A novel steganography approach for audio files

We present a novel robust and secure steganography technique to hide images into audio files aiming at increasing the carrier medium capacity. The audio files are in the standard WAV format, which is based on the LSB algorithm while images are compressed by the GMPR technique which is based on the Discrete Cosine Transform (DCT) and high frequency minimization encoding algorithm. The method involves compression-encryption of an image file by the GMPR technique followed by hiding it into audio data by appropriate bit substitution. The maximum number of bits without significant effect on audio signal for LSB audio steganography is 6 LSBs. The encrypted image bits are hidden into variable and multiple LSB layers in the proposed method. Experimental results from observed listening tests show that there is no significant difference between the stego audio reconstructed from the novel technique and the original signal. A performance evaluation has been carried out according to quality measurement criteria of Signal-to-Noise Ratio (SNR) and Peak Signal-to-Noise Ratio (PSNR)

Integrating knowledge tracing and item response theory: A tale of two frameworks

Traditionally, the assessment and learning science commu-nities rely on different paradigms to model student performance. The assessment community uses Item Response Theory which allows modeling different student abilities and problem difficulties, while the learning science community uses Knowledge Tracing, which captures skill acquisition. These two paradigms are complementary - IRT cannot be used to model student learning, while Knowledge Tracing assumes all students and problems are the same. Recently, two highly related models based on a principled synthesis of IRT and Knowledge Tracing were introduced. However, these two models were evaluated on different data sets, using different evaluation metrics and with different ways of splitting the data into training and testing sets. In this paper we reconcile the models' results by presenting a unified view of the two models, and by evaluating the models under a common evaluation metric. We find that both models are equivalent and only differ in their training procedure. Our results show that the combined IRT and Knowledge Tracing models offer the best of assessment and learning sciences - high prediction accuracy like the IRT model, and the ability to model student learning like Knowledge Tracing

Towards durabale resistance to apple scab using cisgenes

Apple (Malus x domestica) is one of the important fruit crops of the world. It is mainly cultivated in temperate regions. Apple fruit contains many health beneficial compounds which may play an important role in reducing cancer cell proliferation and lowering the level of cholesterol. Apple production can suffer from several pests and diseases and among them scab is very important. Apple scab is a fungal disease caused by Venturia inaequalis. The pathogen is a facultative saprophyte that grows during the growing season subcuticularly on the host. Most of the present day high quality apple cultivars are susceptible to apple scab. The crop loss due to apple scab has been amount to more than 70%. Fruit growers usually spray fungicides 15 times or more in a season to control the scab disease. To reduce the use of chemicals, it is absolute necessary to develop apple varieties with durable scab resistance. Conventional breeding in apple has some drawbacks such as long generation period, genetic drag and the self-incompatible sexual reproduction system. Therefore, stacking of more than one resistance gene by classical introgression breeding is inefficient. Genetic modification is an alternative option to improve the existing scab-susceptible varieties into scab-resistant ones. However, consumer acceptance of transgenic food in Europe is a problem. Therefore, we developed a genetic modification system with cisgenes and intragenes instead of transgenes. Cisgenes are genes from the plant itself or from crossable species with their natural introns and own regulatory elements in normal sense orientation. Intragenes are like cisgenes containing only functional parts of genes from the plant itself or from crossable species, however, these functional parts originate from different genes. All these genes or gene parts are belonging to the normal breeder’s gene pool. Transgenes are synthetic genes or (partly) origination from non-crossable species, like viruses and microorganisms. Transgenes are representing a new gene pool for plant breeding. GMO-regulations have been developed for transgenes. Societal research showed that consumer preference for cisgenic food is higher than for transgenic food. Cisgenic or intragenic plants can be developed by transferring the desired scab resistant genes into the scab-susceptible cultivar through Agrobacterium tumefaciens-mediated transformation. Transformation aimed at cisgenesis or intragenesis should be done either without the use of selectable marker genes or by using selection markers first and eliminating them subsequently after selection of transformants. In this thesis almost all steps have been made to come to cisgenic apple plants with resistance to scab disease (chapter 2). Although many scab resistance genes have been identified and mapped, only Vf has been positionally cloned. Vf is a locus with four paralogs namely HcrVf1 (Homologues of Cladosporium fulvum resistance genes of Vf region), HcrVf2, HcrVf3, and HcrVf4. Only HcrVf1 and HcrVf2 are considered as being functional. In conventional breeding Vf inherits as a single locus so it is not possible to study the individual role of HcrVf1 and HcrVf2 in conferring resistance against scab using conventionally bred material. The present study was set up to study in depth the roles of HcrVf1 and HcrVf2 separately in conferring resistance to apple scab, using A. tumefaciens mediated transformation. Both isolated genes were regulated as cisgenes by their own promoter and terminator sequences. The two cisgenes were used in two different lengths of the 5’-upstream sequences, so with a short promoter (SP) and a long promoter (LP) i.e. 312 bp and 1990 bp for HcrVf1 and 288 bp and 2000 bp for HcrVf2. HcrVf1 and HcrVf2 were also combined with the apple rubisco promoter and terminator into intragenes because these regulatory elements were found to give high expression in plants. The HcrVf1 and HcrVf2 cisgenes and intragenes were inserted into the susceptible cv. ‘Gala’, using the marker free system pMF1. Several apple transformants were selected for further characterization. Micrografting was carried out in order to take the ‘in vitro’ transformants to the greenhouse. This method proved to promote growth better than rooting of ‘in vitro’ transformants. Apple transformant ‘in vitro’ shoots were used as scions and grafted onto the apple seedling rootstocks. Micrografts were ready for further testing 4 to 5 weeks after grafting. At this stage the young leaves were collected for isolation of DNA and RNA. Southern hybridization was performed to check the inserted T-DNA copy number. For this, the selection marker gene nptII was used as a probe. Most of the transformants (17) were found to have a single T-DNA insert and seven transformants showed two T-DNA inserts. Subsequently, HcrVf gene expression in transformed lines was studied through quantitative RT-PCR (qRT-PCR) in relation to the natural HcrVf expression in the resistant cv. ‘Santana’. In case of HcrVf1 transformants, expression by LP was significantly higher than by SP, while in HcrVf2 transformants no significant difference between SP and LP could be demonstrated. Both HcrVf1 and HcrVf2 genes showed highest expression when regulated by the apple rubisco promoter and terminator. Two HcrVf2 transformants, LPHcrVf2-4 and PMdRbcHcrVf2-12, showed the highest gene expression for the cisgene and intragene situation, respectively. Among HcrVf transformants, no significant correlation was observed between inserted gene copy number and gene expression level (Chapter 3). Micrografted cvs. ‘Santana’ (resistant control containing Vf through classical breeding), ‘Gala’ (susceptible control) and different micrografted apple transformants were tested for scab resistance against V. inaequalis isolate EU-B05. The top four leaves were Summary 125 used for inoculation with V. inaequalis. Seventeen days after inoculation, the plants were scored for sporulation using a quantitative scale. All the HcrVf1 transformants showed complete sporulation similar to the level in cv. ‘Gala’, indicating that HcrVf1 is not giving resistance. On the other hand, 10 out of the 13 HcrVf2 transformants showed resistance at levels that were statistically similar to cv. ‘Santana’. Two HcrVf2 transformants, LPHcrVf2-4 and PMdRbcHcrVf2-12, showed the best resistance. A negative correlation between HcrVf2 gene expression and sporulation was observed i.e. as gene expression increased there was a decrease in the fungal sporulation (Chapter 4). The results obtained by the scab experiment were used to select HcrVf1 and HcrVf2 transformants to check the resistance spectrum against different isolates of V. inaequalis. The plants were inoculated with four avirulent isolates of the pathogen and two isolates virulent to the resistant cv. ‘Santana’. The top two leaves were inoculated with fungal spores and the inoculated plants were scored for sporulation 21 days after inoculation. All the HcrVf1 transformants showed heavy sporulation of all the isolates used and they were behaving like untransformed cv. ‘Gala’. The HcrVf2 transformants were behaving like cv. ‘Santana’ indicating that the resistance coming from the Vf gene cluster is from HcrVf2 alone (Chapter 5). In order to increase the durability of resistance against scab, it is desired to stack several resistance genes into apple cultivars either by classical breeding or by genetic modification. To use it in a cisgenic or intragenic approach, new scab resistance genes have to be identified in apple and cloned. In chapter 6 it is described how a novel scab resistance gene, Vd3, has been identified and genetically mapped in the resistant selection “1980-015-025”. In the study we used the F1 progeny 2000-012 that is derived from the crossing between the resistant parent 1980-015-025 and the susceptible parent 1973-001-041. Mainly DArT markers were used in this genetic mapping study. Other known markers, such as SSRs, P-136 (RAPD marker), and Vf2ARD (RGA marker), were used for annotation of the linkage groups. The Vd3 gene has been mapped 1 cM to the south of the Vf gene cluster in repulsion phase on linkage group 1. Paternity tests have indicated that clone 1980-015-025 has inherited the Vd3 gene from founder accession D3. This gene can provide resistance against the virulent isolate EU-NL24, which can overcome the resistance of Vf and Vg. However, this gene cannot provide resistance against other isolates (Chapter 6). The results described in this thesis are of practical importance. Cisgenesis or intragenesis can be employed to provide multiple gene resistance against scab in apple without linkage drag problems as observed during classical introgression breeding. Our first potential cisgenic scab resistant ‘Gala’ plants with the HcrVf2 gene are being developed which can be used in regions free of virulent isolates. The cisgenic approach is essential in rapid improving a crop such as apple where it takes many decades through conventional breeding. <br/

Attitudes and behaviour towards food attributes and organic food – a triangular methodological investigation of occasional organic consumers

Organic food is increasingly available in the conventional food retail, where organic products are offered alongside with various other types of products and compete mainly with conventional and the so-called conventional-plus products. The latter are conventional products displaying particular quality attributes on the product packaging, such as ‘no artificial additives’, or ‘from animal welfare husbandry’. Often, these quality attributes also apply to organic products. Occasional organic consumers might prefer such conventional-plus alternatives that are perceived to be ‘between’ organic and conventional products. The overall objective of this PhD thesis was to provide information about the segment of occasional organic consumers. In particular, the thesis focussed on consumer perceptions and attitudes towards the quality of, and preferences for, organic, conventional and conventional-plus products in two countries: Germany and Switzerland. To achieve these objectives, qualitative and quantitative consumer research was combined in order to explore occasional organic consumers’ perceptions and attitudes as well as to observe their preferences and buying behaviour regarding different types of food products: organic, conventional and conventional-plus products. The qualitative research showed that, depending on single criteria, organic production was both positively as well as negatively assessed by consumers. Consumer perception of organic food was found to be highly selective and primarily focussed on the final stage of the particular production process. A major problem is that consumers are still mostly unfamiliar with factors associated with organic production, have a lack of confidence, and often confuse organic with conventional products. Besides this, consumer expectations of organic products are different from the expectations of conventional products. The quantitative research revealed that attitudes strongly determine consumers’ preferences for organic, conventional and conventional-plus products. Consumer attitudes tended to differ more between organic and conventional choices rather than conventional-plus and conventional choices. Furthermore, occasional organic consumers are heterogeneous in their preferences. They can be grouped into two segments: the consumers in one segment were less price sensitive and preferred organic products. The consumers in the other segment were more price sensitive and rather preferred conventional-plus or conventional products. To conclude, given the selective and subjective nature of consumer perception and the strong focus of consumer perception on the final stage of the food production process, specific additional values of organic farming should be communicated in clear and catchy messages. At the same time, these messages should be particularly focussed on the final stage of organic food production. The communication of specific added values in relation with organic products to improve the perceived price-performance-ratio is important since conventional-plus products represent an interesting alternative particularly for price sensitive occasional organic consumers. Besides this, it is important to strengthen affirmative consumer attitudes towards organic production. Therefore, policy support should emphasise on long-term communication campaigns and education programmes to increase the consumer awareness and knowledge of organic food and farming. Since consumers expect that organic food is regionally or at least domestically produced while they less accept organic imports, policy support of domestic and regional producers is a crucial measure to fill the current gap between the increasing consumer demand of organic food and the stagnation of the domestic and regional organic food supply

Beyond ‘mainstream’ and ‘alternative’ in organic food supply chains: empirical examples of added value distribution from eight European countries

Purpose – This research investigates the supply chains for organic milk, apples and pasta in eight European countries and how added value is distributed among market players. Design/methodology/approach – Using secondary data and expert interviews, a market overview for the three products is provided as the basis of a more detailed analysis of the added value in twelve organic supply chain examples. For this, interviews with market players and an ‘added value calculator’ tool are employed. Findings – The farm gate and retail price of organic products is higher than conventional. Super-markets are the main outlet for organic milk and apples in the countries studied, whereas the situation for organic pasta is varied, suggesting that the use of different sale channels is influ-enced by the food product. The farmers’ share of added value ranges between 3% and 65% of the added value created in the organic supply chains analysed. Organic offers opportunities to increase the farmers’ share of added value both in supermarkets and alternative sale channels, by developing collaboration, physical infrastructures for organic and integrating operations upstream of the chain. Research limitations/implications – While more research is needed into a larger number of chains, this paper indicates that there are dynamics and features at supply chain level, such as the distribution of added value and the target markets used, that cannot be interpreted according to the binary division between ‘mainstream’ and ‘alternative’ organic suggested by the con-ventionalisation hypothesis. Originality/value – The distribution of added value for existing supply chains in eight European countries is calculated by using an effective added value calculator tool