jacques

2015-03-13

Ethnopharmacological surveys were conducted in two regions of Gabon. This led to highlighting some of the medicinal plants used by local populations in the management of HIV/AIDS opportunistic diseases. Two regions with the highest occurrence of HIV/AIDS cases were visited and ethnopharmarcological data was gathered. These regions were the Estuaire Province (Libreville and its neighborhood) and the Haut-Ogooué Province (Franceville and its neighborhood). The opportunistic diseases and symptomatic conditions considered during this study were: diarrhea, respiratory tract infections, cough, tuberculosis, abscesses, stomach ache, skin rashes, venereal diseases, typhoid fever, anemia, general tiredness, hepatitis and vomiting. The reported species were evaluated through three parameters: specificity, reliability and frequency. Plant parts of relevant species were harvested and extracted with an aqueous alcohol solution (ethanol/water: 1/1). The extracts obtained were submitted to phytochemical screening and in vitro microbiological assays on some clinical isolates and ATCC strains, involved in HIV/AIDS opportunistic diseases through the Agar well diffusion and Microbroth dilution methods. Among the 52 species identified during this survey, Coelocaryon klainei Pierre ex Heckel (Myristicaceae), Dacryodes klaineana (Pierre) H.J. Lam (Bursecaceae), Phyllanthus diandrus Pax (Euphorbiaceae), Saccoglotys gabonensis (Baill.) Urb. (Humiriaceae) and Tetrorchidium didymostemon (Baill.) Pax & K. Hoffm. (Euphorbiaceae) were submitted to in vitro microbiological assays. Phyllanthus diandrus bark and leaves show best antibacterial activities against Pseudomonas aeruginosa and Klebsiella pneumoniae with MIC value of 0.25 respectively. Phytochemical screening revealed the presence in all the plant parts extracts of potentially bioactive molecules, including polyphenols, especially flavonoids and tannins. It is concluded that some of these plants might be submitted to further scientific

High Performance Computing in Science and Engineering '16 : Transactions of the High Performance Computing Center, Stuttgart (HLRS) 2016

CERN Document Server

Kröner, Dietmar; Resch, Michael

2016-01-01

This book presents the state-of-the-art in supercomputer simulation. It includes the latest findings from leading researchers using systems from the High Performance Computing Center Stuttgart (HLRS) in 2016. The reports cover all fields of computational science and engineering ranging from CFD to computational physics and from chemistry to computer science with a special emphasis on industrially relevant applications. Presenting findings of one of Europe’s leading systems, this volume covers a wide variety of applications that deliver a high level of sustained performance. The book covers the main methods in high-performance computing. Its outstanding results in achieving the best performance for production codes are of particular interest for both scientists and engineers. The book comes with a wealth of color illustrations and tables of results.

Camel calves as opportunistic milk thefts? The first description of allosuckling in domestic bactrian camel (Camelus bactrianus.

Directory of Open Access Journals (Sweden)

Karolína Brandlová

Full Text Available Allosuckling is a situation when a female nurses a non-filial offspring. It was described in various ungulate species; however for camels this is the first description of this behaviour. The aim of the study was to assess the occurrence of allosuckling in captive camels (Camelus bactrianus and to test whether it can be explained as a 'milk-theft' (opportunistic behaviour of calves or alternatively as an altruistic behaviour of females. During 2005 and 2007, nine camel females and ten calves in four zoological gardens in the Czech Republic were observed. In total, 373 sucking bouts were recorded, from which 32 were non-filial (the calf sucked from the non-maternal female. Allosuckling regularly appeared in captive camel herds. As predicted for the milk-theft explanation, the non-filial calves sucked more often in the lateral position and even did not suck in the antiparallel position at all. The non-filial calves preferably joined the filial calf when sucking but in five cases (15.6% of non-filial sucking bouts the calves sucked from non-maternal dam without the presence of filial calf. We then expected the differences in terminations of sucking bouts by females but did not find any difference in sucking terminations for filial and non-filial calves. As the calves were getting older, the incidence of allosucking increased. This was probably because skills of the calf to outwit the non-maternal dam increased and/or the older calves might be more motivated for allosucking due to the weaning process. Finally, duration of a sucking bout was shorter with non-filial than filial calves. The results of the study support the hypothesis of 'milk theft', being mostly performed by calves behaving as opportunistic parasites, but we cannot reject certain level of altruism from the allonursing females or their increased degree of tolerance to non-filial calves.

The 14-3-3 homolog, ArtA, regulates development and secondary metabolism in the opportunistic plant pathogen Aspergillus flavus

Science.gov (United States)

The opportunistic plant pathogenic fungus Aspergillus flavus produces carcinogenic mycotoxins denominated aflatoxins (AFs). Aflatoxin contamination of agriculturally important crops such as maize, peanut, sorghum and tree nuts is responsible for serious adverse health and economic impacts worldwide....

Complexities and constraints influencing learner performance in physical science

Directory of Open Access Journals (Sweden)

Mavhungu Abel Mafukata

2016-01-01

Full Text Available This paper explores complexities and constraints affecting performance and output of physical science learners in Vhembe District, Limpopo Province, South Africa. The study was motivated by the desire of the researcher to establish, profile and characterise the complexities and constraints reminiscence of poor performance of learners in physical science as measured through end-of-year Grade 12 (final year of high school education examination results. Twenty six schools (n=26 were purposively selected from three circuits of education (n=3. From these schools, two learners were randomly selected (n=52 for interviews. In addition, two circuit managers (n=2 were conveniently selected as part of Key Informant Interviews (KII. For the Focus Group Discussions (FGDs, twelve (n=12 parents were randomly selected to form two groups of six members each. Multi-factor complexities and constraints impeding performance of learners were discovered. Intensive teacher in-service programme is recommended. Community engagement should be encouraged to educate parents on the value of involvement in the education of their children. Free access learner support structures such as Homework and Extra-lessons Assistance Centre (H&EACs should be established.

Science learning and literacy performance of typically developing, at-risk, and disabled, non-English language background students

Science.gov (United States)

Larrinaga McGee, Patria Maria

Current education reform calls for excellence, access, and equity in all areas of instruction, including science and literacy. Historically, persons of diverse backgrounds or with disabilities have been underrepresented in science. Gaps are evident between the science and literacy achievement of diverse students and their mainstream peers. The purpose of this study was to document, describe, and examine patterns of development and change in the science learning and literacy performance of Hispanic students. The two major questions of this study were: (1) How is science content knowledge, as evident in oral and written formats, manifested in the performance of typically developing, at-risk, and disabled non-English language background (NELB) students? and (2) What are the patterns of literacy performance in science, and as evident in oral and written formats, among typically developing, at-risk, and disabled NELB students? This case study was part of a larger research project, the Promise Project, undertaken at the University of Miami, Coral Gables, Florida, under the sponsorship of the National Science Foundation. The study involved 24 fourth-grade students in seven classrooms located in Promise Project schools where teachers were provided with training and materials for instruction on two units of science content: Matter and Weather. Four students were selected from among the fourth-graders for a closer analysis of their performance. Qualitative and quantitative data analysis methods were used to document, describe, and examine specific events or phenomena in the processes of science learning and literacy development. Important findings were related to (a) gains in science learning and literacy development, (b) students' science learning and literacy development needs, and (c) general and idiosyncratic attitudes toward science and literacy. Five patterns of science "explanations" identified indicated a developmental cognitive/linguistic trajectory in science

Effective Social Relationship Measurement and Cluster Based Routing in Mobile Opportunistic Networks †

Science.gov (United States)

Zeng, Feng; Zhao, Nan; Li, Wenjia

2017-01-01

In mobile opportunistic networks, the social relationship among nodes has an important impact on data transmission efficiency. Motivated by the strong share ability of “circles of friends” in communication networks such as Facebook, Twitter, Wechat and so on, we take a real-life example to show that social relationships among nodes consist of explicit and implicit parts. The explicit part comes from direct contact among nodes, and the implicit part can be measured through the “circles of friends”. We present the definitions of explicit and implicit social relationships between two nodes, adaptive weights of explicit and implicit parts are given according to the contact feature of nodes, and the distributed mechanism is designed to construct the “circles of friends” of nodes, which is used for the calculation of the implicit part of social relationship between nodes. Based on effective measurement of social relationships, we propose a social-based clustering and routing scheme, in which each node selects the nodes with close social relationships to form a local cluster, and the self-control method is used to keep all cluster members always having close relationships with each other. A cluster-based message forwarding mechanism is designed for opportunistic routing, in which each node only forwards the copy of the message to nodes with the destination node as a member of the local cluster. Simulation results show that the proposed social-based clustering and routing outperforms the other classic routing algorithms. PMID:28498309

Career-Oriented Performance Tasks in Chemistry: Effects on Students Integrated Science Process Skills

OpenAIRE

Allen A. Espinosa; Sheryl Lyn C. Monterola; Amelia E. Punzalan

2013-01-01

The study was conducted to assess the effectiveness of Career-Oriented Performance Task (COPT) approach against the traditional teaching approach (TTA) in enhancing students’ integrated science process skills. Specifically, it sought to find out if students exposed to COPT have higher integrated science process skills than those students exposed to the traditional teaching approach (TTA). Career-Oriented Performance Task (COPT) approach aims to integrate career-oriented examples and inquiry-b...

Implementing an Affordable High-Performance Computing for Teaching-Oriented Computer Science Curriculum

Science.gov (United States)

Abuzaghleh, Omar; Goldschmidt, Kathleen; Elleithy, Yasser; Lee, Jeongkyu

2013-01-01

With the advances in computing power, high-performance computing (HPC) platforms have had an impact on not only scientific research in advanced organizations but also computer science curriculum in the educational community. For example, multicore programming and parallel systems are highly desired courses in the computer science major. However,…

Effective but costly, evolved mechanisms of defense against a virulent opportunistic pathogen in Drosophila melanogaster.

OpenAIRE

Yixin H Ye; Stephen F Chenoweth; Elizabeth A McGraw

2009-01-01

Drosophila harbor substantial genetic variation for antibacterial defense, and investment in immunity is thought to involve a costly trade-off with life history traits, including development, life span, and reproduction. To understand the way in which insects invest in fighting bacterial infection, we selected for survival following systemic infection with the opportunistic pathogen Pseudomonas aeruginosa in wild-caught Drosophila melanogaster over 10 generations. We then examined genome-wide...

A Preemptive Link State Spanning Tree Source Routing Scheme for Opportunistic Data Forwarding in MANET

OpenAIRE

R. Poonkuzhali; M. Y. Sanavullah; A. Sabari

2014-01-01

Opportunistic Data Forwarding (ODF) has drawn much attention in mobile adhoc networking research in recent years. The effectiveness of ODF in MANET depends on a suitable routing protocol which provides a powerful source routing services. PLSR is featured by source routing, loop free and small routing overhead. The update messages in PLSR are integrated into a tree structure and no need to time stamp routing updates which reduces the routing overhead.

Analysis Framework for Opportunistic Spectrum OFDMA and its Application to the IEEE 802.22 Standard

OpenAIRE

Park, Jihoon; Pawełczak, Przemysław; Grønsund, Pål; Čabrić, Danijela

2010-01-01

We present an analytical model that enables throughput evaluation of Opportunistic Spectrum Orthogonal Frequency Division Multiple Access (OS-OFDMA) networks. The core feature of the model, based on a discrete time Markov chain, is the consideration of different channel and subchannel allocation strategies under different Primary and Secondary user types, traffic and priority levels. The analytical model also assesses the impact of different spectrum sensing strategies on the throughput of OS...

CD4 descriptions at various clinical HIV/AIDS stages with tuberculosis and non-tuberculosis opportunistic infections at dr. Zainoel Abidin hospital in Banda Aceh, Indonesia

Science.gov (United States)

Shaleh, A. S.; Fahrial; Siregar, M. L.; Jamil, K. F.

2018-03-01

Human Immunodeficiency Virus (HIV) / Acquired Immune Deficiency Syndrome (AIDS) is a retrovirus that infects the human immune system. Damaged immunity in HIV/AIDS patients is marked by a decline in CD4 cells. Opportunistic infections appear differently, depending on the levels of immunosuppressive degrees, and the frequency of opportunistic infections in the environment. This study aims to describe the CD4 at various clinical stages of HIV/AIDS with tuberculosis and non-tuberculosis opportunistic infections (OI). Descriptive study with a cross-sectional design. This study is secondary data obtained from the medical records of patients with HIV/AIDS in the period of January 2011 - December 2015 at dr. Zainoel Abidin Hospital in Banda Aceh. The samples that met the inclusion criteria were 135 people with 63 cases were tuberculosis OI, 33 cases were non-tuberculosis and 39 cases were without OI. The study showed CD4 tuberculosis OI and 93.9% for non-tuberculosis OI.

Simulation of emergency response operations for a static chemical spill within a building using an opportunistic resource utilization network

NARCIS (Netherlands)

Lilien, L.T.; Elbes, M.W.; Ben Othmane, L.; Salih, R.M.

2013-01-01

We investigate supporting emergency response operations with opportunistic resource utilization networks ("oppnets"), based on a network paradigm for inviting and integrating diverse devices and systems available in the environment. We simulate chemical spill on a single floor of a building and

The Black Yeast Exophiala dermatitidis and Other Selected Opportunistic Human Fungal Pathogens Spread from Dishwashers to Kitchens.

Directory of Open Access Journals (Sweden)

Jerneja Zupančič

Full Text Available We investigated the diversity and distribution of fungi in nine different sites inside 30 residential dishwashers. In total, 503 fungal strains were isolated, which belong to 10 genera and 84 species. Irrespective of the sampled site, 83% of the dishwashers were positive for fungi. The most frequent opportunistic pathogenic species were Exophiala dermatitidis, Candida parapsilosis sensu stricto, Exophiala phaeomuriformis, Fusarium dimerum, and the Saprochaete/Magnusiomyces clade. The black yeast E. dermatitidis was detected in 47% of the dishwashers, primarily at the dishwasher rubber seals, at up to 106 CFU/cm2; the other fungi detected were in the range of 102 to 105 CFU/cm2. The other most heavily contaminated dishwasher sites were side nozzles, doors and drains. Only F. dimerum was isolated from washed dishes, while dishwasher waste water contained E. dermatitidis, Exophiala oligosperma and Sarocladium killiense. Plumbing systems supplying water to household appliances represent the most probable route for contamination of dishwashers, as the fungi that represented the core dishwasher mycobiota were also detected in the tap water. Hot aerosols from dishwashers contained the human opportunistic yeast C. parapsilosis, Rhodotorula mucilaginosa and E. dermatitidis (as well as common air-borne genera such as Aspergillus, Penicillium, Trichoderma and Cladosporium. Comparison of fungal contamination of kitchens without and with dishwashers revealed that virtually all were contaminated with fungi. In both cases, the most contaminated sites were the kitchen drain and the dish drying rack. The most important difference was higher prevalence of black yeasts (E. dermatitidis in particular in kitchens with dishwashers. In kitchens without dishwashers, C. parapsilosis strongly prevailed with negligible occurrence of E. dermatitidis. F. dimerum was isolated only from kitchens with dishwashers, while Saprochaete/Magnusiomyces isolates were only found within

Power allocation and cooperative jamming for enhancing physical layer security in opportunistic relay networks in the presence of interference

KAUST Repository

Abd El-Malek, Ahmed H.; Salhab, Anas M.; Zummo, Salam A.; Alouini, Mohamed-Slim

2017-01-01

In this paper, the impact of cochannel interference on the secrecy performance of dual-hop decode-and-forward relaying is investigated. In particular, the outage and intercept probabilities are obtained for the opportunistic relay selection (ORS) model in the presence of nonidentical interfering signals under a single/multiple passive eavesdropper(s) attack. Moreover, the proposed work enhances physical layer security performance of ORS model using cooperative jamming (CJ) techniques. Therefore, new closed-form expressions are derived for the intercept and outage probabilities of the CJ-ORS model in the presence of interference over Rayleigh fading channels. Moreover, the analyses are generalized to the case of multiple eavesdroppers where closed-form expressions are derived for the intercept probability. To reveal more insights on the proposed work secrecy performance, asymptotic closed-form expressions for the intercept and outage probabilities are obtained. Using these asymptotic expressions, a power allocation optimization problem is formulated and solved for enhancing the system security. The derived analytical formulas herein are supported by numerical and simulation results to clarify the main contributions of the paper. The results show that, although the cochannel interference increases the system outage probability, it might improve the system secrecy performance. Moreover, the proposed CJ-ORS model is shown to enhance the system secrecy performance compared to ORS model.

Power allocation and cooperative jamming for enhancing physical layer security in opportunistic relay networks in the presence of interference

KAUST Repository

Abd El-Malek, Ahmed H.

2017-04-18

In this paper, the impact of cochannel interference on the secrecy performance of dual-hop decode-and-forward relaying is investigated. In particular, the outage and intercept probabilities are obtained for the opportunistic relay selection (ORS) model in the presence of nonidentical interfering signals under a single/multiple passive eavesdropper(s) attack. Moreover, the proposed work enhances physical layer security performance of ORS model using cooperative jamming (CJ) techniques. Therefore, new closed-form expressions are derived for the intercept and outage probabilities of the CJ-ORS model in the presence of interference over Rayleigh fading channels. Moreover, the analyses are generalized to the case of multiple eavesdroppers where closed-form expressions are derived for the intercept probability. To reveal more insights on the proposed work secrecy performance, asymptotic closed-form expressions for the intercept and outage probabilities are obtained. Using these asymptotic expressions, a power allocation optimization problem is formulated and solved for enhancing the system security. The derived analytical formulas herein are supported by numerical and simulation results to clarify the main contributions of the paper. The results show that, although the cochannel interference increases the system outage probability, it might improve the system secrecy performance. Moreover, the proposed CJ-ORS model is shown to enhance the system secrecy performance compared to ORS model.

Temperature-dependent inhibition of opportunistic Vibrio pathogens by native coral commensal bacteria.

Science.gov (United States)

Frydenborg, Beck R; Krediet, Cory J; Teplitski, Max; Ritchie, Kim B

2014-02-01

Bacteria living within the surface mucus layer of corals compete for nutrients and space. A number of stresses affect the outcome of this competition. The interactions between native microorganisms and opportunistic pathogens largely determine the coral holobiont's overall health and fitness. In this study, we tested the hypothesis that commensal bacteria isolated from the mucus layer of a healthy elkhorn coral, Acropora palmata, are capable of inhibition of opportunistic pathogens, Vibrio shiloi AK1 and Vibrio coralliilyticus. These vibrios are known to cause disease in corals and their virulence is temperature dependent. Elevated temperature (30 °C) increased the cell numbers of one commensal and both Vibrio pathogens in monocultures. We further tested the hypothesis that elevated temperature favors pathogenic organisms by simultaneously increasing the fitness of vibrios and decreasing the fitness of commensals by measuring growth of each species within a co-culture over the course of 1 week. In competition experiments between vibrios and commensals, the proportion of Vibrio spp. increased significantly under elevated temperature. We finished by investigating several temperature-dependent mechanisms that could influence co-culture differences via changes in competitive fitness. The ability of Vibrio spp. to utilize glycoproteins found in A. palmata mucus increased or remained stable when exposed to elevated temperature, while commensals' tended to decrease utilization. In both vibrios and commensals, protease activity increased at 30 °C, while chiA expression increased under elevated temperatures for Vibrio spp. These results provide insight into potential mechanisms through which elevated temperature may select for pathogenic bacterial dominance and lead to disease or a decrease in coral fitness.

Identification of opportunistic enteric parasites among immunocompetent patients with diarrhoea from Northern India and genetic characterisation of Cryptosporidium and Microsporidia.

Science.gov (United States)

Ghoshal, U; Dey, A; Ranjan, P; Khanduja, S; Agarwal, V; Ghoshal, U C

2016-01-01

Enteric parasitic infestation is a major public health problem in developing countries. Parasites such as Cryptosporidium spp., Cyclospora spp., Cystoisospora spp. and Microsporidia may cause severe diarrhoea among immunocompromised patients. There is scanty data on their frequency among immunocompetent patients. Accordingly, we studied the frequency of enteric opportunistic parasites among immunocompetent patients with diarrhoea from northern India; we also performed genetic characterisation of Cryptosporidia and Microsporidia among them. Stool samples from 80 immunocompetent patients with diarrhoea, and 110 healthy controls were examined. Parasites were detected by direct microscopy, modified acid-fast (Kinyoun's) and modified trichrome stain. Polymerase chain reaction--restriction fragment length polymorphism was used for genetic characterisation of selected species such as Cryptosporidia and Microsporidia. Enteric parasites were detected in 16/80 (20%) patients (mean age 28.8±20 years, 45, 56% males) and in 2/110 (1.8%) healthy controls (P=0.00007). Parasites detected were Cryptosporidium spp. (8/16, 50.0%), Cystoisospora spp. (4/16, 25%), Microsporidia (1/16, 6.25%), Cyclospora spp. (1/16, 6.25%) and Giardia spp. (1/16, 6.25%). One patient had mixed infection with Cystoisospora spp. and Giardia spp. The species of Cryptosporidia and Microsporidia detected were Cryptosporidium hominis and Enterocytozoon bieneusi, respectively. Parasites were more often detected in younger patients (≤20 years of age) than in older. Most of the parasite infected patients presented with chronic diarrhoea. Opportunistic enteric parasitic infestation was more common among immunocompetent patients with diarrhoea than healthy subjects. Special staining as well as molecular methods are essential for appropriate diagnosis of these parasites.

Insights on the Horizontal Gene Transfer of Carbapenemase Determinants in the Opportunistic Pathogen Acinetobacter baumannii

Science.gov (United States)

Da Silva, Gabriela Jorge; Domingues, Sara

2016-01-01

Horizontal gene transfer (HGT) is a driving force to the evolution of bacteria. The fast emergence of antimicrobial resistance reflects the ability of genetic adaptation of pathogens. Acinetobacter baumannii has emerged in the last few decades as an important opportunistic nosocomial pathogen, in part due to its high capacity of acquiring resistance to diverse antibiotic families, including to the so-called last line drugs such as carbapenems. The rampant selective pressure and genetic exchange of resistance genes hinder the effective treatment of resistant infections. A. baumannii uses all the resistance mechanisms to survive against carbapenems but production of carbapenemases are the major mechanism, which may act in synergy with others. A. baumannii appears to use all the mechanisms of gene dissemination. Beyond conjugation, the mostly reported recent studies point to natural transformation, transduction and outer membrane vesicles-mediated transfer as mechanisms that may play a role in carbapenemase determinants spread. Understanding the genetic mobilization of carbapenemase genes is paramount in preventing their dissemination. Here we review the carbapenemases found in A. baumannii and present an overview of the current knowledge of contributions of the various HGT mechanisms to the molecular epidemiology of carbapenem resistance in this relevant opportunistic pathogen. PMID:27681923

Spatial Ability Mediates the Gender Difference in Middle School Students' Science Performance

Science.gov (United States)

Ganley, Colleen M.; Vasilyeva, Marina; Dulaney, Alana

2014-01-01

Prior research has demonstrated a male advantage in spatial skills and science achievement. The present research integrated these findings by testing the potential role of spatial skills in gender differences in the science performance of eighth-grade students (13-15 years old). In "Study 1" (N = 113), the findings showed that mental…

Updates on Aspergillus, Pneumocystis and other opportunistic pulmonary mycoses.

Science.gov (United States)

Curbelo, Jose; Galván, Jose María; Aspa, Javier

2015-12-01

Mycoses are serious diseases with potentially fatal outcome. The introduction of immunosuppressive treatments and life support techniques has led to a growing prevalence of different degrees of immunosuppression. Compromised immune response is the primary risk factor for the development of opportunistic mycoses. Early diagnosis and treatment are crucial for improving prognosis. However, isolation in cultures or identification using antigen detection techniques cannot distinguish between colonization and invasive infection, and the clinical status of the patient often prevents biopsy sampling. Clinicians thus find themselves in an uncertain position, requiring them to quickly recognize clinical and radiological signs and interpret microbiological results in context. The aim of this review is to provide a general overview of the profile of patients susceptible to these infections, the role of the immune system and, in more detail, the major diagnostic developments that have gained most acceptance and recognition among the scientific community. Copyright © 2014 SEPAR. Published by Elsevier Espana. All rights reserved.

The Effects of Item Format and Cognitive Domain on Students' Science Performance in TIMSS 2011

Science.gov (United States)

Liou, Pey-Yan; Bulut, Okan

2017-12-01

The purpose of this study was to examine eighth-grade students' science performance in terms of two test design components, item format, and cognitive domain. The portion of Taiwanese data came from the 2011 administration of the Trends in International Mathematics and Science Study (TIMSS), one of the major international large-scale assessments in science. The item difficulty analysis was initially applied to show the proportion of correct items. A regression-based cumulative link mixed modeling (CLMM) approach was further utilized to estimate the impact of item format, cognitive domain, and their interaction on the students' science scores. The results of the proportion-correct statistics showed that constructed-response items were more difficult than multiple-choice items, and that the reasoning cognitive domain items were more difficult compared to the items in the applying and knowing domains. In terms of the CLMM results, students tended to obtain higher scores when answering constructed-response items as well as items in the applying cognitive domain. When the two predictors and the interaction term were included together, the directions and magnitudes of the predictors on student science performance changed substantially. Plausible explanations for the complex nature of the effects of the two test-design predictors on student science performance are discussed. The results provide practical, empirical-based evidence for test developers, teachers, and stakeholders to be aware of the differential function of item format, cognitive domain, and their interaction in students' science performance.

Mobile Sinks Assisted Geographic and Opportunistic Routing Based Interference Avoidance for Underwater Wireless Sensor Network.

Science.gov (United States)

Ahmed, Farwa; Wadud, Zahid; Javaid, Nadeem; Alrajeh, Nabil; Alabed, Mohamad Souheil; Qasim, Umar

2018-04-02

The distinctive features of acoustic communication channel-like high propagation delay, multi-path fading, quick attenuation of acoustic signal, etc. limit the utilization of underwater wireless sensor networks (UWSNs). The immutable selection of forwarder node leads to dramatic death of node resulting in imbalanced energy depletion and void hole creation. To reduce the probability of void occurrence and imbalance energy dissipation, in this paper, we propose mobility assisted geo-opportunistic routing paradigm based on interference avoidance for UWSNs. The network volume is divided into logical small cubes to reduce the interference and to make more informed routing decisions for efficient energy consumption. Additionally, an optimal number of forwarder nodes is elected from each cube based on its proximity with respect to the destination to avoid void occurrence. Moreover, the data packets are recovered from void regions with the help of mobile sinks which also reduce the data traffic on intermediate nodes. Extensive simulations are performed to verify that our proposed work maximizes the network lifetime and packet delivery ratio.

Mobile Sinks Assisted Geographic and Opportunistic Routing Based Interference Avoidance for Underwater Wireless Sensor Network

Directory of Open Access Journals (Sweden)

Farwa Ahmed

2018-04-01

Full Text Available The distinctive features of acoustic communication channel-like high propagation delay, multi-path fading, quick attenuation of acoustic signal, etc. limit the utilization of underwater wireless sensor networks (UWSNs. The immutable selection of forwarder node leads to dramatic death of node resulting in imbalanced energy depletion and void hole creation. To reduce the probability of void occurrence and imbalance energy dissipation, in this paper, we propose mobility assisted geo-opportunistic routing paradigm based on interference avoidance for UWSNs. The network volume is divided into logical small cubes to reduce the interference and to make more informed routing decisions for efficient energy consumption. Additionally, an optimal number of forwarder nodes is elected from each cube based on its proximity with respect to the destination to avoid void occurrence. Moreover, the data packets are recovered from void regions with the help of mobile sinks which also reduce the data traffic on intermediate nodes. Extensive simulations are performed to verify that our proposed work maximizes the network lifetime and packet delivery ratio.

Performance on large-scale science tests: Item attributes that may impact achievement scores

Science.gov (United States)

Gordon, Janet Victoria

Significant differences in achievement among ethnic groups persist on the eighth-grade science Washington Assessment of Student Learning (WASL). The WASL measures academic performance in science using both scenario and stand-alone question types. Previous research suggests that presenting target items connected to an authentic context, like scenario question types, can increase science achievement scores especially in underrepresented groups and thus help to close the achievement gap. The purpose of this study was to identify significant differences in performance between gender and ethnic subgroups by question type on the 2005 eighth-grade science WASL. MANOVA and ANOVA were used to examine relationships between gender and ethnic subgroups as independent variables with achievement scores on scenario and stand-alone question types as dependent variables. MANOVA revealed no significant effects for gender, suggesting that the 2005 eighth-grade science WASL was gender neutral. However, there were significant effects for ethnicity. ANOVA revealed significant effects for ethnicity and ethnicity by gender interaction in both question types. Effect sizes were negligible for the ethnicity by gender interaction. Large effect sizes between ethnicities on scenario question types became moderate to small effect sizes on stand-alone question types. This indicates the score advantage the higher performing subgroups had over the lower performing subgroups was not as large on stand-alone question types compared to scenario question types. A further comparison examined performance on multiple-choice items only within both question types. Similar achievement patterns between ethnicities emerged; however, achievement patterns between genders changed in boys' favor. Scenario question types appeared to register differences between ethnic groups to a greater degree than stand-alone question types. These differences may be attributable to individual differences in cognition

Experimental Physical Sciences Vistas Performance through Science Winter 2017

Energy Technology Data Exchange (ETDEWEB)

Kippen, Karen Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cruz, James Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hockaday, Mary Yvonne P. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lacerda, Alex Hugo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wilburn, Wesley Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Batha, Steven H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bronkhorst, Curt Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Brown, Eric [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carnes, Jay Russell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Del Mauro, Diana [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); DeYoung, Anemarie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Freibert, Franz Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Fronzak, Hannah Kristina [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gray, III, George Thompson [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hooks, Daniel Edwin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martineau, Rick Lorne [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martz, Joseph Christopher [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Migliori, Albert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Poling, Charles C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Prestridge, Katherine Philomena [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schraad, Mark William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stevens, Michael Francis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); White, Morgan Curtis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-02-23

This issue of Experimental Physical Sciences Vistas focuses on the integrated science that plays a critical role in Los Alamos National Laboratory’s support of the nation’s nuclear deterrent. I hope you will enjoy reading about these accomplishments, opportunities, and challenges.

Threshold Based Opportunistic Scheduling of Secondary Users in Underlay Cognitive Radio Networks

KAUST Repository

Song, Yao

2011-12-01

In underlay cognitive radio networks, secondary users can share the spectrum with primary users as long as the interference caused by the secondary users to primary users is below a certain predetermined threshold. It is reasonable to assume that there is always a large pool of secondary users trying to access the channel, which can be occupied by only one secondary user at a given time. As a result, a multi-user scheduling problem arises among the secondary users. In this thesis, by manipulating basic schemes based on selective multi-user diversity, normalized thresholding, transmission power control, and opportunistic round robin, we propose and analyze eight scheduling schemes of secondary users in an underlay cognitive radio set-up. The system performance of these schemes is quantified by using various performance metrics such as the average system capacity, normalized average feedback load, scheduling outage probability, and system fairness of access. In our proposed schemes, the best user out of all the secondary users in the system is picked to transmit at each given time slot in order to maximize the average system capacity. Two thresholds are used in the two rounds of the selection process to determine the best user. The first threshold is raised by the power constraint from the primary user. The second threshold, which can be adjusted by us, is introduced to reduce the feedback load. The overall system performance is therefore dependent on the choice of these two thresholds and the number of users in the system given the channel conditions for all the users. In this thesis, by deriving analytical formulas and presenting numerical examples, we try to provide insights of the relationship between the performance metrics and the involved parameters including two selection thresholds and the number of active users in the system, in an effort to maximize the average system capacity as well as satisfy the requirements of scheduling outage probability and

Opportunistic Neurologic Infections in Patients with Acquired Immunodeficiency Syndrome (AIDS).

Science.gov (United States)

Albarillo, Fritzie; O'Keefe, Paul

2016-01-01

Infections of the central nervous system (CNS) in individuals with human immunodeficiency virus (HIV) remain a substantial cause of morbidity and mortality despite the introduction of highly active antiretroviral therapy (HAART) especially in the resource-limited regions of the world. Diagnosis of these infections may be challenging because findings on cerebrospinal fluid (CSF) analysis and brain imaging are nonspecific. While brain biopsy provides a definitive diagnosis, it is an invasive procedure associated with a relatively low mortality rate, thus less invasive modalities have been studied in recent years. Diagnosis, therefore, can be established based on a combination of a compatible clinical syndrome, radiologic and CSF findings, and understanding of the role of HIV in these infections. The most common CNS opportunistic infections are AIDS-defining conditions; thus, treatment of these infections in combination with HAART has greatly improved survival.

The Open Science Grid status and architecture

Energy Technology Data Exchange (ETDEWEB)

Pordes, Ruth; Petravick, Don; /Fermilab; Kramer, Bill; Olsen, James D.; /LBL, Berkeley; Livny, Miron; Roy, Gordon A.; /Wisconsin U., Madison; Avery, Paul Ralph; /Florida U.; Blackburn, Kent; /Caltech; Wenaus, Torre J.; /Brookhaven; Wuerthwein, Frank K.; /UC, San Diego; Foster, Ian; /Chicago U. /Indiana U.

2007-09-01

The Open Science Grid (OSG) provides a distributed facility where the Consortium members provide guaranteed and opportunistic access to shared computing and storage resources. The OSG project[1] is funded by the National Science Foundation and the Department of Energy Scientific Discovery through Advanced Computing program. The OSG project provides specific activities for the operation and evolution of the common infrastructure. The US ATLAS and US CMS collaborations contribute to and depend on OSG as the US infrastructure contributing to the World Wide LHC Computing Grid on which the LHC experiments distribute and analyze their data. Other stakeholders include the STAR RHIC experiment, the Laser Interferometer Gravitational-Wave Observatory (LIGO), the Dark Energy Survey (DES) and several Fermilab Tevatron experiments- CDF, D0, MiniBoone etc. The OSG implementation architecture brings a pragmatic approach to enabling vertically integrated community specific distributed systems over a common horizontal set of shared resources and services. More information can be found at the OSG web site: www.opensciencegrid.org.

The Open Science Grid status and architecture

International Nuclear Information System (INIS)

Pordes, R; Petravick, D; Kramer, B; Olson, D; Livny, M; Roy, A; Avery, P; Blackburn, K; Wenaus, T; Wuerthwein, F; Foster, I; Gardner, R; Wilde, M; Blatecky, A; McGee, J; Quick, R

2008-01-01

The Open Science Grid (OSG) provides a distributed facility where the Consortium members provide guaranteed and opportunistic access to shared computing and storage resources. The OSG project[1] is funded by the National Science Foundation and the Department of Energy Scientific Discovery through Advanced Computing program. The OSG project provides specific activities for the operation and evolution of the common infrastructure. The US ATLAS and US CMS collaborations contribute to and depend on OSG as the US infrastructure contributing to the World Wide LHC Computing Grid on which the LHC experiments distribute and analyze their data. Other stakeholders include the STAR RHIC experiment, the Laser Interferometer Gravitational-Wave Observatory (LIGO), the Dark Energy Survey (DES) and several Fermilab Tevatron experiments- CDF, D0, MiniBoone etc. The OSG implementation architecture brings a pragmatic approach to enabling vertically integrated community specific distributed systems over a common horizontal set of shared resources and services. More information can be found at the OSG web site: www.opensciencegrid.org

Effects of Reading Skills on Students’ Performance in Science and Mathematics in Public and Private Secondary Schools

Directory of Open Access Journals (Sweden)

Ombra A. Imam

2016-05-01

Full Text Available In the Philippine education system, reading, mathematics, and science formed part of the core areas of basic education curriculum. For the last decade, the quality of Philippine education was put into a big question due to poor performance of students in mathematics and science tests both local and abroad. The initial result of current efforts of the government by adopting K-12 curriculum didn’t do much to change the status quo. The purpose of this study is to determine the reading predictors of students’ performance in Mathematics and Science and identify its effects to such performance. A total of 660 freshmen students from public and private high schools in Cotabato City, Philippines were taken as sample. A validated and reliable 150-item test in reading comprehension skills, mathematics and science was used to get primary data to perform correlation and regression analysis. Findings showed that only making inference and getting main idea were predictors of mathematics performance of students in public school and private schools, respectively.  Data analysis also revealed that two reading skills such as noting details and making inference had an influence on science performance of students in public school while skills in getting main idea and drawing conclusion influenced science performance of students in private schools.  However, there was only one skill such as vocabulary in context which was predictor of overall science performance of all students. Moreover, separate effects of making inference, identifying main idea explained only 1.8 percent and 1.3 percent of students’ math performance while their combined effects provided only .1 percent or nearly zero percent. Furthermore, the study found out that separate effects of noting details contributed 3.3 percent and its combined effects with making inference explained 4.2 percent of science performance of students in public schools. In terms of effects of reading to science

Symbiotic mutualism with a community of opportunistic ants: protection, competition, and ant occupancy of the myrmecophyte Barteria nigritana (Passifloraceae)

Science.gov (United States)

Djiéto-Lordon, Champlain; Dejean, Alain; Gibernau, Marc; Hossaert-McKey, Martine; McKey, Doyle

2004-10-01

Barteria nigritana is a myrmecophyte tree of Lower Guinea coastal vegetation. Unlike the more specialised B. fistulosa, which harbours a single host-specific mutualistic ant, B. nigritana is associated with several opportunistic ants. Such symbiotic, yet opportunistic, ant-plant associations have been little studied. On 113 clumps of B. nigritana, we censused ant associates and herbivores and compared herbivory on plants occupied by different ants. In addition to these correlative data, protection conferred by different ant species was compared by herbivore-placement experiments. Identity of ant associate changed predictably over plant ontogeny. Pheidole megacephala was restricted to very small plants; saplings were occupied by either Oecophylla longinoda or Crematogaster sp., and the latter species was the sole occupant of larger trees. Damage by caterpillars of the nymphalid butterfly Acraea zetes accounted for much of the herbivory to leaves. Ant species differed in the protection provided to hosts. While P. megacephala provided no significant protection, plants occupied by O. longinoda and Crematogaster sp. suffered less damage than did unoccupied plants or those occupied by P. megacephala. Furthermore, O. longinoda provided more effective protection than did Crematogaster sp. Herbivore-placement experiments confirmed these results. Workers of O. longinoda killed or removed all larval instars of A. zetes. Crematogaster preyed on only the two first larval instars, and P. megacephala preyed mainly on eggs, only rarely attacking the two first larval instars. Opportunistic ants provided significant protection to this relatively unspecialised myrmecophyte. The usual associate of mature trees was not the species that provided most protection.

Application of diffusion tensor imaging in AIDS patients with brain opportunistic diseases: A comparative study of tuberculosis and toxoplasmosis

Directory of Open Access Journals (Sweden)

Xiang-le Chu

2015-06-01

Conclusions: Quantitative DTI is valuable for diagnosis and differential diagnosis of patients with AIDS-associated infections, and also could provide references for clinical physicians for proper medications. The quantitative FA value could help better reveal different changes of microstructural integrity between different opportunistic infections.

Science as Performance: Communicating and Educating through Theater, Music, and Dance

Science.gov (United States)

Schwartz, Brian B.

2010-01-01

Theater, music, dance, the literary and the visual arts can convey the joys and controversies of science. We describe a program at the Graduate Center entitled Science & the Arts which is designed to communicate to the public the excitement and wonder of science, technology, engineering and mathematics. Over the past few years there have been major successes in communicating science to the public through the arts. This is especially evident in theater, film and opera with such recent plays as Copenhagen, the Oscar winning film A Beautiful Mind and the opera Doctor Atomic at the Met. The performance series Science & the Arts has been developed and tested at the Graduate Center of the City University of New York (CUNY) in mid-Manhattan for more than nine years, see http://web.gc.cuny.edu/sciart/ . We have established working relationships with actors, playwrights, dancers, choreographers, musicians, composers, artists and scientists who work at the intersection of science and the arts. In this presentation we will illustrate many of our collaborations in theater, dance, music and art. Faculty members, professionals and students from the university, other educational institutions, museums, theaters and government laboratories as well as the public with an interest science and arts programs should find this presentation of particular interest. Supported in part by the National Science Foundation, NSF PHY-0431660.

African musical arts creativity and performance: The science of the ...

African Journals Online (AJOL)

... arts idioms, ensemble rationalizations and performance norms aim to humanize the individual and bond humanity, and 'the African science of instrument technology' which proves that scientific research informed the design, material and construction of peculiar timbres or sonic vibrancies of indigenous music instruments.

Hierarchical Effects of School-, Classroom-, and Student-Level Factors on the Science Performance of Eighth-Grade Taiwanese Students

Science.gov (United States)

Tsai, Liang-Ting; Yang, Chih-Chien

2015-05-01

This study was conducted to understand the effect of student-, classroom-, and school-level factors on the science performance of 8th-grade Taiwanese students in the Trends in International Mathematics and Science Study (TIMSS) 2011 by using multilevel analysis. A total of 5,042 students from 153 classrooms of 150 schools participated in the TIMSS 2011 study, in which they were required to complete questionnaires. A 3-level multilevel analysis was used to assess the influence of factors at 3 levels on the science performance of 8th-grade Taiwanese students. The results showed that the provision of education resources at home, teachers' level of education, and school climate were the strongest predictor of science performance at the student, classroom, and school level, respectively. It was concluded that the science performance of 8th-grade Taiwanese students is driven largely by individual factors. Classroom-level factors accounted for a smaller proportion of the total variance in science performance than did school-level factors.

The effects of gender stereotypic and counter-stereotypic textbook images on science performance.

Science.gov (United States)

Good, Jessica J; Woodzicka, Julie A; Wingfield, Lylan C

2010-01-01

We investigated the effect of gender stereotypic and counter-stereotypic images on male and female high school students' science comprehension and anxiety. We predicted stereotypic images to induce stereotype threat in females and impair science performance. Counter-stereotypic images were predicted to alleviate threat and enhance female performance. Students read one of three chemistry lessons, each containing the same text, with photograph content varied according to stereotype condition. Participants then completed a comprehension test and anxiety measure. Results indicate that female students had higher comprehension after viewing counter-stereotypic images (female scientists) than after viewing stereotypic images (male scientists). Male students had higher comprehension after viewing stereotypic images than after viewing counter-stereotypic images. Implications for alleviating the gender gap in science achievement are discussed.

Pithy Review on Routing Protocols in Wireless Sensor Networks and Least Routing Time Opportunistic Technique in WSN

Science.gov (United States)

Salman Arafath, Mohammed; Rahman Khan, Khaleel Ur; Sunitha, K. V. N.

2018-01-01

Nowadays due to most of the telecommunication standard development organizations focusing on using device-to-device communication so that they can provide proximity-based services and add-on services on top of the available cellular infrastructure. An Oppnets and wireless sensor network play a prominent role here. Routing in these networks plays a significant role in fields such as traffic management, packet delivery etc. Routing is a prodigious research area with diverse unresolved issues. This paper firstly focuses on the importance of Opportunistic routing and its concept then focus is shifted to prime aspect i.e. on packet reception ratio which is one of the highest QoS Awareness parameters. This paper discusses the two important functions of routing in wireless sensor networks (WSN) namely route selection using least routing time algorithm (LRTA) and data forwarding using clustering technique. Finally, the simulation result reveals that LRTA performs relatively better than the existing system in terms of average packet reception ratio and connectivity.

ANTIBIOTIC RESISTANCE IN THE OPPORTUNISTIC PATHOGEN STENOTROPHOMONAS MALTOPHILIA

Directory of Open Access Journals (Sweden)

María Blanca Sánchez

2015-06-01

Full Text Available Stenotrophomonas maltophilia is an environmental bacterium found in the soil, associated with plants and animals, and in aquatic environments. It is also an opportunistic pathogen now causing an increasing number of nosocomial infections. The treatment of S. maltophilia is quite difficult given its intrinsic resistance to a number of antibiotics, and because it is able to acquire new resistances via horizontal gene transfer and mutations. Certainly, strains resistant to quinolones, cotrimoxale and/or cephalosporins - antibiotics commonly used to treat S. maltophilia infections - have emerged. The increasing number of available S. maltophilia genomes has allowed the identification and annotation of a large number of antimicrobial and heavy metal resistance genes. Most encode inactivating enzymes and efflux pumps, but information on their role in intrinsic and acquired resistance is limited. Non-typical antibiotic resistance mechanisms that also form part of the intrinsic resistome have been identified via mutant library screening. These include non-typical antibiotic resistance genes, such as bacterial metabolism genes, and non-inheritable resistant phenotypes, such as biofilm formation and persistence. Their relationships with resistance are complex and require further study.

The role and regulation of catalase in respiratory tract opportunistic bacterial pathogens.

Science.gov (United States)

Eason, Mia M; Fan, Xin

2014-09-01

Respiratory tract bacterial pathogens are the etiologic agents of a variety of illnesses. The ability of these bacteria to cause disease is imparted through survival within the host and avoidance of pathogen clearance by the immune system. Respiratory tract pathogens are continually bombarded by reactive oxygen species (ROS), which may be produced by competing bacteria, normal metabolic function, or host immunological responses. In order to survive and proliferate, bacteria have adapted defense mechanisms to circumvent the effects of ROS. Bacteria employ the use of anti-oxidant enzymes, catalases and catalase-peroxidases, to relieve the effects of the oxidative stressors to which they are continually exposed. The decomposition of ROS has been shown to provide favorable conditions in which respiratory tract opportunistic bacterial pathogens such as Haemophilus influenzae, Mycobacterium tuberculosis, Legionella pneumophila, and Neisseria meningitidis are able to withstand exposure to highly reactive molecules and yet survive. Bacteria possessing mutations in the catalase gene have a decreased survival rate, yet may be able to compensate for the lack of catalatic activity if peroxidatic activity is present. An incomplete knowledge of the mechanisms by which catalase and catalase-peroxidases are regulated still persists, however, in some bacterial species, a regulatory factor known as OxyR has been shown to either up-regulate or down-regulate catalase gene expression. Yet, more research is still needed to increase the knowledge base in relation to this enzyme class. As with this review, we focus on major respiratory tract opportunistic bacterial pathogens in order to elucidate the function and regulation of catalases. The importance of the research could lead to the development of novel treatments against respiratory bacterial infections. Copyright © 2014 Elsevier Ltd. All rights reserved.

Performance-based classrooms: A case study of two elementary teachers of mathematics and science

Science.gov (United States)

Jones, Kenneth W.

This case study depicts how two elementary teachers develop classrooms devoted to performance-based instruction in mathematics and science. The purpose is to develop empirical evidence of classroom practices that leads to a conceptual framework about the nature of performance-based instruction. Performance-based assessment and instruction are defined from the literature to entail involving students in tasks that are complex and engaging, requiring them to apply knowledge and skills in authentic contexts. In elementary mathematics and science, such an approach emphasizes problem solving, exploration, inquiry, and reasoning. The body of the work examines teacher beliefs, curricular orientations, instructional strategies, assessment approaches, management and organizational skills, and interpersonal relationships. The focus throughout is on those aspects that foster student performance in elementary mathematics and science. The resulting framework describes five characteristics that contribute to performance-based classrooms: a caring classroom community, a connectionist learning theory, a thinking and doing curriculum, diverse opportunities for learning, and ongoing assessment, feedback, and adjustment. The conclusion analyzes factors external to the classroom that support or constrain the development of performance-based classrooms and discusses the implications for educational policy and further research.

Opportunistic Relay Selection with Cooperative Macro Diversity

Directory of Open Access Journals (Sweden)

Yu Chia-Hao

2010-01-01

Full Text Available We apply a fully opportunistic relay selection scheme to study cooperative diversity in a semianalytical manner. In our framework, idle Mobile Stations (MSs are capable of being used as Relay Stations (RSs and no relaying is required if the direct path is strong. Our relay selection scheme is fully selection based: either the direct path or one of the relaying paths is selected. Macro diversity, which is often ignored in analytical works, is taken into account together with micro diversity by using a complete channel model that includes both shadow fading and fast fading effects. The stochastic geometry of the network is taken into account by having a random number of randomly located MSs. The outage probability analysis of the selection differs from the case where only fast fading is considered. Under our framework, distribution of the received power is formulated using different Channel State Information (CSI assumptions to simulate both optimistic and practical environments. The results show that the relay selection gain can be significant given a suitable amount of candidate RSs. Also, while relay selection according to incomplete CSI is diversity suboptimal compared to relay selection based on full CSI, the loss in average throughput is not too significant. This is a consequence of the dominance of geometry over fast fading.

Opportunistic insights into occupational health hazards associated with waterpipe tobacco smoking premises in the United Kingdom.

Science.gov (United States)

Al-Bakri, Ali; Jawad, Mohammed; Salameh, Pascale; al'Absi, Mustafa; Kassim, Saba

2015-01-01

Smokefree laws aim to protect employees and the public from the dangers of secondhand smoke. Waterpipe premises have significantly increased in number in the last decade, with anecdotal reports of poor compliance with the smokefree law. The literature is bereft of information pertaining to waterpipe premise employees. This study aimed to opportunistically gather knowledge about the occupational health hazards associated with working in waterpipe premises in London, England. Employees from seven convenience-sampled, smokefree-compliant waterpipe premises in London were observed for occupational activities. Opportunistic carbon monoxide (CO) measurements were made among those with whom a rapport had developed. Observations were thematically coded and analysed. Occupational hazards mainly included environmental smoke exposure. Waterpipe-serving employees were required to draw several puffs soon after igniting the coals, thereby providing quality assurance of the product. Median CO levels were 27.5 ppm (range 21-55 ppm) among these employees. Self-reported employee health was poor, with some suggestion that working patterns and smoke exposure was a contributory factor. The smokefree law in England does not appear to protect waterpipe premise employees from high levels of CO. Continued concerns surrounding chronic smoke exposure may contribute to poor self-reported physical and mental wellbeing.

Draft genome sequences of two opportunistic pathogenic strains of Staphylococcus cohnii isolated from human patients

OpenAIRE

Mendoza-Olazar?n, Soraya; Garcia-Mazcorro, Jos? F.; Morf?n-Otero, Rayo; Villarreal-Trevi?o, Licet; Camacho-Ortiz, Adri?n; Rodr?guez-Noriega, Eduardo; Bocanegra-Ibarias, Paola; Maldonado-Garza, H?ctor J.; Dowd, Scot E.; Garza-Gonz?lez, Elvira

2017-01-01

Herein, we report the draft-genome sequences and annotation of two opportunistic pathogenic strains of Staphylococcus cohnii isolated from humans. One strain (SC-57) was isolated from blood from a male patient in May 2006 and the other (SC-532) from a catheter from a male patient in June 2006. Similar to other genomes of Staphylococcus species, most genes (42%) of both strains are involved in metabolism of amino acids and derivatives, carbohydrates and proteins. Eighty (4%) genes are involved...

Museums, zoos, and gardens: how formal-informal partnerships can impact urban students' performance in science.

Science.gov (United States)

Weinstein, Meryle; Whitesell, Emilyn Ruble; Schwartz, Amy Ellen

2014-12-01

Informal science education institutions (ISEIs) are critical partners in public science education, as they support the science efforts of school systems by providing authentic opportunities for scientific inquiry. This study reports findings from an evaluation of urban advantage (UA), a collaboration between the New York City Department of Education and eight ISEIs designed to improve science education in New York City (NYC) middle schools. Now in its 10th year, the program harnesses the resources and expertise of NYC's ISEIs to (a) enhance the science content knowledge of middle school science teachers, (b) develop teachers' skills at using inquiry-based approaches in their classrooms, and (c) improve the science achievement of middle school students. We examine whether the UA program has led to increased student achievement on the eighth-grade New York State standardized science exam for students in participating schools; in supplemental analyses, we examine the effects on longer term (ninth-grade) outcomes. We use a difference-in-differences framework with school fixed effects to estimate the impact of attending a UA school in eighth grade on science achievement. Our key outcome is performance on New York State's eighth-grade intermediate-level science assessment; longer term outcomes include enrollment at specialized science, technology, engineering, and math high schools as well as taking and passing the high school (Regents) science exams. We find that attending a UA school increases student performance on the eighth-grade science exam by approximately 0.05 SD, and there is some evidence of small effects on Regents taking and passing rates. © The Author(s) 2014.

Camel Calves as Opportunistic Milk Thefts? The First Description of Allosuckling in Domestic Bactrian Camel (Camelus bactrianus)

Science.gov (United States)

Brandlová, Karolína; Bartoš, Luděk; Haberová, Tamara

2013-01-01

Allosuckling is a situation when a female nurses a non-filial offspring. It was described in various ungulate species; however for camels this is the first description of this behaviour. The aim of the study was to assess the occurrence of allosuckling in captive camels (Camelus bactrianus) and to test whether it can be explained as a ‘milk-theft’ (opportunistic behaviour of calves) or alternatively as an altruistic behaviour of females. During 2005 and 2007, nine camel females and ten calves in four zoological gardens in the Czech Republic were observed. In total, 373 sucking bouts were recorded, from which 32 were non-filial (the calf sucked from the non-maternal female). Allosuckling regularly appeared in captive camel herds. As predicted for the milk-theft explanation, the non-filial calves sucked more often in the lateral position and even did not suck in the antiparallel position at all. The non-filial calves preferably joined the filial calf when sucking but in five cases (15.6% of non-filial sucking bouts) the calves sucked from non-maternal dam without the presence of filial calf. We then expected the differences in terminations of sucking bouts by females but did not find any difference in sucking terminations for filial and non-filial calves. As the calves were getting older, the incidence of allosucking increased. This was probably because skills of the calf to outwit the non-maternal dam increased and/or the older calves might be more motivated for allosucking due to the weaning process. Finally, duration of a sucking bout was shorter with non-filial than filial calves. The results of the study support the hypothesis of ‘milk theft’, being mostly performed by calves behaving as opportunistic parasites, but we cannot reject certain level of altruism from the allonursing females or their increased degree of tolerance to non-filial calves. PMID:23326378

Using citizen science data to identify the sensitivity of species to human land use.

Science.gov (United States)

Todd, Brian D; Rose, Jonathan P; Price, Steven J; Dorcas, Michael E

2016-12-01

Conservation practitioners must contend with an increasing array of threats that affect biodiversity. Citizen scientists can provide timely and expansive information for addressing these threats across large scales, but their data may contain sampling biases. We used randomization procedures to account for possible sampling biases in opportunistically reported citizen science data to identify species' sensitivities to human land use. We analyzed 21,044 records of 143 native reptile and amphibian species reported to the Carolina Herp Atlas from North Carolina and South Carolina between 1 January 1990 and 12 July 2014. Sensitive species significantly associated with natural landscapes were 3.4 times more likely to be legally protected or treated as of conservation concern by state resource agencies than less sensitive species significantly associated with human-dominated landscapes. Many of the species significantly associated with natural landscapes occurred primarily in habitats that had been nearly eradicated or otherwise altered in the Carolinas, including isolated wetlands, longleaf pine savannas, and Appalachian forests. Rare species with few reports were more likely to be associated with natural landscapes and 3.2 times more likely to be legally protected or treated as of conservation concern than species with at least 20 reported occurrences. Our results suggest that opportunistically reported citizen science data can be used to identify sensitive species and that species currently restricted primarily to natural landscapes are likely at greatest risk of decline from future losses of natural habitat. Our approach demonstrates the usefulness of citizen science data in prioritizing conservation and in helping practitioners address species declines and extinctions at large extents. © 2016 Society for Conservation Biology.

The opportunistic transmission of wireless worms between mobile devices

Science.gov (United States)

Rhodes, C. J.; Nekovee, M.

2008-12-01

The ubiquity of portable wireless-enabled computing and communications devices has stimulated the emergence of malicious codes (wireless worms) that are capable of spreading between spatially proximal devices. The potential exists for worms to be opportunistically transmitted between devices as they move around, so human mobility patterns will have an impact on epidemic spread. The scenario we address in this paper is proximity attacks from fleetingly in-contact wireless devices with short-range communication range, such as Bluetooth-enabled smart phones. An individual-based model of mobile devices is introduced and the effect of population characteristics and device behaviour on the outbreak dynamics is investigated. The model uses straight-line motion to achieve population, though it is recognised that this is a highly simplified representation of human mobility patterns. We show that the contact rate can be derived from the underlying mobility model and, through extensive simulation, that mass-action epidemic models remain applicable to worm spreading in the low density regime studied here. The model gives useful analytical expressions against which more refined simulations of worm spread can be developed and tested.

Optimal Pricing of Spectrum Resources in Wireless Opportunistic Access

Directory of Open Access Journals (Sweden)

Hanna Bogucka

2012-01-01

Full Text Available We consider opportunistic access to spectrum resources in cognitive wireless networks. The users equipment, or the network nodes in general are able to sense the spectrum and adopt a subset of available resources (the spectrum and the power individually and independently in a distributed manner, that is, based on their local channel quality information and not knowing the Channel State Information (CSI of the other nodes' links in the considered network area. In such a network scenery, the competition of nodes for available resources is observed, which can be modeled as a game. To obtain spectrally efficient and fair spectrum allocation in this competitive environment with the nodes having no information on the other players, taxation of resources is applied to coerce desired behavior of the competitors. In the paper, we present mathematical formulation of the problem of finding the optimal taxation rate (common for all nodes and propose a reduced-complexity algorithm for this optimization. Simulation results for these derived optimal values in various scenarios are also provided.

Strategic Innovation for Business Performance: The Art and Science of Transformation

OpenAIRE

Harold Schroeder

2013-01-01

Despite the well-documented association between innovation and business performance, many organizations struggle in their attempts to become successful innovators. This article discusses a recommended “art and science of transformation” approach to help companies improve their innovation performance through effective organizational change. The approach is focused on four key factors: culture, collaboration, strategy, and systems. Examples are drawn from a review of previous research to demons...

TIMSS 2011 Science Assessment Results: A Review of Ghana's Performance

Science.gov (United States)

Buabeng, Isaac; Owusu, Kofi Acheaw; Ntow, Forster Danso

2014-01-01

This paper reviews Ghana's performance in the TIMSS 2011 survey in comparison with other African and some high performing countries which participated in the TIMSS assessment. Students' achievement in the science content areas assessed were summarized and teacher preparation constructs of teachers of the students who took part in the assessment…

Reflexivity in performative science shop projects

OpenAIRE

Beunen, R.; Duineveld, M.; During, R.; Straver, G.H.M.B.; Aalvanger, A.

2012-01-01

Science shop research projects offer possibilities for universities to engage with communities. Many science shop projects directly or indirectly intend to empower certain marginalised groups or interests within a decision-making process. In this article we argue that it is important to reflect on the role and position the researchers have in these projects. We present three science shop projects to illustrate some of the dilemmas that may arise in relation to citizen empowerment, democracy, ...

The Intraperitoneal Transcriptome of the Opportunistic Pathogen Enterococcus faecalis in Mice.

Directory of Open Access Journals (Sweden)

Cécile Muller

Full Text Available Enterococcus faecalis is a Gram-positive lactic acid intestinal opportunistic bacterium with virulence potential. For a better understanding of the adapation of this bacterium to the host conditions, we performed a transcriptome analysis of bacteria isolated from an infection site (mouse peritonitis by RNA-sequencing. We identified a total of 211 genes with significantly higher transcript levels and 157 repressed genes. Our in vivo gene expression database reflects well the infection process since genes encoding important virulence factors like cytolysin, gelatinase or aggregation substance as well as stress response proteins, are significantly induced. Genes encoding metabolic activities are the second most abundant in vivo induced genes demonstrating that the bacteria are metabolically active and adapt to the special nutrient conditions of the host. α- and β- glucosides seem to be important substrates for E. faecalis inside the host. Compared to laboratory conditions, the flux through the upper part of glycolysis seems to be reduced and more carbon may enter the pentose phosphate pathway. This may reflect the need of the bacteria under infection conditions to produce more reducing power for biosynthesis. Another important substrate is certainly glycerol since both pathways of glycerol catabolism are strongly induced. Strongly in vivo induced genes should be important for the infection process. This assumption has been verified in a virulence test using well characterized mutants affected in glycerol metabolism. This showed indeed that mutants unable to metabolize this sugar alcohol are affected in organ colonisation in a mouse model.

Opportunistic microorganisms in patients undergoing antibiotic therapy for pulmonary tuberculosis

Directory of Open Access Journals (Sweden)

Silvia Maria Rodrigues Querido

2011-12-01

Full Text Available Antimicrobial therapy may cause changes in the resident oral microbiota, with the increase of opportunistic pathogens. The aim of this study was to compare the prevalence of Candida, Staphylococcus, Pseudomonas and Enterobacteriaceae in the oral cavity of fifty patients undergoing antibiotic therapy for pulmonary tuberculosis and systemically healthy controls. Oral rinsing and subgingival samples were obtained, plated in Sabouraud dextrose agar with chloramphenicol, mannitol agar and MacConkey agar, and incubated for 48 h at 37ºC. Candida spp. and coagulase-positive staphylococci were identified by phenotypic tests, C. dubliniensis, by multiplex PCR, and coagulase-negative staphylococci, Enterobacteriaceae and Pseudomonas spp., by the API systems. The number of Candida spp. was significantly higher in tuberculosis patients, and C. albicans was the most prevalent specie. No significant differences in the prevalence of other microorganisms were observed. In conclusion, the antimicrobial therapy for pulmonary tuberculosis induced significant increase only in the amounts of Candida spp.

Enhancing visuospatial performance through video game training to increase learning in visuospatial science domains.

Science.gov (United States)

Sanchez, Christopher A

2012-02-01

Although previous research has demonstrated that performance on visuospatial assessments can be enhanced through relevant experience, an unaddressed question is whether such experience also produces a similar increase in target domains (such as science learning) where visuospatial abilities are directly relevant for performance. In the present study, participants completed either spatial or nonspatial training via interaction with video games and were then asked to read and learn about the geologic topic of plate tectonics. Results replicate the benefit of playing appropriate video games in enhancing visuospatial performance and demonstrate that this facilitation also manifests itself in learning science topics that are visuospatial in nature. This novel result suggests that visuospatial training not only can impact performance on measures of spatial functioning, but also can affect performance in content areas in which these abilities are utilized.

Two-Way Multiuser Mixed RF/FSO Relaying: Performance Analysis and Power Allocation

KAUST Repository

Al-Eryani, Yasser F.; Salhab, Anas; Zummo, Salam A.; Alouini, Mohamed-Slim

2018-01-01

In this paper, the performance of two-way multiuser mixed radio frequency/free space optical (RF/FSO) relay networks with opportunistic user scheduling and asymmetric channel fading is studied. RF links are used to conduct data transmission between

Security-Reliability Trade-Off Analysis for Multiuser SIMO Mixed RF/FSO Relay Networks With Opportunistic User Scheduling

KAUST Repository

El-Malek, Ahmed H. Abd

2016-05-24

In this paper, we study the performance of multiuser single-input multiple-output mixed radio frequency (RF)/free space optical (FSO) relay network with opportunistic user scheduling. The considered system includes multiple users, one amplify-and-forward relay, one destination, and a multiple-antenna eavesdropper. The users are connected with the relay node through RF links and the relay is connected with the destination through an FSO link. Both maximum ratio combining and selection combining schemes are used at the multiple-antenna relay to combine the signal received from the best user on different antennas. The RF/FSO channels models are assumed to follow Nakagami-m/gamma-gamma fading models with pointing errors. Closed-form expressions are derived for the outage probability, average symbol error probability, and ergodic channel capacity. Then, the power of the selected best user is determined to minimize the system asymptotic outage probability under the dominant RF or FSO link. Then, the considered system secrecy performance is investigated, where the closed-form expressions for the intercept probability are derived. Finally, we propose a new cooperative jamming model in which the worst user is selected by the authorized system to jam the existing eavesdropper. Monte-Carlo simulations are provided to validate the achieved exact and asymptotic results.

Molecular Diagnostics of Arthroconidial Yeasts, Frequent Pulmonary Opportunists.

Science.gov (United States)

Kaplan, Engin; Al-Hatmi, Abdullah M S; Ilkit, Macit; Gerrits van den Ende, A H G; Hagen, Ferry; Meis, Jacques F; de Hoog, G Sybren

2018-01-01

Magnusiomyces capitatus and Saprochaete clavata are members of the clade of arthroconidial yeasts that represent emerging opportunistic pulmonary pathogens in immunocompromised patients. Given that standard ribosomal DNA (rDNA) identification often provides confusing results, in this study, we analyzed 34 isolates with the goal of finding new genetic markers for classification using multilocus sequencing and amplified fragment length polymorphism (AFLP). The interspecific similarity obtained using rDNA markers (the internal transcribed spacer [ITS] and large subunit regions) was in the range of 96 to 99%, whereas that obtained using protein-coding loci ( Rbp2 , Act , and Tef1α ) was lower at 89.4 to 95.2%. Ultimately, Rbp2 was selected as the best marker for species distinction. On the basis of cloned ITS data, some strains proved to be misidentified in comparison with the identities obtained with phenotypic characters, protein sequences, and AFLP profiles, indicating that different copies of the ribosomal operon were present in a single species. Antifungal susceptibility testing revealed that voriconazole had the lowest MIC against M. capitatus , while amphotericin B had the lowest MIC against S. clavata Both species exhibited in vitro resistance to fluconazole and micafungin. Copyright © 2017 American Society for Microbiology.

Addressing the Issue of Routing Unfairness in Opportunistic Backhaul Networks for Collecting Sensed Data

Directory of Open Access Journals (Sweden)

Tekenate E. Amah

2017-12-01

Full Text Available Widely deploying sensors in the environment and embedding them in physical objects is a crucial step towards realizing smart and sustainable cities. To cope with rising resource demands and limited budgets, opportunistic networks (OppNets offer a scalable backhaul option for collecting delay-tolerant data from sensors to gateways in order to enable efficient urban operations and services. While pervasive devices such as smartphones and tablets contribute significantly to the scalability of OppNets, closely following human movement patterns and social structure introduces network characteristics that pose routing challenges. Our study on the impact of these characteristics reveals that existing routing protocols subject a key set of devices to higher resource consumption, to which their users may respond by withdrawing participation. Unfortunately, existing solutions addressing this unfairness do not guarantee achievable throughput since they are not specifically designed for sensed data collection scenarios. Based on concepts derived from the study, we suggest design guidelines for adapting applicable routing protocols to sensed data collection scenarios. We also follow our design guidelines to propose the Fair Locality Aware Routing (FLARoute technique. Evaluating FLARoute within an existing routing protocol confirms improved fairness and throughput under conditions that compromise the performance of existing solutions.

ExoMars Trace Gas Orbiter Instrument Modelling Approach to Streamline Science Operations

Science.gov (United States)

Munoz Fernandez, Michela; Frew, David; Ashman, Michael; Cardesin Moinelo, Alejandro; Garcia Beteta, Juan Jose; Geiger, Bernhard; Metcalfe, Leo; Nespoli, Federico; Muniz Solaz, Carlos

2018-05-01

ExoMars Trace Gas Orbiter (TGO) science operations activities are centralised at ESAC's Science Operations Centre (SOC). The SOC receives the inputs from the principal investigators (PIs) in order to implement and deliver the spacecraft pointing requests and instrument timelines to the Mission Operations Centre (MOC). The high number of orbits per planning cycle has made it necessary to abstract the planning interactions between the SOC and the PI teams at the observation level. This paper describes the modelling approach we have conducted for TGOís instruments to streamline science operations. We have created dynamic observation types that scale to adapt to the conditions specified by the PI teams including observation timing, and pointing block parameters calculated from observation geometry. This approach is considered and improvement with respect to previous missions where the generation of the observation pointing and commanding requests was performed manually by the instrument teams. Automation software assists us to effectively handle the high density of planned orbits with increasing volume of scientific data and to successfully meet opportunistic scientific goals and objectives. Our planning tool combines the instrument observation definition files provided by the PIs together with the flight dynamics products to generate the Pointing Requests and the instrument timeline (ITL). The ITL contains all the validated commands at the TC sequence level and computes the resource envelopes (data rate, power, data volume) within the constraints. At the SOC, our main goal is to maximise the science output while minimising the number of iterations among the teams, ensuring that the timeline does not violate the state transitions allowed in the Mission Operations Rules and Constraints Document.

Simulation-Based Performance Assessment: An Innovative Approach to Exploring Understanding of Physical Science Concepts

Science.gov (United States)

Gale, Jessica; Wind, Stefanie; Koval, Jayma; Dagosta, Joseph; Ryan, Mike; Usselman, Marion

2016-01-01

This paper illustrates the use of simulation-based performance assessment (PA) methodology in a recent study of eighth-grade students' understanding of physical science concepts. A set of four simulation-based PA tasks were iteratively developed to assess student understanding of an array of physical science concepts, including net force,…

Enhancing Diversity in Undergraduate Science: Self-Efficacy Drives Performance Gains with Active Learning

OpenAIRE

Ballen, Cissy J.; Wieman, Carl; Salehi, Shima; Searle, Jeremy B.; Zamudio, Kelly R.

2017-01-01

Efforts to retain underrepresented minority (URM) students in science, technology, engineering, and mathematics (STEM) have shown only limited success in higher education, due in part to a persistent achievement gap between students from historically underrepresented and well-represented backgrounds. To test the hypothesis that active learning disproportionately benefits URM students, we quantified the effects of traditional versus active learning on student academic performance, science self...

Validating Performance Level Descriptors (PLDs) for the AP® Environmental Science Exam

Science.gov (United States)

Reshetar, Rosemary; Kaliski, Pamela; Chajewski, Michael; Lionberger, Karen

2012-01-01

This presentation summarizes a pilot study conducted after the May 2011 administration of the AP Environmental Science Exam. The study used analytical methods based on scaled anchoring as input to a Performance Level Descriptor validation process that solicited systematic input from subject matter experts.

Energy Efficient Four Level Cooperative Opportunistic Communication for Wireless Personal Area Networks (WPAN)

DEFF Research Database (Denmark)

Rohokale, Vandana M.; Inamdar, Sandeep; Prasad, Neeli R.

2013-01-01

For wireless sensor networks (WSN),energy is a scarce resource. Due to limited battery resources, the energy consumption is the critical issue for the transmission as well as reception of the signals in the wireless communication. WSNs are infrastructure-less shared network demanding more energy...... consumption due to collaborative transmissions. This paper proposes a new cooperative opportunistic four level model for IEEE 802.15.4 Wireless Personal Area Network (WPAN).The average per node energy consumption is observed merely about 0.17mJ for the cooperative wireless communication which proves...... the proposed mechanism to be energy efficient. This paper further proposes four levels of cooperative data transmission from source to destination to improve network coverage with energy efficiency....

The Use of Theater and the Performing Arts in Science Education and the Teaching of History

Science.gov (United States)

Schwartz, Brian

2015-03-01

Over the past 15 years there has been a surge in the general field of the interaction of STEM and the arts including theatre, music dance and the visual arts leading to STEAM. There seems to be no limits to the amount of creativity and diversity of subject matter especially in areas of biography, major science events, scientific and technical innovation, the benefits and dangers of modern science, and science as metaphor. For the past 15 years, I and my colleagues have been running a science outreach series under the title Science & the Performing Arts at the Graduate Center of the City University of New York. The objective is to bring science to students and the public in ways that are engaging, instructive, and artistic and always, content-driven: the medium is the arts; the message is the joy of science. This has resulted in over 120 science and performing arts programs which have been documented on the website http://sciart.commons.gc.cuny.edu/ . The author co-taught a course titled Staging Science, http://sciart.commons.gc.cuny.edu/staging-science/outline-of-the-course-staging-science/ with Marvin Carlson, Professor of Theatre at CUNY. An excellent book, Science on Stage: From Doctor Faustus to Copenhagen by Kirsten Shepherd-Barr, can be used to develop a customized courses on Science, Theatre and History for both science and non-science majors. The book's appendix includes an annotated listing of plays on such subjects as quantum mechanics, chaos theory, evolution, genetics and morality and responsibility. The talk will include many examples how courses on science and theatre can actively engage students and enhance active participation and learning. Supported in part by the National Science Foundation.

Using Project-Based Data in Physics to Examine Television Viewing in Relation to Student Performance in Science

Science.gov (United States)

Espinoza, Fernando

2009-10-01

Mass media, particularly television, influence public conceptions and attitudes toward learning science. The discovery of an original method that does not rely on self-reported viewing habits to measure the impact of television on students' performance in science arose from a study of a unit on electricity in a Physics course. In determining the number of television sets at home and the number of hours of operation, data emerged that allowed an investigation of associations between each of these variables and student performance in physics. A negative impact on performance was found in its consistent decrease as both the number of sets and the time the sets are on increase. These results provide dramatic independent confirmation of the negative impact of television viewing on achievement determined through meta-analysis of many studies, and are also consistent with those in the literature at large, particularly from the Third International Mathematics and Science Study, and the National Assessment of Educational Progress. Furthermore, the totally `blind' participation of the subjects lends a degree of authenticity rarely found in a classically designed study. The findings impact scientific literacy, since performance in science and conceptions of science and scientists, are all inextricably linked.

Review of Street-Fighting Mathematics: The Art of Educated Guessing and Opportunistic Problem Solving by Sanjoy Mahajan

OpenAIRE

Thomas J. Pfaff

2015-01-01

Mahajan, Sanjoy. Street-Fighting Mathematics: The Art of Educated Guessing and Opportunistic Problem Solving (The MIT Press, Cambridge, Massachusetts, 2010). 152 pp. ISBN 978--0--262--51429--3 Street-Fighting Mathematics is an engaging collection of problem-solving techniques. The book is not for a general audience, as it requires a significant level of mathematical and scientific background knowledge. In particular, most of the book requires knowledge of Calculus I and there are examples ...

Peculiarities of cell-cell interactions in basal decidual membrane at vaginitis associated with contamination by opportunistic microorganisms

Directory of Open Access Journals (Sweden)

L. R. Mustafina

2012-01-01

Full Text Available An important role in anti-infection protection during pregnancy belongs to local immunity mechanisms. At contamination of lower genital tracts by Ureaplasma urealyticum and Mycoplasma hominis, the activation of natural killers in basal decidual membrane was absent, which can be considered as a marker of immune compromise of women in the aspect of reliability of control of the population of urinogenital opportunistic flora and prognostic factor of possible intrauterine infection.

Recent Developments in SRF Cavity Science and Performance

Energy Technology Data Exchange (ETDEWEB)

G. Ciovati

2006-08-10

The performances of SRF cavities made of high purity bulk niobium have been improving in the last few years and surface magnetic fields (Bp) close to the thermodynamic critical field of niobium have been achieved in a few cases. The recommendation made in 2004 in favor of SRF as the technology of choice for the International Linear Collider (ILC), requires improving the reliability of multi-cell cavities operating at accelerating gradients (Eacc) of the order of 35 MV/m. Additionally, a better understanding of the present limitations to cavity performance, such as the high-field Q-drop is needed. This contribution presents some recent developments in SRF cavity science and performance. Among the most significant advances of the last few years, new cavity shapes with lower ratio Bp/Eacc were designed and tested. Cavities made of large-grain niobium became available, promising lower cost at comparable performance to standard fine-grain ones and several tests on single-cell cavities were done to gain a better understanding of high-field losses. In addition, studies to improve the reliability of electropolishing are being carried out by several research groups.

Opportunistic disease and mortality in patients coinfected with hepatitis B or C virus in the strategic management of antiretroviral therapy (SMART) study

DEFF Research Database (Denmark)

Tedaldi, Ellen; Peters, Lars; Neuhaus, Jacquie

2008-01-01

BACKGROUND: In the Strategic Management of Antiretroviral Therapy (SMART) study, the risk of opportunistic disease (OD) and/or death due to any cause was elevated in the drug conservation (i.e., interrupt antiretroviral therapy until the CD4(+) cell count is

Predictions from the cloud: using data science to predict sports performance

NARCIS (Netherlands)

Blaauw, Frank; Emerencia, Armando Celino; den Hartigh, Jan Rudolf; Milovanović, Marko; Stoter, Inge; de Jonge, Peter

2018-01-01

In sport science, a major aim is to unravel the variables and parameters that influence sports performance. A key requirement for investigating these parameters is the availability of high quality data. More specifically, data that contains the variables of interest, and data that could be analyzed

A cross sectional study on the motivators for Asian women to attend opportunistic mammography screening in a private hospital in Malaysia: the MyMammo study.

Science.gov (United States)

Hassan, Norhashimah; Ho, Weang Kee; Mariapun, Shivaani; Teo, Soo Hwang

2015-06-12

To date, because of limited budgets and lower incidence of breast cancer, the majority of Asian countries do not have population-based screening programmes, but instead offer opportunistic screening. However, there have been few studies which have assessed the motivators for women attending such programmes and the appropriateness of the programmes in terms of targeting women at risk. We conducted a prospective cross-sectional study of 1,619 women aged 40 to 74 years attending a subsidized opportunistic screening mammogram from October 2011 to October 2013 at a private hospital in Malaysia. Breast cancer risk was estimated using the Gail Model and two-step cluster analysis was used to examine the motivators of attending screening. Although Malaysia comprises 54.5% Malay, 24.5% Chinese and 7.3% Indian, the majority of women in the MyMammo Study were Chinese (70.1%) and 99.2% had a motivators. Of those with only secondary school education, their main motivators were doctors. Taken together, our results suggest the women attending opportunistic mammography screening in Asia are at low risk of breast cancer and this poses challenges to cost-effective and equitable strategies for cancer control. We propose that to improve uptake of screening mammography, awareness programmes should target both doctors and members of the public.

Evolutionary Game Analysis on Opportunistic Behavior Based on Cooperative Spillover%基于合作溢出的机会主义行为演化博弈分析

Institute of Scientific and Technical Information of China (English)

邢乐斌; 王旭

2011-01-01

Enterprises in the market economy and knowledge society are forming strategic alliance with each other in order to obtain necessary skills and capabilities. Strategic alliance opportunities inevitably create opportunistic and self-interest behaviors, thereby resulting in disorderly competition and reduced alliance profit. It is important to learn how to develop a healthy alliance by reducing opportunism behaviors and improving alliance profits. In reality, alliance members tend to take effective supervisory and preventive measures to avoid cooperative spillover of exclusion resource, and reduce or avoid the loss of their own interests. Therefore, research of alliance stability and alliance income should be based on at least two aspects: supervisory and preventive measures, as well as cooperative spillover of exclusion resource.The current research on alliance and opportunism behaviors of alliance members is mainly based on single factor, such as information symmetry, supervision and prevention, external environment, cooperative spillover effect of exclusion resource, trust or culture. Two or more influencing factors were rarely considered at the same time. According to the evolutionary game theory, this paper uses a replicator equation as our basic model to characterize the change of opportunist proportion and mutually beneficial proportion when cooperative spillover occurs. We also analyze evolution laws under stable alliance equilibrium, and potential influence of cooperative spillover on alliance profits.In the first part we construct an alliance system that is created by many individuals. The evolutionary game model is based on exclusion resources that takes opportunist proportion in alliance and mutually beneficial proportion. In the second part, we calculate the stable alliance equilibrium point and study the evolution law of opportunistic behavior according to the Jacobin matrix. Excessive prevention cost can stop cooperative spillover of mutually beneficial

Factors associated with development of opportunistic infections in HIV-1 infected adults with high CD4 cell counts: a EuroSIDA study

DEFF Research Database (Denmark)

Podlekareva, Daria; Mocroft, A; Dragsted, Ulrik Bak

2006-01-01

BACKGROUND: Limited data exist on factors predicting the development of opportunistic infections (OIs) at higher-than-expected CD4(+) cell counts in human immunodeficiency virus (HIV) type 1-infected adults. METHODS: Multivariate Poisson regression models were used to determine factors related to...

Determining the Factors That Affect the Objectives of Pre-Service Science Teachers to Perform Outdoor Science Activities

Science.gov (United States)

Karademir, Ersin; Erten, Sinan

2013-01-01

The purpose of this study is to determine whether pre-service teachers have an aim to perform outdoor education activities within the scope of science and technology course; by which factors this aim is affected, through The Theory of Planned Behaviour and the opinions of pre-service teachers. Accordingly, the study was designed as mixed research…

The Influence of Contrarians and Opportunists on the Stability of a Democracy in the Sznajd Model

Science.gov (United States)

Schneider, Johannes J.

Sznajd-Weron and Sznajd introduced a model investigating the democratic development in a closed community. This model is based on the USDF-principle ("united we stand, divided we fall"). However, it faces the problem that the system tends either to a dictatorship (i.e., 100% pro or 100% contra) or to a stalemate state (i.e., exactly 50% pro, 50% contra). Based on their model, I will show that a democratic system keeps alive due to the existence of both opportunists and persons in opposition.

System Design and Performance of the Two-Gyro Science Mode For the Hubble Space Telescope

Science.gov (United States)

Prior, Michael; Dunham, Larry

2005-01-01

For fifteen years, the science mission of the Hubble Space Telescope (HST) required using at least three of the six on-board rate gyros for attitude control. Failed gyros were eventually replaced through Space Shuttle Servicing Missions. The tragic loss of the Space Shuttle Columbia has resulted in the cancellation of all planned Shuttle based missions to HST. While a robotic servicing mission is currently being planned instead, controlling with alternate sensors to replace failed gyros can extend the HST science gathering until a servicing mission can be performed, and also extend science at HST s end of life. Additionally, sufficient performance may allow a permanent transition to operations with less than 3 gyros (by intentionally turning off working gyros saving them for later use) allowing for an even greater science mission extension. To meet this need, a Two Gyro Science (TGS) mode has been designed and implemented using magnetometers (Magnetic Sensing System - MSS), Fixed Head Star Trackers (FHSTs), and Fine Guidance Sensors (FGSs) to control vehicle rate about the missing gyro input axis. The development of the TGS capability is the largest re-design of HST operations undertaken, since it affects several major spacecraft subsystems, the most heavily being the Pointing Control System (PCS) and Flight Software (FSW). Additionally, and equally important, are the extensive modifications and enhancements of the Planning and Scheduling system which must now be capable of scheduling science observations while taking into account several new constraints imposed by the TGS operational modes (such as FHST availability and magnetic field geometry) that will impact science gathering efficiency and target availability. This paper discusses the systems engineering design, development, and performance of the TGS mode, now in its final stages of completion.

Crowdsourcing, the great meteor storm of 1833, and the founding of meteor science.

Science.gov (United States)

Littmann, Mark; Suomela, Todd

2014-06-01

Yale science professor Denison Olmsted used crowdsourcing to gather observations from across the United States of the unexpected deluge of meteors on 13 November 1833--more than 72,000/h. He used these observations (and newspaper accounts and correspondence from scientists) to make a commendably accurate interpretation of the meteor storm, overturning 2100 years of erroneous teachings about shooting stars and establishing meteor science as a new branch of astronomy. Olmsted's success was substantially based on his use of newspapers and their practice of news pooling to solicit observations from throughout the country by lay and expert observers professionally unaffiliated with Yale College and him. In today's parlance, Olmsted was a remarkably successful early practitioner of scientific crowdsourcing, also known as citizen science. He may have been the first to use mass media for crowdsourcing in science. He pioneered many of the citizen-science crowdsourcing practices that are still in use today: an open call for citizen participation, a clearly defined task, a large geographical distribution for gathering data and a rapid response to opportunistic events. Olmsted's achievement is not just that he used crowdsourcing in 1833 but that crowdsourcing helped him to advance science significantly. Copyright © 2014 Elsevier Ltd. All rights reserved.

[Acceptability of the opportunistic search for human immunodeficiency virus infection by serology in patients recruited in Primary Care Centres in Spain].

Science.gov (United States)

Puentes Torres, Rafael Carlos; Aguado Taberné, Cristina; Pérula de Torres, Luis Angel; Espejo Espejo, José; Castro Fernández, Cristina; Fransi Galiana, Luís

2016-01-01

To assess the acceptability of opportunistic search for human immunodeficiency virus (HIV). Cross-sectional, observational study. Primary Care Centres (PCC) of the Spanish National Health Care System. patients aged 18 to 65 years who had never been tested for HIV, and were having a blood test for other reasons. RECORDED VARIABLES: age, gender, stable partner, educational level, tobacco/alcohol use, reason for blood testing, acceptability of taking the HIV test, reasons for refusing to take the HIV test, and reasons for not having taken an HIV test previously. A descriptive, bivariate, multivariate (logistic regression) statistical analysis was performed. A total of 208 general practitioners (GPs) from 150 health care centres recruited 3,314 patients. Most (93.1%) of patients agreed to take the HIV test (95%CI: 92.2-93.9). Of these patients, 56.9% reported never having had an HIV test before because they considered not to be at risk of infection, whereas 34.8% reported never having been tested for HIV because their doctor had never offered it to them. Of the 6.9% who refused to take the HIV test, 73.9% considered that they were not at risk. According to the logistic regression analysis, acceptability was positively associated to age (higher among between 26 and 35 year olds, OR=1.79; 95%CI: 1.10-2.91) and non-smokers (OR=1.39; 95%CI: 1.01-1.93). Those living in towns with between 10,000 and 50,000 inhabitants showed less acceptance to the test (OR=0.57; 95%CI: 0.40-0.80). The HIV prevalence detected was 0.24% Acceptability of HIV testing is very high among patients having a blood test in primary care settings in Spain. Opportunistic search is cost-effective. Copyright © 2015 Elsevier España, S.L.U. All rights reserved.

Perceptions of success in performance-based procurement: Differences between clients and contractors

NARCIS (Netherlands)

van Duren, J.M.A.; Doree, Andries G.; Voordijk, Johannes T.

2015-01-01

Purpose – The purpose of this study is to analyse, from the perspective of agency theory, differences between client and contractor in their perceptions of changes in uncertainty and in inclination to opportunistic behaviour while using a performance-based procurement procedure. In agency theory,

Academic Performance and Pass Rates: Comparison of Three First-Year Life Science Courses

Science.gov (United States)

Downs, C. T.

2009-01-01

First year students' academic performance in three Life Science courses (Botany, Zoology and Bioscience) was compared. Pass rates, as well as the means and distributions of final marks were analysed. Of the three components (coursework, practical and theory examinations) contributing to the final mark of each course, students performed best in the…

Lipopolysaccharides from Commensal and Opportunistic Bacteria: Characterization and Response of the Immune System of the Host Sponge Suberites domuncula

Science.gov (United States)

Gardères, Johan; Bedoux, Gilles; Koutsouveli, Vasiliki; Crequer, Sterenn; Desriac, Florie; Le Pennec, Gaël

2015-01-01

Marine sponges harbor a rich bacterioflora with which they maintain close relationships. However, the way these animals make the distinction between bacteria which are consumed to meet their metabolic needs and opportunistic and commensal bacteria which are hosted is not elucidated. Among the elements participating in this discrimination, bacterial cell wall components such as lipopolysaccharides (LPS) could play a role. In the present study, we investigated the LPS chemical structure of two bacteria associated with the sponge Suberites domuncula: a commensal Endozoicomonas sp. and an opportunistic Pseudoalteromonas sp. Electrophoretic patterns indicated different LPS structures for these bacteria. The immunomodulatory lipid A was isolated after mild acetic acid hydrolysis. The electrospray ionization ion-trap mass spectra revealed monophosphorylated molecules corresponding to tetra- and pentaacylated structures with common structural features between the two strains. Despite peculiar structural characteristics, none of these two LPS influenced the expression of the macrophage-expressed gene S. domuncula unlike the Escherichia coli ones. Further research will have to include a larger number of genes to understand how this animal can distinguish between LPS with resembling structures and discriminate between bacteria associated with it. PMID:26262625

14th annual Results and Review Workshop on High Performance Computing in Science and Engineering

CERN Document Server

Nagel, Wolfgang E; Resch, Michael M; Transactions of the High Performance Computing Center, Stuttgart (HLRS) 2011; High Performance Computing in Science and Engineering '11

2012-01-01

This book presents the state-of-the-art in simulation on supercomputers. Leading researchers present results achieved on systems of the High Performance Computing Center Stuttgart (HLRS) for the year 2011. The reports cover all fields of computational science and engineering, ranging from CFD to computational physics and chemistry, to computer science, with a special emphasis on industrially relevant applications. Presenting results for both vector systems and microprocessor-based systems, the book allows readers to compare the performance levels and usability of various architectures. As HLRS

Additive opportunistic capture explains group hunting benefits in African wild dogs.

Science.gov (United States)

Hubel, Tatjana Y; Myatt, Julia P; Jordan, Neil R; Dewhirst, Oliver P; McNutt, J Weldon; Wilson, Alan M

2016-03-29

African wild dogs (Lycaon pictus) are described as highly collaborative endurance pursuit hunters based on observations derived primarily from the grass plains of East Africa. However, the remaining population of this endangered species mainly occupies mixed woodland savannah where hunting strategies appear to differ from those previously described. We used high-resolution GPS and inertial technology to record fine-scale movement of all members of a single pack of six adult African wild dogs in northern Botswana. The dogs used multiple short-distance hunting attempts with a low individual kill rate (15.5%), but high group feeding rate due to the sharing of prey. Use of high-level cooperative chase strategies (coordination and collaboration) was not recorded. In the mixed woodland habitats typical of their current range, simultaneous, opportunistic, short-distance chasing by dogs pursuing multiple prey (rather than long collaborative pursuits of single prey by multiple individuals) could be the key to their relative success in these habitats.

LABORATORY DIAGNOSIS OF OPPORTUNISTIC INFECTIONS AT LONG-SUBFEBRILITES AND OBSTRUCTIVE BRONCHITIS IN CHILDREN WITH MIXED INFECTION

Directory of Open Access Journals (Sweden)

T. N. Rybalkina

2013-01-01

Full Text Available The article discusses the role of agents of opportunistic infections (OI in the etiology of children’s infectious diseases illustrated by the long-subfebrilites and obstructivebronchitis. When children without expressed immunity disorders are infected with mixed infections OI have more pronounced manifestations, which requires appropriate treatment. At the same time, the similarity of the clinical manifestations does not mean that an etiological diagnosis can be determined without laboratory diagnostic methods. The importance of routine pediatrics monitoring of children with latent forms of OI is emphasized.

High Performance Computing in Science and Engineering '02 : Transactions of the High Performance Computing Center

CERN Document Server

Jäger, Willi

2003-01-01

This book presents the state-of-the-art in modeling and simulation on supercomputers. Leading German research groups present their results achieved on high-end systems of the High Performance Computing Center Stuttgart (HLRS) for the year 2002. Reports cover all fields of supercomputing simulation ranging from computational fluid dynamics to computer science. Special emphasis is given to industrially relevant applications. Moreover, by presenting results for both vector sytems and micro-processor based systems the book allows to compare performance levels and usability of a variety of supercomputer architectures. It therefore becomes an indispensable guidebook to assess the impact of the Japanese Earth Simulator project on supercomputing in the years to come.

Contributions of Science and Technology Parks Towards Firms' Performance in Pakistan

International Nuclear Information System (INIS)

Mangrio, W.B.; Naqvi, I.B.

2013-01-01

Several countries have adopted different strategies, models and policies to assist companies to develop their technological capabilities. These include high tech cluster development, creation of venture capital fund, establishment of technology incubation center, and Science and Technology parks. In turn, the creation of knowledge base industries, regional development, improves the technological infrastructure and life standard of the people. This paper discusses the contribution of science and technology parks in firms' performance in particularly employment, sales and profitability and also in creation of new businesses in information technology sector in Pakistan. This study is based on the case study of STPs (Software Technology Parks) of Islamabad. The results revealed that the establishment of STPs could be helpful in the creation of new companies as half of firms located at the STPs were startup enterprises. It helps firms to enhance its growth performance in the first five years after starting their business at these STPs. By developing software parks in three major cities, Pakistan Software Export Board have achieved partially its objectives. (author)

The power of simplicity: a fast-and-frugal heuristics approach to performance science.

Science.gov (United States)

Raab, Markus; Gigerenzer, Gerd

2015-01-01

Performance science is a fairly new multidisciplinary field that integrates performance domains such as sports, medicine, business, and the arts. To give its many branches a structure and its research a direction, it requires a theoretical framework. We demonstrate the applications of this framework with examples from sport and medicine. Because performance science deals mainly with situations of uncertainty rather than known risks, the needed framework can be provided by the fast-and-frugal heuristics approach. According to this approach, experts learn to rely on heuristics in an adaptive way in order to make accurate decisions. We investigate the adaptive use of heuristics in three ways: the descriptive study of the heuristics in the cognitive "adaptive toolbox;" the prescriptive study of their "ecological rationality," that is, the characterization of the situations in which a given heuristic works; and the engineering study of "intuitive design," that is, the design of transparent aids for making better decisions.

The power of simplicity: a fast-and-frugal heuristics approach to performance science

Science.gov (United States)

Raab, Markus; Gigerenzer, Gerd

2015-01-01

Performance science is a fairly new multidisciplinary field that integrates performance domains such as sports, medicine, business, and the arts. To give its many branches a structure and its research a direction, it requires a theoretical framework. We demonstrate the applications of this framework with examples from sport and medicine. Because performance science deals mainly with situations of uncertainty rather than known risks, the needed framework can be provided by the fast-and-frugal heuristics approach. According to this approach, experts learn to rely on heuristics in an adaptive way in order to make accurate decisions. We investigate the adaptive use of heuristics in three ways: the descriptive study of the heuristics in the cognitive “adaptive toolbox;” the prescriptive study of their “ecological rationality,” that is, the characterization of the situations in which a given heuristic works; and the engineering study of “intuitive design,” that is, the design of transparent aids for making better decisions. PMID:26579051

The OCO-3 Mission: Science Objectives and Instrument Performance

Science.gov (United States)

Eldering, A.; Basilio, R. R.; Bennett, M. W.

2017-12-01

The Orbiting Carbon Observatory 3 (OCO-3) will continue global CO2 and solar-induced chlorophyll fluorescence (SIF) using the flight spare instrument from OCO-2. The instrument is currently being tested, and will be packaged for installation on the International Space Station (ISS) (launch readiness in early 2018.) This talk will focus on the science objectives, updated simulations of the science data products, and the outcome of recent instrument performance tests. The low-inclination ISS orbit lets OCO-3 sample the tropics and sub-tropics across the full range of daylight hours with dense observations at northern and southern mid-latitudes (+/- 52º). The combination of these dense CO2 and SIF measurements provides continuity of data for global flux estimates as well as a unique opportunity to address key deficiencies in our understanding of the global carbon cycle. The instrument utilizes an agile, 2-axis pointing mechanism (PMA), providing the capability to look towards the bright reflection from the ocean and validation targets. The PMA also allows for a snapshot mapping mode to collect dense datasets over 100km by 100km areas. Measurements over urban centers could aid in making estimates of fossil fuel CO2 emissions. Similarly, the snapshot mapping mode can be used to sample regions of interest for the terrestrial carbon cycle. In addition, there is potential to utilize data from ISS instruments ECOSTRESS (ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station) and GEDI (Global Ecosystem Dynamics Investigation), which measure other key variables of the control of carbon uptake by plants, to complement OCO-3 data in science analysis. In 2017, the OCO-2 instrument was transformed into the ISS-ready OCO-3 payload. The transformed instrument was thoroughly tested and characterized. Key characteristics, such as instrument ILS, spectral resolution, and radiometric performance will be described. Analysis of direct sun measurements taken during testing

Panax ginseng has anti-infective activity against opportunistic pathogen Pseudomonas aeruginosa by inhibiting quorum sensing, a bacterial communication process critical for establishing infection

DEFF Research Database (Denmark)

Song, Z; Kong, K F; Wu, H

2010-01-01

Virulent factors produced by pathogens play an important role in the infectious process, which is regulated by a cell-to-cell communication mechanism called quorum sensing (QS). Pseudomonas aeruginosa is an important opportunistic human pathogen, which causes infections in patients with compromis...

Scientific Grand Challenges: Forefront Questions in Nuclear Science and the Role of High Performance Computing

International Nuclear Information System (INIS)

Khaleel, Mohammad A.

2009-01-01

This report is an account of the deliberations and conclusions of the workshop on 'Forefront Questions in Nuclear Science and the Role of High Performance Computing' held January 26-28, 2009, co-sponsored by the U.S. Department of Energy (DOE) Office of Nuclear Physics (ONP) and the DOE Office of Advanced Scientific Computing (ASCR). Representatives from the national and international nuclear physics communities, as well as from the high performance computing community, participated. The purpose of this workshop was to (1) identify forefront scientific challenges in nuclear physics and then determine which-if any-of these could be aided by high performance computing at the extreme scale; (2) establish how and why new high performance computing capabilities could address issues at the frontiers of nuclear science; (3) provide nuclear physicists the opportunity to influence the development of high performance computing; and (4) provide the nuclear physics community with plans for development of future high performance computing capability by DOE ASCR.

Scientific Grand Challenges: Forefront Questions in Nuclear Science and the Role of High Performance Computing

Energy Technology Data Exchange (ETDEWEB)

Khaleel, Mohammad A.

2009-10-01

This report is an account of the deliberations and conclusions of the workshop on "Forefront Questions in Nuclear Science and the Role of High Performance Computing" held January 26-28, 2009, co-sponsored by the U.S. Department of Energy (DOE) Office of Nuclear Physics (ONP) and the DOE Office of Advanced Scientific Computing (ASCR). Representatives from the national and international nuclear physics communities, as well as from the high performance computing community, participated. The purpose of this workshop was to 1) identify forefront scientific challenges in nuclear physics and then determine which-if any-of these could be aided by high performance computing at the extreme scale; 2) establish how and why new high performance computing capabilities could address issues at the frontiers of nuclear science; 3) provide nuclear physicists the opportunity to influence the development of high performance computing; and 4) provide the nuclear physics community with plans for development of future high performance computing capability by DOE ASCR.

Enabling Efficient Climate Science Workflows in High Performance Computing Environments

Science.gov (United States)

Krishnan, H.; Byna, S.; Wehner, M. F.; Gu, J.; O'Brien, T. A.; Loring, B.; Stone, D. A.; Collins, W.; Prabhat, M.; Liu, Y.; Johnson, J. N.; Paciorek, C. J.

2015-12-01

A typical climate science workflow often involves a combination of acquisition of data, modeling, simulation, analysis, visualization, publishing, and storage of results. Each of these tasks provide a myriad of challenges when running on a high performance computing environment such as Hopper or Edison at NERSC. Hurdles such as data transfer and management, job scheduling, parallel analysis routines, and publication require a lot of forethought and planning to ensure that proper quality control mechanisms are in place. These steps require effectively utilizing a combination of well tested and newly developed functionality to move data, perform analysis, apply statistical routines, and finally, serve results and tools to the greater scientific community. As part of the CAlibrated and Systematic Characterization, Attribution and Detection of Extremes (CASCADE) project we highlight a stack of tools our team utilizes and has developed to ensure that large scale simulation and analysis work are commonplace and provide operations that assist in everything from generation/procurement of data (HTAR/Globus) to automating publication of results to portals like the Earth Systems Grid Federation (ESGF), all while executing everything in between in a scalable environment in a task parallel way (MPI). We highlight the use and benefit of these tools by showing several climate science analysis use cases they have been applied to.

Opportunistic Computing with Lobster: Lessons Learned from Scaling up to 25k Non-Dedicated Cores

Science.gov (United States)

Wolf, Matthias; Woodard, Anna; Li, Wenzhao; Hurtado Anampa, Kenyi; Yannakopoulos, Anna; Tovar, Benjamin; Donnelly, Patrick; Brenner, Paul; Lannon, Kevin; Hildreth, Mike; Thain, Douglas

2017-10-01

We previously described Lobster, a workflow management tool for exploiting volatile opportunistic computing resources for computation in HEP. We will discuss the various challenges that have been encountered while scaling up the simultaneous CPU core utilization and the software improvements required to overcome these challenges. Categories: Workflows can now be divided into categories based on their required system resources. This allows the batch queueing system to optimize assignment of tasks to nodes with the appropriate capabilities. Within each category, limits can be specified for the number of running jobs to regulate the utilization of communication bandwidth. System resource specifications for a task category can now be modified while a project is running, avoiding the need to restart the project if resource requirements differ from the initial estimates. Lobster now implements time limits on each task category to voluntarily terminate tasks. This allows partially completed work to be recovered. Workflow dependency specification: One workflow often requires data from other workflows as input. Rather than waiting for earlier workflows to be completed before beginning later ones, Lobster now allows dependent tasks to begin as soon as sufficient input data has accumulated. Resource monitoring: Lobster utilizes a new capability in Work Queue to monitor the system resources each task requires in order to identify bottlenecks and optimally assign tasks. The capability of the Lobster opportunistic workflow management system for HEP computation has been significantly increased. We have demonstrated efficient utilization of 25 000 non-dedicated cores and achieved a data input rate of 30 Gb/s and an output rate of 500GB/h. This has required new capabilities in task categorization, workflow dependency specification, and resource monitoring.

GPRA (Government Performance and Results Act) and research evaluation for basic science

International Nuclear Information System (INIS)

Takahashi, Shoji

2002-08-01

The purpose of the Government Performance and Results Act of 1993 (GPRA) is to ask federal agencies for evaluating their program performance especially from cost-efficiency aspect and to report to Congress. GPRA is to hold agencies accountable for their programs by requiring that they think strategically (in most cases every 5 years) and set, measure and report goals annually. The agencies which have responsibilities for enhancing basic science like Department of Energy (DOE) and National Science Fund (NSF) are not excluded by reasons of the difficulties of economic evaluations. In Japan, based on 'the Rationalization program for the public corporations' of 2001, the research developing type corporations should make a cost-performance evaluation in addition to the conventional ones. They have same theme as US agencies struggles. The purpose of this report is to get some hints for this theme by surveying GPRA reports of DOE and NSF and analyzing related information. At present, I have to conclude although everybody accepts the necessities of socio-economic evaluations and investment criteria for basic research, studies and discussions about ways and means are still continuing even in the US. (author)

Indigenous opportunistic bacteria inhabit mammalian gut-associated lymphoid tissues and share a mucosal antibody-mediated symbiosis.

Science.gov (United States)

Obata, Takashi; Goto, Yoshiyuki; Kunisawa, Jun; Sato, Shintaro; Sakamoto, Mitsuo; Setoyama, Hiromi; Matsuki, Takahiro; Nonaka, Kazuhiko; Shibata, Naoko; Gohda, Masashi; Kagiyama, Yuki; Nochi, Tomonori; Yuki, Yoshikazu; Fukuyama, Yoshiko; Mukai, Akira; Shinzaki, Shinichiro; Fujihashi, Kohtaro; Sasakawa, Chihiro; Iijima, Hideki; Goto, Masatoshi; Umesaki, Yoshinori; Benno, Yoshimi; Kiyono, Hiroshi

2010-04-20

The indigenous bacteria create natural cohabitation niches together with mucosal Abs in the gastrointestinal (GI) tract. Here we report that opportunistic bacteria, largely Alcaligenes species, specifically inhabit host Peyer's patches (PPs) and isolated lymphoid follicles, with the associated preferential induction of antigen-specific mucosal IgA Abs in the GI tract. Alcaligenes were identified as the dominant bacteria on the interior of PPs from naïve, specific-pathogen-free but not from germ-free mice. Oral transfer of intratissue uncultured Alcaligenes into germ-free mice resulted in the presence of Alcaligenes inside the PPs of recipients. This result was further supported by the induction of antigen-specific Ab-producing cells in the mucosal (e.g., PPs) but not systemic compartment (e.g., spleen). The preferential presence of Alcaligenes inside PPs and the associated induction of intestinal secretory IgA Abs were also observed in both monkeys and humans. Localized mucosal Ab-mediated symbiotic immune responses were supported by Alcaligenes-stimulated CD11c(+) dendritic cells (DCs) producing the Ab-enhancing cytokines TGF-beta, B-cell-activating factor belonging to the TNF family, and IL-6 in PPs. These CD11c(+) DCs did not migrate beyond the draining mesenteric lymph nodes. In the absence of antigen-specific mucosal Abs, the presence of Alcaligenes in PPs was greatly diminished. Thus, indigenous opportunistic bacteria uniquely inhabit PPs, leading to PP-DCs-initiated, local antigen-specific Ab production; this may involve the creation of an optimal symbiotic environment on the interior of the PPs.

Enhancing Diversity in Undergraduate Science: Self-Efficacy Drives Performance Gains with Active Learning.

Science.gov (United States)

Ballen, Cissy J; Wieman, Carl; Salehi, Shima; Searle, Jeremy B; Zamudio, Kelly R

2017-01-01

Efforts to retain underrepresented minority (URM) students in science, technology, engineering, and mathematics (STEM) have shown only limited success in higher education, due in part to a persistent achievement gap between students from historically underrepresented and well-represented backgrounds. To test the hypothesis that active learning disproportionately benefits URM students, we quantified the effects of traditional versus active learning on student academic performance, science self-efficacy, and sense of social belonging in a large (more than 250 students) introductory STEM course. A transition to active learning closed the gap in learning gains between non-URM and URM students and led to an increase in science self-efficacy for all students. Sense of social belonging also increased significantly with active learning, but only for non-URM students. Through structural equation modeling, we demonstrate that, for URM students, the increase in self-efficacy mediated the positive effect of active-learning pedagogy on two metrics of student performance. Our results add to a growing body of research that supports varied and inclusive teaching as one pathway to a diversified STEM workforce. © 2017 C. J. Ballen et al. CBE—Life Sciences Education © 2017 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Opportunistic nectar-feeding birds are effective pollinators of bird-flowers from Canary Islands: experimental evidence from Isoplexis canariensis (Scrophulariaceae).

Science.gov (United States)

Rodríguez-Rodríguez, María C; Valido, Alfredo

2008-11-01

Insular floras, characterized by simple pollination networks, sometimes include novel mutualistic agents such as nonspecialist nectarivores. In this study we confirmed the effective pollination of Isoplexis canariensis by opportunistic nectar-feeding birds in Tenerife, Canary Islands, Spain. This plant is among the ornithophilous species of the Canarian flora that lack past and present specialist nectarivorous birds. Experimental hand pollinations revealed self-compatibility, but cross-pollinated flowers produced a greater percentage of viable seeds than self-pollinated ones. Flowers were visited by five species of birds (Phylloscopus canariensis, Parus caeruleus, Sylvia melanocephala, Serinus canarius, and Fringilla coelebs) and by the endemic lizard (Gallotia galloti, Lacertidae). Insect pollination was absent, and the few insect visitors acted as nectar thieves or secondary nectar robbers. Birds represented 93.1% of total visits, with the Canarian Chiffchaff, Ph. canariensis, being the most frequent visitor. Flowers visited by birds set more, larger, and heavier fruit than flowers from which birds were excluded. Bird visitation also enhanced seed viability. These results demonstrate the active role of these opportunistic birds as effective pollinators of this Canarian bird-flower species. Further, the results reveal the need to consider the effect of these birds on the evolution of ornithophilous floral traits in absence of specialist nectarivores.

High Performance Computing in Science and Engineering '99 : Transactions of the High Performance Computing Center

CERN Document Server

Jäger, Willi

2000-01-01

The book contains reports about the most significant projects from science and engineering of the Federal High Performance Computing Center Stuttgart (HLRS). They were carefully selected in a peer-review process and are showcases of an innovative combination of state-of-the-art modeling, novel algorithms and the use of leading-edge parallel computer technology. The projects of HLRS are using supercomputer systems operated jointly by university and industry and therefore a special emphasis has been put on the industrial relevance of results and methods.

Candida and Fusarium species known as opportunistic human pathogens from customer-accessible parts of residential washing machines.

Science.gov (United States)

Babič, Monika Novak; Zalar, Polona; Ženko, Bernard; Schroers, Hans-Josef; Džeroski, Sašo; Gunde-Cimerman, Nina

2015-03-01

Energy constraints have altered consumer practice regarding the use of household washing machines. Washing machines were developed that use lower washing temperatures, smaller amounts of water and biodegradable detergents. These conditions may favour the enrichment of opportunistic human pathogenic fungi. We focused on the isolation of fungi from two user-accessible parts of washing machines that often contain microbial biofilms: drawers for detergents and rubber door seals. Out of 70 residential washing machines sampled in Slovenia, 79% were positive for fungi. In total, 72 strains belonging to 12 genera and 26 species were isolated. Among these, members of the Fusarium oxysporum and Fusarium solani species complexes, Candida parapsilosis and Exophiala phaeomuriformis represented 44% of fungi detected. These species are known as opportunistic human pathogens and can cause skin, nail or eye infections also in healthy humans. A machine learning analysis revealed that presence of detergents and softeners followed by washing temperature, represent most critical factors for fungal colonization. Three washing machines with persisting malodour that resulted in bad smelling laundry were analysed for the presence of fungi and bacteria. In these cases, fungi were isolated in low numbers (7.5 %), while bacteria Micrococcus luteus, Pseudomonas aeruginosa, and Sphingomonas species prevailed. Copyright © 2014 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

FY01 Supplemental Science and Performance Analysis: Volume 1, Scientific Bases and Analyses

International Nuclear Information System (INIS)

Bodvarsson, G.S.; Dobson, David

2001-01-01

The U.S. Department of Energy (DOE) is considering the possible recommendation of a site at Yucca Mountain, Nevada, for development as a geologic repository for the disposal of high-level radioactive waste and spent nuclear fuel. To facilitate public review and comment, in May 2001 the DOE released the Yucca Mountain Science and Engineering Report (S and ER) (DOE 2001 [DIRS 153849]), which presents technical information supporting the consideration of the possible site recommendation. The report summarizes the results of more than 20 years of scientific and engineering studies. A decision to recommend the site has not been made: the DOE has provided the S and ER and its supporting documents as an aid to the public in formulating comments on the possible recommendation. When the S and ER (DOE 2001 [DIRS 153849]) was released, the DOE acknowledged that technical and scientific analyses of the site were ongoing. Therefore, the DOE noted in the Federal Register Notice accompanying the report (66 FR 23013 [DIRS 155009], p. 2) that additional technical information would be released before the dates, locations, and times for public hearings on the possible recommendation were announced. This information includes: (1) the results of additional technical studies of a potential repository at Yucca Mountain, contained in this FY01 Supplemental Science and Performance Analyses: Vol. 1, Scientific Bases and Analyses; and FY01 Supplemental Science and Performance Analyses: Vol. 2, Performance Analyses (McNeish 2001 [DIRS 155023]) (collectively referred to as the SSPA) and (2) a preliminary evaluation of the Yucca Mountain site's preclosure and postclosure performance against the DOE's proposed site suitability guidelines (10 CFR Part 963 [64 FR 67054 [DIRS 124754

FY01 Supplemental Science and Performance Analysis: Volume 1,Scientific Bases and Analyses

Energy Technology Data Exchange (ETDEWEB)

Bodvarsson, G.S.; Dobson, David

2001-05-30

The U.S. Department of Energy (DOE) is considering the possible recommendation of a site at Yucca Mountain, Nevada, for development as a geologic repository for the disposal of high-level radioactive waste and spent nuclear fuel. To facilitate public review and comment, in May 2001 the DOE released the Yucca Mountain Science and Engineering Report (S&ER) (DOE 2001 [DIRS 153849]), which presents technical information supporting the consideration of the possible site recommendation. The report summarizes the results of more than 20 years of scientific and engineering studies. A decision to recommend the site has not been made: the DOE has provided the S&ER and its supporting documents as an aid to the public in formulating comments on the possible recommendation. When the S&ER (DOE 2001 [DIRS 153849]) was released, the DOE acknowledged that technical and scientific analyses of the site were ongoing. Therefore, the DOE noted in the Federal Register Notice accompanying the report (66 FR 23013 [DIRS 155009], p. 2) that additional technical information would be released before the dates, locations, and times for public hearings on the possible recommendation were announced. This information includes: (1) the results of additional technical studies of a potential repository at Yucca Mountain, contained in this FY01 Supplemental Science and Performance Analyses: Vol. 1, Scientific Bases and Analyses; and FY01 Supplemental Science and Performance Analyses: Vol. 2, Performance Analyses (McNeish 2001 [DIRS 155023]) (collectively referred to as the SSPA) and (2) a preliminary evaluation of the Yucca Mountain site's preclosure and postclosure performance against the DOE's proposed site suitability guidelines (10 CFR Part 963 [64 FR 67054 [DIRS 124754

Crossing the Gender Gap: A Study of Female Participation and Performance in Advanced Maths and Sciences

Science.gov (United States)

Haseltine, Jessica

2006-10-01

A statistical analysis of enrollment in AP maths and sciences in the Abilene Independent School District, between 2000 and 2005, studied the relationship between gender, enrollment, and performance. Data suggested that mid-scoring females were less likely than their male counterparts to enroll in AP-level courses. AISD showed higher female : male score ratios than national and state averages but no improvement in enrollment comparisons. Several programs are suggested to improve both participation and performance of females in upper-level math and science courses.

Assessing the Groundwater Quality at a Saudi Arabian Agricultural Site and the Occurrence of Opportunistic Pathogens on Irrigated Food Produce

KAUST Repository

Alsalah, Dhafer

2015-10-05

This study examines the groundwater quality in wells situated near agricultural fields in Saudi Arabia. Fruits (e.g., tomato and green pepper) irrigated with groundwater were also assessed for the occurrence of opportunistic pathogens to determine if food safety was compromised by the groundwater. The amount of total nitrogen in most of the groundwater samples exceeded the 15 mg/L permissible limit for agricultural irrigation. Fecal coliforms in densities > 12 MPN/100 mL were detected in three of the groundwater wells that were in close proximity to a chicken farm. These findings, coupled with qPCR-based fecal source tracking, show that groundwater in wells D and E, which were nearest to the chicken farm, had compromised quality. Anthropogenic contamination resulted in a shift in the predominant bacterial phyla within the groundwater microbial communities. For example, there was an elevated presence of Proteobacteria and Cyanobacteria in wells D and E but a lower overall microbial richness in the groundwater perturbed by anthropogenic contamination. In the remaining wells, the genus Acinetobacter was detected at high relative abundance ranging from 1.5% to 48% of the total groundwater microbial community. However, culture-based analysis did not recover any antibiotic-resistant bacteria or opportunistic pathogens from these groundwater samples. In contrast, opportunistic pathogenic Enterococcus faecalis and Pseudomonas aeruginosa were isolated from the fruits irrigated with the groundwater from wells B and F. Although the groundwater was compromised, quantitative microbial risk assessment suggests that the annual risk incurred from accidental consumption of E. faecalis on these fruits was within the acceptable limit of 10−4. However, the annual risk arising from P. aeruginosa was 9.55 × 10−4, slightly above the acceptable limit. Our findings highlight that the groundwater quality at this agricultural site in western Saudi Arabia is not pristine and that better

The relationship between emotional intelligence with administrators’ performance at Mashhad University of Medical Sciences

Science.gov (United States)

Sadeghi, Tooraj; Saeidi, Masumeh; Moghaddam, Habibolah Taghizade; Ghodsi, Mohammad Jafari; Hoseini, Rasoul

2018-01-01

Background The leadership of an organization requires specific features to adapt to changes and to survive and grow in new environments, and emotional intelligence is one of the most important attributes that can help leaders and managers respond to these changes. Objective This study aimed to determine the relationship between emotional intelligence with administrators’ performance at Mashhad University of Medical Sciences, Mashhad, Iran. Methods This cross-sectional study was conducted on 100 basic and middle managers of Mashhad University of Medical Sciences, Mashhad, Iran who were selected by census method in 2016. The instrument of data collecting was the “Inventory Shrinkage”, and the “Organizational performance evaluation forms”. The data were analyzed by SPSS version 16 using descriptive statistics and Spearman correlation. Results The results showed there was a significant negative correlation between emotional intelligence and organizational performance in administrators (r=−0.214, p=0.032). The findings also showed that among the components of emotional intelligence and administrators’ performance, only components of empathy, was there a significant negative correlation (r=−0.199, p=0.047). Also, there was no statistically significant relationship between emotional intelligence and demographic variables such as work experience, age, marital status and education level (p>0.05). There was no significant relationship between organizational performance and demographic variables, either (p>0.05). But between the components of emotional intelligence, only for social skills and work place of administrators, a significant positive correlation was confirmed (r=0.203, p=0.043). Conclusions The results of this study showed that there was a negative and significant correlation between the components of emotional intelligence and administrators’ performance of Mashhad University of Medical Sciences administrators, only in the empathy component. PMID

Personalized Opportunistic Computing for CMS at Large Scale

CERN Multimedia

CERN. Geneva

2015-01-01

**Douglas Thain** is an Associate Professor of Computer Science and Engineering at the University of Notre Dame, where he designs large scale distributed computing systems to power the needs of advanced science and...

Candida glabrata: an emerging oral opportunistic pathogen.

Science.gov (United States)

Li, L; Redding, S; Dongari-Bagtzoglou, A

2007-03-01

Following the widespread use of immunosuppressive therapy and broad-spectrum antimycotic prophylaxis, C. glabrata has emerged as an important opportunistic pathogen in the oral mucosa. In the past, studies on the virulence factors and host-pathogen interactions of this organism were scarce, but continued to rise in recent years. Denture-wearing, immunosuppression, antibiotic therapy, and aging are risk factors for oral colonization or infection with C. glabrata. Compared with C. albicans, C. glabrata exhibits lower oral keratinocyte-adherence capacity, but higher denture-surface-adherence ability. The role of extracellular hydrolase production in the virulence of this organism does not appear to be as important as it is in C. albicans pathogenesis. Although traditionally thought of as a non-transforming yeast organism, both phenotypic switching and pseudohyphal formation have recently been identified in C. glabrata, but their role in pathogenesis is not known. With the exception of granulocyte monocyte colony-stimulating factor, C. glabrata triggers a lower proinflammatory cytokine response in oral epithelial cells than does C. albicans, in a strain-dependent manner. C. glabrata is less susceptible to killing by human beta-defensins than is C. albicans and exhibits various degrees of resistance to the antifungal activity of salivary histatins and mucins. In addition, C. glabrata possesses both innate and acquired resistance against antifungal drugs, due to its ability to modify ergosterol biosynthesis, mitochondrial function, or antifungal efflux. This resistance allows for its relative overgrowth over other susceptible species and may contribute to the recent emergence of C. glabrata infections in chronically immunocompromised populations. Further investigations on the virulence and host-pathogen interactions of C. glabrata are needed to better define the pathogenesis of oral C. glabrata infection in susceptible hosts.

Performing the Future. On the Use of Drama in Philosophy Courses for Science Students

Science.gov (United States)

Toonders, Winnie; Verhoeff, Roald P.; Zwart, Hub

2016-10-01

Drama is a relatively unexplored tool in academic science education. This paper addresses in what way the use of drama may allow science students to deepen their understanding of recent developments in the emerging and controversial field of neuro-enhancement, by means of a case study approach. First, we emphasise the congruency between drama and science, notably the dramatic dimension of experimental research. Subsequently, we draw on educational literature to elaborate the potential of using drama as a teaching modality, specifically focusing on the ethical and moral dimensions of future techno-scientific innovations. Our case study consisted of a drama experiment as a module in a philosophy course on human enhancement. Twenty-two students from various science disciplines performed multiple roles, as authors, actors, audience and reviewers. Qualitative data were collected on the educational process and student performance during the course, i.e. observations and video recordings of class discussions, group work and plays, interviews and questionnaires. Our drama experiment proved to be effective in enabling students to explore and relate to a future life world affected by enhancement technologies. It allowed them to deepen their awareness of social and ethical implications of neuro-technologies and of the different viewpoints people may have on this issue in academic, professional or everyday settings. Moreover, drama allowed them to develop a reflexive position of their own in the neuro-enhancement debate by enacting a moral dilemma in front of an audience. Our results confirm the potential of drama as a tool for exploring techno-scientific futures in science education.

Antimicrobial therapy for the treatment of opportunistic infections in HIV/AIDS patients: a critical appraisal

Directory of Open Access Journals (Sweden)

Seddon J

2011-04-01

Full Text Available Jo Seddon1, Sanjay Bhagani21Department of Infectious Diseases, Imperial College Healthcare NHS Trust, London, UK; 2Department of Infection and Immunity, Royal Free Hospital NHS Trust, London, UKAbstract: The widespread use of antiretroviral therapy (ART has entirely changed the management of human immunodeficiency virus (HIV infection and dramatically reduced the rates of opportunistic infections (OI. However, OI continue to cause significant morbidity and mortality in both developed countries, where presentation with advanced HIV infection is common, and also in developing countries where ART is less widely available. Evidence to direct OI guidelines is partly limited by the fact that many large-scale studies date from the pre-ART era and more recent studies are sometimes poorly powered due to the falling rates of OI. Treatment of OI is now known to be as much about antimicrobials as about immune reconstitution with ART, and recent studies help guide the timing of initiation of ART in different infections. OI have also become complicated by the immune reconstitution inflammatory syndrome phenomenon which may occur once successful immune recovery begins. Trimethoprim-sulfamethoxazole has long been one of the most important antibiotics in the treatment and prevention of OI and remains paramount. It has a broad spectrum of activity against Pneumocystis jiroveci, toxoplasmosis, and bacterial infections and has an important role to play in preventing life-threatening OI. New advances in treating OI are coming from a variety of quarters: in cytomegalovirus eye disease, the use of oral rather than intravenous drugs is changing the face of therapy; in cryptococcal meningitis, improved drug formulations and combination therapy is improving clearance rates and reducing drug toxicities; and in gut disease, the possibility of rapid immune restitution with ART is replacing the need for antimicrobials against cryptosporidia and microsporidia.Keywords: HIV

The opportunistic screening of refractive errors in school-going children by pediatrician using enhanced Brückner test

Directory of Open Access Journals (Sweden)

Piyush Jain

2016-01-01

Full Text Available Aim: The aim of this study was to compare the results of enhanced Brückner test (EBT performed by a pediatrician and an experienced pediatric ophthalmologist. Subjects and Methods: In this prospective double-masked cohort study, a pediatrician and a pediatric ophthalmologist performed the EBT in a classroom of a school in semi-dark lighting condition using a direct ophthalmoscope. The results of the test were compared using 2 × 2 Bayesian table and kappa statistics. The findings of the pediatric ophthalmologists were considered gold standard. Results: Two hundred and thirty-six eyes of 118 subjects, mean age 6.8 ± 0.5 years (range, 5.4–7.8 years, were examined. The time taken to complete this test was <10 s per subject. The ophthalmologist identified 59 eyes as ametropic (12 hyperopic and 47 myopic eyes and 177 as emmetropic compared to 61 eyes as ametropic and 175 emmetropic by pediatrician. The prevalence of the test positive was 25.9%. The sensitivity of the pediatrician was 90.2%, specificity was 97.7%, predictive value of the positive test was 93.2%, and predictive value of the negative test was 96.6%. The clinical agreement (kappa between the pediatric ophthalmologist and the pediatrician was 0.9. Conclusion: The results of the EBT performed by pediatrician were comparable to that of an experienced pediatric ophthalmologist. Opportunistic screening of refractive errors using EBT by a pediatrician can be an important approach in the detection of ametropia in children.

Performance study and optimization of cooperative diversity networks with co-channel interference

KAUST Repository

Ikki, Salama Said

2014-01-01

In this paper, we investigate the effect of co-channel interference on the performance of cooperative diversity networks with amplify-and-forward (AF) relaying. We consider both conventional and opportunistic relaying. First, we obtain a tight upper-bound for the equivalent signal-to-interference-plus-noise ratio (SINR) at the destination. Subsequently, the cumulative distribution function (CDF), probability density function (PDF) and moment generating function (MGF) of the effective SINR are determined based on the upper-bound. Expressions for the error probabilities in both conventional and opportunistic relaying are derived utilizing the statistical characterization of the effective SINR. We also derive an approximate PDF of the equivalent instantaneous SINR at the destination. This leads to a simple and general asymptotic error probability expression which facilitates better insight into the effect of different system parameters on the error probability. Furthermore, we investigate the problem of optimum resource allocation in the network aiming at improving performance in the presence of resource constraints. We present numerical results that illustrate the excellent match between the analytical results and the simulation results, and the performance enhancement resulting from the proposed optimal resource allocation. © 2014 IEEE.

Opportunistic beam training with hybrid analog/digital codebooks for mmWave systems

KAUST Repository

Eltayeb, Mohammed E.

2016-02-25

© 2015 IEEE. Millimeter wave (mmWave) communication is one solution to provide more spectrum than available at lower carrier frequencies. To provide sufficient link budget, mmWave systems will use beamforming with large antenna arrays at both the transmitter and receiver. Training these large arrays using conventional approaches taken at lower carrier frequencies, however, results in high overhead. In this paper, we propose a beam training algorithm that efficiently designs the beamforming vectors with low training overhead. Exploiting mmWave channel reciprocity, the proposed algorithm relaxes the need for an explicit feedback channel, and opportunistically terminates the training process when a desired quality of service is achieved. To construct the training beamforming vectors, a new multi-resolution codebook is developed for hybrid analog/digital architectures. Simulation results show that the proposed algorithm achieves a comparable rate to that obtained by exhaustive search solutions while requiring lower training overhead when compared to prior work.

Opportunistic beam training with hybrid analog/digital codebooks for mmWave systems

KAUST Repository

Eltayeb, Mohammed E.; Alkhateeb, Ahmed; Heath, Robert W.; Al-Naffouri, Tareq Y.

2016-01-01

© 2015 IEEE. Millimeter wave (mmWave) communication is one solution to provide more spectrum than available at lower carrier frequencies. To provide sufficient link budget, mmWave systems will use beamforming with large antenna arrays at both the transmitter and receiver. Training these large arrays using conventional approaches taken at lower carrier frequencies, however, results in high overhead. In this paper, we propose a beam training algorithm that efficiently designs the beamforming vectors with low training overhead. Exploiting mmWave channel reciprocity, the proposed algorithm relaxes the need for an explicit feedback channel, and opportunistically terminates the training process when a desired quality of service is achieved. To construct the training beamforming vectors, a new multi-resolution codebook is developed for hybrid analog/digital architectures. Simulation results show that the proposed algorithm achieves a comparable rate to that obtained by exhaustive search solutions while requiring lower training overhead when compared to prior work.

Comparative analysis of glutaredoxin domains from bacterial opportunistic pathogens

International Nuclear Information System (INIS)

Leeper, Thomas; Zhang, Suxin; Van Voorhis, Wesley C.; Myler, Peter J.; Varani, Gabriele

2011-01-01

NMR structures of the glutaredoxin (GLXR) domains from Br. melitensis and Ba. henselae have been determined as part of the SSGCID initiative. Comparison of the domains with known structures reveals overall structural similarity between these proteins and previously determined E. coli GLXR structures, with minor changes associated with the position of helix 1 and with regions that diverge from similar structures found in the closest related human homolog. Glutaredoxin proteins (GLXRs) are essential components of the glutathione system that reductively detoxify substances such as arsenic and peroxides and are important in the synthesis of DNA via ribonucleotide reductases. NMR solution structures of glutaredoxin domains from two Gram-negative opportunistic pathogens, Brucella melitensis and Bartonella henselae, are presented. These domains lack the N-terminal helix that is frequently present in eukaryotic GLXRs. The conserved active-site cysteines adopt canonical proline/tyrosine-stabilized geometries. A difference in the angle of α-helix 2 relative to the β-sheet surface and the presence of an extended loop in the human sequence suggests potential regulatory regions and/or protein–protein interaction motifs. This observation is consistent with mutations in this region that suppress defects in GLXR–ribonucleotide reductase interactions. These differences between the human and bacterial forms are adjacent to the dithiol active site and may permit species-selective drug design

Factors influencing cerebrospinal fluid and plasma HIV-1 RNA detection rate in patients with and without opportunistic neurological disease during the HAART era

Directory of Open Access Journals (Sweden)

Aleixo Agdemir W

2007-12-01

Full Text Available Abstract Background In the central nervous system, HIV replication can occur relatively independent of systemic infection, and intrathecal replication of HIV-1 has been observed in patients with HIV-related and opportunistic neurological diseases. The clinical usefulness of HIV-1 RNA detection in the cerebrospinal fluid (CSF of patients with opportunistic neurological diseases, or the effect of opportunistic diseases on CSF HIV levels in patients under HAART has not been well defined. We quantified CSF and plasma viral load in HIV-infected patients with and without different active opportunistic neurological diseases, determined the characteristics that led to a higher detection rate of HIV RNA in CSF, and compared these two compartments. Methods A prospective study was conducted on 90 HIV-infected patients submitted to lumbar puncture as part of a work-up for suspected neurological disease. Seventy-one patients had active neurological diseases while the remaining 19 did not. Results HIV-1 RNA was quantified in 90 CSF and 70 plasma samples. The HIV-1 RNA detection rate in CSF was higher in patients with neurological diseases, in those with a CD4 count lower than 200 cells/mm3, and in those not receiving antiretroviral therapy, as well as in patients with detectable plasma HIV-1 RNA. Median viral load was lower in CSF than in plasma in the total population, in patients without neurological diseases, and in patients with toxoplasmic encephalitis, while no significant difference between the two compartments was observed for patients with cryptococcal meningitis and HIV-associated dementia. CSF viral load was lower in patients with cryptococcal meningitis and neurotoxoplasmosis under HAART than in those not receiving HAART. Conclusion Detection of HIV-1 RNA in CSF was more frequent in patients with neurological disease, a CD4 count lower than 200 cells/mm3 and detectable plasma HIV-1. Median HIV-1 RNA levels were generally lower in CSF than in

Performance-based alternative assessments as a means of eliminating gender achievement differences on science tests

Science.gov (United States)

Brown, Norman Merrill

1998-09-01

Historically, researchers have reported an achievement difference between females and males on standardized science tests. These differences have been reported to be based upon science knowledge, abstract reasoning skills, mathematical abilities, and cultural and social phenomena. This research was designed to determine how mastery of specific science content from public school curricula might be evaluated with performance-based assessment models, without producing gender achievement differences. The assessment instruments used were Harcourt Brace Educational Measurement's GOALSsp°ler: A Performance-Based Measure of Achievement and the performance-based portion of the Stanford Achievement Testspcopyright, Ninth Edition. The identified independent variables were test, gender, ethnicity, and grade level. A 2 x 2 x 6 x 12 (test x gender x ethnicity x grade) factorial experimental design was used to organize the data. A stratified random sample (N = 2400) was selected from a national pool of norming data: N = 1200 from the GOALSsp°ler group and N = 1200 from the SAT9spcopyright group. The ANOVA analysis yielded mixed results. The factors of test, gender, ethnicity by grade, gender by grade, and gender by grade by ethnicity failed to produce significant results (alpha = 0.05). The factors yielding significant results were ethnicity, grade, and ethnicity by grade. Therefore, no significant differences were found between female and male achievement on these performance-based assessments.

Using Decision Tree Analysis to Understand Foundation Science Student Performance. Insight Gained at One South African University

Science.gov (United States)

Kirby, Nicola Frances; Dempster, Edith Roslyn

2014-11-01

The Foundation Programme of the Centre for Science Access at the University of KwaZulu-Natal, South Africa provides access to tertiary science studies to educationally disadvantaged students who do not meet formal faculty entrance requirements. The low number of students proceeding from the programme into mainstream is of concern, particularly given the national imperative to increase participation and levels of performance in tertiary-level science. An attempt was made to understand foundation student performance in a campus of this university, with the view to identifying challenges and opportunities for remediation in the curriculum and processes of selection into the programme. A classification and regression tree analysis was used to identify which variables best described student performance. The explanatory variables included biographical and school-history data, performance in selection tests, and socio-economic data pertaining to their year in the programme. The results illustrate the prognostic reliability of the model used to select students, raise concerns about the inefficiency of school performance indicators as a measure of students' academic potential in the Foundation Programme, and highlight the importance of accommodation arrangements and financial support for student success in their access year.

Association of Health Sciences Reasoning Test scores with academic and experiential performance.

Science.gov (United States)

Cox, Wendy C; McLaughlin, Jacqueline E

2014-05-15

To assess the association of scores on the Health Sciences Reasoning Test (HSRT) with academic and experiential performance in a doctor of pharmacy (PharmD) curriculum. The HSRT was administered to 329 first-year (P1) PharmD students. Performance on the HSRT and its subscales was compared with academic performance in 29 courses throughout the curriculum and with performance in advanced pharmacy practice experiences (APPEs). Significant positive correlations were found between course grades in 8 courses and HSRT overall scores. All significant correlations were accounted for by pharmaceutical care laboratory courses, therapeutics courses, and a law and ethics course. There was a lack of moderate to strong correlation between HSRT scores and academic and experiential performance. The usefulness of the HSRT as a tool for predicting student success may be limited.

Learning approaches as predictors of academic performance in first year health and science students.

Science.gov (United States)

Salamonson, Yenna; Weaver, Roslyn; Chang, Sungwon; Koch, Jane; Bhathal, Ragbir; Khoo, Cheang; Wilson, Ian

2013-07-01

To compare health and science students' demographic characteristics and learning approaches across different disciplines, and to examine the relationship between learning approaches and academic performance. While there is increasing recognition of a need to foster learning approaches that improve the quality of student learning, little is known about students' learning approaches across different disciplines, and their relationships with academic performance. Prospective, correlational design. Using a survey design, a total of 919 first year health and science students studying in a university located in the western region of Sydney from the following disciplines were recruited to participate in the study - i) Nursing: n = 476, ii) Engineering: n = 75, iii) Medicine: n = 77, iv) Health Sciences: n = 204, and v) Medicinal Chemistry: n = 87. Although there was no statistically significant difference in the use of surface learning among the five discipline groups, there were wide variations in the use of deep learning approach. Furthermore, older students and those with English as an additional language were more likely to use deep learning approach. Controlling for hours spent in paid work during term-time and English language usage, both surface learning approach (β = -0.13, p = 0.001) and deep learning approach (β = 0.11, p = 0.009) emerged as independent and significant predictors of academic performance. Findings from this study provide further empirical evidence that underscore the importance for faculty to use teaching methods that foster deep instead of surface learning approaches, to improve the quality of student learning and academic performance. Copyright © 2013 Elsevier Ltd. All rights reserved.

A review of boiling water reactor water chemistry: Science, technology, and performance

International Nuclear Information System (INIS)

Fox, M.J.

1989-02-01

Boiling water reactor (BWR) water chemistry (science, technology, and performance) has been reviewed with an emphasis on the relationships between BWR water quality and corrosion fuel performance, and radiation buildup. A comparison of Nuclear Regulatory Commission (NRC) Regulatory Guide 1.56, the Boiling Water Reactor Owners Group (BWROG) Water Chemistry Guidelines, and Plant Technical Specifications showed that the BWROG Guidelines are more stringent than the NRC Regulatory Guide, which is almost identical to Plant Technical Specifications. Plant performance with respect to BWR water chemistry has shown dramatic improvements in recent years. Up until 1979 BWRs experienced an average of 3.0 water chemistry incidents per reactor-year. Since 1979 the water chemistry technical specifications have been violated an average of only 0.2 times per reactor-year, with the most recent data from 1986-1987 showing only 0.05 violations per reactor-year. The data clearly demonstrate the industry-wide commitment to improving water quality in BWRs. In addition to improving water quality, domestic BWRs are beginning to switch to hydrogen water chemistry (HWC), a remedy for intergranular stress corrosion cracking. Three domestic BWRs are presently operating on HWC, and fourteen more have either performed HWC mini tests or are in various stages of HWC implementation. This report includes a detailed review of HWC science and technology as well as areas in which further research on BWR chemistry may be needed. 43 refs., 30 figs., 8 tabs

Response of benthic opportunistic polychaetes and amphipods index to different perturbations in coastal oligotrophic areas (Canary archipelago, North East Atlantic Ocean)

OpenAIRE

Riera, Rodrigo; de-la-Ossa-Carretero, Jose Antonio

2014-01-01

Oligotrophic areas harbour low macrofaunal abundance and patchy distribution. In these areas it is necessary to test the reliability of biological indicators, especially those based on taxonomic sufficiency where the level of identification is balanced against the need for ecological information and could affect the efficiency of bioindicators. The BOPA (benthic opportunistic polychaetes and amphipods) index was applied in five coastal areas subjected to different perturbations (aquaculture, ...

Assessing does not mean threatening: the purpose of assessment as a key determinant of girls' and boys' performance in a science class.

Science.gov (United States)

Souchal, Carine; Toczek, Marie-Christine; Darnon, Céline; Smeding, Annique; Butera, Fabrizio; Martinot, Delphine

2014-03-01

Is it possible to reach performance equality between boys and girls in a science class? Given the stereotypes targeting their groups in scientific domains, diagnostic contexts generally lower girls' performance and non-diagnostic contexts may harm boys' performance. The present study tested the effectiveness of a mastery-oriented assessment, allowing both boys and girls to perform at an optimal level in a science class. Participants were 120 boys and 72 girls (all high-school students). Participants attended a science lesson while expecting a performance-oriented assessment (i.e., an assessment designed to compare and select students), a mastery-oriented assessment (i.e., an assessment designed to help students in their learning), or no assessment of this lesson. In the mastery-oriented assessment condition, both boys and girls performed at a similarly high level, whereas the performance-oriented assessment condition reduced girls' performance and the no-assessment condition reduced boys' performance. One way to increase girls' performance on a science test without harming boys' performance is to present assessment as a tool for improving mastery rather than as a tool for comparing performances. © 2013 The British Psychological Society.

Minimizing predatory lending: Designing a long-term compensation structure to minimize the actions of opportunistic mortgage brokers

Directory of Open Access Journals (Sweden)

Patrick Payne

2013-07-01

Full Text Available This paper addresses the inadequacies in the current compensation structure for mortgage brokers, and asserts that the resulting opportunistic behavior by brokers played a major role in the 2008 collapse of the mortgage market. We utilize agency theory as an underpinning to suggest that increased regulation will have only a limited impact on self-serving behavior due to the complex information asymmetries possessed by brokers. We posit that a restructured long-term compensation package would be effective in aligning the interests of borrowers and brokers, ultimately reducing the level of mortgage defaults and foreclosures.

High Performance Computing in Science and Engineering '98 : Transactions of the High Performance Computing Center

CERN Document Server

Jäger, Willi

1999-01-01

The book contains reports about the most significant projects from science and industry that are using the supercomputers of the Federal High Performance Computing Center Stuttgart (HLRS). These projects are from different scientific disciplines, with a focus on engineering, physics and chemistry. They were carefully selected in a peer-review process and are showcases for an innovative combination of state-of-the-art physical modeling, novel algorithms and the use of leading-edge parallel computer technology. As HLRS is in close cooperation with industrial companies, special emphasis has been put on the industrial relevance of results and methods.

NCI's High Performance Computing (HPC) and High Performance Data (HPD) Computing Platform for Environmental and Earth System Data Science

Science.gov (United States)

Evans, Ben; Allen, Chris; Antony, Joseph; Bastrakova, Irina; Gohar, Kashif; Porter, David; Pugh, Tim; Santana, Fabiana; Smillie, Jon; Trenham, Claire; Wang, Jingbo; Wyborn, Lesley

2015-04-01

The National Computational Infrastructure (NCI) has established a powerful and flexible in-situ petascale computational environment to enable both high performance computing and Data-intensive Science across a wide spectrum of national environmental and earth science data collections - in particular climate, observational data and geoscientific assets. This paper examines 1) the computational environments that supports the modelling and data processing pipelines, 2) the analysis environments and methods to support data analysis, and 3) the progress so far to harmonise the underlying data collections for future interdisciplinary research across these large volume data collections. NCI has established 10+ PBytes of major national and international data collections from both the government and research sectors based on six themes: 1) weather, climate, and earth system science model simulations, 2) marine and earth observations, 3) geosciences, 4) terrestrial ecosystems, 5) water and hydrology, and 6) astronomy, social and biosciences. Collectively they span the lithosphere, crust, biosphere, hydrosphere, troposphere, and stratosphere. The data is largely sourced from NCI's partners (which include the custodians of many of the major Australian national-scale scientific collections), leading research communities, and collaborating overseas organisations. New infrastructures created at NCI mean the data collections are now accessible within an integrated High Performance Computing and Data (HPC-HPD) environment - a 1.2 PFlop supercomputer (Raijin), a HPC class 3000 core OpenStack cloud system and several highly connected large-scale high-bandwidth Lustre filesystems. The hardware was designed at inception to ensure that it would allow the layered software environment to flexibly accommodate the advancement of future data science. New approaches to software technology and data models have also had to be developed to enable access to these large and exponentially

On performing concepts during science lectures

Science.gov (United States)

Pozzer-Ardenghi, Lilian; Roth, Wolff-Michael

2007-01-01

When lecturing, teachers make use of both verbal and nonverbal communication. What is called teaching, therefore, involves not only the words and sentences a teacher utters and writes on the board during a lesson, but also all the hands/arms gestures, body movements, and facial expressions a teacher performs in the classroom. All of these communicative modalities constitute resources that are made available to students for making sense of and learning from lectures. Yet in the literature on teaching science, these other means of communication are little investigated and understood - and, correspondingly, they are undertheorized. The purpose of this position paper is to argue for a different view of concepts in lectures: they are performed simultaneously drawing on and producing multiple resources that are different expressions of the same holistic meaning unit. To support our point, we provide examples from a database of 26 lectures in a 12th-grade biology class, where the human body was the main topic of study. We analyze how different types of resources - including verbal and nonverbal discourse and various material artifacts - interact during lectures. We provide evidence for the unified production of these various sense-making resources during teaching to constitute a meaning unit, and we emphasize particularly the use of gestures and body orientations inside this meaning unit. We suggest that proper analyses of meaning units need to take into account not only language and diagrams but also a lecturer's pointing and depicting gestures, body positions, and the relationships between these different modalities. Scientific knowledge (conceptions) exists in the concurrent display of all sense-making resources, which we, following Vygotsky, understand as forming a unit (identity) of nonidentical entities.

Predictors of science success: The impact of motivation and learning strategies on college chemistry performance

Science.gov (United States)

Obrentz, Shari B.

As the number of college students studying science continues to grow, it is important to identify variables that predict their success. The literature indicates that motivation and learning strategy use facilitate science success. Research findings show these variables can change throughout a semester and differ by performance level, gender and ethnicity. However, significant predictors of performance vary by research study and by group. The current study looks beyond the traditional predictors of grade point averages, SAT scores and completion of advanced placement (AP) chemistry to consider a comprehensive set of variables not previously investigated within the same study. Research questions address the predictive ability of motivation constructs and learning strategies for success in introductory college chemistry, how these variables change throughout a semester, and how they differ by performance level, gender and ethnicity. Participants were 413 introductory college chemistry students at a highly selective university in the southeast. Participants completed the Chemistry Motivation Questionnaire (CMQ) and Learning Strategies section of the Motivated Strategies for Learning Questionnaire (MSLQ) three times during the semester. Self-efficacy, effort regulation, assessment anxiety and previous achievement were significant predictors of chemistry course success. Levels of motivation changed with significant decreases in self-efficacy and increases in personal relevance and assessment anxiety. Learning strategy use changed with significant increases in elaboration, critical thinking, metacognitive self-regulation skills and peer learning, and significant decreases in time and study management and effort regulation. High course performers reported the highest levels of motivation and learning strategy use. Females reported lower intrinsic motivation, personal relevance, self-efficacy and critical thinking, and higher assessment anxiety, rehearsal and organization

Science of science.

Science.gov (United States)

Fortunato, Santo; Bergstrom, Carl T; Börner, Katy; Evans, James A; Helbing, Dirk; Milojević, Staša; Petersen, Alexander M; Radicchi, Filippo; Sinatra, Roberta; Uzzi, Brian; Vespignani, Alessandro; Waltman, Ludo; Wang, Dashun; Barabási, Albert-László

2018-03-02

Identifying fundamental drivers of science and developing predictive models to capture its evolution are instrumental for the design of policies that can improve the scientific enterprise-for example, through enhanced career paths for scientists, better performance evaluation for organizations hosting research, discovery of novel effective funding vehicles, and even identification of promising regions along the scientific frontier. The science of science uses large-scale data on the production of science to search for universal and domain-specific patterns. Here, we review recent developments in this transdisciplinary field. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Learning and study strategies correlate with medical students' performance in anatomical sciences.

Science.gov (United States)

Khalil, Mohammed K; Williams, Shanna E; Gregory Hawkins, H

2018-05-06

Much of the content delivered during medical students' preclinical years is assessed nationally by such testing as the United States Medical Licensing Examination ® (USMLE ® ) Step 1 and Comprehensive Osteopathic Medical Licensing Examination ® (COMPLEX-USA ® ) Step 1. Improvement of student study/learning strategies skills is associated with academic success in internal and external (USMLE Step 1) examinations. This research explores the strength of association between the Learning and Study Strategies Inventory (LASSI) scores and student performance in the anatomical sciences and USMLE Step 1 examinations. The LASSI inventory assesses learning and study strategies based on ten subscale measures. These subscales include three components of strategic learning: skill (Information processing, Selecting main ideas, and Test strategies), will (Anxiety, Attitude, and Motivation) and self-regulation (Concentration, Time management, Self-testing, and Study aid). During second year (M2) orientation, 180 students (Classes of 2016, 2017, and 2018) were administered the LASSI survey instrument. Pearson Product-Moment correlation analyses identified significant associations between five of the ten LASSI subscales (Anxiety, Information processing, Motivation, Selecting main idea, and Test strategies) and students' performance in the anatomical sciences and USMLE Step 1 examinations. Identification of students lacking these skills within the anatomical sciences curriculum allows targeted interventions, which not only maximize academic achievement in an aspect of an institution's internal examinations, but in the external measure of success represented by USMLE Step 1 scores. Anat Sci Educ 11: 236-242. © 2017 American Association of Anatomists. © 2017 American Association of Anatomists.

Life science experiments performed in space in the ISS/Kibo facility and future research plans.

Science.gov (United States)

Ohnishi, Takeo

2016-08-01

Over the past several years, current techniques in molecular biology have been used to perform experiments in space, focusing on the nature and effects of space radiation. In the Japanese 'Kibo' facility in the International Space Station (ISS), the Japan Aerospace Exploration Agency (JAXA) has performed five life science experiments since 2009, and two additional experiments are currently in progress. The first life science experiment in space was the 'Rad Gene' project, which utilized two human cultured lymphoblastoid cell lines containing a mutated P53 : gene (m P53 : ) and a parental wild-type P53 : gene (wt P53 : ) respectively. Four parameters were examined: (i) detecting space radiation-induced DSBs by observing γH2AX foci; (ii) observing P53 : -dependent gene expression during space flight; (iii) observing P53 : -dependent gene expression after space flight; and (iv) observing the adaptive response in the two cell lines containing the mutated and wild type P53 : genes after exposure to space radiation. These observations were completed and have been reported, and this paper is a review of these experiments. In addition, recent new information from space-based experiments involving radiation biology is presented here. These experiments involve human cultured cells, silkworm eggs, mouse embryonic stem cells and mouse eggs in various experiments designed by other principal investigators in the ISS/Kibo. The progress of Japanese science groups involved in these space experiments together with JAXA are also discussed here. The Japanese Society for Biological Sciences in Space (JSBSS), the Utilization Committee of Space Environment Science (UCSES) and the Science Council of Japan (ACJ) have supported these new projects and new experimental facilities in ISS/Kibo. Currently, these organizations are proposing new experiments for the ISS through 2024. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and

Life science experiments performed in space in the ISS/Kibo facility and future research plans

International Nuclear Information System (INIS)

Ohnishi, Takeo

2016-01-01

Over the past several years, current techniques in molecular biology have been used to perform experiments in space, focusing on the nature and effects of space radiation. In the Japanese ‘Kibo’ facility in the International Space Station (ISS), the Japan Aerospace Exploration Agency (JAXA) has performed five life science experiments since 2009, and two additional experiments are currently in progress. The first life science experiment in space was the ‘Rad Gene’ project, which utilized two human cultured lymphoblastoid cell lines containing a mutated p53 gene (mp53) and a parental wild-type p53 gene (wtp53) respectively. Four parameters were examined: (i) detecting space radiation–induced DSBs by observing γH2AX foci; (ii) observing p53-dependent gene expression during space flight; (iii) observing p53-dependent gene expression after space flight; and (iv) observing the adaptive response in the two cell lines containing the mutated and wild type p53 genes after exposure to space radiation. These observations were completed and have been reported, and this paper is a review of these experiments. In addition, recent new information from space-based experiments involving radiation biology is presented here. These experiments involve human cultured cells, silkworm eggs, mouse embryonic stem cells and mouse eggs in various experiments designed by other principal investigators in the ISS/Kibo. The progress of Japanese science groups involved in these space experiments together with JAXA are also discussed here. The Japanese Society for Biological Sciences in Space (JSBSS), the Utilization Committee of Space Environment Science (UCSES) and the Science Council of Japan (ACJ) have supported these new projects and new experimental facilities in ISS/Kibo. Currently, these organizations are proposing new experiments for the ISS through 2024

Identification of quorum-sensing regulated proteins in the opportunistic pathogen Pseudomonas aeruginosa by proteomics

DEFF Research Database (Denmark)

Arevalo-Ferro, C.; Hentzer, Morten; Reil, G.

2003-01-01

The Gram-negative bacterium Pseudomonas aeruginosa is an opportunistic human pathogen which is responsible for severe nosocomial infections in immunocompromised patients and is the major pathogen in cystic fibrosis. The bacterium utilizes two interrelated quorum-sensing (QS) systems, which rely......-controlled protein spots of the surface fraction, confirming the high specificity of the compound. Importantly, 20 novel QS-regulated proteins were identified, many of which are involved in iron utilization, suggesting a link between quorum sensing and the iron regulatory system. Two of these proteins, PhuR and Has......Ap, are components of the two distinct haem-uptake systems present in P. aeruginosa. In agreement with the finding that both proteins are positively regulated by the QS cascade, we show that the lasI rhlI double mutant grows poorly with haemoglobin as the only iron source when compared with the wild type...

Consensus on measurement properties and feasibility of performance tests for the exercise and sport sciences: a Delphi study.

Science.gov (United States)

Robertson, Sam; Kremer, Peter; Aisbett, Brad; Tran, Jacqueline; Cerin, Ester

2017-12-01

Performance tests are used for multiple purposes in exercise and sport science. Ensuring that a test displays an appropriate level of measurement properties for use within a population is important to ensure confidence in test findings. The aim of this study was to obtain subject matter expert consensus on the measurement and feasibility properties that should be considered for performance tests used in the exercise and sport sciences and how these should be defined. This information was used to develop a checklist for broader dissemination. A two-round Delphi study was undertaken including 33 exercise scientists, academics and sport scientists. Participants were asked to rate the importance of a range of measurement properties relevant to performance tests in exercise and sport science. Responses were obtained in binary and Likert-scale formats, with consensus defined as achieving 67% agreement on each question. Consensus was reached on definitions and terminology for all items. Ten level 1 items (those that achieved consensus on all four questions) and nine level 2 items (those achieving consensus on ≥2 questions) were included. Both levels were included in the final checklist. The checklist developed from this study can be used to inform decision-making and test selection for practitioners and researchers in the exercise and sport sciences. This can facilitate knowledge sharing and performance comparisons across sub-disciplines, thereby improving existing field practice and research methodological quality.

A social activity and physical contact-based routing algorithm in mobile opportunistic networks for emergency response to sudden disasters

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Wang, Xiaoming; Lin, Yaguang; Zhang, Shanshan; Cai, Zhipeng

2017-05-01

Sudden disasters such as earthquake, flood and hurricane necessitate the employment of communication networks to carry out emergency response activities. Routing has a significant impact on the functionality, performance and flexibility of communication networks. In this article, the routing problem is studied considering the delivery ratio of messages, the overhead ratio of messages and the average delay of messages in mobile opportunistic networks (MONs) for enterprise-level emergency response communications in sudden disaster scenarios. Unlike the traditional routing methods for MONS, this article presents a new two-stage spreading and forwarding dynamic routing algorithm based on the proposed social activity degree and physical contact factor for mobile customers. A new modelling method for describing a dynamic evolving process of the topology structure of a MON is first proposed. Then a multi-copy spreading strategy based on the social activity degree of nodes and a single-copy forwarding strategy based on the physical contact factor between nodes are designed. Compared with the most relevant routing algorithms such as Epidemic, Prophet, Labelled-sim, Dlife-comm and Distribute-sim, the proposed routing algorithm can significantly increase the delivery ratio of messages, and decrease the overhead ratio and average delay of messages.

Perceived Gender Differences in Performance in Science: The Case of Lesotho Secondary Schools

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Khanyane, Marethabile; Mokuku, Tšepo; Nthathakane, Malefu C.

2016-01-01

The paper reports on a study aimed at investigating perceived gender differences in performance in science at secondary school level, as well as beliefs on possible underlying causes for these differences. The study is situated within the interpretivist paradigm and uses a typology of factors drawn from the Educational Effectiveness Research model…

Convergence of emerging science and technology trends for defense, security, and human performance

International Nuclear Information System (INIS)

Vaseashta, Ashok

2010-01-01

Full text: Recent technological innovations have changed the landscape of traditional scientific research. Advances in the nano- and bio-sciences, and materials and information processing are driving innovations at a phenomenal rate, resulting in greater interest yet uncertainty in the chemical-biological threat environment, research and development and other fields of policy, and overall preparedness. Conversely, the synergy arising from the convergence of nanotechnology, biotechnology, information processing and cognitive sciences (NBIC) offers great potential for transformational, revolutionary opportunities with many technological applications. Employing a new initiative termed 'Technology Foresight, Assessment, and Road-Mapping' (Tech-FARM TM ) - a multi dimensional futures-oriented approach for identification and management of emerging and/or disruptive science and technology. In literature similar initiative termed as GRAIN and BANG appear with similarity to NBIC - however Tech-FARM is comprehensive and an exhaustive method. Trans-disciplinary principles underlying NBIC convergence facilitates the development of visions and projections of future possible scientific and technological advances, environments, and productive collaborations for integrated, novel and/or unconventional solutions for 21 st century chem. -bio defense challenges. Incorporation of cognitive sciences refers to human performance enhancement in battlefield theatre. The dynamic relationship between contextual influence (socio-economical factors) and technological development is of critical consideration for S and T futures analyses. The Tech-FARM approach comprises three over-lapping practices of futures studies, including: foresight, the identification of future S and T development and their interaction with society and environment with the purpose of guiding actions to produce a more favorable future; assessment, which is concerned with the unintended, indirect, and delayed impacts of

Opportunistic detection of atrial fibrillation in subjects aged 65 years or older in primare care: a randomised clinical trial of efficacy. DOFA-AP study protocol

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Pérula-de-Torres LuisÁ

2012-10-01

Full Text Available Abstract Background Clinical Practice Guidelines recommend using peripheral blood pulse measuring as a screening test for Atrial Fibrillation. However, there is no adequate evidence supporting the efficacy of such procedure in primary care clinical practice. This paper describes a study protocol designed to verify whether early opportunistic screening for Atrial Fibrillation by measuring blood pulse is more effective than regular practice in subjects aged 65 years attending primary care centers. Methods/design An cluster-randomized controlled trial conducted in Primary Care Centers of the Spanish National Health Service. A total of 269 physicians and nurses will be allocated to one of the two arms of the trial by stratified randomization with a 3:2 ratio (three practitioners will be assigned to the Control Group for every two practitioners assigned to the Experimental Group. As many as 12 870 patients aged 65 years or older and meeting eligibility criteria will be recruited (8 580 will be allocated to the Experimental Group and 4 290 to the Control Group. Randomization and allocation to trial groups will be carried out by a central computer system. The Experimental Group practitioners will conduct an opportunistic case finding for patients with Atrial Fibrillation, while the Control Group practitioners will follow the regular guidelines. The first step will be finding new Atrial Fibrillation cases. A descriptive inferential analysis will be performed (bivariate and multivariate by multilevel logistic regression analysis. Discussion If our hypothesis is confirmed, we expect Primary Care professionals to take a more proactive approach and adopt a new protocol when a patient meeting the established screening criteria is identified. Finally, we expect this measure to be incorporated into Clinical Practice Guidelines. Trial registration The study is registered as NCT01291953 (ClinicalTrials.gob

Opportunistic detection of atrial fibrillation in subjects aged 65 years or older in primare care: a randomised clinical trial of efficacy. DOFA-AP study protocol.

Science.gov (United States)

Pérula-de-Torres, Luis Á; Martínez-Adell, Miguel Á; González-Blanco, Virginia; Baena-Díez, José M; Martín-Rioboó, Enrique; Parras-Rejano, Juan M; González-Lama, Jesús; Martín-Alvarez, Remedios; Ruiz-Moral, Roger; Fernández-García, José Á; Pérez-Díaz, Modesto; Ruiz-de-Castroviejo, Joaquin; Pérula-de-Torres, Carlos; Valero-Martín, Antonio; Roldán-Villalobos, Ana; Criado-Larumbe, Margarita; Burdoy-Joaquín, Emili; Coma-Solé, Montserrat; Cervera-León, Mercè; Cuixart-Costa, Lluís

2012-10-30

Clinical Practice Guidelines recommend using peripheral blood pulse measuring as a screening test for Atrial Fibrillation. However, there is no adequate evidence supporting the efficacy of such procedure in primary care clinical practice. This paper describes a study protocol designed to verify whether early opportunistic screening for Atrial Fibrillation by measuring blood pulse is more effective than regular practice in subjects aged 65 years attending primary care centers. An cluster-randomized controlled trial conducted in Primary Care Centers of the Spanish National Health Service. A total of 269 physicians and nurses will be allocated to one of the two arms of the trial by stratified randomization with a 3:2 ratio (three practitioners will be assigned to the Control Group for every two practitioners assigned to the Experimental Group). As many as 12 870 patients aged 65 years or older and meeting eligibility criteria will be recruited (8 580 will be allocated to the Experimental Group and 4 290 to the Control Group). Randomization and allocation to trial groups will be carried out by a central computer system. The Experimental Group practitioners will conduct an opportunistic case finding for patients with Atrial Fibrillation, while the Control Group practitioners will follow the regular guidelines. The first step will be finding new Atrial Fibrillation cases. A descriptive inferential analysis will be performed (bivariate and multivariate by multilevel logistic regression analysis). If our hypothesis is confirmed, we expect Primary Care professionals to take a more proactive approach and adopt a new protocol when a patient meeting the established screening criteria is identified. Finally, we expect this measure to be incorporated into Clinical Practice Guidelines. The study is registered as NCT01291953 (ClinicalTrials.gob).

Performance Evaluation of Relay Selection Schemes in Beacon-Assisted Dual-Hop Cognitive Radio Wireless Sensor Networks under Impact of Hardware Noises.

Science.gov (United States)

Hieu, Tran Dinh; Duy, Tran Trung; Dung, Le The; Choi, Seong Gon

2018-06-05

To solve the problem of energy constraints and spectrum scarcity for cognitive radio wireless sensor networks (CR-WSNs), an underlay decode-and-forward relaying scheme is considered, where the energy constrained secondary source and relay nodes are capable of harvesting energy from a multi-antenna power beacon (PB) and using that harvested energy to forward the source information to the destination. Based on the time switching receiver architecture, three relaying protocols, namely, hybrid partial relay selection (H-PRS), conventional opportunistic relay selection (C-ORS), and best opportunistic relay selection (B-ORS) protocols are considered to enhance the end-to-end performance under the joint impact of maximal interference constraint and transceiver hardware impairments. For performance evaluation and comparison, we derive the exact and asymptotic closed-form expressions of outage probability (OP) and throughput (TP) to provide significant insights into the impact of our proposed protocols on the system performance over Rayleigh fading channel. Finally, simulation results validate the theoretical results.

Toward High-Performance Communications Interfaces for Science Problem Solving

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Oviatt, Sharon L.; Cohen, Adrienne O.

2010-12-01

From a theoretical viewpoint, educational interfaces that facilitate communicative actions involving representations central to a domain can maximize students' effort associated with constructing new schemas. In addition, interfaces that minimize working memory demands due to the interface per se, for example by mimicking existing non-digital work practice, can preserve students' attentional focus on their learning task. In this research, we asked the question: What type of interface input capabilities provide best support for science problem solving in both low- and high- performing students? High school students' ability to solve a diverse range of biology problems was compared over longitudinal sessions while they used: (1) hardcopy paper and pencil (2) a digital paper and pen interface (3) pen tablet interface, and (4) graphical tablet interface. Post-test evaluations revealed that time to solve problems, meta-cognitive control, solution correctness, and memory all were significantly enhanced when using the digital pen and paper interface, compared with tablet interfaces. The tangible pen and paper interface also was the only alternative that significantly facilitated skill acquisition in low-performing students. Paradoxically, all students nonetheless believed that the tablet interfaces provided best support for their performance, revealing a lack of self-awareness about how to use computational tools to best advantage. Implications are discussed for how pen interfaces can be optimized for future educational purposes, and for establishing technology fluency curricula to improve students' awareness of the impact of digital tools on their performance.

Factors associated with non-attendance, opportunistic attendance and reminded attendance to cervical screening in an organized screening program: a cross-sectional study of 12,058 Norwegian women

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Eriksen Tormod

2011-04-01

Full Text Available Abstract Background Cervical cancer incidence and mortality may be reduced by organized screening. Participant compliance with the attendance recommendations of the screening program is necessary to achieve this. Knowledge about the predictors of compliance is needed in order to enhance screening attendance. Methods The Norwegian Co-ordinated Cervical Cancer Screening Program (NCCSP registers all cervix cytology diagnoses in Norway and individually reminds women who have no registered smear for the past three years to make an appointment for screening. In the present study, a questionnaire on lifestyle and health was administered to a random sample of Norwegian women. The response rate was 68%. To address the predictors of screening attendance for the 12,058 women aged 25-45 who were eligible for this study, individual questionnaire data was linked to the cytology registry of the NCCSP. We distinguished between non-attendees, opportunistic attendees and reminded attendees to screening for a period of four years. Predictors of non-attendance versus attendance and reminded versus opportunistic attendance were established by multivariate logistic regression. Results Women who attended screening were more likely than non-attendees to report that they were aware of the recommended screening interval, a history of sexually transmitted infections and a history of hormonal contraceptive and condom use. Attendance was also positively associated with being married/cohabiting, being a non-smoker and giving birth. Women who attended after being reminded were more likely than opportunistic attendees to be aware of cervical cancer and the recommended screening interval, but less likely to report a history of sexually transmitted infections and hormonal contraceptive use. Moreover, the likelihood of reminded attendance increased with age. Educational level did not significantly affect the women's attendance status in the fully adjusted models. Conclusions The

The effect of parental education, prior achievement, self-efficacy, goal orientation, and effort on undergraduate science performance of Latinos and Caucasians

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Stansbury, Sydney Lynn

Compared with majority students, underrepresented minorities have demonstrated weaker undergraduate science performance. Previous research has attributed the weaker performance to socioeconomic factors that influence poorer precollege preparation. Studies also have found that, compared with majority students, underrepresented minorities are less confident about their science skills and more interested in extrinsic rewards of science careers. Social Cognitive Theory posits that low self-efficacy coupled with high extrinsic goal orientation diminishes cognitive engagement, resulting in weak performance. Applying motivational characteristics of underrepresented minority students to a Social Cognitive Model may explain why their performance is weaker than that of Caucasians. Thus, the purpose of this study was to investigate the degree to which motivation variables account for the difference between underrepresented minority and majority students' undergraduate science performance. The study was conducted at a large, predominantly Caucasian, private university located in an urban setting in the Southwest. Two hundred twenty-two students--154 Caucasians and 68 Latinos--enrolled in a general chemistry course participated. Students were administered the Motivation for Learning Questionnaire, designed specifically for this study, consisting of scales measuring the following variables: ethnicity, level of parental education, and effort exertion; self-efficacy, effort regulation, intrinsic goal orientation, and extrinsic goal orientation, measures from the Motivated Strategies for Learning Questionnaire (Pintrich, Smith, Garcia, & McKeachie, 1991); and ability orientation, a measure from the Patterns of Adaptive Learning Survey (Midgley, Maehr, & Urdan, 1995). Financial aid information, chemistry and math placement test scores, and chemistry grades were obtained from other on-campus departments. Results demonstrated that the hypotheses were only partially confirmed by the

Science on Stage: Engaging and teaching scientific content through performance art

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Posner, Esther

2016-04-01

Engaging teaching material through performance art and music can improve the long-term retention of scientific content. Additionally, the development of effective performance skills are a powerful tool to communicate scientific concepts and information to a broader audience that can have many positive benefits in terms of career development and the delivery of professional presentations. While arts integration has been shown to increase student engagement and achievement, relevant artistic materials are still required for use as supplemental activities in STEM (science, technology, engineering, mathematics) courses. I will present an original performance poem, "Tectonic Petrameter: A Journey Through Earth History," with instructions for its implementation as a play in pre-university and undergraduate geoscience classrooms. "Tectonic Petrameter" uses a dynamic combination of rhythm and rhyme to teach the geological time scale, fundamental concepts in geology and important events in Earth history. I propose that using performance arts, such as "Tectonic Petrameter" and other creative art forms, may be an avenue for breaking down barriers related to teaching students and the broader non-scientific community about Earth's long and complex history.

Designing a performance appraisal system based on balanced scorecard for improving productivity: Case study in Semnan technology and science park

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Mohammad Hemati

2012-08-01

Full Text Available Today, organizations for holding and improving their competing merit use performance measurement for evaluation, control, supervision and improvement of their trading processes. Medium and small companies in technology and science parks are very useful in economic revivification and technology development. Technology and science parks have provided necessary consultations, information, suitable equipments, and services for developing technology unites and prepare them for independent presence in industry. One of the necessary elements for the success and improvement of performance in these companies is to establish and implement balanced scorecard, which can be used to reach desired goals, strategies and to improve performance. In this article, we use a structured method for calculating efficiency of four perspectives of balanced scorecard. Statistical society of this research was Semnan technology and Science Park and seven experts are selected for answering questions of the survey. We also complete questionnaire and determine index and relative importance of all indices. For developing strategic goals of Semnan technology and science park according to four perspectives of balanced score card (finance, growth and learning, internal process, six meetings were hold and finally all crisis macro goals index were identified and they were analyzed for evaluating performance.

Performance of high technology industries. The Science Park of Basque Country

International Nuclear Information System (INIS)

Blanco Valbuena, C.; Pena Legazkue, I.

2007-01-01

We examine the performance of high technology based SMEs located in the three Science Parks of the Basque Country. Our findings suggest that intangible assets representing the human capital and organizational learning capacity of firms are positively related to business growth. We found that about 80% of sample firms established a collaborative agreement with partner firms. Results show that the formation of a larger number of formal alliances with R and D firms (i.e., universities, innovation centers, was positively associated with firm growth. (Author) 21 refs

Opportunistic and non-opportunistic intestinal parasites in HIV/ AIDS patients in relation to their clinical and epidemiological status in a specialized medical service in Goiás, Brazil.

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Barcelos, Natane Barbosa; Silva, Lorena de Freitas E; Dias, Regyane Ferreira Guimarães; Menezes Filho, Hélio Ranes de; Rodrigues, Rosângela Maria

2018-03-08

Patients infected with the Human Immunodeficiency Virus (HIV) often have opportunistic infections, among which strongyloidiasis and coccidiosis are the most common parasitic infections that aggravate their health status. This study examined the prevalence of intestinal parasites, particularly of Strongyloides stercoralis and intestinal coccidia in patients with the Human Immunodeficiency Virus (HIV)/ Acquired Immunodeficiency Syndrome (AIDS) who were treated at the Specialized Assistance Service (SAE) of Jataí, State of Goiás, Brazil, and analyzed its correlation with clinical, laboratory, and socio-epidemiological parameters. A total of 270 stool samples were analyzed by the Lutz technique, Rugai's method, Agar Plate Culture, Ritchie's method and specific staining, Ziehl-Neelsen modified technique, Kinyoun's method and the rapid safranin method. The prevalence of intestinal parasites was 28.88% including 3.8% of S. stercoralis, Cryptosporidium sp. and Cystoisospora belli. There was a significant positive correlation between intestinal parasites and the clinical status and the use of antiretroviral therapy (ART), smoking, CD4+ lymphocyte counts and sexual orientation. In conclusion, the widespread use of antiretroviral therapy and health assistance contributed to the low prevalence of S. stercoralis and coccidiosis in patients with HIV/ AIDS who were followed up at the SAE.

Rate of Opportunistic Pap Smear Screening and Patterns of Epithelial Cell Abnormalities in Pap Smears in Ajman, United Arab Emirates

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Rizwana B. Shaik

2012-11-01

Full Text Available Objectives: The aim of this study was to estimate the proportion of women undergoing Papanicolaou (Pap smear examinations, and the frequency of epithelial cell abnormalities in a teaching hospital in one emirate of the United Arab Emirates (UAE during a three-year period. Methods: A retrospective study of 602 patient records from July 2007 to July 2010 was done in a teaching hospital in Ajman, UAE. The variables studied were age, ethnicity, menopausal status, and abnormalities in the Pap smear. Data were analysed using the Statistical Package for the Social Sciences and presented mainly as percentages; to assess associations, the chi-square test was used. Results: The total number of outpatients who attended the Obstetrics & Gynaecology Department from July 2007 to July 2010 was 150,111 patients, of which 602 (0.4% of the total had a Pap smear test. The sample was 50.1% Arabs and 49.9% other nationalities. While 73% of the outpatients had specific complaints, 27% came for a routine screening. Epithelial cell abnormalities were seen in 3.3% of the sample, with atypical squamous cells of undetermined significance (ASCUS found in 1.8%, low-grade squamous intraepithelial lesions (LSILs found in 1.2%, and high-grade squamous intraepithelial lesions (HSILs found in 0.3%. There were no cases of squamous cell carcinoma. Conclusion: Voluntary routine Pap smear screening was remarkably low in the study group. ASCUS was the most common epithelial cell abnormality. Community health education and opportunistic screening for cervical cancer are recommended for both national and expatriate women in the region.

Rate of Opportunistic Pap Smear Screening and Patterns of Epithelial Cell Abnormalities in Pap Smears in Ajman, United Arab Emirates

Science.gov (United States)

Al Eyd, Ghaith J.; Shaik, Rizwana B.

2012-01-01

Objectives: The aim of this study was to estimate the proportion of women undergoing Papanicolaou (Pap) smear examinations, and the frequency of epithelial cell abnormalities in a teaching hospital in one emirate of the United Arab Emirates (UAE) during a three-year period. Methods: A retrospective study of 602 patient records from July 2007 to July 2010 was done in a teaching hospital in Ajman, UAE. The variables studied were age, ethnicity, menopausal status, and abnormalities in the Pap smear. Data were analysed using the Statistical Package for the Social Sciences and presented mainly as percentages; to assess associations, the chi-square test was used. Results: The total number of outpatients who attended the Obstetrics & Gynaecology Department from July 2007 to July 2010 was 150,111 patients, of which 602 (0.4% of the total) had a Pap smear test. The sample was 50.1% Arabs and 49.9% other nationalities. While 73% of the outpatients had specific complaints, 27% came for a routine screening. Epithelial cell abnormalities were seen in 3.3% of the sample, with atypical squamous cells of undetermined significance (ASCUS) found in 1.8%, low-grade squamous intraepithelial lesions (LSILs) found in 1.2%, and high-grade squamous intraepithelial lesions (HSILs) found in 0.3%. There were no cases of squamous cell carcinoma. Conclusion: Voluntary routine Pap smear screening was remarkably low in the study group. ASCUS was the most common epithelial cell abnormality. Community health education and opportunistic screening for cervical cancer are recommended for both national and expatriate women in the region. PMID:23275844

Outage performance of opportunistic two-way amplify-and-forward relaying with outdated channel state information

KAUST Repository

Hwang, Kyusung; Ju, Minchul; Alouini, Mohamed-Slim

2013-01-01

In this paper, we study the outage performance of an amplify-and-forward (AF)-based two-way relaying (TWR) system with multiple relays where a single relay selection is performed based on outdated channel state information (CSI). Specifically, we

Activity of antiretroviral drugs in human infections by opportunistic agents

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Izabel Galhardo Demarchi

2012-03-01

Full Text Available Highly active antiretroviral therapy (HAART is used in patients infected with HIV. This treatment has been shown to significantly decrease opportunist infections such as those caused by viruses, fungi and particularly, protozoa. The use of HAART in HIV-positive persons is associated with immune reconstitution as well as decreased prevalence of oral candidiasis and candidal carriage. Antiretroviral therapy benefits patients who are co-infected by the human immunodeficiency virus (HIV, human herpes virus 8 (HHV-8, Epstein-Barr virus, hepatitis B virus (HBV, parvovirus B19 and cytomegalovirus (CMV. HAART has also led to a significant reduction in the incidence, and the modification of characteristics, of bacteremia by etiological agents such as Staphylococcus aureus, coagulase negative staphylococcus, non-typhoid species of Salmonella, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Mycobacterium tuberculosis. HAART can modify the natural history of cryptosporidiosis and microsporidiosis, and restore mucosal immunity, leading to the eradication of Cryptosporidium parvum. A similar restoration of immune response occurs in infections by Toxoplasma gondii. The decline in the incidence of visceral leishmaniasis/HIV co-infection can be observed after the introduction of protease inhibitor therapy. Current findings are highly relevant for clinical medicine and may serve to reduce the number of prescribed drugs thereby improving the quality of life of patients with opportunistic diseases.A terapia HAART (terapia antirretroviral altamente ativa é usada em pacientes infectados pelo vírus da imunodeficiência humana (HIV e demonstrou diminuição significativa de infecções oportunistas, tais como as causadas por vírus, fungos, protozoários e bactérias. O uso da HAART está associado com a reconstituição imunológica e diminuição na prevalência de candidíase oral. A terapia antirretroviral beneficia pacientes co-infectados pelo HIV, v

Dual roles of an algal farming damselfish as a cultivator and opportunistic browser of an invasive seaweed.

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Kimberly A Peyton

Full Text Available Herbivory is a fundamental process determining reef resilience, and while algal farming damselfishes can help shape benthic assemblages, an understanding of their contribution to areas outside of defended territories is relatively unexplored. Here, we demonstrate how the farming damselfish Stegastes marginatus plays a dual role in benthic structuring by 1 contributing to persistence of the invasive macroalga Acanthophora spicifera within a Hawaiian marine protected area, where the macroalga occurred exclusively inside Stegastes territories, and 2 behaving as an opportunistic browser of the exotic alga outside their territorial borders. Greater than 50% of the biomass of tethered A. spicifera was consumed within one-hour when placed outside Stegastes territories, compared to <5% lost from tethers within territories or herbivore exclusion cages. In situ remote video revealed that tethered A. spicifera located outside territories was grazed primarily by the surgeonfish Acanthurus nigrofuscus (∼68% of total bites and, surprisingly, by S. marginatus (∼27% of total bites that left their territories to feed on this resource on 107 occasions during 400 min of filming. Further, for over half of those occurrences where S. marginatus grazed on the tethered macroalga outside of territories, they fed alongside conspecifics and other species, displaying little of the aggressiveness that characterizes this damselfish. These results show that S. marginatus plays a wider role in determining benthic assemblages than previously recognized, acting both as cultivators of a canopy-forming invasive macroalga within their territories, and as opportunistic browsers in neighboring sites. Consequently, S. marginatus can affect benthic species composition across their territory borders. These results provide a rare example of interspecific facilitation of an exotic alga by an indigenous marine fish. Accounting for fish behaviors more broadly is important to further our

A Survey of Cultural Infrastructure and Performance in Medical Sciences Universities of Iran

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Mahmood Feizi

2015-08-01

Full Text Available ​Background and objectives: Recently, the role of universities in developing and education of culture is considered increasingly but Iranian universities have great distance in achieving the desired objectives in this context. So, this study aimed to survey the cultural infrastructure and performance in medical sciences universities of Iran. Material and Methods: This is a cross-sectional study that was done using researcher-made checklist which its face and content validity were approved by the cultural experts' opinion via statistical indicators. The study was conducted in census method by responses of 25 managers of cultural affairs in medical sciences universities of Iran. The obtained data were analyzed descriptively and results were reported as frequency (percentages for qualitative and mean (standard deviation for quantitative variable. Results: The study results were presented in four areas: “the general status of universities in cultural affairs”, “cultural facilities of the universities”, “the activity of cultural organizations and publications in universities” and “performance of cultural deputies”. The results showed that although there are considerable strengths, the significant weaknesses are evident in all areas. The results of the present study were focused solely on the quantity of functions, and quality evaluation of each activity requires special attention and further investigations and interventions. Conclusion: Researchers hope that the authorities and planners use the results of this study and similar studies especially in quality of cultural practices of universities and move towards improving the status of culture in medical sciences universities in developing Iranian-Islamic culture.

How Planful Is Routine Behavior? A Selective-Attention Model of Performance in the Tower of Hanoi

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Patsenko, Elena G.; Altmann, Erik M.

2010-01-01

Routine human behavior has often been attributed to plans--mental representations of sequences goals and actions--but can also be attributed to more opportunistic interactions of mind and a structured environment. This study asks whether performance on a task traditionally analyzed in terms of plans can be better understood from a "situated" (or…

Wavefront-Error Performance Characterization for the James Webb Space Telescope (JWST) Integrated Science Instrument Module (ISIM) Science Instruments

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Aronstein, David L.; Smith, J. Scott; Zielinski, Thomas P.; Telfer, Randal; Tournois, Severine C.; Moore, Dustin B.; Fienup, James R.

2016-01-01

The science instruments (SIs) comprising the James Webb Space Telescope (JWST) Integrated Science Instrument Module (ISIM) were tested in three cryogenic-vacuum test campaigns in the NASA Goddard Space Flight Center (GSFC)'s Space Environment Simulator (SES). In this paper, we describe the results of optical wavefront-error performance characterization of the SIs. The wavefront error is determined using image-based wavefront sensing (also known as phase retrieval), and the primary data used by this process are focus sweeps, a series of images recorded by the instrument under test in its as-used configuration, in which the focal plane is systematically changed from one image to the next. High-precision determination of the wavefront error also requires several sources of secondary data, including 1) spectrum, apodization, and wavefront-error characterization of the optical ground-support equipment (OGSE) illumination module, called the OTE Simulator (OSIM), 2) plate scale measurements made using a Pseudo-Nonredundant Mask (PNRM), and 3) pupil geometry predictions as a function of SI and field point, which are complicated because of a tricontagon-shaped outer perimeter and small holes that appear in the exit pupil due to the way that different light sources are injected into the optical path by the OGSE. One set of wavefront-error tests, for the coronagraphic channel of the Near-Infrared Camera (NIRCam) Longwave instruments, was performed using data from transverse translation diversity sweeps instead of focus sweeps, in which a sub-aperture is translated andor rotated across the exit pupil of the system.Several optical-performance requirements that were verified during this ISIM-level testing are levied on the uncertainties of various wavefront-error-related quantities rather than on the wavefront errors themselves. This paper also describes the methodology, based on Monte Carlo simulations of the wavefront-sensing analysis of focus-sweep data, used to establish the

Next Generation Science Standards and edTPA: Evidence of Science and Engineering Practices

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Brownstein, Erica M.; Horvath, Larry

2016-01-01

Science teacher educators in the United States are currently preparing future science teachers to effectively implement the "Next Generation Science Standards" (NGSS) and, in thirteen states, to successfully pass a content-specific high stakes teacher performance assessment, the edTPA. Science education and teacher performance assessment…

CONCERNING THE ADVANCED SCIENCE IN HIGH PERFORMANCE SPORT

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Gagea Adrian

2010-04-01

Full Text Available The advanced sciences are based on the most recent huge increasing of technology and on interdisciplinary commencement of great interest topics, as top sport is considering. The main problem in top sport seems to be the obtaining high sport’s performance in as short as possible time, having great efficiency and minimum risks.The cell-engineering domain, in which the author of this paper has a modest contribution, is a means of genetic control for human performance, including sport, gene expression, molecular interactions within the cell, intracellular signalling, cell mechanics and motility etc.The domain of Psyche, of controlling feelings and manifestations, is also, on the focus of top sport interest, especially for the reason that, from inside of this domain, is feasible to accede at the biological reserves unavoidable in normal conditions, but avoidable in emergency or surviving situations. The new knowledge about energetic metabolism, about the rotation of ATP molecules, or coming out from scientifically experiments of association of nutrients or of reconsidering the recovery stimulants after effort, are providing, also, very useful information for top sport practitioners.It is not to disregard the contribution of the new information about the human physical limits, biomechanics, tactics of doing and controls the physical effort by means of sensorial biofeedback or theperformance’s advantages coming from new high-minded techniques and materials of sport accessories

Prevention and treatment of opportunistic infections and other coinfections in HIV-infected patients: May 2015.

Science.gov (United States)

Iribarren, José Antonio; Rubio, Rafael; Aguirrebengoa, Koldo; Arribas, Jose Ramón; Baraia-Etxaburu, Josu; Gutiérrez, Félix; Lopez Bernaldo de Quirós, Juan Carlos; Losa, Juan Emilio; Miró, José Ma; Moreno, Santiago; Pérez Molina, José; Podzamczer, Daniel; Pulido, Federico; Riera, Melchor; Rivero, Antonio; Sanz Moreno, José; Amador, Concha; Antela, Antonio; Arazo, Piedad; Arrizabalaga, Julio; Bachiller, Pablo; Barros, Carlos; Berenguer, Juan; Caylá, Joan; Domingo, Pere; Estrada, Vicente; Knobel, Hernando; Locutura, Jaime; López Aldeguer, José; Llibre, Josep Ma; Lozano, Fernando; Mallolas, Josep; Malmierca, Eduardo; Miralles, Celia; Miralles, Pilar; Muñoz, Agustín; Ocampo, Agustín; Olalla, Julián; Pérez, Inés; Pérez Elías, Ma Jesús; Pérez Arellano, José Luis; Portilla, Joaquín; Ribera, Esteban; Rodríguez, Francisco; Santín, Miguel; Sanz Sanz, Jesús; Téllez, Ma Jesús; Torralba, Miguel; Valencia, Eulalia; Von Wichmann, Miguel Angel

2016-10-01

Despite the huge advance that antiretroviral therapy represents for the prognosis of infection by the human immunodeficiency virus (HIV), opportunistic infections (OIs) continue to be a cause of morbidity and mortality in HIV-infected patients. OIs often arise because of severe immunosuppression resulting from poor adherence to antiretroviral therapy, failure of antiretroviral therapy, or unawareness of HIV infection by patients whose first clinical manifestation of AIDS is an OI. The present article updates our previous guidelines on the prevention and treatment of various OIs in HIV-infected patients, namely, infections by parasites, fungi, viruses, mycobacteria, and bacteria, as well as imported infections. The article also addresses immune reconstitution inflammatory syndrome. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

Impact of few failure data on the opportunistic replacement policy for multi-component systems

International Nuclear Information System (INIS)

Laggoune, Radouane; Chateauneuf, Alaa; Aissani, Djamil

2010-01-01

In continuous operating units, the production loss is often very large during the system shut down. Their economic profitability is conditioned by the implementation of suitable maintenance policy that could increase the availability and reduce the operating costs. In this paper, an opportunistic replacement policy is proposed for multi-component series system in the context of data uncertainty, where the expected total cost per unit time is minimized under general lifetime distribution. When the system is down, either correctively or preventively, the opportunity to replace preventively non-failed components is considered. To deal with the problem of the small size of failure data samples, the Bootstrap technique is applied, in order to model the uncertainties in parameter estimates. The Weibull parameters are considered as random variables rather than just deterministic point estimates. A solution procedure based on Monte Carlo simulations with informative search method is proposed and applied to the optimization of preventive maintenance plan for a hydrogen compressor in an oil refinery.

The Impacts of the Annual Professional Performance Review in New York State: Science Teachers' and Administrators' Perspectives

Science.gov (United States)

Mintz, Jessica A.

The goal of this study was to investigate New York State’s Annual Professional Performance Review (APPR) from the perspectives of secondary science teachers and their administrators. Examining their perceptions through interviews was insightful due to the subjects’ proximity to the teaching and learning processes. Five science teacher/administrator pairs from selected school districts were interviewed; all had varied ranges of experience and content certifications. The study also investigated the unintended consequences the teachers and administrators experienced using the APPR system. This phenomenological research study lays the groundwork for making policy recommendations for science teacher evaluations. The goal was to examine teacher and administrator perceptions, the clarity and practicality of teacher evaluation reforms, as well as how motivational theory might incentivize teacher change through future reform efforts. Provisional coding was used in this study based upon prior research. The list of codes was generated using motivational theories applied to the design of teacher evaluation policy and reform implementation constructs. Although the science teachers agreed with the importance of being evaluated, they generally viewed aspects of the process of quantifying their effectiveness as unclear, unfair, and flawed. The science teachers indicated that student variations in ability and performance were not considered when APPR was established. The science teachers recommended that the focus of teacher evaluations should be on content specific professional development. They proposed the establishment of peer review systems, teacher collaboration networks, and self-reflection documentation as means to improve their science teaching practices. The administrators agreed that accountability was important, however, holding individual teachers accountable for student outcomes was not reliably measured through the APPR process. They recommended other forms of

Correlation between Lymphocyte CD4 Count, Treatment Duration, Opportunistic Infection and Cognitive Function in Human Immunodeficiency Virus-Acquired Immunodeficiency Syndrome (HIV-AIDS) Patients.

Science.gov (United States)

Fitri, Fasihah Irfani; Rambe, Aldy Safruddin; Fitri, Aida

2018-04-15

Human immunodeficiency virus (HIV) infection is an epidemic worldwide, despite the marked benefits of antiretroviral therapy (ARV) in reducing severe HIV-associated dementia. A milder form of neurocognitive disorders are still prevalent and remain a challenge. This study aimed to determine the correlation between plasma cluster of differentiation 4 (CD4) lymphocyte, duration of ARV treatment, opportunistic infections, and cognitive function in HIV-AIDS patients. A cross-sectional study involving 85 HIV-AIDS patients was conducted at Adam Malik General Hospital Medan, Indonesia. All subjects were subjected to physical, neurologic examination and Montreal Cognitive Assessment-Indonesian Version (MoCA-INA) to assess cognitive function and measurement of lymphocyte CD4 counts. Out of the 85 subjects evaluated, the proportion concerning sexes include 52 males (61.2 %) and 33 females (38.8%). The mean age was 38.53 ± 9.77 years old. There was a significant correlation between CD4 lymphocyte counts and MoCA-INA score (r = 0.271, p = 0.012), but there was no significant correlation between duration of ARV treatment and MoCA-INA score. There was also no difference in MoCA-INA score based on the presence of opportunistic infection. Lymphocyte CD4 count was independently correlated with cognitive function in HIV-AIDS patients.

Host Defense against Opportunist Microorganisms Following Trauma.