CSD: Discriminance with Conic Section for Improving Reverse k Nearest Neighbors Queries

The reverse $k$ nearest neighbor (R$k$NN) query finds all points that have the query point as one of their $k$ nearest neighbors ($k$NN), where the $k$NN query finds the $k$ closest points to its query point. Based on the characteristics of conic section, we propose a discriminance, named CSD (Conic Section Discriminance), to determine points whether belong to the R$k$NN set without issuing any queries with non-constant computational complexity. By using CSD, we also implement an efficient R$k$NN algorithm CSD-R$k$NN with a computational complexity at $O(k^{1.5}\cdot log\,k)$. The comparative experiments are conducted between CSD-R$k$NN and other two state-of-the-art RkNN algorithms, SLICE and VR-R$k$NN. The experimental results indicate that the efficiency of CSD-R$k$NN is significantly higher than its competitors

Distribution-Based Trajectory Clustering

Trajectory clustering enables the discovery of common patterns in trajectory data. Current methods of trajectory clustering rely on a distance measure between two points in order to measure the dissimilarity between two trajectories. The distance measures employed have two challenges: high computational cost and low fidelity. Independent of the distance measure employed, existing clustering algorithms have another challenge: either effectiveness issues or high time complexity. In this paper, we propose to use a recent Isolation Distributional Kernel (IDK) as the main tool to meet all three challenges. The new IDK-based clustering algorithm, called TIDKC, makes full use of the distributional kernel for trajectory similarity measuring and clustering. TIDKC identifies non-linearly separable clusters with irregular shapes and varied densities in linear time. It does not rely on random initialisation and is robust to outliers. An extensive evaluation on 7 large real-world trajectory datasets confirms that IDK is more effective in capturing complex structures in trajectories than traditional and deep learning-based distance measures. Furthermore, the proposed TIDKC has superior clustering performance and efficiency to existing trajectory clustering algorithms

QED effects on phase transition and Ruppeiner geometry of Euler-Heisenberg-AdS black holes

Taking the quantum electrodynamics (QED) effect into account, we study the black hole phase transition and Ruppeiner geometry for the Euler-Heisenberg anti-de Sitter black hole in the extended phase space. For negative and small positive QED parameter, we observe a small/large black hole phase transition and reentrant phase transition, respectively. While a large positive value of the QED parameter ruins the phase transition. The phase diagrams for each case are explicitly exhibited. Then we construct the Ruppeiner geometry in the thermodynamic parameter space. Different features of the corresponding scalar curvature are shown for both the small/large black hole phase transition and reentrant phase transition cases. Of particular interest is that an additional region of positive scalar curvature indicating dominated repulsive interaction among black hole microstructure is present for the black hole with a small positive QED parameter. Furthermore, the universal critical phenomena are also observed for the scalar curvature of the Ruppeiner geometry. These results indicate that the QED parameter has a crucial influence on the black hole phase transition and microstructure.Comment: 19 pages, 14 figure

The Chinese (Cantonese) Montreal Cognitive Assessment in Patients with Subcortical Ischemic Vascular Dementia

Background: Subcortical ischemic vascular dementia (SIVD) has been proposed as the most frequent subtype of vascular cognitive impairment. The aim of this study was to evaluate the psychometric properties of the Chinese (Cantonese) Montreal Cognitive Assessment (CC- MoCA) in patients with SIVD in the Guangdong Province of China. Methods: 71 SIVD patients and 60 matched controls were recruited for the CC-MoCA, Mini Mental State Examination and executive clock drawing tasks. Receiver-operating characteristic curve analyses were performed to determine optimal sensitivity and specificity of the CC-MoCA total score in differentiating mild vascular dementia (VaD) patients from moderate VaD patients and controls. Results: The mean CC-MoCA scores of the controls, and mild and moderate VaD patients were 25.2 ± 3.8, 16.4 ± 3.7, and 10.0 ± 5.1, respectively. In our study, the optimal cutoff value for the CC-MoCA to be able to differentiate patients with mild VaD from controls is 21/22, and 13/14 to differentiate mild VaD from moderate VaD. Conclusion: The CC-MoCA is a useful cognitive screening instrument in SIVD patients

Effects of root phenotypic changes on the deep rooting of Populus euphratica seedlings under drought stresses

Background Deep roots are critical for the survival of Populus euphratica seedlings on the floodplains of arid regions where they easily suffer drought stress. Drought typically suppresses root growth, but P. euphratica seedlings can adjust phenotypically in terms of root-shoot allocation and root architecture and morphology, thus promoting deep rooting. However, the root phenotypic changes undertaken by P. euphratica seedlings as a deep rooting strategy under drought conditions remain unknown. Methods We quantified deep rooting capacity by the relative root depth (RRD), which represents the ratio of taproot length to plant biomass and is controlled by root mass fraction (RMF), taproot mass fraction (TRMF), and specific taproot length (STRL). We recorded phenotypic changes in one-year-old P. euphratica seedlings under control, moderate and severe drought stress treatments and assessed the effects of RMF, TRMF, and STRL on RRD. Results Drought significantly decreased absolute root depth but substantially increased RRD via exerting positive effects on TRMF, RMF, and STRL. Under moderate drought, TRMF contributed 55%, RMF 27%, and STRL 18% to RRD variation. Under severe drought, the contribution of RMF to RRD variation increased to 37%, which was similar to the 41% for TRMF. The contribution of STRL slightly increased to 22%. Conclusion These results suggest that the adjustments in root architecture and root-shoot allocation were predominantly responsible for deep rooting in P. euphratica seedlings under drought conditions, while morphological changes played a minor role. Moreover, P. euphratica seedlings rely mostly on adjusting their root architecture to maintain root depth under moderate drought conditions, whereas root-shoot allocation responds more strongly under severe drought conditions, to the point where it plays a role as important as root architecture does on deep rooting

Seroprevalence of Toxoplasma gondii infection in pet dogs in Lanzhou, Northwest China

<p>Abstract</p> <p>Background</p> <p>In recent years, surveys of <it>Toxoplasma gondii </it>infection in dogs have been reported worldwide, including China. However, little is known about the prevalence of <it>T. gondii </it>in pet dogs in Northwest China. In the present study, the prevalence of <it>T. gondii </it>in pet dogs in Lanzhou, China was investigated using the modified agglutination test (MAT).</p> <p>Results</p> <p>In this survey, antibodies to <it>T. gondii </it>were found in 28 of 259 (10.81%) pet dogs, with MAT titers of 1:20 in 14 dogs, 1:40 in nine, 1:80 in four, and 1:160 or higher in one dog. The prevalence ranged from 6.67% to 16.67% among dogs of different ages, with low rates in young pet dogs, and high rates in older pet dogs. The seroprevalence in dogs >3 years old was higher than that in dogs ≤1 years old, but the difference was not statistically significant (<it>P ></it>0.05). The seroprevalence in male dogs was 12.50% (17 of 136), and in female dogs it was 8.94% (11 of 123), but the difference was not statistically significant (<it>P ></it>0.05).</p> <p>Conclusions</p> <p>A high prevalence of <it>T. gondii </it>infection was found in pet dogs in Lanzhou, Northwest China, which has implications for public health in this region. In order to reduce the risk of exposure to <it>T. gondii</it>, further measures and essential control strategies should be carried out rationally in this region.</p