oalib

OALib Journal期刊

ISSN: 2333-9721

费用：99美元

投稿

时间不限

( 2673 )

( 2672 )

( 2208 )

( 2024 )

自定义范围…

匹配条件： “J. Karhunen” ，找到相关结果约356586条。
列表显示的所有文章，均可免费获取
第1页/共356586条
每页显示 条
Development of a neural network model for cloud fraction detection using NASA-Aura OMI VIS radiance measurements
G. Saponaro,P. Kolmonen,J. Karhunen,J. Tamminen
Atmospheric Measurement Techniques Discussions , 2013, DOI: 10.5194/amtd-6-1649-2013
Abstract: The discrimination of cloudy pixels is required in almost any estimate of a parameter retrieved from a satellite image in the ultraviolet (UV), visual (VIS) or infra-red (IR) parts of the electromagnetic spectrum. Also, the distincion of clouds within satellite imagery and the distribution of their micro-physical properties is essential to the understanding of radiative transfer through the atmosphere. This paper reports the development of neural network algorithms for cloud detection for the NASA-Aura Ozone Monitoring Instrument (OMI). We present and discuss the results obtained by training mathematical neural networks with simultaneous application to OMI and Aqua-MODerate Resolution Imaging Spectrometer (MODIS) data. The neural network delivers cloud fraction estimates in a fast and automated way. The developed neural network approach performs generally well in the training. Highly reflective surfaces, such as ice, snow, sun glint and desert, or atmospheric dust mislead the neural network to a wrong predicted cloud fraction.
High prevalence of lactase non-persistence among indigenous nomadic Nenets, north-west Russia
Yulia Khabarova,Valentina Grigoryeva,Sari Tuomisto,Pekka J. Karhunen
International Journal of Circumpolar Health , 2012, DOI: 10.3402/ijch.v71i0.17898
Abstract: Objectives. The frequency of adult-type hypolactasia (lactase non-persistence) varies widely among different ethnic groups. The cultural historical hypothesis assumes a link between the occurrence of hypolactasia and the distribution of dairy farming. The nomadic Nenets have been reindeer herders for generations and have therefore not consumed any dairy products. The hypotheses here was that the prevalence of lactase non-persistence ( 13910 C/C genotype) among Nenets people having four Nenets grandparents is high, while the prevalence among Nenets originating from ethnically mixed families is lower. Study design. The material was collected in four typical Nenets settlements in the Nenets Autonomous Okrug in Russia. One-third of the adult Nenets population were invited to answer a questionnaire and to donate buccal samples for genotyping by a doctor from the team of medical professionals who make rounds in this area. The total number of available participants was 177. Methods. Genotyping was performed with the AbiPrism system. We used the method of concordance of grandparents’ national origin to ascribe ethnicity. Results. The prevalence of adult-type hypolactasia ( 13910 C/C) among Nenets who had four Nenets grandparents was found to be 90%. The figures among others reporting three, two and one grandparent of Nenets origin were 72, 60 and 28%, respectively. Conclusion. The findings are in accord with the cultural historical hypothesis.
Low redshift quasars in the SDSS Stripe 82. The local environments
K. Karhunen,J. K. Kotilainen,R. Falomo,D. Bettoni
Physics , 2014, DOI: 10.1093/mnras/stu688
Abstract: We study the environments of low redshift (z < 0.5) quasars based on a large and homogeneous dataset from the Stripe 82 region of the Sloan Digital Sky Survey (SDSS). We have compared the < 1 Mpc scale envi- ronments of 302 quasars that were resolved in our recent study to those of 288 inactive galaxies with closely matched redshifts. Crucially, the lu- minosities of the inactive galaxies and the quasar host galaxies are also closely matched, unlike in most previous studies. The environmental overdensities were studied by measuring the num- ber density of galaxies within a projected distance of 200 kpc to 1 Mpc. The galaxy number density of the quasar environments is comparable to that of the inactive galaxies with similar luminosities, both classes of ob- jects showing significant excess compared to the background galaxy density for distances < 400 kpc. There is no significant dependence of the galaxy number density on redshift, quasar or host galaxy luminosity, black hole mass or radio loudness. This suggests that the fueling and triggering of the nuclear activity is only weakly dependent on the local environment of quasars, and the quasar phase may be a short-lived common phase in the life cycle of all massive galaxies.
Dynamics of a Sex-Linked Deleterious Mutation in Populations Subject to Sex Reversal
Markku Karhunen
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0025362
Abstract: The heterogametic sex chromosomes (i.e. mammalian Y and avian W) do not usually recombine with the homogametic sex chromosomes which is known to lead into rapid degeneration of Y and W due to accumulation of deleterious mutations. On the other hand, some 96% of amphibian species have homomorphic, i.e. non-degenerate chromosomes. Nicolas Perrin's fountain-of-youth hypothesis states that this is a result of recombination between and chromosomes in sex-reversed individuals. In this study, I model the consequences of such recombination for the dynamics of a deleterious mutation occurring in chromosomes. As expected, even relatively low levels of sex reversal help to purge deleterious mutations. However, the population-dynamic consequences of this depend on the type of selection that operates on the population undergoing sex reversal. Under fecundity selection, sex reversal can be beneficial for some parameter values, whereas under survival selection, it seems to be always harmful.
Regional Energy Balance and Its Implementation to South Karelia  [PDF]
Mika Laihanen, Antti Karhunen, Tapio Ranta
Journal of Sustainable Bioenergy Systems (JSBS) , 2011, DOI: 10.4236/jsbs.2011.11001
Abstract: All EU countries have targets for increasing the use of renewable energy at a national level. However this effort should become concrete at regional and local levels where investments on bioenergy are made. This study introduces a systematical and universally applicable method for constructing regional energy balance. This study focuses on the method how to combine specific regional primary energy sources with their end uses. The primary energy sources include different fuels and the net import of electricity. The energy end uses are heat, electricity and losses. The concept of the regional energy balance was illustrated through a case of South Karelia. The total use of primary energy in South Karelia was 25.2 TWh (or 91 PJ) in 2010 and the share of renewable energy sources was 65%. The regional energy balance analysis can be utilized as a guideline for strategically planning and allocating regional energy sources for example, increasing the use of renewable energy sources. It can provide local decision makers and shareholders about the current status of energy supply, convincing them to take proper actions and consider producing energy at a local and regional level.
Supply and Demand of a Forest Biomass in Application to the Region of South-East Finland  [PDF]
Antti Karhunen, Mika Laihanen, Tapio Ranta
Smart Grid and Renewable Energy (SGRE) , 2012, DOI: 10.4236/sgre.2012.31005
Abstract: In Finland it is estimated that forest biomass will be the main source of bioenergy when meeting the national target: 38% renewable from total energy consumption by 2020. This target must become concrete for regional and local level participators of a forest industry and actions should take place in large combined heat and power generation (CHP) plants, district heating plants and independent heating systems. In energy production replacing fossil fuels with renewa-ble energy is reasonable in many cases. However, there are usually doubts about the availability and security of supply of forest biomass. The aim of this study is to introduce a systematical method for analyzing the availability and demand of forest biomass in regional and local level. This study introduces an objective method for analyzing local possibilities on where and how much the use of forest biomass could be increased. By replacing use of fossil fuels with renewable and domestic energy sources carbon dioxide (CO2) emissions and dependency on imported fossil fuels can be reduced. Utilization of biomass creates also local employment on energy sector.
Implementation of National Renewable Energy Obligations at the Regional Level  [PDF]
Mika Laihanen, Antti Karhunen, Tapio Ranta
Journal of Sustainable Bioenergy Systems (JSBS) , 2019, DOI: 10.4236/jsbs.2019.94010
Abstract: The aim of the paper described here was to clarify the potential of decreasing the use of fossil fuels regionally. According to Finnish national obligations, the use of oil and other fossil fuels should be minimised by 2030. The study combines the regional consumption of primary energy sources with national obligations introduced in the national climate and energy strategy. This set up a basis when evaluating the regional state of future energy supply for 2030. The paper utilises the region of South Savo as a case study. In the region, the consumption of renewable energy sources is already above the national average, but it can be increased further by 2030. Wood fuels and especially forest biomass have regionally a major role. Local and national targets, support schemes and willingness to invest play key roles when increasing the use of renewable energy sources in the future.
Development of the Bioenergy as a Part of Renewable Energy in the Nordic Countries: A Comparative Analysis  [PDF]
Tapio Ranta, Mika Laihanen, Antti Karhunen
Journal of Sustainable Bioenergy Systems (JSBS) , 2020, DOI: 10.4236/jsbs.2020.103008
Abstract: A comparative assessment of the bioenergy and renewable energy situation in the Nordic countries, Finland, Sweden, Denmark and Norway, was conducted in this study. What factors have contributed to the current high use of renewable energy and especially bioenergy in the Nordic countries? What are the sources of renewable energy and where renewable energy is being used? The development of renewable energy use is described by time series and compared to the overall development of the EU. All of the Nordic countries have high renewable energy consumption and have already met the target for gross final energy consumption according to the Europe 2020 strategy while the EU is behind the 20% target. In total, 53.1 Mtoe renewable energy was used in the Nordic countries in 2018, which was 51% of the final energy consumption, 103.3 Mtoe. Bioenergy accounts for approximately half of renewable energy, 25.8 Mtoe, and is anticipated to develop further. Especially in Norway and Sweden the share of renewable energy was high (73% and 55%) compared to Finland and Denmark (41% and 36%). Norway is famous for hydropower (81% share of Renewable Energy Sources (RES) in 2018) and Denmark for wind power production (20%), while Finland utilizes a lot of biomass for co-generation and heating (79%), followed by Denmark (64%) and Sweden (55%) in 2018. At EU level, bioenergy plays even a higher role than in Nordic countries in renewable energy production (56%) in 2017 and is anticipated to continue to grow in all end-use sectors such as heating and cooling, electricity generation and transport, in the 2020s.
The Role of Bioenergy in Achieving the Carbon Neutrality Target in Finland by 2035—A Case Study of Student Surveyed at University in Finland  [PDF]
Tapio Ranta, Mika Laihanen, Antti Karhunen
Journal of Sustainable Bioenergy Systems (JSBS) , 2021, DOI: 10.4236/jsbs.2021.112005
Abstract: The largest share of renewable energy in Finland comes from bioenergy. In 2019, bioenergy accounted for 82% (416 PJ, 116 TWh) of renewable energy in Finland. This study assesses the potential for increasing bioenergy in energy production by 2035 and what role it will play in achieving the carbon neutrality target in Finland. The role of different energy sources in the energy system was examined using existing scenarios developed for The National Long-Term Strategy. Two alternative low-emission scenarios have been developed to last until 2050 to meet the 2035 carbon neutrality target. In 2035, the amount of bioenergy has risen to 520 - 550 PJ (144 - 153 TWh), which is about 70% of renewable energy consumption. This means, that the bioenergy resource has been fully deployed and the relative share of bioenergy in renewables has decreased slightly. The study also included a survey to university students to map out how likely a carbon neutrality target is to be considered by 2035. University students were unsure of achieving the carbon neutrality target by 2035. The schedule was considered challenging especially in the transport sector. Bioenergy was also seen as still playing an important role, especially in heat production. Achieving significant emission reductions will require significant electrification in all energy use sectors, as fossil fuels cannot be sustainably replaced by bioenergy on a sufficiently large scale.
CLU, CR1 and PICALM genes associate with Alzheimer's-related senile plaques
Eloise H Kok, Teemu Luoto, Satu Haikonen, Sirkka Goebeler, Hannu Haapasalo, Pekka J Karhunen
Alzheimer's Research & Therapy , 2011, DOI: 10.1186/alzrt71
Abstract: We investigated the associations of senile plaques (SP) and neurofibrillary tangles (NFT) with the proposed risk genes and APOE, in the Tampere Autopsy Study (TASTY) series (603 cases), a sample of the general population (0 to 97 yrs), who died out-of-hospital.Age and the APOEε4 allele associated strongly with all phenotypes of SP, as expected. In age and APOEε4 adjusted analyses, compared to the most common homozygous genotype, burnt out SP were more common among carriers of the C-allele of CLU, whereas the T-allele of PICALM and C-allele of CR1 were linked with lower SP coverage. We found no significant associations between any of the genetic variants and NFT.Marginal effects from CLU, CR1 and PICALM suggest that these genes have minimal effects on the development of AD lesions.Alzheimer's disease (AD) is the most common form of dementia in Western society and is, and will continue to be, a burden on health systems in the future as the population ages. Age is the largest risk factor for the disease, with higher incidences in older populations [1,2].Identification of genes related to sporadic AD risk has been slow with study groups isolating only one strongly associated gene: APOE [3,4]. The epsilon 4 allele of apolipoprotein E (APOEε4) provides odds ratios (ORs) of between 3 and 25 [5,6] for disease association. APOEε4 is suspected to have a lower effectiveness at transporting cholesterol and is not as efficient at repairing neuronal damage as APOEε3 [7]. One or even two copies of the allele, however, are not sufficient to cause the disease, as many carriers of two ε4 alleles do not develop AD [5].Studies aiming to detect genes associated with disease risk have used heterogeneous AD cohorts and ascertained few polymorphisms with only a minor impact on disease incidence. One of the problems is to distinguish between pure AD, vascular dementia and other dementia types in clinical cohorts [8-10]. The only consistent and currently accepted method for confirming AD is
第1页/共356586条
每页显示 条


Home
Copyright © 2008-2020 Open Access Library. All rights reserved.