914 resultados para principal component


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The use of near infrared (NIR) hyperspectral imaging and hyperspectral image analysis for distinguishing between hard, intermediate and soft maize kernels from inbred lines was evaluated. NIR hyperspectral images of two sets (12 and 24 kernels) of whole maize kernels were acquired using a Spectral Dimensions MatrixNIR camera with a spectral range of 960-1662 nm and a sisuChema SWIR (short wave infrared) hyperspectral pushbroom imaging system with a spectral range of 1000-2498 nm. Exploratory principal component analysis (PCA) was used on absorbance images to remove background, bad pixels and shading. On the cleaned images. PCA could be used effectively to find histological classes including glassy (hard) and floury (soft) endosperm. PCA illustrated a distinct difference between glassy and floury endosperm along principal component (PC) three on the MatrixNIR and PC two on the sisuChema with two distinguishable clusters. Subsequently partial least squares discriminant analysis (PLS-DA) was applied to build a classification model. The PLS-DA model from the MatrixNIR image (12 kernels) resulted in root mean square error of prediction (RMSEP) value of 0.18. This was repeated on the MatrixNIR image of the 24 kernels which resulted in RMSEP of 0.18. The sisuChema image yielded RMSEP value of 0.29. The reproducible results obtained with the different data sets indicate that the method proposed in this paper has a real potential for future classification uses.

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The purpose of this research was to evaluate the special vocational training programme, which aimed at enhancing the pupils with autism spectrum to prepare themselves for work and independent life. The vocational training programme is based on TEACCH (Treatment and Education of Autistic and Related Communication handicapped CHildren), which takes into account the autism spectrum disorders and autistic behaviour. TEACCH is based on the principles of structured teaching, functional teaching and preparation training for work and independent life. The TEACCH has been adapted to Finnish society and the educational system. Treatment programmes were individually designed for each student´s educational needs. There is also an important role for the AAPEP rating scale (Adolescent and Adult Psychoeducational Profile). The AAPEP has been the major tool for planning and following the courses. The AAPEP is an assessment instrument designed by the TEACCH programme, and it is used to provide an evaluation of current and potential skills. The AAPEP contains three scales: a direct observation scale, a home scale and a school / work scale. The AAPEP includes six test variables: vocational skills, independent functions, functional communication, interpersonal behaviour, vocational behaviour and leisure skills; these are evaluated at three levels: pass, emerge and fail. The subjects were 49 students (65% male and 35 % female) with autism spectrum, who have been followed and tested several times, also one year after the vocational training. The design is therefore a longitudinal one. The research data were collected 1997-2004 using the AAPEP rating scales. The teachers have used the AAPEP scales and the codings have been checked by the researcher. The results of the principal component analysis (PCA) suggested that the structure of AAPEP rating scales works quite well as a hypothesis. The factor structure of the scales of the AAPEP was almost the same in these data as in the original publications. The learning-and-changes results showed that learning is a slow process, but that there were also intended changes in several AAPEP areas. The Cohen´s kappa was used as an effect-size measure and the most important result of this research showed that the student´s skills were developing on a school / work scale; vocational skills variable (0,34), vocational behaviour variable (0,28), leisure skills variable (0,26) and on a direct observation scale; interpersonal behaviour variable (0,21). On a home scale skills of some students were developing negatively and also that effect-size was small. The results showed that the students´ vocational skills and vocational behaviour will continue to develop after school in many areas. There were differences between scales. The result of this research shows that the student´s skills were developing significantly in 3 of 48 variables on a direct observation scale and also on a home scale. On a school / work scale student´s skills were developing significantly in 17 of 48 variables. This result implies that students can do the work without extra assistance if there exist continuing supports for the skills after the vocational training. The fully independent life of students will be difficult, because their independent functions, functional communications and leisure skills regressed after the schooling. This seems to indicate that they will not manage their daily life without support. The students and their parents said that the treatment programmes were individually designed for each student s educational needs, and that they were satisfied with the programmes and services. Generally, it can be concluded that vocational special education can be developed for pupils with autistic syndrome and the detailed teaching can be done using TEACCH principles and applying the tool of AAPEP.

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The aim of this study was to find out how immersion students experience immersion education, how they feel about the implementation of immersion education methods and what role immersion plays in immersion students’ lives outside the school context. In addition, the influence of sex, grade level, school and type of immersion education on students’ perceptions was studied. The population included all students at the lower secondary level in Helsinki who participated in Swedish immersion education during 2002–2003. The sample consisted of 128 students who represented two different forms of immersion: 47% of the students had previously participated in early total immersion while 53 % of the students had taken part in early partial immersion. The data were gathered through a questionnaire and interviews. All 128 students answered the questionnaire, and 10 students were chosen to focus interviews through purposive sampling. In addition, students’ parents were invited to fill in a questionnaire where students’ background information was requested. The data were collected during the spring of 2003. Principal Component Analysis and one-way variance analysis were used as statistical analysis methods. Also frequencies, average, correlations and cross tabs were studied. In the PCA a right-angled varimax-rotation was performed separately to every thematic entity that arose from the theoretical background. Sum variables were formed from the Principal Components by summing up all the items that received over .400 charges for the specific Principal Component. Significance testing of the mean was performed with F and t-tests. Results indicate that immersion students in lower secondary school experience immersion quite diversely as a whole. Students are satisfied with the fact that they are in the immersion class but not with the amount of teaching in Swedish. Students feel it is very important and useful to learn Swedish bearing in mind their future studies and working life. The students estimate their language skills to be very high. Yet they prefer using Finnish during classes. The fact that teachers use Swedish does not considerably affect how well the students learn the factual content in various subjects, especially if the student knows Swedish well. Theoretical subjects seemed to cause most problems. Swedish played only a very small part in students’ lives outside the school context and it was used merely when travelling abroad and in different kinds of guiding situations. Unless the students were talked to in Swedish, they kept on speaking Finnish. When asked about students’ experiences no statistically significant differences between sexes were found in this study. On the contrary, in some cases their grade level but especially their school and form of immersion had clear statistically significant differences on students’ perceptions.

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This comprehensive study aimed to determine the sources and driving factors of organic carbon (OC) and elemental carbon (EC) concentrations in ambient PM2.5 in urban schools. Sampling was conducted outdoors at 25 schools in the Brisbane Metropolitan Area, Australia. Concentrations of primary and secondary OC were quantified using the EC tracer method, with secondary OC accounting for an average of 60%. Principal component analysis distinguished the contributing sources above the background and identified groups of schools with differing levels of primary and secondary carbonaceous aerosols. Overall, the results showed that vehicle emissions, local weather conditions and secondary organic aerosols (SOA) were the key factors influencing concentrations of carbonaceous component of PM2.5 at these schools. These results provide insights into children’s exposure to vehicle emissions and SOA at such urban schools.

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Polycyclic Aromatic Hydrocarbons (PAHs) represent a major class of toxic pollutants because of their carcinogenic and mutagenic characteristics. People living in urban areas are regularly exposed to PAHs because of abundance of their emission sources. Within this context, this study aimed to: (i) identify and quantify the levels of ambient PAHs in an urban environment; (ii) evaluate their toxicity; and (iii) identify their sources as well as the contribution of specific sources to measured concentrations. Sixteen PAHs were identified and quantified in air samples collected from Brisbane. Principal Component Analysis – Absolute Principal Component Scores (PCA- APCS) was used in order to conduct source apportionment of the measured PAHs. Vehicular emissions, natural gas combustion, petrol emissions and evaporative/unburned fuel were the sources identified; contributing 56%, 21%, 15% and 8% of the total PAHs emissions, respectively, all of which need to be considered for any pollution control measures implemented in urban areas.

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Major depressive disorder (MDD) is a common complex disorder with a partly genetic etiology. We conducted a genome-wide association study of the MDD2000+ sample (2431 cases, 3673 screened controls and >1 M imputed single-nucleotide polymorphisms (SNPs)). No SNPs achieved genome-wide significance either in the MDD2000+ study, or in meta-analysis with two other studies totaling 5763 cases and 6901 controls. These results imply that common variants of intermediate or large effect do not have main effects in the genetic architecture of MDD. Suggestive but notable results were: (a) gene-based tests suggesting roles for adenylate cyclase 3 (ADCY3, 2p23.3) and galanin (GAL, 11q13.3); published functional evidence relates both of these to MDD and serotonergic signaling; (b) support for the bipolar disorder risk variant SNP rs1006737 in CACNA1C (P=0.020, odds ratio=1.10), and; (c) lack of support for rs2251219, a SNP identified in a meta-analysis of affective disorder studies (P=0.51). We estimate that sample sizes 1.8- to 2.4-fold greater are needed for association studies of MDD compared with those for schizophrenia to detect variants that explain the same proportion of total variance in liability. Larger study cohorts characterized for genetic and environmental risk factors accumulated prospectively are likely to be needed to dissect more fully the etiology of MDD.

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Quality of fresh-cut carambola (Averrhoa carambola L) is related to many chemical and biochemical variables especially those involved with softening and browning, both influenced by storage temperature. To study these effects, a multivariate analysis was used to evaluate slices packaged in vacuum-sealed polyolefin bags, and stored at 2.5 degrees C, 5 degrees C and 10 degrees C, for up to 16 d. The quality of slices at each temperature was correlated with the duration of storage, O(2) and CO(2) concentration in the package, physical chemical constituents, and activity of enzymes involved in softening (PG) and browning (PPO) metabolism. Three quality groups were identified by hierarchical cluster analysis, and the classification of the components within each of these groups was obtained from a principal component analysis (PCA). The characterization of samples by PCA clearly distinguished acceptable and non-acceptable slices. According to PCA, acceptable slices presented higher ascorbic acid content, greater hue angles ((o)h) and final lightness (L-5) in the first principal component (PC1). On the other hand, non-acceptable slices presented higher total pectin content. PPO activity in the PC1. Non-acceptable slices also presented higher soluble pectin content, increased pectin solubilisation and higher CO(2) concentration in the second principal component (PC2) whereas acceptable slices showed lower total sugar content. The hierarchical cluster and PCA analyses were useful for discriminating the quality of slices stored at different temperatures.

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In this report, we describe a simple correction for multiple testing of single-nucleotide polymorphisms (SNPs) in linkage disequilibrium (LD) with each other, on the basis of the spectral decomposition (SpD) of matrices of pairwise LD between SNPs. This method provides a useful alternative to more computationally intensive permutation tests. Additionally, output from SNPSpD includes eigenvalues, principal-component coefficients, and factor "loadings" after varimax rotation, enabling the selection of a subset of SNPs that optimize the information in a genomic region.

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Cardiovascular diseases (CVDs) are the leading cause of mortality in the world. Studies of the impact of single nutrients on the risk for CVD have often provided inconclusive results, and recent research in nutritional epidemiology with a more holistic whole-diet approach has proven fruitful. Moreover, dietary habits in childhood and adolescence may play a role in later health and disease, either independently or by tracking into adulthood. The main aims of this study were to find childhood and adulthood determinants of adulthood diet, to identify dietary patterns present among the study population and to study the associations between long-term food choices and cardiovascular health in young Finnish adults. The study is a part of the multidisciplinary Cardiovascular Risk in Young Finns study, which is an ongoing, prospective cohort study with a 21-year follow-up. At baseline in 1980, the subjects were children and adolescents aged 3 to 18 years (n included in this study = 1768), and young adults aged 24 to 39 years at the latest follow-up study in 2001 (n = 1037). Food consumption and nutrient intakes were assessed with repeated 48-hour dietary recalls. Other determinations have included comprehensive risk factor assessments using blood tests, physical measurements and questionnaires. In the latest follow-up, ultrasound examinations were performed to study early atherosclerotic vascular changes. The average intakes showed substantial changes since 1980. Intakes of fat and saturated fat had decreased, whereas the consumption of fruits and vegetables had increased. Intake of fat and consumption of vegetables in childhood and physical activity in adulthood were important health behavioural determinants of adult diet. Additionally, a principal component analysis was conducted to identify major dietary patterns at each study point. A similar set of two major patterns was recognised throughout the study. The traditional dietary pattern positively correlated with the consumption of traditional Finnish foods, such as rye, potatoes, milk, butter, sausages and coffee, and negatively correlated with fruit, berries and dairy products other than milk. This type of diet was independently associated with several risk factors of CVD, such as total and low-density lipoprotein cholesterol, apolipoprotein B and C-reactive protein concentrations among both genders, as well as with systolic blood pressure and insulin levels among women. The traditional pattern was also independently associated with intima media thickness (IMT), a subclinical predictor of CVD, in men but not in women. The health-conscious pattern, predominant among female subjects, non-smokers and urbanites, was characterised by more health-conscious food choices such as vegetables, legumes and nuts, tea, rye, fish, cheese and other dairy products, as well as by the consumption of alcoholic beverages. This pattern was inversely, but less strongly, associated with cardiovascular risk factors. Tracking of the dietary pattern scores was observed, particularly among subjects who were adolescents at baseline. Moreover, a long-term high intake of protein concurrent with a low intake of fat was positively associated with IMT. These findings suggest that food behaviour and food choices are to some extent established as early as in childhood or adolescence and may significantly track into adulthood. Long-term adherence to traditional food choices seems to increase the risk for developing CVD, especially among men. Those with intentional or unintentional low fat diets, but with high intake of protein may also be at increased risk for CVD. The findings offer practical, food-based information on the relationship between diet and CVD and encourage further use of the whole-diet approach in epidemiological research. The results support earlier findings that long-term food choices play a role in the development of CVD. The apparent influence of childhood habits is important to bear in mind when planning educational strategies for the primary prevention of CVD. Further studies on food choices over the entire lifespan are needed.

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BACKGROUND: Twenty-two diverse sorghum landraces, classified as normal and opaque types obtained from Ethiopia, were characterised for grain quality parameters using near infra-red spectroscopy (NIRS), chemical and Rapid Visco-Analyzer (RVA) characteristics. RESULTS: Protein content ranged from 77 to 182 g kg-1, and starch content from 514 to 745 g kg(-1). The NIRS analysis indicated the pig faecal digestible energy range from 14.6 to 15.7MJ kg(-1) as fed, and the ileal digestible energy range from 11.3 to 13.9MJ kg(-1) as fed. The normal sorghums had higher digestible energy than the opaque sorghums, which exhibited lower RVA viscosities, and higher pasting temperatures and setback ratios. The RVA parameterswere positively correlated with the starch content and negatively correlated with the protein content. The normal and opaque types formed two distinct groups based on principal component and cluster analyses. CONCLUSION: The landraces were different for the various grain quality parameters with some landraces displaying unique RVA and NIRS profiles. This study will guide utilisation of the sorghum landraces in plant improvement programs, and provides a basis for further studies into how starch and other constituents behave in and affect the properties of these landraces. (C) 2011 Society of Chemical Industry

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Historical sediment nutrient concentrations and heavy-metal distributions were studied in five embayments in the Gulf of Finland and an adjacent lake. The main objective of the study was to examine the response of these water bodies to temporal changes in human activities. Sediment cores were collected from the sites and dated using 210Pb and 137Cs. The cores were analyzed for total carbon (TC), total nitrogen (TN), total phosphorus (TP), organic phosphorus (OP), inorganic phosphorus (IP), biogenic silica (BSi), loss on ignition (LOI), grain size, Cu, Zn, Al, Fe, Mn, K, Ca, Mg and Na. Principal component analysis (PCA) was used to summarize the trends in the geochemical variables and to compare trends between the different sites. The links between the catchment land use and sediment geochemical data were studied using a multivariate technique of redundancy analysis (RDA). Human activities produce marked geochemical variations in coastal sediments. These variations and signals are often challenging to interpret due to various sedimentological and post-depositional factors affecting the sediment profiles. In general, the sites studied here show significant upcore increases in sedimentation rates, TP and TN concentrations. Also Cu, which is considered to be a good indicator of anthropogenic influence, showed clear increases from 1850 towards the top part of the cores. Based on the RDA-analysis, in the least disturbed embayments with high forest cover, the sediments are dominated by lithogenic indicators Fe, K, Al and Mg. In embayments close to urban settlement, the sediments have high Cu concentrations and a high sediment Fe/Mn ratio. This study suggests that sediment accumulation rates vary significantly from site to site and that the overall sedimentation can be linked to the geomorphology and basin bathymetry, which appear to be the major factors governing sedimentation rates; i.e. a high sediment accumulation rate is not characteristic either to urban or to rural sites. The geochemical trends are strongly site specific and depend on the local geochemical background, basin characteristics and anthropogenic metal and nutrient loading. Of the studied geochemical indicators, OP shows the least monotonic trends in all studied sites. When compared to other available data, OP seems to be the most reliable geochemical indicator describing the trophic development of the study sites, whereas Cu and Zn appear to be good indicators for anthropogenic influence. As sedimentation environments, estuarine and marine sites are more complex than lacustrine basins with multiple sources of sediment input and more energetic conditions in the former. The crucial differences between lacustrine and estuarine/coastal sedimentation environments are mostly related to Fe. P sedimentation is largely governed by Fe redox-reactions in estuarine environments. In freshwaters, presence of Fe is clearly linked to the sedimentation of other lithogenic metals, and therefore P sedimentation and preservation has a more direct linkage to organic matter sedimentation.

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What can the statistical structure of natural images teach us about the human brain? Even though the visual cortex is one of the most studied parts of the brain, surprisingly little is known about how exactly images are processed to leave us with a coherent percept of the world around us, so we can recognize a friend or drive on a crowded street without any effort. By constructing probabilistic models of natural images, the goal of this thesis is to understand the structure of the stimulus that is the raison d etre for the visual system. Following the hypothesis that the optimal processing has to be matched to the structure of that stimulus, we attempt to derive computational principles, features that the visual system should compute, and properties that cells in the visual system should have. Starting from machine learning techniques such as principal component analysis and independent component analysis we construct a variety of sta- tistical models to discover structure in natural images that can be linked to receptive field properties of neurons in primary visual cortex such as simple and complex cells. We show that by representing images with phase invariant, complex cell-like units, a better statistical description of the vi- sual environment is obtained than with linear simple cell units, and that complex cell pooling can be learned by estimating both layers of a two-layer model of natural images. We investigate how a simplified model of the processing in the retina, where adaptation and contrast normalization take place, is connected to the nat- ural stimulus statistics. Analyzing the effect that retinal gain control has on later cortical processing, we propose a novel method to perform gain control in a data-driven way. Finally we show how models like those pre- sented here can be extended to capture whole visual scenes rather than just small image patches. By using a Markov random field approach we can model images of arbitrary size, while still being able to estimate the model parameters from the data.

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This thesis studies human gene expression space using high throughput gene expression data from DNA microarrays. In molecular biology, high throughput techniques allow numerical measurements of expression of tens of thousands of genes simultaneously. In a single study, this data is traditionally obtained from a limited number of sample types with a small number of replicates. For organism-wide analysis, this data has been largely unavailable and the global structure of human transcriptome has remained unknown. This thesis introduces a human transcriptome map of different biological entities and analysis of its general structure. The map is constructed from gene expression data from the two largest public microarray data repositories, GEO and ArrayExpress. The creation of this map contributed to the development of ArrayExpress by identifying and retrofitting the previously unusable and missing data and by improving the access to its data. It also contributed to creation of several new tools for microarray data manipulation and establishment of data exchange between GEO and ArrayExpress. The data integration for the global map required creation of a new large ontology of human cell types, disease states, organism parts and cell lines. The ontology was used in a new text mining and decision tree based method for automatic conversion of human readable free text microarray data annotations into categorised format. The data comparability and minimisation of the systematic measurement errors that are characteristic to each lab- oratory in this large cross-laboratories integrated dataset, was ensured by computation of a range of microarray data quality metrics and exclusion of incomparable data. The structure of a global map of human gene expression was then explored by principal component analysis and hierarchical clustering using heuristics and help from another purpose built sample ontology. A preface and motivation to the construction and analysis of a global map of human gene expression is given by analysis of two microarray datasets of human malignant melanoma. The analysis of these sets incorporate indirect comparison of statistical methods for finding differentially expressed genes and point to the need to study gene expression on a global level.

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Three different Norway spruce cutting clones growing in three environments with different soil and climatic conditions were studied. The purpose was to follow variation in the radial growth rate, wood properties and lignin content and to modify wood lignin with a natural monolignol, coniferyl alcohol, by making use of inherent wood peroxidases. In addition, the incorporation of chlorinated anilines into lignin was studied with synthetic model compounds and synthetic lignin preparations to show whether unnatural compounds originating from pesticides could be bound in the lignin polymer. The lignin content of heartwood, sapwood and earlywood was determined by applying Fourier transform infrared (FTIR) spectroscopy and a principal component regression (PCR) technique. Wood blocks were treated with coniferyl alcohol by using a vacuum impregnation method. The effect of impregnation was assessed by FTIR and by a fungal decay test. Trees from a fertile site showed the highest growth rate and sapwood lignin content and the lowest latewood proportion, weight density and modulus of rupture (MOR). Trees from a medium fertile site had the lowest growth rate and the highest latewood proportion, weight density, modulus of elasticity (MOE) and MOR. The most rapidly growing clone showed the lowest latewood proportion, weight density, MOE and MOR. The slowest growing clone had the lowest sapwood lignin content and the highest latewood proportion, weight density, MOE and MOR. Differences between the sites and clones were small, while fairly large variation was found between the individual trees and growing seasons. The cutting clones maintained clone-dependent wood properties in the different growing sites although variation between trees was high and climatic factors affected growth. The coniferyl alcohol impregnation increased the content of different lignin-type phenolic compounds in the wood as well as wood decay resistance against a white-rot fungus, Coriolus versicolor. During the synthetic lignin preparation 3,4-dichloroaniline became bound by a benzylamine bond to β-O-4 structures in the polymer and it could not be released by mild acid hydrolysis. The natural monolignol, coniferyl alcohol, and chlorinated anilines could be incorporated into the lignin polymer in vivo and in vitro, respectively.

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Objectives In China, “serious road traffic crashes” (SRTCs) are those in which there are 10-30 fatalities, 50-100 serious injuries or a total cost of 50-100 million RMB ($US8-16m), and “particularly serious road traffic crashes” (PSRTCs) are those which are more severe or costly. Due to the large number of fatalities and injuries as well as the negative public reaction they elicit, SRTCs and PSRTCs have become great concerns to China during recent years. The aim of this study is to identify the main factors contributing to these road traffic crashes and to propose preventive measures to reduce their number. Methods 49 contributing factors of the SRTCs and PSRTCs that occurred from 2007 to 2013 were collected from the database “In-depth Investigation and Analysis System for Major Road traffic crashes” (IIASMRTC) and were analyzed through the integrated use of principal component analysis and hierarchical clustering to determine the primary and secondary groups of contributing factors. Results Speeding and overloading of passengers were the primary contributing factors, featuring in up to 66.3% and 32.6% of accidents respectively. Two secondary contributing factors were road-related: lack of or nonstandard roadside safety infrastructure, and slippery roads due to rain, snow or ice. Conclusions The current approach to SRTCs and PSRTCs is focused on the attribution of responsibility and the enforcement of regulations considered relevant to particular SRTCs and PSRTCs. It would be more effective to investigate contributing factors and characteristics of SRTCs and PSRTCs as a whole, to provide adequate information for safety interventions in regions where SRTCs and PSRTCs are more common. In addition to mandating of a driver training program and publicisation of the hazards associated with traffic violations, implementation of speed cameras, speed signs, markings and vehicle-mounted GPS are suggested to reduce speeding of passenger vehicles, while increasing regular checks by traffic police and passenger station staff, and improving transportation management to increase income of contractors and drivers are feasible measures to prevent overloading of people. Other promising measures include regular inspection of roadside safety infrastructure, and improving skid resistance on dangerous road sections in mountainous areas.