6,474 research outputs found
An Exploratory Study of Online Information Regarding Colony Collapse Disorder
The cause or causes of Colony Collapse Disorder (CCD) are uncertain. CCD defines specific characteristics of the nationwide deaths of honey bee colonies in the last decade. Adult bees often disappear from the hive and die, leaving the colony weak and vulnerable to disease. Environmental scientists and agriculturalists have developed many different theories about CCD and its origins. The different theories create challenges regarding the effective dissemination of information about CCD to the different realms of public information seekers. There is a need for an exploration of the online communication of CCD information using federal environmental agency web resources. CCD research information dissemination practices are one example of the trans-disciplinary complexity surrounding many current environmental issues. The study addresses different information “packages” offered or not offered for different types of CCD information seekers. The goal of the study is to inform future research addressing the comprehensive construction of federal e-government science information by finding strengths and weaknesses in the current information landscape of CCD resources on the web
IUE observations of Herbig-Haro and related objects
The I.U.E. spectra of the Herbig-Haro objectives H-H 1, H-H 2H, H-H 2G and H-H 32 A are considered. In order to obtain a better understanding of the physics of these intriguing objects and of the formation of the ultraviolet continua and emission lines in H-H objects, the UV spectra of the Cohen-Schwartz star, the T Tauri star AS 353A, and of the reflection nebula NGC 1999 (which is illuminated by the young object V 380 Orionis), are also examined
Beneficial and Harmful Agile Practices for Product Quality
There is the widespread belief that Agile neglects the product quality. This
lack of understanding how Agile processes assure the quality of the product
prevents especially companies from regulated domains from an adoption of Agile.
This work aims to identify which Agile Practices contribute towards product
quality. Hence, data from a survey study is analyzed to identify Ag-ile
Practices which are beneficial or harmful for the quality of the product. From
49 practices that were used in the survey so far, 36 were perceived to have a
positive impact on product quality, while four practices were rated as being
harmful. The results enrich understanding of how product quality can be
achieved in Agile, and support selection of practices to improve quality
Classification of Big Point Cloud Data Using Cloud Computing
Point cloud data plays an significant role in various geospatial applications as it conveys plentiful information which can be used for different types of analysis. Semantic analysis, which is an important one of them, aims to label points as different categories. In machine learning, the problem is called classification. In addition, processing point data is becoming more and more challenging due to the growing data volume. In this paper, we address point data classification in a big data context. The popular cluster computing framework Apache Spark is used through the experiments and the promising results suggests a great potential of Apache Spark for large-scale point data processing
A new framework for interactive segmentation of point clouds
Point cloud segmentation is a fundamental problem in point processing. Segmenting a point cloud fully automatically is very challenging due to the property of point cloud as well as different requirements of distinct users. In this paper, an interactive segmentation method for point clouds is proposed. Only two strokes need to be drawn intuitively to indicate the target object and the background respectively. The draw strokes are sparse and don't necessarily cover the whole object. Given the strokes, a weighted graph is built and the segmentation is formulated as a minimization problem. The problem is solved efficiently by using the Max Flow Min Cut algorithm. In the experiments, the mobile mapping data of a city area is utilized. The resulting segmentations demonstrate the efficiency of the method that can be potentially applied for general point clouds
Prospects for measuring coherent neutrino-nucleus elastic scattering at a stopped-pion neutrino source
Rates of coherent neutrino-nucleus elastic scattering at a high-intensity
stopped-pion neutrino source in various detector materials (relevant for novel
low-threshold detectors) are calculated. Sensitivity of a coherent
neutrino-nucleus elastic scattering experiment to new physics is also explored.Comment: 9 pages, 14 figures; minor modifications for publicatio
Bacteriophage and their potential roles in the human oral cavity.
The human oral cavity provides the perfect portal of entry for viruses and bacteria in the environment to access new hosts. Hence, the oral cavity is one of the most densely populated habitats of the human body containing some 6 billion bacteria and potentially 35 times that many viruses. The role of these viral communities remains unclear; however, many are bacteriophage that may have active roles in shaping the ecology of oral bacterial communities. Other implications for the presence of such vast oral phage communities include accelerating the molecular diversity of their bacterial hosts as both host and phage mutate to gain evolutionary advantages. Additional roles include the acquisitions of new gene functions through lysogenic conversions that may provide selective advantages to host bacteria in response to antibiotics or other types of disturbances, and protection of the human host from invading pathogens by binding to and preventing pathogens from crossing oral mucosal barriers. Recent evidence suggests that phage may be more involved in periodontal diseases than were previously thought, as their compositions in the subgingival crevice in moderate to severe periodontitis are known to be significantly altered. However, it is unclear to what extent they contribute to dysbiosis or the transition of the microbial community into a state promoting oral disease. Bacteriophage communities are distinct in saliva compared to sub- and supragingival areas, suggesting that different oral biogeographic niches have unique phage ecology shaping their bacterial biota. In this review, we summarize what is known about phage communities in the oral cavity, the possible contributions of phage in shaping oral bacterial ecology, and the risks to public health oral phage may pose through their potential to spread antibiotic resistance gene functions to close contacts
NOSQL For Storage and Retrieval of Large LiDAR Data Collections
Developments in LiDAR technology over the past decades have made LiDAR to become a mature and widely accepted source of geospatial information. This in turn has led to an enormous growth in data volume. The central idea for a file-centric storage of LiDAR point clouds is the observation that large collections of LiDAR data are typically delivered as large collections of files, rather than single files of terabyte size. This split of the dataset, commonly referred to as tiling, was usually done to accommodate a specific processing pipeline. It makes therefore sense to preserve this split. A document oriented NoSQL database can easily emulate this data partitioning, by representing each tile (file) in a separate document. The document stores the metadata of the tile. The actual files are stored in a distributed file system emulated by the NoSQL database. We demonstrate the use of MongoDB a highly scalable document oriented NoSQL database for storing large LiDAR files. MongoDB like any NoSQL database allows for queries on the attributes of the document. As a specialty MongoDB also allows spatial queries. Hence we can perform spatial queries on the bounding boxes of the LiDAR tiles. Inserting and retrieving files on a cloud-based database is compared to native file system and cloud storage transfer speed
MeV-mass dark matter and primordial nucleosynthesis
The annihilation of new dark matter candidates with masses in the MeV
range may account for the galactic positrons that are required to explain the
511 keV -ray flux from the galactic bulge. We study the impact of
MeV-mass thermal relic particles on the primordial synthesis of H, He,
and Li. If the new particles are in thermal equilibrium with neutrinos
during the nucleosynthesis epoch they increase the helium mass fraction for
m_X\alt 10 MeV and are thus disfavored. If they couple primarily to the
electromagnetic plasma they can have the opposite effect of lowering both
helium and deuterium. For --10 MeV they can even improve the overall
agreement between the predicted and observed H and He abundances.Comment: 11 pages, 10 figures, references and two appendices added,
conclusions unchanged; accepted for publication in Phys.Rev.
- …