LIVIVO - Search results -

Search results

Result 1 - 10 of total 25

Search options

Article ; Online: Detecting and Visualizing Observation Hot-Spots in Massive Volunteer-Contributed Geographic Data across Spatial Scales Using GPU-Accelerated Kernel Density Estimation

Guiming Zhang

ISPRS International Journal of Geo-Information, Vol 11, Iss 55, p

2022 Volume 55

Abstract: Volunteer-contributed geographic data (VGI) is an important source of geospatial big data that support research and applications. A major concern on VGI data quality is that the underlying observation processes are inherently biased. Detecting ... ...

Abstract	Volunteer-contributed geographic data (VGI) is an important source of geospatial big data that support research and applications. A major concern on VGI data quality is that the underlying observation processes are inherently biased. Detecting observation hot-spots thus helps better understand the bias. Enabled by the parallel kernel density estimation (KDE) computational tool that can run on multiple GPUs (graphics processing units), this study conducted point pattern analyses on tens of millions of iNaturalist observations to detect and visualize volunteers’ observation hot-spots across spatial scales. It was achieved by setting varying KDE bandwidths in accordance with the spatial scales at which hot-spots are to be detected. The succession of estimated density surfaces were then rendered at a sequence of map scales for visual detection of hot-spots. This study offers an effective geovisualization scheme for hierarchically detecting hot-spots in massive VGI datasets, which is useful for understanding the pattern-shaping drivers that operate at multiple spatial scales. This research exemplifies a computational tool that is supported by high-performance computing and capable of efficiently detecting and visualizing multi-scale hot-spots in geospatial big data and contributes to expanding the toolbox for geospatial big data analytics.
Keywords	volunteered geographic information (VGI) ; geospatial big data ; point pattern analysis ; kernel density estimation ; hot-spot detection and visualization ; spatial bias ; Geography (General) ; G1-922
Language	English
Publishing date	2022-01-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Spatial and Temporal Patterns in Volunteer Data Contribution Activities

Guiming Zhang

ISPRS International Journal of Geo-Information, Vol 9, Iss 597, p

A Case Study of eBird

2020 Volume 597

Abstract: Volunteered geographic information (VGI) has great potential to reveal spatial and temporal dynamics of geographic phenomena. However, a variety of potential biases in VGI are recognized, many of which root from volunteer data contribution activities. ... ...

Abstract	Volunteered geographic information (VGI) has great potential to reveal spatial and temporal dynamics of geographic phenomena. However, a variety of potential biases in VGI are recognized, many of which root from volunteer data contribution activities. Examining patterns in volunteer data contribution activities helps understand the biases. Using eBird as a case study, this study investigates spatial and temporal patterns in data contribution activities of eBird contributors. eBird sampling efforts are biased in space and time. Most sampling efforts are concentrated in areas of denser populations and/or better accessibility, with the most intensively sampled areas being in proximity to big cities in developed regions of the world. Reported bird species are also spatially biased towards areas where more sampling efforts occur. Temporally, eBird sampling efforts and reported bird species are increasing over the years, with significant monthly fluctuations and notably more data reported on weekends. Such trends are driven by the expansion of eBird and characteristics of bird species and observers. The fitness of use of VGI should be assessed in the context of applications by examining spatial, temporal and other biases. Action may need to be taken to account for the biases so that robust inferences can be made from VGI observations.
Keywords	volunteered geographic information (VGI) ; data contribution activities ; spatial and temporal patterns ; biases ; eBird ; Geography (General) ; G1-922
Subject code	310
Language	English
Publishing date	2020-10-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Editorial

Wen Luo / Guiming Zhang

Frontiers in Earth Science, Vol

Advances and applications of geospatial modeling and analysis in digital twins

2023 Volume 11

Keywords	high-precision modeling ; scene recognition ; behavioral simulation ; smart cities ; smart coasts ; Science ; Q
Language	English
Publishing date	2023-05-01T00:00:00Z
Publisher	Frontiers Media S.A.
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Enhancing VGI application semantics by accounting for spatial bias

Guiming Zhang

Big Earth Data, Vol 3, Iss 3, Pp 255-

2019 Volume 268

Abstract: Volunteered geographic information (VGI) is becoming an important source of geospatial big data that support many applications. The application semantics of VGI, i.e. how well VGI reflects the real-world geographic phenomena of interest to the ... ...

Abstract	Volunteered geographic information (VGI) is becoming an important source of geospatial big data that support many applications. The application semantics of VGI, i.e. how well VGI reflects the real-world geographic phenomena of interest to the application, is essential for any VGI applications. VGI observations often are spatially biased (e.g. spatially clustered). Spatial bias poses challenges on VGI application semantics because it may impede the quality of inferences made from VGI. Using species distribution modeling (SDM) as an example application, this article argues that spatial bias impedes VGI application semantics, as gauged by SDM model performance, and accounting for bias enhances application semantics. VGI observations from eBird were used in a case study for modeling the distribution of the American Robin (Turdus migratorius) in U.S. T. migratorius observations from the North American Breeding Bird Survey were used as independent validation data for model performance evaluation. A grid-based strategy was adopted to filter eBird species observations to reduce spatial bias. Evaluations show that spatial bias in species observations degrades SDM model performance and filtering species observations improves model performance. This study demonstrates that VGI application semantics can be enhanced by accounting for the spatial bias in VGI observations.
Keywords	volunteered geographic information (vgi) ; application semantics ; spatial bias ; species distribution modeling (sdm) ; Geography. Anthropology. Recreation ; G ; Geology ; QE1-996.5
Subject code	310
Language	English
Publishing date	2019-07-01T00:00:00Z
Publisher	Taylor & Francis Group
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: The time- and distance-decay effects of hurricane relevancy on social media

Mackenzie Kottwitz / Guiming Zhang / Jin Xu

Annals of GIS, Pp 1-

an empirical study of three hurricanes in the United States

2023 Volume 16

Abstract: ABSTRACTHurricane activity has been increasing in frequency and severity in recent years. This has serious implications for coastal and nearby communities who, when recovering from hurricanes, seek outside assistance from relevant government, non- ... ...

Abstract	ABSTRACTHurricane activity has been increasing in frequency and severity in recent years. This has serious implications for coastal and nearby communities who, when recovering from hurricanes, seek outside assistance from relevant government, non-governmental agencies, and nearby communities. The ever-increasing popularity of social media offers a new medium through which such social relevancy can be derived to inform targeted assistance-seeking efforts. This study utilizes Twitter to develop an understanding of disaster relevancy across space and time to establish a clearer context for impacted communities as to when and where assistance may be derived. Tweets were collected for three hurricanes within the contiguous United States (Hurricane Harvey in 2017, Florence in 2018 and Laura in 2020) and examined over a 12-week period following hurricane landfalls. The relationships between tweets and time and between tweets and distance were examined through correlation analysis. Results show statistically significant time- and distance-decay effects of hurricane relevancy on social media, though the time-decay effect was stronger. Most tweets occurred during the first week following hurricane landfall within the states wherein the hurricanes made landfall as well as around large cities. These findings could inform aid-seeking efforts in the event of hurricanes and other disasters.
Keywords	Hurricanes ; online relevancy ; social media ; distance- and time-decay ; Volunteered Geographic Information (VGI) ; Mathematical geography. Cartography ; GA1-1776
Language	English
Publishing date	2023-07-01T00:00:00Z
Publisher	Taylor & Francis Group
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Neoadjuvant Chemotherapy for Different Stages of Muscle-Invasive Bladder Cancer

Shuai Liu / Yu Yao / Fengju Guan / Lijiang Sun / Guiming Zhang

Disease Markers, Vol

A Systematic Review and Meta-analysis

2022 Volume 2022

Abstract: The purpose of this meta-analysis is to determine the survival benefits and pathological outcomes of neoadjuvant chemotherapy (NAC) combined with radical cystectomy (RC) administered to patients with cT2 or cT3-4N0M0 muscle-invasive bladder cancer (MIBC). ...

Abstract	The purpose of this meta-analysis is to determine the survival benefits and pathological outcomes of neoadjuvant chemotherapy (NAC) combined with radical cystectomy (RC) administered to patients with cT2 or cT3-4N0M0 muscle-invasive bladder cancer (MIBC). PubMed, Embase, and the Cochrane Library were searched for comparing the use of NAC in combination with RC and RC alone in patients with different MIBC stages. A fixed effects model was used to calculate hazard ratio (HR) and odds ratio (OR) with 95% confidence intervals (CIs), and the I2 statistic was used to assess heterogeneity. Moreover, we determined possible sources of heterogeneity by subgroup and sensitivity analyses. Fifteen studies were finally selected. For cT2 bladder cancer, NAC combined with RC significantly increased the rates of pathological complete response (pCR) (OR=4.84, 95% CI: 1.18–19.92, p=0.029) but did not improve overall survival (OS) (HR=0.86, 95% CI: 0.72–1.02, p=0.078) across six studies. Regarding cT3-4 bladder cancer, NAC has a significantly improved effect on OS (HR=0.69; 95% CI: 0.59–0.81, p<0.001, across seven studies and 5726 patients) and pCR (pooled OR=4.80; 95% CI: 2.06–11.23, p<0.001, across two studies) than RC alone. Most studies were randomized prospective trials (level 1 evidence), and all the effects were irrespective of the type of study design and did not vary between subgroups of patients. In conclusion, NAC combined with RC is recommended for patients with T3-4aN0M0 but not for patients with T2N0M0.
Keywords	Medicine (General) ; R5-920
Subject code	610
Language	English
Publishing date	2022-01-01T00:00:00Z
Publisher	Hindawi Limited
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Construction of a TTT-η Diagram of High-Refractive Polyurethane Based on Curing Kinetics

Shidi Huang / Guiming Zhang / Weiping Du / Huifang Chen

Polymers, Vol 13, Iss 3474, p

2021 Volume 3474

Abstract: A time–temperature–transformation–viscosity (TTT-η) diagram can reflect changes in the physical states of a resin, which take on significance for the study of the curing process of polyurethane resin lenses. Coupling the differential scanning calorimetry ...

Abstract	A time–temperature–transformation–viscosity (TTT-η) diagram can reflect changes in the physical states of a resin, which take on significance for the study of the curing process of polyurethane resin lenses. Coupling the differential scanning calorimetry (DSC) test, the curing kinetic parameters of 1,4-bis(isocyanatomethyl)cyclohexane (H 6 XDI)/2,3-bis((2-mercaptoethyl)thio)-1-propanethiol (BES) polyurethane system were obtained. By phenomenological modeling, the relationships between degree, temperature, and time were obtained. An isothermal DSC test was carried out at 423 K. Based on the DiBenedetto equation, the relationships between glass transition temperature, degree of cure, and time were obtained, and the glass transition temperature was thus correlated with temperature and time. The gelation time at different temperatures was measured by rotary rheometry, and the relationship between gelation time and gelation temperature was established. The time–temperature–transformation (TTT) diagram of H 6 XDI/BES system was constructed accordingly. Subsequently, a six-parameter double Arrhenius equation was used as the basis for the rheological study. The viscosity was examined during the curing process. The TTT-η diagram was obtained, which laid the theoretical foundation for the optimization and setting of processing parameters.
Keywords	polyurethane ; curing kinetics ; TTT diagram ; TTT-η diagram ; Organic chemistry ; QD241-441
Subject code	620
Language	English
Publishing date	2021-10-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Cancer-Associated Fibroblasts Regulate Bladder Cancer Invasion and Metabolic Phenotypes through Autophagy

Dahai Dong / Yu Yao / Jinlei Song / Lijiang Sun / Guiming Zhang

Disease Markers, Vol

2021 Volume 2021

Abstract: Recently, both cancer-associated fibroblasts (CAFs) and autophagy have been proven to play an important role in tumor development, including bladder cancer (BCa). However, the real mechanisms remain largely unclear. Here, we reconstruct a mimic tumor ... ...

Abstract	Recently, both cancer-associated fibroblasts (CAFs) and autophagy have been proven to play an important role in tumor development, including bladder cancer (BCa). However, the real mechanisms remain largely unclear. Here, we reconstruct a mimic tumor microenvironment to explore the interaction between CAFs and the BCa cell line T24 using a coculture system. Autophagy in CAFs was induced or inhibited by rapamycin or siRNA, respectively. After coculture with CAFs, T24 cell proliferation, invasion, and aerobic glycolysis were tested in vitro. Rapamycin induced and siAtg5 inhibited autophagy in CAFs. Enhanced autophagy in CAFs promoted cell proliferation and invasion in T24 cells in vitro, while there was no significant difference between the autophagy-inhibited group and the controls. Lactate concentration was elevated in both rapamycin-treated and siAtg5-treated groups compared with the control group. In addition, the expression levels of MCT1, MCT4, HK2, SLC2A1, and MMP-9 were all increased in T24 cells in the autophagy-enhanced group. Our results indicated that CAFs could regulate BCa invasion and metabolic phenotypes through autophagy, providing us with new alternative treatments for BCa in the future.
Keywords	Medicine (General) ; R5-920
Subject code	616
Language	English
Publishing date	2021-01-01T00:00:00Z
Publisher	Hindawi Limited
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: A 5-lncRNA Signature Associated with Smoking Predicts the Overall Survival of Patients with Muscle-Invasive Bladder Cancer

Haoyue Sheng / Guiming Zhang / Yongqiang Huang / Lijiang Sun / Guohai Shi / Dingwei Ye

Disease Markers, Vol

2021 Volume 2021

Abstract: Increasing evidence demonstrated that noncoding RNA is abnormally expressed in cancer tissues and serves a vital role in tumorigenesis, tumor development, and metastasis. The aim of the present study was to determine an lncRNA signature in order to ... ...

Abstract	Increasing evidence demonstrated that noncoding RNA is abnormally expressed in cancer tissues and serves a vital role in tumorigenesis, tumor development, and metastasis. The aim of the present study was to determine an lncRNA signature in order to predict the overall survival (OS) of patients with muscle-invasive bladder cancer (MIBC). A total of 246 patients with pathologically confirmed MIBC in The Cancer Genome Atlas (TCGA) dataset were recruited and included in the present study. We choose patients who have smoked less (including never smoking) or more than 15 years. A total of 44 differentially expressed lncRNAs were identified with a fold change larger than 1.5 and a P value < 0.05 through the limma package. Subsequently, a comparison between patients with no tobacco smoke exposure for <15 years and patients who had been exposed to tobacco smoke for >15 years was performed by using the matchIt package. Among the 44 differentially expressed lncRNAs, 5 lncRNAs were identified to be significantly associated with OS. Based on the characteristic risk scores of these 5 lncRNAs, patients were divided into low-risk and high-risk groups and exhibited significant differences in OS. Multivariate Cox regression analysis demonstrated that the 5-lncRNA signature was independent of age, tumor-node metastasis (TNM) staging, lymphatic node status, and adjuvant postoperative radiotherapy. In the present study, a novel 5-lncRNA signature was developed and was demonstrated to be useful in predicting the survival of patients with MIBC. If validated, this lncRNA signature may assist in the selection of a high-risk subpopulation that requires more aggressive therapeutic intervention. The risk scores involved in several associated pathways were identified using gene set enrichment analysis (GSEA). However, the clinical implications and mechanism of these 5 lncRNAs require further investigation.
Keywords	Medicine (General) ; R5-920
Subject code	610
Language	English
Publishing date	2021-01-01T00:00:00Z
Publisher	Hindawi Limited
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

Article ; Online: Urine Culture in Hospitalized Patients during 2014-2018

Dongkai Sun / Peishan Cong / Fengju Guan / Shuai Liu / Lijiang Sun / Guiming Zhang

Disease Markers, Vol

An Analysis on Pathogen Distribution and Drug Sensitivity

2021 Volume 2021

Abstract: Objective. We sought to analyze the distribution and antibiotic sensitivity of pathogens in hospitalized patients and to provide a scientific reference for the rational application of antibiotics. Methods. From January 2014 to December 2018, urine ... ...

Abstract	Objective. We sought to analyze the distribution and antibiotic sensitivity of pathogens in hospitalized patients and to provide a scientific reference for the rational application of antibiotics. Methods. From January 2014 to December 2018, urine cultures from patients in our hospital were collected and analyzed retrospectively for the presence, distribution, and drug sensitivity of pathogens. Results. A total of 42,854 midstream urine cultures were collected from which 11,891 (27.75%) pathogens were isolated, including 8101 (68.13%) strains of gram-negative bacteria, 2580 (21.69%) strains of gram-positive bacteria, and 1210 (10.18%) strains of fungi. Escherichia coli and Enterococci were the most common species of gram-negative and gram-positive bacteria, respectively. Drug sensitivity varied among different pathogens. Clear drug resistance was observed in bacteria, while fungus exhibited relatively lower resistance. Conclusion. Pathogens responsible for urinary tract infections in hospitalized patients are diversiform and display resistance to some antibiotics. Drug resistance monitoring should be enhanced to optimize antimicrobial therapy.
Keywords	Medicine (General) ; R5-920
Subject code	610
Language	English
Publishing date	2021-01-01T00:00:00Z
Publisher	Hindawi Limited
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

Full text online

Full text

Inter-library loan at ZB MED

Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

To top

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED

Full text online

More links

Kategorien

Inter-library loan at ZB MED