Preface

The papers in this Special Issue originated from the energy forecasting stream at the 1995 Symposium on Energy Models for Policy and Planning, held at the London Business School in association with the International Federation of Operational Research Societies. The motivation of the Symposium was to focus upon model-based insights into energy issues. The papers selected here, which survived the refereeing process, indicate the range and importance of modelling in this context. We are grateful to the referees, participants of the symposium and the institutional support which facilitated this work.     

A ground-based transmission spectrum of the super-Earth exoplanet GJ 1214b

In contrast to planets with masses similar to that of Jupiter and higher, the bulk compositions of planets in the so-called super-Earth regime (masses 2-10 times that of the Earth) cannot be uniquely determined from a measurement of mass and radius alone. For these planets, there is a degeneracy between the mass and composition of both the interior and a possible atmosphere in theoretical models. The recently discovered transiting super-Earth exoplanet GJ 1214b is one example of this problem. Three distinct models for the planet that are consistent with its mass and radius have been suggested. Breaking the degeneracy between these models requires obtaining constraints on the planet's atmospheric composition. Here we report a ground-based measurement of the transmission spectrum of GJ 1214b between wavelengths of 780 and 1,000?nm. The lack of features in this spectrum rules out (at 4.9σ confidence) cloud-free atmospheres composed primarily of hydrogen. If the planet's atmosphere is hydrogen-dominated, then it must contain clouds or hazes that are optically thick at the observed wavelengths at pressures less than 200?mbar. Alternatively, the featureless transmission spectrum is also consistent with the presence of a dense, water vapour atmosphere.     

Identification of loci associated with schizophrenia by genome-wide association and follow-up

We carried out a genome-wide association study of schizophrenia (479 cases, 2,937 controls) and tested loci with P < 10(-5) in up to 16,726 additional subjects. Of 12 loci followed up, 3 had strong independent support (P < 5 x 10(-4)), and the overall pattern of replication was unlikely to occur by chance (P = 9 x 10(-8)). Meta-analysis provided strongest evidence for association around ZNF804A (P = 1.61 x 10(-7)) and this strengthened when the affected phenotype included bipolar disorder (P = 9.96 x 10(-9)).     

Collaborative genome-wide association analysis supports a role for ANK3 and CACNA1C in bipolar disorder

To identify susceptibility loci for bipolar disorder, we tested 1.8 million variants in 4,387 cases and 6,209 controls and identified a region of strong association (rs10994336, P = 9.1 x 10(-9)) in ANK3 (ankyrin G). We also found further support for the previously reported CACNA1C (alpha 1C subunit of the L-type voltage-gated calcium channel; combined P = 7.0 x 10(-8), rs1006737). Our results suggest that ion channelopathies may be involved in the pathogenesis of bipolar disorder.     

When did Darwin ‘clearly conceive’ his theory of evolution?

Darwin’s theory of evolution by natural selection as espoused in his classic book, On the Origin of Species, constitutes one of the most important scientific advances of the last millennium. In his autobiography, Darwin apparently claimed to have ‘clearly conceived’ the theory in 1839, but the Origin was not published until 1859, following a brief excerpt of his theorizing published in mid-1858. Much scholarship has been devoted to explaining this apparent gap. Yet, examination of Darwin’s explicit theorizing fails to support the generally accepted ‘clear conception’ by 1839 as an accurate reference to an immature version of the Origin theory, a theory of continuous and universal organic change. However, by articulating both broad and narrow versions of the theory, as well as considering the inevitable theory development over decades, Darwin’s ‘clear conception’ is explained in relation to two distinct broad theories and the enduring core element, the mechanism of natural selection. This explanation casts the famous ‘gap’ in an entirely new light.     

Newly identified genetic risk variants for celiac disease related to the immune response

Our genome-wide association study of celiac disease previously identified risk variants in the IL2-IL21 region. To identify additional risk variants, we genotyped 1,020 of the most strongly associated non-HLA markers in an additional 1,643 cases and 3,406 controls. Through joint analysis including the genome-wide association study data (767 cases, 1,422 controls), we identified seven previously unknown risk regions (P < 5 x 10(-7)). Six regions harbor genes controlling immune responses, including CCR3, IL12A, IL18RAP, RGS1, SH2B3 (nsSNP rs3184504) and TAGAP. Whole-blood IL18RAP mRNA expression correlated with IL18RAP genotype. Type 1 diabetes and celiac disease share HLA-DQ, IL2-IL21, CCR3 and SH2B3 risk regions. Thus, this extensive genome-wide association follow-up study has identified additional celiac disease risk variants in relevant biological pathways.     

Germline rates of de novo meiotic deletions and duplications causing several genomic disorders

Meiotic recombination between highly similar duplicated sequences (nonallelic homologous recombination, NAHR) generates deletions, duplications, inversions and translocations, and it is responsible for genetic diseases known as 'genomic disorders', most of which are caused by altered copy number of dosage-sensitive genes. NAHR hot spots have been identified within some duplicated sequences. We have developed sperm-based assays to measure the de novo rate of reciprocal deletions and duplications at four NAHR hot spots. We used these assays to dissect the relative rates of NAHR between different pairs of duplicated sequences. We show that (i) these NAHR hot spots are specific to meiosis, (ii) deletions are generated at a higher rate than their reciprocal duplications in the male germline and (iii) some of these genomic disorders are likely to have been underascertained clinically, most notably that resulting from the duplication of 7q11, the reciprocal of the deletion causing Williams-Beuren syndrome.     

Modulation of Kv7 channels and excitability in the brain

Neuronal Kv7 channels underlie a voltage-gated non-inactivating potassium current known as the M-current. Due to its particular characteristics, Kv7 channels show pronounced control over the excitability of neurons. We will discuss various factors that have been shown to drastically alter the activity of this channel such as protein and phospholipid interactions, phosphorylation, calcium, and numerous neurotransmitters. Kv7 channels locate to key areas for the control of action potential initiation and propagation. Moreover, we will explore the dynamic surface expression of the channel modulated by neurotransmitters and neural activity. We will also focus on known principle functions of neural Kv7 channels: control of resting membrane potential and spiking threshold, setting the firing frequency, afterhyperpolarization after burst firing, theta resonance, and transient hyperexcitability from neurotransmitter-induced suppression of the M-current. Finally, we will discuss the contribution of altered Kv7 activity to pathologies such as epilepsy and cognitive deficits.