A mosaic maternal splice donor mutation in the EHMT1 gene leads to aberrant transcripts and to Kleefstra syndrome in the offspring

The euchromatic histone-lysine N-methyltransferase 1 (EHMT1) gene was examined in a 3-year-old boy with characteristic clinical features of Kleefstra syndrome. Sequencing of all 27 EHMT1 exons revealed a novel mutation, NM_024757.4:c.2712+1G>A, which affects the splice donor of intron 18. Whereas the index patient is heterozygous for that mutation, his phenotypically normal mother shows tissue-specific mosaicism. Sequencing of EHMT1 RT-PCR products revealed two aberrant transcript variants: in one variant, exon 18 was skipped; in the other, a near-by GT motif was used as splice donor and intronic sequence was inserted between exons 18 and 19. Both transcript variants were found in the patient and his mother. The latter had lower amounts of these transcripts consistent with mosaic status. This is the first description of an EHMT1 point mutation being inherited from a parent with verified mosaicism. The constitutive c.2712+1G>A splice site mutation in EHMT1 is fully pathogenic, and the transcript variants produced do not attenuate the severity of the disease.European Journal of Human Genetics advance online publication, 12 December 2012; doi:10.1038/ejhg.2012.267

Coherence of neutrino flavor mixing in quantum field theory

In the simplistic quantum mechanical picture of flavor mixing, conditions on the maximum size and minimum coherence time of the source and detector regions for the observation of interference---as well as the very viability of the approach---can only be argued in an ad hoc way from principles external to the formalism itself. To examine these conditions in a more fundamental way, the quantum field theoretical $S$-matrix approach is employed in this paper, without the unrealistic assumption of microscopic stationarity. The fully normalized, time-dependent neutrino flavor mixing event rates presented here automatically reveal the coherence conditions in a natural, self-contained, and physically unambiguous way, while quantitatively describing the transition to their failure.Comment: 12 pages, submitted to Phys. Rev.

The lesbian, gay, bisexual and transgender community online: discussions of bullying and self-disclosure in YouTube videos

Computer-mediated communication has become a popular platform for identity construction and experimentation as well as social interaction for those who identify as lesbian, gay, bisexual or transgender (LGBT). The creation of user-generated videos has allowed content creators to share experiences on LGBT topics. With bullying becoming more common amongst LGBT youth, it is important to obtain a greater understanding of this phenomenon. In our study, we report on the analysis of 151 YouTube videos which were identified as having LGBT- and bullying-related content. The analysis reveals how content creators openly disclose personal information about themselves and their experiences in a non-anonymous rhetoric with an unknown public. These disclosures could indicate a desire to seek friendship, support and provide empathy

Label-free electrochemical monitoring of DNA ligase activity

This study presents a simple, label-free electrochemical technique for the monitoring of DNA ligase activity. DNA ligases are enzymes that catalyze joining of breaks in the backbone of DNA and are of significant scientific interest due to their essential nature in DNA metabolism and their importance to a range of molecular biological methodologies. The electrochemical behavior of DNA at mercury and some amalgam electrodes is strongly influenced by its backbone structure, allowing a perfect discrimination between DNA molecules containing or lacking free ends. This variation in electrochemical behavior has been utilized previously for a sensitive detection of DNA damage involving the sugar-phosphate backbone breakage. Here we show that the same principle can be utilized for monitoring of a reverse process, i.e., the repair of strand breaks by action of the DNA ligases. We demonstrate applications of the electrochemical technique for a distinction between ligatable and unligatable breaks in plasmid DNA using T4 DNA ligase, as well as for studies of the DNA backbone-joining activity in recombinant fragments of E. coli DNA ligase

Search for Radiative Decays of Cosmic Background Neutrino using Cosmic Infrared Background Energy Spectrum

We propose to search for the neutrino radiative decay by fitting a photon energy spectrum of the cosmic infrared background to a sum of the photon energy spectrum from the neutrino radiative decay and a continuum. By comparing the present cosmic infrared background energy spectrum observed by AKARI and Spitzer to the photon energy spectrum expected from neutrino radiative decay with a maximum likelihood method, we obatined a lifetime lower limit of $3.1 \times 10^{12}$ to $3.8 \times 10^{12}$ years at 95% confidence level for the third generation neutrino $\nu_3$ in the $\nu_3$ mass range between 50 \mmev and 150 \mmev under the present constraints by the neutrino oscillation measurements. In the left-right symmetric model, the minimum lifetime of $\nu_3$ is predicted to be $1.5 \times 10^{17}$ years for $m_3$ of 50 \mmev. We studied the feasibility of the observation of the neutrino radiative decay with a lifetime of $1.5 \times 10^{17}$ years, by measuring a continuous energy spectrum of the cosmic infrared background

Utility of the US National Ignition Facility for Development of Inertial Fusion Energy

The demonstration of inertial fusion ignition and gain in the proposed US National Ignition Facility (NIF), along with the parallel demonstration of the feasibility of an efficient, high-repetition-rate driver, would provide the basis for a follow-on Engineering Test Facility (ETF), a facility for integrated testing of the technologies needed for inertial fusion-energy (IFE) power plants. A workshop was convened at the University of California, Berkeley on February 22--24, 1994, attended by 61 participants from 17 US organizations, to identify possible NIF experiments relevant to IFE. We considered experiments in four IFE areas: Target physics, target chamber dynamics, fusion power ethnology, and target systems, as defined in the following sections

Can Large u,du, d Quark Masses be Inferred from the Ds→nπD_s \to n \pi decay rate?

The $D_s \rightarrow n \pi$ measured branching could lead to information on $u, d$ quark masses if it is dominated by the (helicity suppressed) $D_s \rightarrow u \bar d$ annihilation channel. The data would then suggest anomalously high $m_u \approx m_d \approx 30$MeV masses. We find however that $D_s \rightarrow u {\bar d} g$ can explain $\sum Br(D_s \rightarrow n \pi)$ with zero up and down quark masses. We also argue that the present $D_s \rightarrow n \pi$ data may not even convincingly imply any annihilation process whatsoever.Comment: 4 double-column pages, revtex, 3 figure

Teacher interventions in students’ collaborative work in a technology-rich educational makerspace

This study reports on an investigation of teacher interventions in students' collaborative work in an educational makerspace. We draw on a qualitative analysis of video data on teacher-student interaction derived from 94 students (aged 9-12) and their teachers in a Finnish school. The results show that the teacher interventions were both student- and teacher-initiated. Three leading teacher intervention strategies were identified, namely authoritative, orchestrating and unleashing which emerged in teacher-student interactions dealing with conceptual, procedural, technological, behavioural and motivational issues. The study demonstrates the demands makerspaces pose for teacher-student interaction, and how moving from authoritative to collaborative interaction requires collective efforts and cultural change.Peer reviewe

Tracing controversies in hacker communities: ethical considerations for internet research

This paper reflects on the ethics of internet research on community controversies. Specifically, it focuses on controversies concerning gendered, social interaction in hacking communities. It addresses the question how internet researchers should treat and represent content that individuals controversially discussed online. While many internet sources are likewise technically public, they may yet suggest distinct privacy expectations on the part of involved individuals. In internet research, ethical decision-making regarding which online primary sources may be, e.g., referenced and quoted or require anonymisation is still ambiguous and contested. Instead of generalisable rules, the context dependence of internet research ethics has been frequently stressed. Given this ambiguity, the paper elaborates on ethical decisions and their implications by exploring the case of a controversial hackerspaces.org mailing list debate. In tracing data across different platforms, it analyses the emerging ethico-methodological challenges