Some properties of a Rudin-Shapiro-like sequence

We introduce the sequence $(i_n)_{n \geq 0}$ defined by $i_n = (-1)^{inv_2(n)}$, where $inv_2(n)$ denotes the number of inversions (i.e., occurrences of 10 as a scattered subsequence) in the binary representation of n. We show that this sequence has many similarities to the classical Rudin-Shapiro sequence. In particular, if S(N) denotes the N-th partial sum of the sequence $(i_n)_{n \geq 0}$, we show that $S(N) = G(\log_4 N)\sqrt{N}$, where G is a certain function that oscillates periodically between $\sqrt{3}/3$ and $\sqrt{2}$.Comment: 21 pages, 6 figure

On the effectiveness of isogeny walks for extending cover attacks on elliptic curves

Cryptographic systems based on the elliptic curve discrete logarithm problem (ECDLP) are widely deployed in the world today. In order for such a system to guarantee a particular security level, the elliptic curve selected must be such that it avoids a number of well-known attacks. Beyond this, one also needs to be wary of attacks whose reach can be extended via the use of isogenies. It is an open problem as to whether there exists a field for which the isogeny walk strategy can render all elliptic curves unsuitable for cryptographic use. This thesis provides a survey of the theory of elliptic curves from a cryptographic perspective and overviews a few of the well-known algorithms for computing elliptic curve discrete logarithms. We perform some experimental verification for the assumptions used in the analysis of the isogeny walk strategy for extending Weil descent-type cover attacks, and explore its applicability to elliptic curves of cryptographic size. In particular, we demonstrate for the first time that the field F_2^{150} is partially weak for elliptic curve cryptography

Online Disinhibition: Conceptualization, Measurement, and Relation to Aggressive Behaviors

The Internet has changed the way we communicate and interact with other people. Individuals become loosen up and feel less restrained to say or do things in the online space that they would not ordinarily say and do in the offline environment. This online disinhibition effect has been found to be associated with online aggressive and deviant behaviors. Though the concept of online disinhibition has been introduced to the literature for almost two decades, there is still a lack of consensus regarding its conceptualization and operationalization. In this research-in-progress paper, we first revisit the concept of online disinhibition. We then propose a rigorous approach in scale development and validation. We believe that this research will contribute to the development of literature related to the societal impacts of technology use. The newly developed and validated measures of online disinhibition will be added to the repository of rigorous research instruments

“Because we have really unique art”: Decolonizing Research with Indigenous Youth Using the Arts

Indigenous communities in Canada share a common history of colonial oppression. As a result, many Indigenous populations are disproportionately burdened with poor health outcomes, including HIV. Conventional public health approaches have not yet been successful in reversing this trend. For this study, a team of community- and university-based researchers came together to imagine new possibilities for health promotion with Indigenous youth. A strengths-based approach was taken that relied on using the energies and talents of Indigenous youth as a leadership resource. Art-making workshops were held in six different Indigenous communities across Canada in which youth could explore the links between community, culture, colonization, and HIV. Twenty artists and more than 85 youth participated in the workshops. Afterwards, youth participants reflected on their experiences in individual in-depth interviews. Youth participants viewed the process of making art as fun, participatory, and empowering; they felt that their art pieces instilled pride, conveyed information, raised awareness, and constituted a tangible achievement. Youth participants found that both the process and products of arts-based methods were important. Findings from this project support the notion that arts-based approaches to the development of HIV-prevention knowledge and Indigenous youth leadership are helping to involve a diverse cross-section of youth in a critical dialogue about health. Arts-based approaches represent one way to assist with decolonization for future generations

Online disinhibition: conceptualization, measurement, and implications for online deviant behavior

Purpose: Online disinhibition is one of the key factors leading to the occurrence of cyberaggression, cyberbullying and various forms of deviant behaviors in the online environment. To understand the composition of online disinhibition, this study aims to conceptualize online disinhibition and develop a measurement instrument for online disinhibition. Design/methodology/approach: We followed a rigorous procedure to develop and validate the multidimensional instrument of online disinhibition in three phases: item generation, measurement development and instrument testing. Findings: We developed a 23-item online disinhibition scale and identified six key dimensions: dissociative anonymity, invisibility, asynchronicity, solipsistic introjections, dissociative imagination and minimization of authority. Practical implications: The online disinhibition instrument is an accessible and easily administered measure that can be used as a checklist for systems designers and administrators to evaluate the level of online disinhibition among users. It offers systems design information on how to prevent and combat online deviant behaviors on platforms. Originality/value: This work provides a rich conceptualization of an online disinhibition instrument that can serve as a springboard for future work to understand online deviant behaviors. The newly developed measurement instrument of online disinhibition also adds to the repository of rigorous research scales in this area

Contribution of copy number variants to schizophrenia from a genome-wide study of 41,321 subjects

Copy number variants (CNVs) have been strongly implicated in the genetic etiology of schizophrenia (SCZ). However, genome-wide investigation of the contribution of CNV to risk has been hampered by limited sample sizes. We sought to address this obstacle by applying a centralized analysis pipeline to a SCZ cohort of 21,094 cases and 20,227 controls. A global enrichment of CNV burden was observed in cases (OR=1.11, P=5.7×10−15), which persisted after excluding loci implicated in previous studies (OR=1.07, P=1.7 ×10−6). CNV burden was enriched for genes associated with synaptic function (OR = 1.68, P = 2.8 ×10−11) and neurobehavioral phenotypes in mouse (OR = 1.18, P= 7.3 ×10−5). Genome-wide significant evidence was obtained for eight loci, including 1q21.1, 2p16.3 (NRXN1), 3q29, 7q11.2, 15q13.3, distal 16p11.2, proximal 16p11.2 and 22q11.2. Suggestive support was found for eight additional candidate susceptibility and protective loci, which consisted predominantly of CNVs mediated by non-allelic homologous recombination

No Reliable Association between Runs of Homozygosity and Schizophrenia in a Well-Powered Replication Study

It is well known that inbreeding increases the risk of recessive monogenic diseases, but it is less certain whether it contributes to the etiology of complex diseases such as schizophrenia. One way to estimate the effects of inbreeding is to examine the association between disease diagnosis and genome-wide autozygosity estimated using runs of homozygosity (ROH) in genome-wide single nucleotide polymorphism arrays. Using data for schizophrenia from the Psychiatric Genomics Consortium (n = 21,868), Keller et al. (2012) estimated that the odds of developing schizophrenia increased by approximately 17% for every additional percent of the genome that is autozygous (β = 16.1, CI(β) = [6.93, 25.7], Z = 3.44, p = 0.0006). Here we describe replication results from 22 independent schizophrenia case-control datasets from the Psychiatric Genomics Consortium (n = 39,830). Using the same ROH calling thresholds and procedures as Keller et al. (2012), we were unable to replicate the significant association between ROH burden and schizophrenia in the independent PGC phase II data, although the effect was in the predicted direction, and the combined (original + replication) dataset yielded an attenuated but significant relationship between Froh and schizophrenia (β = 4.86,CI(β) = [0.90,8.83],Z = 2.40,p = 0.02). Since Keller et al. (2012), several studies reported inconsistent association of ROH burden with complex traits, particularly in case-control data. These conflicting results might suggest that the effects of autozygosity are confounded by various factors, such as socioeconomic status, education, urbanicity, and religiosity, which may be associated with both real inbreeding and the outcome measures of interest

Genetic correlation between amyotrophic lateral sclerosis and schizophrenia

A. Palotie on työryhmän Schizophrenia Working Grp Psychiat jäsen.We have previously shown higher-than-expected rates of schizophrenia in relatives of patients with amyotrophic lateral sclerosis (ALS), suggesting an aetiological relationship between the diseases. Here, we investigate the genetic relationship between ALS and schizophrenia using genome-wide association study data from over 100,000 unique individuals. Using linkage disequilibrium score regression, we estimate the genetic correlation between ALS and schizophrenia to be 14.3% (7.05-21.6; P = 1 x 10(-4)) with schizophrenia polygenic risk scores explaining up to 0.12% of the variance in ALS (P = 8.4 x 10(-7)). A modest increase in comorbidity of ALS and schizophrenia is expected given these findings (odds ratio 1.08-1.26) but this would require very large studies to observe epidemiologically. We identify five potential novel ALS-associated loci using conditional false discovery rate analysis. It is likely that shared neurobiological mechanisms between these two disorders will engender novel hypotheses in future preclinical and clinical studies.Peer reviewe

Severe early onset preeclampsia: short and long term clinical, psychosocial and biochemical aspects

Preeclampsia is a pregnancy specific disorder commonly defined as de novo hypertension and proteinuria after 20 weeks gestational age. It occurs in approximately 3-5% of pregnancies and it is still a major cause of both foetal and maternal morbidity and mortality worldwide1. As extensive research has not yet elucidated the aetiology of preeclampsia, there are no rational preventive or therapeutic interventions available. The only rational treatment is delivery, which benefits the mother but is not in the interest of the foetus, if remote from term. Early onset preeclampsia (<32 weeks’ gestational age) occurs in less than 1% of pregnancies. It is, however often associated with maternal morbidity as the risk of progression to severe maternal disease is inversely related with gestational age at onset2. Resulting prematurity is therefore the main cause of neonatal mortality and morbidity in patients with severe preeclampsia3. Although the discussion is ongoing, perinatal survival is suggested to be increased in patients with preterm preeclampsia by expectant, non-interventional management. This temporising treatment option to lengthen pregnancy includes the use of antihypertensive medication to control hypertension, magnesium sulphate to prevent eclampsia and corticosteroids to enhance foetal lung maturity4. With optimal maternal haemodynamic status and reassuring foetal condition this results on average in an extension of 2 weeks. Prolongation of these pregnancies is a great challenge for clinicians to balance between potential maternal risks on one the eve hand and possible foetal benefits on the other. Clinical controversies regarding prolongation of preterm preeclamptic pregnancies still exist – also taking into account that preeclampsia is the leading cause of maternal mortality in the Netherlands5 - a debate which is even more pronounced in very preterm pregnancies with questionable foetal viability6-9. Do maternal risks of prolongation of these very early pregnancies outweigh the chances of neonatal survival? Counselling of women with very early onset preeclampsia not only comprises of knowledge of the outcome of those particular pregnancies, but also knowledge of outcomes of future pregnancies of these women is of major clinical importance. This thesis opens with a review of the literature on identifiable risk factors of preeclampsia