16,474 research outputs found
Environmental Activism, Social Networks and the Internet
Social networks and the internet both have a substantial individual effect on environmental activism in China. In this article, we speculate that social linking patterns between environmental actors, which often facilitate activism on the ground, may also exist in cyberspace in the form of an online network. The article addresses the following empirical questions. Does such an online network exist? If so, who are the constituent actors? Are these the same actors observed on the ground? In addressing these questions the article aims to contribute to the growing debate on the implications of the internet for the potential emergence of social movements in China
A Systematic Approach to Identifying Protein-Ligand Binding Profiles on a Proteome Scale
Identification of protein-ligand interaction networks on a proteome scale is crucial to address a wide range of biological problems such as correlating molecular functions to physiological processes and designing safe and efficient therapeutics. We have developed a novel computational strategy to identify ligand binding profiles of proteins across gene families and applied it to predicting protein functions, elucidating molecular mechanisms of drug adverse effects, and repositioning safe pharmaceuticals to treat different diseases
Two-stage hybrid feature selection algorithms for diagnosing erythemato-squamous diseases
This paper proposes two-stage hybrid feature selection algorithms to build the stable and efficient diagnostic models where a new accuracy measure is introduced to assess the models. The two-stage hybrid algorithms adopt Support Vector Machines (SVM) as a classification tool, and the extended Sequential Forward Search (SFS), Sequential Forward Floating Search (SFFS), and Sequential Backward Floating Search (SBFS), respectively, as search strategies, and the generalized F-score (GF) to evaluate the importance of each feature. The new accuracy measure is used as the criterion to evaluated the performance of a temporary SVM to direct the feature selection algorithms. These hybrid methods combine the advantages of filters and wrappers to select the optimal feature subset from the original feature set to build the stable and efficient classifiers. To get the stable, statistical and optimal classifiers, we conduct 10-fold cross validation experiments in the first stage; then we merge the 10 selected feature subsets of the 10-cross validation experiments, respectively, as the new full feature set to do feature selection in the second stage for each algorithm. We repeat the each hybrid feature selection algorithm in the second stage on the one fold that has got the best result in the first stage. Experimental results show that our proposed two-stage hybrid feature selection algorithms can construct efficient diagnostic models which have got better accuracy than that built by the corresponding hybrid feature selection algorithms without the second stage feature selection procedures. Furthermore our methods have got better classification accuracy when compared with the available algorithms for diagnosing erythemato-squamous diseases
A Tale of Three Galaxies: Anomalous Dust Properties in IRASF10398+1455, IRASF21013-0739 and SDSSJ0808+3948
On a galactic scale the 9.7um silicate emission is usually only seen in type
1 active galactic nuclei (AGNs). They usually also display a flat emission
continuum at ~5--8um and the absence of polycyclic aromatic hydrocarbon (PAH)
emission bands. In contrast, starburst galaxies, luminous infrared (IR)
galaxies (LIRGs), and ultraluminous IR galaxies (ULIRGs) exhibit a red 5--8um
emission continuum, strong 10um and 18um silicate absorption features, and
strong PAH emission bands. Here we report the detection of anomalous dust
properties by Spitzer/Infrared Spectrograph in three galaxies (IRASF10398+1455,
IRASF21013-0739 and SDSSJ0808+3948) which are characterized by the simultaneous
detection of a red 5--8um emission continuum, the 9.7 and 18um silicate
emission features as well as strong PAH emission bands. These apparently
contradictory dust IR emission properties are discussed in terms of iron-poor
silicate composition, carbon dust deficit, small grain size and low dust
temperature in the young AGN phase of these three galaxies.Comment: accepted for publication in ApJ
Interaction induced topological phase transition in Bernevig-Hughes-Zhang model
We study interaction induced topological phase transition in
Bernevig-Hughes-Zhang model. Topological nature of the phase transition is
revealed by directly calculating the Z2 index of the interacting system from
the single-particle Green's function. The interacting Z2 index is also
consistently checked through the edge spectra. Combined with ab initio methods,
present approach is a useful tool searching for correlated topological
insulating materials from the first-principle point of view.Comment: 4.5 pages, 4 figures, reference adde
Information-Coupled Turbo Codes for LTE Systems
We propose a new class of information-coupled (IC) Turbo codes to improve the
transport block (TB) error rate performance for long-term evolution (LTE)
systems, while keeping the hybrid automatic repeat request protocol and the
Turbo decoder for each code block (CB) unchanged. In the proposed codes, every
two consecutive CBs in a TB are coupled together by sharing a few common
information bits. We propose a feed-forward and feed-back decoding scheme and a
windowed (WD) decoding scheme for decoding the whole TB by exploiting the
coupled information between CBs. Both decoding schemes achieve a considerable
signal-to-noise-ratio (SNR) gain compared to the LTE Turbo codes. We construct
the extrinsic information transfer (EXIT) functions for the LTE Turbo codes and
our proposed IC Turbo codes from the EXIT functions of underlying convolutional
codes. An SNR gain upper bound of our proposed codes over the LTE Turbo codes
is derived and calculated by the constructed EXIT charts. Numerical results
show that the proposed codes achieve an SNR gain of 0.25 dB to 0.72 dB for
various code parameters at a TB error rate level of , which complies
with the derived SNR gain upper bound.Comment: 13 pages, 12 figure
Illusion of Motion: Variation of Subjective Value of Travel Time on Freeways and Ramp Meters
This paper explores drivers' subjective value of time under moving and stopped freeway travel conditions using a stated preference survey. Unlike previous studies that assume a constant value of time, this research relates perceived satisfaction of a freeway trip to its quality indicators. Sixty-nine subjects in the Twin Cities are asked in the survey to rank sixteen driving scenarios in four condition sets with different durations of ramp wait and freeway travel. Several utility functions are specified where the weight of ramp delay is a function of the length of the delay itself and subject specific variables, and the resulting choice models estimated using rank-ordered logit and binary logit techniques. Results suggest that drivers perceive ramp wait as more onerous than freeway travel. Drivers also weight each minute of ramp wait more heavily as the length of the delay gets longer. Although the subjects show some tolerance to the first several minutes of ramp delay (less than 5 minutes), they perceive long delays as much as twelve times more onerous than time in motion. The derived weighting function for ramp wait can improve the design of freeway traffic control strategies that trade-off freeway delay with ramp wait. The findings also enable a more utility-based approach for freeway operations than the current method which has the engineering efficiency objective of minimizing total system delay or maximizing throughput. Minimizing total perceived travel time is probably more appropriate than minimizing total absolute travel time which does not take into account driver acceptance. The weighting function can also be easily transformed into a value of time function for project evaluation purposes.Value of time, value of travel time, Time perception, Driver acceptance, Freeway congestion, Ramp meter
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