Origin and Evolution of Prebiotic Organic Matter as Inferred from the Tagish Lake Meteorite

The complex suite of organic materials in carbonaceous chondrite meteorites probably originally formed in the interstellar medium and/or the solar protoplanetary disk, but was subsequently modified in the meteorites' asteroidal parent bodies. The mechanisms of formation and modification are still very poorly understood. We carried out a systematic study of variations in the mineralogy, petrology, and soluble and insoluble organic matter in distinct fragments of the Tagish Lake meteorite. The variations correlate with indicators of parent body aqueous alteration and at least some molecules of pre-biotic importance formed during the alteration

Adaptive responses to static conditions in nutrient-rich cultures of luminous Ralstonia eutropha

The lux-gene fused Ralstonia eutropha, when adapting to static conditions, causes stratification of air-exposed and nutrient-rich cultures at above 0.15 mg biomass ml(-1). The O-2 respiring biofilm (luminous neuston) phase, along with the dark sub-neustonic suspension phase, develops within 5-60 min. The instability of the biphasic static culture was identified as a reason for occasionally observable oscillatory bioluminescence

Properties of mEPSCs recorded in layer II neurones of rat barrel cortex

Voltage-clamp recordings from layer II neurones in somatosensory cortex of rats aged between 12 and 17 days showed a high frequency of spontaneous postsynaptic currents (sPSCs), which on average was 33 ± 13 Hz (s.d.). sPSCs were mediated largely by glutamatergic AMPA receptors. Their rates and amplitudes were independent of blocking sodium channels with 1 μm tetrodotoxin (TTX). Most of them, therefore, represent genuine miniature excitatory postsynaptic currents (mEPSCs). The rise time of the fastest (10 %) mEPSCs was 288 ± 86 μs (10-90 %) and the half-width was 1073 ± 532 μs. The amplitude was −5.9 ± 1.1 pA with a coefficient of variation (CV) of 0.44 ± 0.14. The rate of mEPSCs was very temperature sensitive with a Q10 (33-37 °C) of 8.9 ± 0.9. Due to this temperature sensitivity, we estimated that the microscope lamp contributed an increase in temperature of about 4 °C to the tissue in the focal volume of the condenser. Cell-type differences in the rate of mEPSCs were found between pyramidal/multipolar and bipolar cells. The latter had a frequency of about a third of that seen in the other cell groups. Recordings in layer II are ideally suited to investigate mechanisms of spontaneous transmitter release

Controlled query evaluation over lightweight ontologies

We study confidentiality enforcement in ontologies under the Controlled Query Evaluation (CQE) framework. In a CQE system, a policy specifies the sensitive information, and a censor ensures that answers to user's queries that could violate the policy are not returned. Our goal is the design of optimal CQE algorithms, which ensure confidentiality while maximising access to information. We study two natural classes of censors that can be realised using existing infrastructure for query answering and propose optimal CQE algorithms for the standardised profiles of the ontology language OWL 2

The grayness of the origin of life

In the search for life beyond Earth, distinguishing the living from the non-living is paramount. However, this distinction is often elusive, as the origin of life is likely a stepwise evolutionary process, not a singular event. Regardless of the favored origin of life model, an inherent “grayness” blurs the theorized threshold defining life. Here, we explore the ambiguities between the biotic and the abiotic at the origin of life. The role of grayness extends into later transitions as well. By recognizing the limitations posed by grayness, life detection researchers will be better able to develop methods sensitive to prebiotic chemical systems and life with alternative biochemistries