Selective Principal Component Extraction and Reconstruction: A Novel Method for Ground Based Exoplanet Spectroscopy

Context: Infrared spectroscopy of primary and secondary eclipse events probes the composition of exoplanet atmospheres and, using space telescopes, has detected H2O, CH4 and CO2 in three hot Jupiters. However, the available data from space telescopes has limited spectral resolution and does not cover the 2.4 - 5.2 micron spectral region. While large ground based telescopes have the potential to obtain molecular-abundance-grade spectra for many exoplanets, realizing this potential requires retrieving the astrophysical signal in the presence of large Earth-atmospheric and instrument systematic errors. Aims: Here we report a wavelet-assisted, selective principal component extraction method for ground based retrieval of the dayside spectrum of HD 189733b from data containing systematic errors. Methods: The method uses singular value decomposition and extracts those critical points of the Rayleigh quotient which correspond to the planet induced signal. The method does not require prior knowledge of the planet spectrum or the physical mechanisms causing systematic errors. Results: The spectrum obtained with our method is in excellent agreement with space based measurements made with HST and Spitzer (Swain et al. 2009b; Charbonneau et al. 2008) and confirms the recent ground based measurements (Swain et al. 2010) including the strong 3.3 micron emission.Comment: 4 pages, 3 figures; excepted for publication by A&

Confinement and crowding control the morphology and dynamics of a model bacterial chromosome

Motivated by recent experiments probing shape, size and dynamics of bacterial chromosomes in growing cells, we consider a polymer model consisting of a circular backbone to which side-loops are attached, confined to a cylindrical cell. Such a model chromosome spontaneously adopts a helical shape, which is further compacted by molecular crowders to occupy a nucleoid-like subvolume of the cell. With increasing cell length, the longitudinal size of the chromosome increases in a non-linear fashion to finally saturate, its morphology gradually opening up while displaying a changing number of helical turns. For shorter cells, the chromosome extension varies non-monotonically with cell size, which we show is associated with a radial to longitudinal spatial reordering of the crowders. Confinement and crowders constrain chain dynamics leading to anomalous diffusion. While the scaling exponent for the mean squared displacement of center of mass grows and saturates with cell length, that of individual loci displays broad distribution with a sharp maximum.Comment: 12 pages, 12 figure

New Zealand culture of intoxication: Local and global influences

This article shows that attitudes towards and behaviours involving the consumption of alcohol in New Zealand have long been problematic. It provides an historical account of social, economic and legislative factors which have influenced the development of the New Zealand drinking culture. Accordingly, it tracks a combination of local and global alcohol-related influences and documents the interrelationships amongst these factors. In particular, it proposes that the liberalisation of alcohol licensing laws and advertising/sponsorship regulations, alongside the growth of the alcohol-based hospitality industry have promoted the normalisation of an alcohol-based leisure lifestyle. Against this backdrop, the growth of consumer culture , tertiary student culture and the New Zealand drug culture, along with the development of new alcohol products and the establishment of commercial and social-networking websites have conjointly enabled the growth of a culture of intoxication, which is characterised by drinkers intentionally drinking to intoxication and viewing this behaviour as socially acceptable

Massive relic neutrinos in the galactic halo and the knee in the cosmic ray spectrum

Despite many efforts to find a reasonable explanation, the origin of the "knee" in the cosmic ray spectrum at energy around 10**15.5 eV remains mysterious. In this letter we suggest that the "knee" may be due to a GZK-like effect of cosmic rays interacting with massive neutrinos in the galactic halo. Simple kinematics connects the location of the "knee" with the mass of the neutrinos, and, while the required interaction cross section is larger than that predicted by the Standard Model, it can be accommodated by a small neutrino magnetic dipole moment. The values for the neutrino parameters obtained from the analysis of existing experimental data are compatible with present laboratory bounds.Comment: 8 pages, 1 figure, uses RevTe

Ultrasensitivity in phosphorylation-dephosphorylation cycles with little substrate

Cellular decision-making is driven by dynamic behaviours, such as the preparations for sunrise enabled by circadian rhythms and the choice of cell fates enabled by positive feedback. Such behaviours are often built upon ultrasensitive responses where a linear change in input generates a sigmoidal change in output. Phosphorylation-dephosphorylation cycles are one means to generate ultrasensitivity. Using bioinformatics, we show that in vivo levels of kinases and phosphatases frequently exceed the levels of their corresponding substrates in budding yeast. This result is in contrast to the conditions often required by zero-order ultrasensitivity, perhaps the most well known means for how such cycles become ultrasensitive. We therefore introduce a mechanism to generate ultrasensitivity when numbers of enzymes are higher than numbers of substrates. Our model combines distributive and non-distributive actions of the enzymes with two-stage binding and concerted allosteric transitions of the substrate. We use analytical and numerical methods to calculate the Hill number of the response. For a substrate with [Formula: see text] phosphosites, we find an upper bound of the Hill number of [Formula: see text], and so even systems with a single phosphosite can be ultrasensitive. Two-stage binding, where an enzyme must first bind to a binding site on the substrate before it can access the substrate's phosphosites, allows the enzymes to sequester the substrate. Such sequestration combined with competition for each phosphosite provides an intuitive explanation for the sigmoidal shifts in levels of phosphorylated substrate. Additionally, we find cases for which the response is not monotonic, but shows instead a peak at intermediate levels of input. Given its generality, we expect the mechanism described by our model to often underlay decision-making circuits in eukaryotic cells

Pleasure, profit and pain: Alcohol in New Zealand and the contemporary culture of intoxication

This book details the rich, complex and often contested role of alcohol in New Zealand society. It explores the three fundamental alcohol rights that continue to fight for dominance of the national drinking culture: the rights of individual drinkers to enjoy the pleasures of alcohol, the rights of society to protect itself from the harms of alcohol, and the rights of the alcohol industry to profit from the sale of a legal commodity. Historically, most of our intoxicated drinkers were adult males and drinking was typically separated from family, food and entertainment. With the sweeping social changes of the 1960s and 1970s, women and later young people, increasingly engaged with alcohol. A growing proportion of these groups have since joined men in a culture of intoxication, or binge drinking culture as it is often termed. New Zealand is not alone however, in having a culture of intoxication, with similar alcohol consumption patterns evident in many other developed nations. This book identifies the local and the global influences that have affected New Zealand society (and much of the rest of the world) since the late 1900s and details how these influences have sustained the contemporary culture of intoxication. Finally, this book will propose that to implement effective change to our national drinking culture, the rights of the alcohol industry and of individual drinkers will need to be pulled back from the liberal excesses that the 1980s and 1990s provided. A re-balancing is required in order to strengthen and sustain society’s right to protect itself from alcohol-related harm

Molecular Parataxonomy as Taxon Description: Examples from Recently Named Zoanthidea (Cnidaria: Anthozoa) with Revision Based on Serial Histology of Microanatomy.

Current taxonomic practices require corroboration from multiple lines of evidence to provide sufficient rigor for species discovery and description. However, many recently named taxa (species–families) are defined by nucleotide sequence with little or no description of the features that traditionally define higher taxa and link nucleotide-based information to the existing taxonomic system. Without knowledge of form, it may be impossible to identify conspecifics, congeners, and confamiliars of new taxa among the hundreds of specimens and described species for which nucleotide sequencing is not now, and may never be, available. Additionally, some nucleotide sequences are invariant or inconsistently differentiated between congeners; severely limiting the utility of nucleotide-based taxon definitions. Here we use serial histology of paratypes to reveal the microanatomy of internal structures and revise the definitions of the Zoanthidea taxa Corallizoanthus tsukaharai Reimer, Antipathozoanthus hickmani Reimer & Fujii, Parazoanthus darwini Reimer & Fujii, Terrazoanthus onoi Reimer & Fujii, Terrazoanthus sinnigeri Reimer & Fujii, Microzoanthus kagerou Fujii & Reimer, and Zoanthus kuroshio Reimer & Ono; examination of Mesozoanthus lilkweminensis Reimer & Sinniger failed to produce interpretable sections. The results described here, with individual measurements documented in Morphbank (collection 829724) and Encyclopedia of Life (by taxon name), indicate a notably rich diversity of form for an order that is often characterized as depauperate in morphological diversity. One prominent example is a novel marginal muscle structure (cyclically transitional) that is not observable without serial sections. These findings may renew interest in morphological characters and provide the foundation for revision of Zoanthidea higher taxa, particularly now that phylogenetic relationships for these taxa can be inferred

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Ground-based NIR emission spectroscopy of HD189733b

We investigate the K and L band dayside emission of the hot-Jupiter HD 189733b with three nights of secondary eclipse data obtained with the SpeX instrument on the NASA IRTF. The observations for each of these three nights use equivalent instrument settings and the data from one of the nights has previously reported by Swain et al (2010). We describe an improved data analysis method that, in conjunction with the multi-night data set, allows increased spectral resolution (R~175) leading to high-confidence identification of spectral features. We confirm the previously reported strong emission at ~3.3 microns and, by assuming a 5% vibrational temperature excess for methane, we show that non-LTE emission from the methane nu3 branch is a physically plausible source of this emission. We consider two possible energy sources that could power non-LTE emission and additional modelling is needed to obtain a detailed understanding of the physics of the emission mechanism. The validity of the data analysis method and the presence of strong 3.3 microns emission is independently confirmed by simultaneous, long-slit, L band spectroscopy of HD 189733b and a comparison star.Comment: ApJ accepte

The mid-infrared spectrum of the transiting exoplanet HD 209458b

We report the spectroscopic detection of mid-infrared emission from the transiting exoplanet HD 209458b. Using archive data taken with the Spitzer/IRS instrument, we have determined the spectrum of HD 209458b between 7.46 and 15.25 microns. We have used two independent methods to determine the planet spectrum, one differential in wavelength and one absolute, and find the results are in good agreement. Over much of this spectral range, the planet spectrum is consistent with featureless thermal emission. Between 7.5 and 8.5 microns, we find evidence for an unidentified spectral feature. If this spectral modulation is due to absorption, it implies that the dayside vertical temperature profile of the planetary atmosphere is not entirely isothermal. Using the IRS data, we have determined the broad-band eclipse depth to be 0.00315 +/- 0.000315, implying significant redistribution of heat from the dayside to the nightside. This work required development of improved methods for Spitzer/IRS data calibration that increase the achievable absolute calibration precision and dynamic range for observations of bright point sources.Comment: 35 pages, 12 figures, revised version accepted by the Astrophysical Journa