| 1. |
- Regan, P. H., et al.
(författare)
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First Results from the Stopped RISING Campaign at GSI: The Mapping of Isomeric Decays in Highly Exotic Nuclei
- 2007
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Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X. - 9780735413283 ; 899, s. 19-22
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Konferensbidrag (refereegranskat)abstract
- The first results from the Stopped Beam RISING experimental campaign performed at the GSI laboratory in Darmstadt, Germany, are presented. RISING (Rare ISotope INvestigations at GSI) constitutes a major new experimental program in European nuclear structure physics research aimed at using relativistic‐energy, projectile‐fragmentation reactions to study nuclei with exotic proton‐to‐neutron ratios. This paper introduces the physics aims of the Stopped RISING collaboration and presents some technical details and initial results from experiments using the RISING array to study decays from metastable nuclear states in both proton and neutron‐rich nuclei.
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| 2. |
- Ahmed, Nur, et al.
(författare)
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Impact of climate change on rice insect pests and their natural enemies
- 2013
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Konferensbidrag (refereegranskat)abstract
- Rice is one of the important staple foods for half of the world population particularly Asian countries for their livelihood, socio-economic and nutrition. Global warming is predicted to increase frequency of precipitation/rainfall, intensity of drought and solar-radiation/UV-B radiation which might affect the intensity and severity of rice pests in one hand, but also change in other friendly arthropods on the other hand. The present studies discuss the influence of climatic factors (temperature and rainfall) on yellow stem borer (YSB), brown planthopper (BPH), green leafhopper (GLH) and their natural enemies (spider, lady bird beetle, green mirid bug). Light trap and sweep net catches of arthropods from different rice habitats were used in this study. For GLH there is a strong periodicity at 6 months and a somewhat weaker periodicity at 12 months followed by an even weaker periodicity at 3 months, especially valid for both methods of data collection (light trap and sweep-net data). Finally, for GMB there is a strong periodicity at 6 months and a somewhat weaker periodicity at 3 months followed by an even weaker periodicity at 4 months. There is a general increasing trend over the ten years seems to be present in the GLH. This corresponds to that the abundance in 2005 is generally 15 times larger than in January 1996. For LBB, there is an increasing trend of log abundance of LBB over time and shows a strong periodicity at 3 months and a somewhat weaker periodicity at 4 months followed by an even weaker periodicity at about 6 months. For Spider there is a strong periodicity at 2.4 months and a somewhat weaker periodicity at 4 months followed by an even weaker periodicities at about 3 months and 6 months. Results show an increase of maximum temperature of approximately 0.5 to 1°C over 10 years.
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| 3. |
- Alvén, Jennifer, 1989, et al.
(författare)
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A Deep Learning Approach to MR-less Spatial Normalization for Tau PET Images
- 2019
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Ingår i: Medical Image Computing and Computer Assisted Intervention : MICCAI 2019 - 22nd International Conference, Proceedings - MICCAI 2019 - 22nd International Conference, Proceedings. - Cham : Springer International Publishing. - 1611-3349 .- 0302-9743. - 9783030322441 - 9783030322458 ; 11765 LNCS, s. 355-363
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Konferensbidrag (refereegranskat)abstract
- The procedure of aligning a positron emission tomography (PET) image with a common coordinate system, spatial normalization, typically demands a corresponding structural magnetic resonance (MR) image. However, MR imaging is not always available or feasible for the subject, which calls for enabling spatial normalization without MR, MR-less spatial normalization. In this work, we propose a template-free approach to MR-less spatial normalization for [18F]flortaucipir tau PET images. We use a deep neural network that estimates an aligning transformation from the PET input image, and outputs the spatially normalized image as well as the parameterized transformation. In order to do so, the proposed network iteratively estimates a set of rigid and affine transformations by means of convolutional neural network regressors as well as spatial transformer layers. The network is trained and validated on 199 tau PET volumes with corresponding ground truth transformations, and tested on two different datasets. The proposed method shows competitive performance in terms of registration accuracy as well as speed, and compares favourably to previously published results.
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| 4. |
- Çakmak, Kivanç, et al.
(författare)
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Performance of TCP congestion control algorithms with interference in IEEE 802.11ac WLANs
- 2016
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Ingår i: 24th Signal Processing and Communication Application Conference, SIU 2016 - Proceedings. - 9781509016792 ; , s. 473-476
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Konferensbidrag (refereegranskat)abstract
- In order to meet the incremental requirements from clients, fifth generation Wireless Local Area Network(WLAN) protocol IEEE 802.11ac provides a lot more throughput than his predecessors. However, in all distributed channel access 802.11 protocols, probability of packet loss increases with respect to number of available stations; consecutive packet losses in link layer activates congestion control mechanism of TCP which decreases throughput. In this work, we investigated the performance of congestion control algorithms of TCP protocol when interference available wireless medium is used in between the IEEE 802.11ac capable devices. As a benchmark, we repeated the experiments with UDP protocol which does not have reliable connection and congestion control mechanism. According to our experiments, we observed that UDP provides more throughput than all other TCP congestion control algorithms. When we compare TCP congestion control algorithms by themselves, we observed that the algorithms which does not decrease congestion window size too much during interference and have more aggressive increment of congestion window -such as Cubic and Illinois, Scalable have better performance in terms of throughput and standard deviation.
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| 5. |
- Hamidian, Ali, et al.
(författare)
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Deployment and Evaluation of a Wireless Mesh Network
- 2009
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Ingår i: [Host publication title missing]. ; , s. 66-72
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Konferensbidrag (refereegranskat)abstract
- Wireless Mesh Networks (WMNs) have the potentialities to greatly penetrate the marketplace in the next decade. They can be considered a hybrid between wireless infrastructure and ad-hoc networks; no other network infrastructure is needed other than the mesh points, thus providing flexibility in building and expanding the network, allowing for automatic discovery of neighboring nodes, increased reliability and redundancy. In this work, we discuss how WMNs can be practically employed to support wireless multihop communications in an office-wide area. To this aim, we have deployed a real WMN testbed utilizing state-of-the-art technology and analyzed the performance of this architecture when supporting multihop heterogeneous traffic.
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| 6. |
- Mitchell, David G.M., et al.
(författare)
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Approximating Decoding Thresholds of Punctured LDPC Code Ensembles on the AWGN Channel
- 2015
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Ingår i: 2015 IEEE International Symposium on Information Theory (ISIT). - 9781467377041 ; , s. 421-425
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Konferensbidrag (refereegranskat)abstract
- In this paper, we provide an efficient way to predict iterative belief propagation (BP) decoding thresholds of randomly punctured low-density parity-check (LDPC) code ensembles on the binary-input additive white Gaussian noise channel (AWGNC), given only the BP threshold of the mother code ensemble on the binary erasure channel (BEC) and the code design rate. We show that the predictions are accurate by comparing them with values calculated by discretized density evolution for a variety of puncturing fractions. We find that the strength and suitability of an LDPC code ensemble for random puncturing over the AWGNC with respect to iterative decoding threshold is completely determined by a single constant, and this behavior is demonstrated using both LDPC block code and spatially coupled LDPC code ensembles. Finally, we present simulation results that confirm the excellent decoding performance promised by the asymptotic results.
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| 7. |
- Mitchell, David G. M., et al.
(författare)
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On the Block Error Rate Performance of Spatially Coupled LDPC Codes for Streaming Applications
- 2016
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Ingår i: Proc. IEEE Information Theory Workshop. - 9781509010905
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Konferensbidrag (refereegranskat)abstract
- In this paper, we study the block error rate (BLER) performance of spatially coupled low-density parity-check (SC- LDPC) codes using a sliding window decoder suited for streaming applications. Previous studies of SC-LDPC have focused on the bit error rate (BER) performance or the frame error rate (FER) performance over the entire length of the code. Here, we consider protograph-based constructions of SC-LDPC codes in which a window decoder continuously outputs blocks in a streaming fashion, and we examine the BLER associated with these blocks.We begin by examining the effect of protograph design on the streaming BLER by varying the block size and the coupling width in such a way that the overall constraint length of the SC-LDPC code remains constant. Next, we investigate the BLER scaling behavior with block size and coupling width. Lastly, we consider the effect of employing an outer code to protect blocks, so that small numbers of residual errors can be corrected by the outer code. Simulation results for the additive white Gaussian noise channel (AWGNC) are included and comparisons are made to LDPC block codes (LDPC-BCs).
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| 8. |
- Mitchell, David G.M., et al.
(författare)
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Randomly Punctured Spatially Coupled LDPC Codes
- 2014
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- In this paper, we study random puncturing of protograph-based spatially coupled low-density parity-check (SC- LDPC) code ensembles. We show that, with respect to iterative decoding threshold, the strength and suitability of an LDPC code ensemble for random puncturing over the binary erasure channel (BEC) is completely determined by a single constant that depends only on the rate and iterative decoding threshold of the mother code ensemble. We then use this analysis to show that randomly punctured SC-LDPC code ensembles display near capacity thresholds for a wide range of rates. We also perform an asymptotic minimum distance analysis and show that, like the SC-LDPC mother code ensemble, the punctured SC-LDPC code ensembles are also asymptotically good. Finally, we present some simulation results that confirm the excellent decoding performance promised by the asymptotic results.
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