Clustering with shallow trees

We propose a new method for hierarchical clustering based on the optimisation of a cost function over trees of limited depth, and we derive a message--passing method that allows to solve it efficiently. The method and algorithm can be interpreted as a natural interpolation between two well-known approaches, namely single linkage and the recently presented Affinity Propagation. We analyze with this general scheme three biological/medical structured datasets (human population based on genetic information, proteins based on sequences and verbal autopsies) and show that the interpolation technique provides new insight.Comment: 11 pages, 7 figure

Combat and Warfare in the Early Paleolithic and Medically Unexplained Musculo-Facial Pain in the 21st Century War Veterns and Active-Duty Military Personnel

In a series of recent articles, we suggest that family dentists, military dentists and psychiatrists with expertise in posttraumatic stress disorder (especially in the Veterans Health Administration) are likely to see an increased number of patients with symptomatic jaw-clenching and early stages of tooth- grinding (Bracha et al., 2005). Returning warfighters and other returnees from military deployment may be especially at risk for high rates of clenching- induced masticatory muscle disorders at early stages of incisor grinding. The literature we have recently reviewed strongly supports the conclusion that clenching and grinding may primarily be a manifestation of experiencing extreme fear or severe chronic distress (respectively). We have recently reviewed the clinical and paleoanthropological literature and have noted that ancestral warfare and ancestral combat, in the early Paleolithic Environment of Evolutionary Adaptedness (EEA) may be a neglected factor explaining the conservation of the archaic trait of bite-muscle strengthening. We have hypothesized that among ancestral warriors, jaw clenching may have rapidly strengthened the two primary muscles involved in biting, the masseter muscles and the much larger temporalis muscles. The strengthening of these muscles may have served the purpose of enabling a stronger, deeper, and therefore more lethal, defensive bite for early Paleolithic humans. The neuroevolutionary perspective presented here may be novel to many dentists. However, it may be useful in patient education and in preventing progression from jaw-clenching to chronic facial pain

Resilience Through the Lens of Interactionism: A Systematic Review

This systematic review presents findings from a conceptual and methodological review of resilience measures using an interactionist theoretical framework. The review is also intended to update findings from previous systematic reviews. Two databases (EBSCOHost and Scopus) were searched to retrieve empirical studies published up until 2013, with no lower time limit. All articles had to meet specific inclusion criteria, which resulted in 17 resilience measures selected for full review. Measures were conceptually evaluated against an interactionist framework and methodologically reviewed using Skinner's (1981) validity evidence framework. We conclude that inconsistencies associated with the definition and operationalization of resilience warrant further conceptual development to explain resilience as a dynamic and interactive phenomenon. In particular, measures of resilience may benefit from a greater focus on within-person variance typically associated with behavioral consistency across situations. The use of alternative measurement modalities to self-report scales, such as situational judgment tests, is proposed as a way of advancing knowledge in this area

Ternary Syndrome Decoding with Large Weight

The Syndrome Decoding problem is at the core of many code-based cryptosystems. In this paper, we study ternary Syndrome Decoding in large weight. This problem has been introduced in the Wave signature scheme but has never been thoroughly studied. We perform an algorithmic study of this problem which results in an update of the Wave parameters. On a more fundamental level, we show that ternary Syndrome Decoding with large weight is a really harder problem than the binary Syndrome Decoding problem, which could have several applications for the design of code-based cryptosystems

Self-guided mindfulness and cognitive behavioural practices reduce anxiety in autistic adults: A pilot 8-month waitlist-controlled trial of widely available online tools

Anxiety in autism is an important treatment target because of its consequences for quality of life and wellbeing. Growing evidence suggests that Cognitive Behaviour Therapies (CBT) and Mindfulness-Based Therapies (MBT) can ameliorate anxiety in autism but cost-effective delivery remains a challenge. This pilot randomized controlled trial examined whether online CBT and MBT self-help programmes could help reduce anxiety in 54 autistic adults who were randomly allocated to either an online CBT (n=16) or MBT (n=19) programme or a waitlist control group (WL; n=19). Primary outcome measures of anxiety, secondary outcome measures of broader wellbeing, and potential process of change variables were collected at baseline, after programme completion, and then 3 and 6 months post-completion. Baseline data confirmed that intolerance of uncertainty and emotional acceptance accounted for up to 61% of self-reported anxiety across all participants. The 23 participants who were retained in the active conditions (14 MBT, 9 CBT) showed significant decreases in anxiety that were maintained over 3, and to some extent also 6 months. Overall, results suggest that online self-help CBT and MBT tools may provide a cost-effective method for delivering mental health support to those autistic adults who can engage effectively with online support tools

Probabilistic Analysis of Facility Location on Random Shortest Path Metrics

The facility location problem is an NP-hard optimization problem. Therefore, approximation algorithms are often used to solve large instances. Such algorithms often perform much better than worst-case analysis suggests. Therefore, probabilistic analysis is a widely used tool to analyze such algorithms. Most research on probabilistic analysis of NP-hard optimization problems involving metric spaces, such as the facility location problem, has been focused on Euclidean instances, and also instances with independent (random) edge lengths, which are non-metric, have been researched. We would like to extend this knowledge to other, more general, metrics. We investigate the facility location problem using random shortest path metrics. We analyze some probabilistic properties for a simple greedy heuristic which gives a solution to the facility location problem: opening the $\kappa$ cheapest facilities (with $\kappa$ only depending on the facility opening costs). If the facility opening costs are such that $\kappa$ is not too large, then we show that this heuristic is asymptotically optimal. On the other hand, for large values of $\kappa$, the analysis becomes more difficult, and we provide a closed-form expression as upper bound for the expected approximation ratio. In the special case where all facility opening costs are equal this closed-form expression reduces to $O(\sqrt[4]{\ln(n)})$ or $O(1)$ or even $1+o(1)$ if the opening costs are sufficiently small.Comment: A preliminary version accepted to CiE 201

An exploration of applicant perceptions of asynchronous video MMIs in medical selection

Over the last two decades, technological advancements internationally have meant that the Internet has become an important medium for recruitment and selection. Consequently, there is an increased need for research that examines the effectiveness of newer technology-mediated selection methods. This exploratory research study qualitatively explored applicant perceptions of fairness of asynchronous video interviews used in medical selection. Ten undergraduate medical students participated in a pilot asynchronous multiple-mini interview and were invited to share their experiences and perceptions in a follow-up interview. The data was transcribed verbatim and analysed using template analysis, with Gilliland’s (1993) organisational justice theory guiding the original template. Many of the original themes from Gilliland’s model were uncovered during analysis. Additionally, some significant themes were identified that did not form part of the original template and were therefore added to the final coding template – these were specifically relating to technology, including acceptability in a medical context; technical issues and adverse impact. Overall, results suggested that participants perceived asynchronous video interviews to be a fair method of selection. However, participants thought asynchronous interviews should only be used as part of an extensive selection process and furthermore, should not replace face-to-face interviews. Findings are discussed in line with existing research of fairness perceptions and justice theory in selection (Gilliland, 1993) and implications for research and practice are presented

Acceptance and commitment therapy (ACT) for clinically distressed health care workers: Waitlist-controlled evaluation of an ACT workshop in a routine practice setting

OBJECTIVES: To examine the effects of a 1-day acceptance and commitment therapy (ACT) workshop on the mental health of clinically distressed health care employees, and to explore ACT's processes of change in a routine practice setting. DESIGN: A quasi-controlled design, with participants block allocated to an ACT intervention or waiting list control group based on self-referral date. METHODS: Participants were 35 health care workers who had self-referred for the ACT workshop via a clinical support service for staff. Measures were completed by ACT and control group participants at pre-intervention and 3 months post-intervention. Participants allocated to the waitlist condition went on to receive the ACT intervention and were also assessed 3 months later. RESULTS: At 3 months post-intervention, participants in the ACT group reported a significantly lower level of psychological distress compared to the control group (d = 1.41). Across the 3-month evaluation period, clinically significant change was exhibited by 50% of ACT participants, compared to 0% in the control group. When the control group received the same ACT intervention, 69% went on to exhibit clinically significant change. The ACT intervention also resulted in significant improvements in psychological flexibility, defusion, and mindfulness skills, but did not significantly reduce the frequency of negative cognitions. Bootstrapped mediation analyses indicated that the reduction in distress in the ACT condition was primarily associated with an increase in mindfulness skills, especially observing and non-reactivity. CONCLUSIONS: These findings provide preliminary support for providing brief ACT interventions as part of routine clinical support services for distressed workers. PRACTITIONER POINTS: - A 1-day ACT workshop delivered in the context of a routine staff support service was effective for reducing psychological distress among health care workers. - The brief nature of this group intervention means it may be particularly suitable for staff support and primary care mental health service settings. - The findings indicate that the beneficial effects of an ACT workshop on distressed employees' mental health were linked to improvements in specific mindfulness skills. - Study limitations include non-random allocation of participants to the ACT and control groups, and measurement of mediators and outcome at the same time point (3 months post-intervention)

Chosen-ciphertext security from subset sum

We construct a public-key encryption (PKE) scheme whose security is polynomial-time equivalent to the hardness of the Subset Sum problem. Our scheme achieves the standard notion of indistinguishability against chosen-ciphertext attacks (IND-CCA) and can be used to encrypt messages of arbitrary polynomial length, improving upon a previous construction by Lyubashevsky, Palacio, and Segev (TCC 2010) which achieved only the weaker notion of semantic security (IND-CPA) and whose concrete security decreases with the length of the message being encrypted. At the core of our construction is a trapdoor technique which originates in the work of Micciancio and Peikert (Eurocrypt 2012