Leiden University

The goal of this study was to better understand pathways into cybercrime and the various stages that young people move through before engaging in criminal hacking behaviors. The study draws on unique data resulting from interviews with 22 criminal hackers from the Netherlands and the UK, of which 15 were caught by the police, and 7 were self-identified criminal hackers. Qualitative analysis revealed that young hackers tend to have early experiences with information technology and remain preoccupied with computers throughout early adolescence. Here, we identified two primary trajectories: one shaped by exposure to online peers via gaming communities, and another characterized by self-directed exploration of computer skills in relative social isolation. Driven by curiosity and intrinsic motivations, young people use readily available information on YouTube, Google and forums to obtain information and develop skills in the field of computers and technology. By means of experimenting and trying out newly acquired knowledge in practice, lines between legal and illegal behaviors blur and young people risk to become involved in crime. Offending behaviors seem to be influenced by various mechanisms, including parental oversight, cognitions and perceptions about ethics, and encouragements from both online and offline peers. They possibly form critical points for intervention and prevention purposes. Over time, offending behaviors can escalate as they contribute to increased reputation among peers or evolve into more materialistic oriented hacking. We encourage quantitative assessments of risk factors and involvement mechanisms for cybercrime offending to validate the underlying patterns identified in the current analysis. • We interviewed 22 criminal hackers from the Netherlands and the UK • Offenders move through various stages before committing cybercrime • Some are socially isolated but others are exposed to deviant peers online • Google, Youtube and forums are key in the development of computer skill • Various mechanisms influence offending behaviors, including parental oversight

Designing and evaluating alternative chemicals, materials, processes, or products using a Safe and Sustainable by Design (SSbD) approach can be facilitated by integrating decision support methods like multicriteria decision analysis (MCDA) to evaluate safety, environmental, economic, and social sustainability criteria. Clear guidance is needed to assess chemical, material, or product life cycles on various criteria, especially when a wide range of options is available, and multiple stakeholders’ interests must be accounted for. This study adds to guidance on the implementation of MCDA in SSbD assessments. Reviewing a set of 18 papers addressing MCDA and safety and sustainability assessments, we discuss various decision-making features (MCDA process characteristics) that require development for the application of MCDA in the SSbD framework. We identify six features for further exploration, including defining the decision-maker and problem statement, justifying the set of alternatives under evaluation, defining whether the system should allow for rank reversal, taking a life cycle perspective and defining the assessment scope, justifying the set of criteria used for the assessment, and managing uncertainties. These issues motivate the call for guidance on defining SSbD-specific issues that influence the selection of a suitable MCDA method for a specific problem, to ensure tailored decision-making recommendations. Addressing the identified features should help clear the path toward methodologically sound studies, useful results, and appropriate decision support. • The novel SSbD concept can be facilitated by MCDA methods. • Guidance on implementing MCDA for complex decision-making in SSbD is needed. • Six decision-making features toward sound decision support need further attention. • Addressing these features will pave the way toward methodologically sound studies.

'Breast Implant Illness' (BII) refers to non-specific constitutional, rheumatic, mental and cognitive symptoms experienced by women with silicone breast implants (SBIs). This potential late effect of SBIs challenges the safety of SBI-use in oncologic breast reconstruction (BR). Previous studies on BII mainly focused on women with cosmetic SBIs. It remains unclear whether symptoms reported in this population differ from those reported by breast cancer (BC) survivors with SBI-based BR. We conducted a cross-sectional survey in a Dutch cohort including 578 breast augmentation recipients and 2,884 BC survivors, of whom 1,039 had an SBI-based BR. Eighteen BII-related symptoms were assessed. Multivariable logistic regression was used to compare breast augmentation recipients with BC survivors with and without SBIs. Median follow-up time was 8.0 (IQR, 3.9) years. Overall, breast augmentation recipients had a higher risk of myalgia (Odds ratio (OR) 2.10, 95%CI [1.25-3.54]) and food intolerance (OR 1.77, 95%CI [1.01-3.09]) than BC survivors with SBIs, whereas the latter group did not report more BII-associated symptoms than BC survivors without SBIs. In a sensitivity analysis excluding BC patients treated with (neo)adjuvant systemic therapy, breast augmentation recipients reported more BII-related symptoms-headache, myalgia, hair loss, muscle weakness, sleep impairment, and morning stiffness (ORs 1.69-3.35; all p < 0.05) compared to BC survivors with SBIs. Breast augmentation recipients report more BII-related symptoms than BC survivors with or without SBIs. These findings do not support the hypothesis that BII is a distinct disease entity mediated by a generic SBI-related pathogenesis that exists across different populations.Trial registration: This study was preregistered at ClinicalTrials.gov on June 2 nd 2022 (NCT05400954).

ABSTRACT In this study, we examined whether differences in teacher expectations for students from different backgrounds related to differentiation in teachers’ support for and thwarting of students’ psychological needs for autonomy, competence, and relatedness. Data were collected from 62 Dutch primary school teachers and 1,056 students (Grades 4-6) via questionnaires on teacher and student perceived need support and thwarting and teacher expectations, alongside students’ standardized test scores in reading and math. Analyses revealed that teachers had lower expectations for students from lower socioeconomic backgrounds and higher expectations for students from stigmatized ethnic groups compared to other students. Students from lower socioeconomic backgrounds also experienced more need-thwarting teaching but not less need support. However, teacher expectations did not mediate the relationship between student background and need support or thwart. Altogether, the findings indicate that students from lower socioeconomic backgrounds are at greater risk for lower teacher expectations and more perceived need thwarting.

Abstract Measuring the ionizing photon production efficiency ξ ion,0 —the ratio of the ionizing photon output rate <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>Q</mml:mi> </mml:mrow> <mml:mrow> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:msub> </mml:math> to the UV continuum luminosity L UV —in galaxies at z &gt; 6 is crucial for constraining their contribution to cosmic reionization. We present integrated and spatially resolved measurements of ξ ion,0 for 12 exceptionally bright ( M UV ∼ −22 mag) star-forming galaxies at z ∼ 7 from the Reionization Era Bright Emission Line Survey (REBELS). These measurements are based on JWST NIRSpec/Integral Field Unit PRISM spectroscopy, probing the rest-frame UV and optical regime. Notably, in 8 of the 12 galaxies, the spectral coverage includes H α , enabling self-consistent dust attenuation estimates in both the ionized gas and stellar continuum via the Balmer decrement and rest-UV slope, respectively. We find global <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:msub> <mml:mrow> <mml:mi>ξ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">ion,0</mml:mi> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> </mml:math> values ranging from 25.19 ± 0.11 to 25.61 ± 0.11, with a weighted mean of 25.44 ± 0.15, consistent with the canonical value of ∼25.3. Using a sample of 25 star-forming clumps within these galaxies, we explore local variations in the ionizing photon production efficiency, finding a broader range, from 24.52 ± 0.21 to 26.18 ± 0.61. We identify strong correlations between ξ ion,0 and the specific star formation rate, star formation surface density, H β equivalent width, and stellar mass. Clumps with the highest ξ ion,0 exhibit EW 0 (H β ) ≥ 150 Å, consistent with young stellar ages. From previous Ly α measurements in three galaxies, we estimate a typical Ly α escape fraction of f esc,Ly α ∼ 2%, suggesting similar or lower escape fractions for LyC photons. Combining this with our H α measurements, we infer ionized bubble sizes ∼1 pMpc, aligned with expectations from Ly α -detected systems and reionization models.

Fibre-reinforced polymer composites are utilized across many industries for their stiffness and strength. Visualization of their internal structure is critical to understand their mechanical properties, with computed tomography serving as apopular non-destructive method. While classical tomographic reconstruction algorithms do not rely on training data, modern machine-learning-based methods require large datasets that realistically reflect experimental imaging conditions. However, acquiring such datasets for composites is challenging due to limited access to the ground truth and the high cost of repeated scans. There is therefore a need for realistic, controllable and labelled synthetic phantoms. To address this gap, we present FibreSimulator, an open-source Python tool that generates 3D synthetic phantoms of unidirectional fibre-reinforced polymers with customizable material properties, fibre orientations and geometrical features. The simulator is integrated with the ASTRA toolbox to simulate tomographic scans of the generated phantoms. We demonstrate its capacity through experiments evaluating how tomographic scan settings affect reconstruction and segmentation. Simulated tomographic experiments show that reducing the number of X-ray projections or lowering beam intensity (i.e. increasing noise) leads to blurred fibre boundaries, overestimated fibre diameters and fewer detectable fibres. While these qualitative effects are well known, FibreSimulator enables their systematic and quantitative investigation under fully controlled conditions, with access to the ground truth. In particular, by varying acquisition parameters and composite properties, we observe a nonlinear trend in detection accuracy arising from undersampling and fibre-overlap artefacts. Such controlled studies are difficult to perform experimentally due to cost, limited repeatability and absence of the ground truth. These results highlight FibreSimulator as a valuable tool for optimizing parameters and guiding experimental design under controllable conditions.

Abstract The debate over a convention on international cyber security is long-standing, but recent developments suggest that treaty negotiations are becoming increasingly plausible. While Western and like-minded states have long opposed negotiations, Russia has consistently advocated for a treaty on ‘international information security’. Past developments, including the United Nations cybercrime negotiations, also initiated by Russia, suggest that resistance by Western states is not sustainable. This article assesses the likelihood of international cyber security treaty negotiations and draws lessons from developments in cyber diplomacy, coalition success factors in international negotiations and the cybercrime process to identify key factors Western states need to consider for developing a strategy. It explores three options: maintaining a ‘wait and see’ approach, advancing an interest-based counter-proposal or confidentially developing a negotiation position. By outlining these approaches, the article evaluates the risks and rewards of each, offering insights into how Western and like-minded states can safeguard their interests in potential treaty talks.

ABSTRACT Due to their anonymous and large-scale nature, darknet forums dedicated to child sexual abuse material (CSAM) pose a major challenge to law enforcement. Therefore, prioritization on such forums is essential. The current study looks for linguistic indications of more severe behavior on a CSAM forum, focusing on hands-on abuse, expressed interest in the more extreme forms of CSAM, and participation in sharing CSAM. Using the corpus linguistic technique Keyness Analysis, we found that posts displaying more severe behavior showed more cognitive distortions such as sexualizing and objectifying children. The focus on lexical choices is a promising new direction in the investigation of this hidden community.

Previous meta-analyses show that social robots aid learning but were often limited in scope or grouped diverse control conditions together. This meta-analysis examined learning outcomes, focusing on control condition type. We retrieved 146 studies (Google Scholar and reference searches) where a physical social robot was used for training cognitive skills, comprising 183 post-test effect sizes between the robot and the control group, and 372 pre-post effect sizes. Analysis of the 78 studies with control groups indicated that robots generally improved learning, most notably when compared to a no-training control group (d = 0.75). Comparing robots to human teachers yielded an overall positive effect (d = 0.31), although effect sizes varied widely. This variability was explained by the robot’s role: robots in a co-teaching capacity showed a strong positive effect (d = 0.88), while robots replacing the teacher showed no benefit (d = −0.06). LLM-based sentiment analysis indicated that papers from outside Europe received higher positivity scores when describing the robots. We conclude that the effect size is influenced by the robot implementation and the control condition chosen.