72 research outputs found
Homological computation using spanning trees
We introduce here a new F2 homology computation algorithm based on a generalization of the spanning tree technique on a finite 3-dimensional cell complex K embedded in ℝ3. We demonstrate that the complexity of this algorithm is linear in the number of cells. In fact, this process computes an algebraic map φ over K, called homology gradient vector field (HGVF), from which it is possible to infer in a straightforward manner homological information like Euler characteristic, relative homology groups, representative cycles for homology generators, topological skeletons, Reeb graphs, cohomology algebra, higher (co)homology operations, etc. This process can be generalized to others coefficients, including the integers, and to higher dimension
Getting Topological Information for a 80-Adjacency Doxel-Based 4D Volume through a Polytopal Cell Complex
Mapping of mosquito breeding sites in malaria endemic areas in Pos Lenjang, Kuala Lipis, Pahang, Malaysia
<p>Abstract</p> <p>Background</p> <p>The application of the Geographic Information Systems (GIS) to the study of vector transmitted diseases considerably improves the management of the information obtained from the field survey and facilitates the study of the distribution patterns of the vector species.</p> <p>Methods</p> <p>As part of a study to assess remote sensing data as a tool for vector mapping, geographical features like rivers, small streams, forest, roads and residential area were digitized from the satellite images and overlaid with entomological data. Map of larval breeding habitats distribution and map of malaria transmission risk area were developed using a combination of field data, satellite image analysis and GIS technique. All digital data in the GIS were displayed in the WGS 1984 coordinate system. Six occasions of larval surveillance were also conducted to determine the species of mosquitoes, their characteristics and the abundance of habitats.</p> <p>Results</p> <p>Larval survey studies showed that anopheline and culicine larvae were collected and mapped from 79 and 67 breeding sites respectively. Breeding habitats were located at 100-400 m from human settlement. Map of villages with 400 m buffer zone visualizes that more than 80% of <it>Anopheles maculatus s.s</it>. immature habitats were found within the buffer zone.</p> <p>Conclusions</p> <p>This study amplifies the need for a broadening of the GIS approach which is emphasized with the aim of rejuvenating the dynamic aspect of entomological studies in Malaysia. In fact, the use of such basic GIS platforms promote a more rational basis for strategic planning and management in the control of endemic diseases at the national level.</p
Insect Pollinated Crops, Insect Pollinators and US Agriculture: Trend Analysis of Aggregate Data for the Period 1992–2009
In the US, the cultivated area (hectares) and production (tonnes) of crops that require or benefit from insect pollination (directly dependent crops: apples, almonds, blueberries, cucurbits, etc.) increased from 1992, the first year in this study, through 1999 and continued near those levels through 2009; aggregate yield (tonnes/hectare) remained unchanged. The value of directly dependent crops attributed to all insect pollination (2009 USD) decreased from 10.69 billion in 2001, but increased thereafter, reaching 11.68 billion and 15.45 billion in 1996 to 5.39 billion and 4.99 and $7.04 billion. Trend analysis demonstrates that US producers have a continued and significant need for insect pollinators and that a diminution in managed or wild pollinator populations could seriously threaten the continued production of insect pollinated crops and crops grown from seeds resulting from insect pollination
Colony Collapse Disorder: A Descriptive Study
BACKGROUND: Over the last two winters, there have been large-scale, unexplained losses of managed honey bee (Apis mellifera L.) colonies in the United States. In the absence of a known cause, this syndrome was named Colony Collapse Disorder (CCD) because the main trait was a rapid loss of adult worker bees. We initiated a descriptive epizootiological study in order to better characterize CCD and compare risk factor exposure between populations afflicted by and not afflicted by CCD. METHODS AND PRINCIPAL FINDINGS: Of 61 quantified variables (including adult bee physiology, pathogen loads, and pesticide levels), no single measure emerged as a most-likely cause of CCD. Bees in CCD colonies had higher pathogen loads and were co-infected with a greater number of pathogens than control populations, suggesting either an increased exposure to pathogens or a reduced resistance of bees toward pathogens. Levels of the synthetic acaricide coumaphos (used by beekeepers to control the parasitic mite Varroa destructor) were higher in control colonies than CCD-affected colonies. CONCLUSIONS/SIGNIFICANCE: This is the first comprehensive survey of CCD-affected bee populations that suggests CCD involves an interaction between pathogens and other stress factors. We present evidence that this condition is contagious or the result of exposure to a common risk factor. Potentially important areas for future hypothesis-driven research, including the possible legacy effect of mite parasitism and the role of honey bee resistance to pesticides, are highlighted
DNA barcoding and surveillance sampling strategies for Culicoides biting midges (Diptera: Ceratopogonidae) in southern India
Haemoladaps travisi, a new species of mite from the Philippines (Laelaptidae : Aearina)
Volume: 44Start Page: 49End Page: 5
An Unusual New Species of Neocypholaelaps (Acari: Ameroseiidae) from the Nests of Stingless Bees (Apidae: Meliponinae)
A new species of Neocypholaelaps (Ameroseiidae) is described from the nests of stingless bees (Apidae: Meliponinae) from Malaysia. Neocypholaelaps phooni Baker & Delfinado-Baker, n. sp. is unusual among ameroseiids in that it shows morphological specialization found in certain Hypoaspidinae-Laelapidae species inhabiting stingless bee nests. Hyper-trophy of certain body and leg setae to form attachment organs is a common feature of this group. The 11 known species of Neocypholaelaps are primarily tropical in distribution. They occur on various tropical and sub-tropical flowers, and they are believed to be pollen feeders. The mites use the bees (Apis and Trigona spp.), moths and butterflies as means of dispersal. An identification key to Neocypholaelaps species is given as well as distribution and a list of hosts
Geographic variation in Varroa jacobsoni (Acari, Varroidae) : application of multivariate morphometric techniques
International audienc
Racial/ethnic bias and its role in severe maternal morbidity
Racial and ethnic health disparities have been identified by many information sources in recent years, and a specific example of this is severe maternal morbidity and mortality, which includes mortality from postpartum hemorrhage. It is this racial/ethnic health disparity that has been highlighted in news reports that should be of concern to all physicians and healthcare providers, recognizing that women of color have more than three times the risk of dying in childbirth than white women. The details about this are worthy of further exaination
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