A Quantile-Based Watermarking Approach for Distortion Minimization

Distortion-based watermarking techniques embed the watermark by performing tolerable changes in the digital assets being protected. For relational data, mark insertion can be performed over the different data types of the database relations’ attributes. An important goal for distortion-based approaches is to minimize as much as possible the changes that the watermark embedding provokes into data, preserving their usability, watermark robustness, and capacity. This paper proposes a quantile-based watermarking technique for numerical cover type focused on preserving the distribution of attributes used as mark carriers. The experiments performed to validate our proposal show a significant distortion reduction compared to traditional approaches while maintaining watermark capacity levels. Also, positive achievements regarding robustness are visible, evidencing our technique’s resilience against subset attacks

A Double Fragmentation Approach for Improving Virtual Primary Key-Based Watermark Synchronization

Relational data watermarking techniques using virtual primary key schemes try to avoid compromising watermark detection due to the deletion or replacement of the relation's primary key. Nevertheless, these techniques face the limitations that bring high redundancy of the generated set of virtual primary keys, which often compromises the quality of the embedded watermark. As a solution to this problem, this paper proposes double fragmentation of the watermark by using the existing redundancy in the set of virtual primary keys. This way, we guarantee the right identification of the watermark despite the deletion of any of the attributes of the relation. The experiments carried out to validate our proposal show an increment between 81.04% and 99.05% of detected marks with respect to previous solutions found in the literature. Furthermore, we found out that our approach takes advantage of the redundancy present in the set of virtual primary keys. Concerning the computational complexity of the solution, we performed a set of scalability tests that show the linear behavior of our approach with respect to the processes runtime and the number of tuples involved, making it feasible to use no matter the amount of data to be protected

Gender, mental health and resilience in armed conflict: listening to life stories of internally displaced women in Colombia

For over 60 years, Colombia has endured violent civil conflict forcibly displacing more than 8 million people. Recent efforts have begun to explore mental health consequences of these contexts, with an emphasis on national surveys. To date few Colombian studies explore mental health and well-being from a lived experience perspective. Those that do, overlook processes that enable survival. In response to this gap, we conducted a life history study of seven internally displaced Colombian women in the Cundinamarca department, analysing 18 interview sessions and 36 hours of transcripts. A thematic network analysis, informed by Latin-American perspectives on gender and critical resilience frameworks, explored women’s coping strategies in response to conflict-driven hardships related to mental well-being. Analysis illuminated that: (1) the gendered impacts of the armed conflict on women’s emotional well-being work through exacerbating historical gendered violence and inequality, intensifying existing emotional health challenges, and (2) coping strategies reflect women’s ability to mobilise cognitive, bodied, social, material and symbolic power and resources. Our findings highlight that the sociopolitical contexts of women’s lives are inseparable from their efforts to achieve mental well-being, and the value of deep narrative and historical work to capturing the complexity of women’s experiences within conflict settings. We suggest the importance of social interventions to support the mental health of women in conflict settings, in order to centre the social and political contexts faced by such marginalised groups within efforts to improve mental health

HQR-Scheme: A High Quality and resilient virtual primary key generation approach for watermarking relational data

Most of the watermarking techniques designed to protect relational data often use the Primary Key (PK) of relations to perform the watermark synchronization. Despite offering high confidence to the watermark detection, these approaches become useless if the PK can be erased or updated. A typical example is when an attacker wishes to use a stolen relation, unlinked to the rest of the database. In that case, the original values of the PK lose relevance, since they are not employed to check the referential integrity. Then, it is possible to erase or replace the PK, compromising the watermark detection with no need to perform the slightest modification on the rest of the data. To avoid the problems caused by the PK-dependency some schemes have been proposed to generate Virtual Primary Keys (VPK) used instead. Nevertheless, the quality of the watermark synchronized using VPKs is compromised due to the presence of duplicate values in the set of VPKs and the fragility of the VPK schemes against the elimination of attributes. In this paper, we introduce the metrics to allow precise measuring of the quality of the VPKs generated by any scheme without requiring to perform the watermark embedding. This way, time waste can be avoided in case of low-quality detection. We also analyze the main aspects to design the ideal VPK scheme, seeking the generation of high-quality VPK sets adding robustness to the process. Finally, a new scheme is presented along with the experiments carried out to validate and compare the results with the rest of the schemes proposed in the literature

Insights into the Influence of Priors in Posterior Mapping of Discrete Morphological Characters: A Case Study in Annonaceae

Background - Posterior mapping is an increasingly popular hierarchical Bayesian based method used to infer character histories and reconstruct ancestral states at nodes of molecular phylogenies, notably of morphological characters. As for all Bayesian analyses specification of prior values is an integrative and important part of the analysis. He we provide an example of how alternative prior choices can seriously influence results and mislead interpretations. Methods/Principal Findings - For two contrasting discrete morphological characters, namely a slow and a fast evolving character found in the plant family Annonaceae, we specified a total of eight different prior distributions per character. We investigated how these prior settings affected important summary statistics. Our analyses showed that the different prior distributions had marked effects on the results in terms of average number of character state changes. These differences arise because priors play a crucial role in determining which areas of parameter space the values of the simulation will be drawn from, independent of the data at hand. However, priors seemed to fit the data better if they would result in a more even sampling of parameter space (normal posterior distribution), in which case alternative standard deviation values had little effect on the results. The most probable character history for each character was affected differently by the prior. For the slower evolving character, the same character history always had the highest posterior probability independent of the priors used. In contrast, the faster evolving character showed different most probable character histories depending on the prior. These differences could be related to the level of homoplasy exhibited by each character. Conclusions - Although our analyses were restricted to two morphological characters within a single family, our results underline the importance of carefully choosing prior values for posterior mapping. Prior specification will be of crucial importance when interpreting the results in a meaningful way. It is hard to suggest a statistically sound method for prior specification without more detailed studies. Meanwhile, we propose that the data could be used to estimate the prior value of the gamma distribution placed on the transformation rate in posterior mappin

Galactosialidosis: Nueva mutación de novo en el gen CTSA en un paciente afecto de la forma infantil tardía

La galactosialidosis (OMIM #256540) es una enfermedad metabólica lisosomal causada por mutaciones en el gen CTSA, que codifica la proteína protectora catepsina A. La pérdida de función de dicha proteína causa, secundariamente, un déficit combinado de dos enzimas, beta-galactosidasa y neuraminidasa. Se expone el caso de un paciente que presentó manifestaciones clínicas compatibles con el subtipo infantil tardío de galactosialidosis. El análisis bioquímico mostró déficits de las dos enzimas implicadas, mientras que el estudio molecular reveló dos mutaciones: una nueva mutación nunca antes descrita, p.His475Pro (c.1424 A>C), y una mutación previamente reportada, p.Arg441Cys (c.1321C>T), localizadas en los exones 15 y 14, respectivamente. Galactosialidosis (OMIM #256540) is an autosomal recessive lysosomal storage disorder caused by mutations in the CTSA gene, which encodes the protective protein cathepsin A. The loss of function of this protein causes a secondarily deficiency of beta-galactosidase and N-acetyl-á-neuraminidase enzymes activities. We describe the clinical, biochemical and molecular analysis of a case report with a phenotype compatible with the late infantile form. The biochemical analysis reveled deficiencies of beta-galactosidase and neuraminidase activities in dried blood spot and fibroblasts and the molecular study showed two missense mutations in the CTSA gene: A previously reported mutation, p.Arg441Cys (c.1321C>T), and a novel mutation, p.His475Pro (c.1424 A>C), located in exons 14 and 15, respectively

Inter-fraction motion robustness and organ sparing potential of proton therapy for cervical cancer

Purpose: Large-field photon radiotherapy is current standard in the treatment of cervical cancer patients. However, with the increasing availability of Pencil Beam Scanning Proton Therapy (PBS-PT) and robust treatment planning techniques, protons may have significant advantages for cervical cancer patients in the reduction of toxicity. In this study, PBS-PT and photon Volumetric Modulated Arc Therapy (VMAT) were compared, examining target coverage and organ at risk (OAR) dose, taking inter- and intra-fraction motion into account. Materials and methods: Twelve cervical cancer patients were included in this in-silico planning study. In all cases, a planning CT scan, five weekly repeat CT scans (reCTs) and an additional reCT 10 min after the first reCT were available. Two-arc VMAT and robustly optimised two- and four-field (2F and 4F) PBS-PT plans were robustly evaluated on planCTs and reCTs using set-up and range uncertainty. Nominal OAR doses and voxel-wise minimum target coverage robustness were compared. Results: Average voxel-wise minimum accumulated doses for pelvic target structures over all patients were adequate for both photon and proton treatment techniques (D98 > 95%, [91.7–99.3%]). Average accumulated dose of the para-aortic region was lower than the required 95%, D98 > 94.4% [91.1–98.2%]. With PBS-PT 4F, dose to all OARs was significantly lower than with VMAT. Major differences were observed for mean bowel bag V15Gy: 60% [39–70%] for VMAT vs 30% [10–52%] and 32% [9–54%] for PBS-PT 2F and 4F and for mean bone marrow V10Gy: 88% [82–97%] for VMAT vs 66% [60–73%] and 67% [60–75%] for PBS-PT 2F and 4F. Conclusion: Robustly optimised PBS-PT for cervical cancer patients shows equivalent target robustness against inter- and intra-fraction variability compared to VMAT, and offers significantly better OAR sparing

Power Law Scaling for a System of Interacting Units with Complex Internal Structure

We study the dynamics of a system composed of interacting units each with a complex internal structure comprising many subunits. We consider the case in which each subunit grows in a multiplicative manner. We propose a model for such systems in which the interaction among the units is treated in a mean field approximation and the interaction among subunits is nonlinear. To test the model, we identify a large data base spanning 20 years, and find that the model correctly predicts a variety of empirical results.Comment: 4 pages with 4 postscript figures (uses Revtex 3.1, Latex2e, multicol.sty, epsf.sty and rotate.sty). Submitted to PR