Pollen ultrastructure in anther cultures of Datura innoxia. I. Division of the presumptive vegetative cell.

Ultrastructural features of embryogenic pollen in Datura innoxia are described, just prior to, during, and after completion of the first division of the presumptive vegetative cell. In anther cultures initiated towards the end of the microspore phase and incubated at 28 degrees C in darkness, the spores divide within 24 h and show features consistent with those of dividing spores in vivo. Cytokinesis is also normal in most of the spores and the gametophytic cell-plate curves round the presumptive generative nucleus in the usual highly ordered way. Further differentiation of the 2 gametophytic cells does not take place and the pollen either switches to embryogenesis or degenerates. After 48-72 h, the remaining viable pollen shows the vegetative cell in division. The cell, which has a large vacuole and thin layer of parietal cytoplasm carried over from the microspore, divides consistently in a plane parallel to the microspore division. The dividing wall follows a less-ordered course than the gametophytic wall and usually traverses the vacuole, small portions of which are incorporated into the daughter cell adjacent to the generative cell. The only structural changes in the vegetative cell associated with the change in programme appear to be an increase in electron density of both plastids and mitochondria and deposition of an electron-dense material (possibly lipid) on the tonoplast. The generative cell is attached to the intine when the vegetative cell divides. Ribosomal density increases in the generative cell and exceeds that in the vegetative cell. A thin electron-dense layer also appears in the generative-cell wall. It is concluded that embryogenesis commences as soon as the 2 gametophytic cells are laid down. Gene activity associated with postmitotic synthesis of RNA and protein in the vegetative cell is switched off. The data are discussed in relation to the first division of the embryogenic vegetative cells in Nicotiana tabacum.

'Everything is connected, and everything matters': relationships in I ♥ Huckabees

An analysis of two paired moments, both involving bicycle rides, which enables a discussion of the relationships which the film establishes formally between these moments (and other elements of the film) and establishes the parallel between these structures and the film's interest in exploring coincidences, and seeking out a range of economic, political and metaphysical relationships. It explores the way the film dramatises philosophical debates through action.

Synthesis and X-ray crystal structure of the copper(I) dicarboxylic acid complex [Cu(η1-bdoaH)(PPh3)3] (bdoaH2 = benzene-1,2- dioxyacetic acid)

The copper(II) complex [Cu(bdoa)(H2O)2] (bdoaH2 = benzene-1,2-dioxyacetic acid) reacts with triphenylphosphine (1:4 mol ratio) to give the colourless copper(I) complex [Cu(η1-bdoaH)(PPh3)3] (1) in good yield. The X-ray crystal structure of the complex shows the copper atom at the centre of a distorted tetrahedron, and is ligated by the phosphorus atoms of the three triphenylphosphines and one carboxylate oxygen atom of the bdoaH− ligand. Significant intermolecular hydrogen-bonding exists between the pendant carboxylate OH function of one molecule and the uncoordinated “ketonic” oxygen of a neighbouring molecule. Complex 1 is non-conducting in chloroform but ionizes readily in acetonitrile. The cyclic voltammogram of an acetonitrile solution of 1 shows a single irreversible anodic peak for the oxidation of the PPh3 ligands and the copper(I) centre, and a single irreversible cathodic peak for the reduction of the bdoaH− ion. IR and mass spectral data for 1 are given.

Why was urban overcrowding much more severe in Scotland than in the rest of the British Isles? Evidence from the first (1904) official household expenditure survey

This article presents an analysis of British urban working-class housing conditions in 1904, using a rediscovered survey. We investigate overcrowding and find major regional differences. Scottish households in the survey were more overcrowded despite being less poor. Investigating the causes of this overcrowding, we find little support for supply-side theories or for the idea that the Scottish households in our survey experienced particularly great variations in income, causing them to commit to overly modest accommodation. We present evidence that is consistent with idea that particularly tough Scottish tenancy and local tax laws caused excess overcrowding. We also provide evidence that Scottish workers had a relatively high preference for food, rather than housing, expenditure, which can be at least partly attributed to their inheritance of more communal patterns of urban living.

The child and the letter: Anne Brontë’s The Tenant of Wildfell Hall

This essay engages with the question of childhood in Anne Brontë’s The Tenant of Wildfell Hall. Despite narrating a conflict concerning child custody, childhood is a subject rarely broached by the critics of the text. Indeed, the only instance of the child being addressed in criticism grants it the power to enclose potentially subversive narrative. This is a function attributed to the framing structure of the novel by other critics. This essay returns the child to Brontë’s text as a disruptive rather than containing force. Through a detailed close analysis of the novel I track such disruptions, and the extent to which these point to wider theoretical or methodological difficulties in critical accounts of childhood and absence in literature. The essay makes interventions into psychoanalysis, childhood studies, and the discourse of ‘framing’ within C19th literature.

The impact of buy to let residential investment on local housing markets: evidence from Glasgow, Scotland

The advent of the 'buy to let' (BTL) phenomenon in the UK. apart from producing a new wave of individualized rental market investment, has been widely judged to be a speculative and destabilizing force in the housing market. This paper provides a detailed empirical investigation of new residential investment in one city (Glasgow) where BTL has made a relatively large impact. In seeking to overcome data problems, the study employed qualitative (expert interviews and a landlord survey) and quantitative methods (census, the Register of Sasines, standardized house price information and modelling thereof) in order to assess the nature and scale of BTL, the motivations of investors and its impact on the private housing market. The evidence suggests that white Glasgow is in many re.spects different to rental markets elsewhere in the UK and although the investment has thus far largely occurred in a benign environment, the context for future investment, on balance, looks sustainable (i.e.favourable changes to pension planning law and the maturing market for BTL}. Long-term market impact is an empirical question that depends on the specific interactions of market niches or segments (i.e. the first-time buyer market for apartments} with potential buy to let investment. Our conclusion, to borrow a Scottish legal term, is that BTL induced volatility is 'not proven'.

Distribution of β-amylase I haplotypes among European cultivated barleys

The barley β-amylase I (Bmy1) locus encodes a starch breakdown enzyme whose kinetic properties and thermostability are critical during malt production. Studies of allelic variation at the Bmy1 locus have shown that the encoded enzyme can be commonly found in at least three distinct thermostability classes and demonstrated the nucleotide sequence variations responsible for such phenotypic differences. In order to explore the extent of sequence diversity at the Bmy1 locus in cultivated European barley, 464 varieties representing a cross-section of popular varieties grown in western Europe over the past 60 years, were genotyped for three single nucleotide polymorphisms chosen to tag the four common alleles found in the collection. One of these haplotypes, which has not been explicitly recognised in the literature as a distinct allele, was found in 95% of winter varieties in the sample. When release dates of the varieties were considered, the lowest thermostability allele (Bmy1-Sd2L) appeared to decrease in abundance over time, while the highest thermostability allele (Bmy1-Sd2H) was the rarest allele at 5.4% of the sample and was virtually confined to two-row spring varieties. Pedigree analysis was used to track transmission of particular alleles over time and highlighted issues of genetic stratification of the sample.

Effective LAI and CHP of a single tree from small-footprint full-waveform LiDAR

This letter has tested the canopy height profile (CHP) methodology as a way of effective leaf area index (LAIe) and vertical vegetation profile retrieval at a single-tree level. Waveform and discrete airborne LiDAR data from six swaths, as well as from the combined data of six swaths, were used to extract the LAIe of a single live Callitris glaucophylla tree. LAIe was extracted from raw waveform as an intermediate step in the CHP methodology, with two different vegetation-ground reflectance ratios. Discrete point LAIe estimates were derived from the gap probability using the following: 1) single ground returns and 2) all ground returns. LiDAR LAIe retrievals were subsequently compared to hemispherical photography estimates, yielding mean values within ±7% of the latter, depending on the method used. The CHP of a single dead Callitris glaucophylla tree, representing the distribution of vegetation material, was verified with a field profile manually reconstructed from convergent photographs taken with a fixed-focal-length camera. A binwise comparison of the two profiles showed very high correlation between the data reaching R2 of 0.86 for the CHP from combined swaths. Using a study-area-adjusted reflectance ratio improved the correlation between the profiles, but only marginally in comparison to using an arbitrary ratio of 0.5 for the laser wavelength of 1550 nm.

The importance of loop length on the stability of i-motif structures

Using UV and srCD spectroscopy it is found that loop length within the i-motif structure is important for both thermal and pH stability, but in contrast to previous statements, it is the shorter loops that exhibit the highest stability.

Mid-holocene and last glacial maximum climate simulations with the IPSL model-part I: comparing IPSLCM5A to IPSLCM4

The climates of the mid-Holocene (MH), 6,000 years ago, and of the Last Glacial Maximum (LGM), 21,000 years ago, have extensively been simulated, in particular in the framework of the Palaeoclimate Modelling Intercomparion Project. These periods are well documented by paleo-records, which can be used for evaluating model results for climates different from the present one. Here, we present new simulations of the MH and the LGM climates obtained with the IPSL_CM5A model and compare them to our previous results obtained with the IPSL_CM4 model. Compared to IPSL_CM4, IPSL_CM5A includes two new features: the interactive representation of the plant phenology and marine biogeochemistry. But one of the most important differences between these models is the latitudinal resolution and vertical domain of their atmospheric component, which have been improved in IPSL_CM5A and results in a better representation of the mid-latitude jet-streams. The Asian monsoon’s representation is also substantially improved. The global average mean annual temperature simulated for the pre-industrial (PI) period is colder in IPSL_CM5A than in IPSL_CM4 but their climate sensitivity to a CO2 doubling is similar. Here we show that these differences in the simulated PI climate have an impact on the simulated MH and LGM climatic anomalies. The larger cooling response to LGM boundary conditions in IPSL_CM5A appears to be mainly due to differences between the PMIP3 and PMIP2 boundary conditions, as shown by a short wave radiative forcing/feedback analysis based on a simplified perturbation method. It is found that the sensitivity computed from the LGM climate is lower than that computed from 2 × CO2 simulations, confirming previous studies based on different models. For the MH, the Asian monsoon, stronger in the IPSL_CM5A PI simulation, is also more sensitive to the insolation changes. The African monsoon is also further amplified in IPSL_CM5A due to the impact of the interactive phenology. Finally the changes in variability for both models and for MH and LGM are presented taking the example of the El-Niño Southern Oscillation (ENSO), which is very different in the PI simulations. ENSO variability is damped in both model versions at the MH, whereas inconsistent responses are found between the two versions for the LGM. Part 2 of this paper examines whether these differences between IPSL_CM4 and IPSL_CM5A can be distinguished when comparing those results to palaeo-climatic reconstructions and investigates new approaches for model-data comparisons made possible by the inclusion of new components in IPSL_CM5A.