Slipping into and out of Poverty: The Dynamics of Spells

This paper examines the dynamics of poverty. Previous analyses of the dynamics of poverty have either examined only fluctuations in the male heads earnings or looked at the frequency of poverty periods over a fixed time frame. We argue that a more appropriate way to understand the dynamics of poverty is to define spells of poverty. Using this methodology we find that the majority of poor persons at any point in time are in fact in the midst of a rather long spell of poverty. The methodology also allows us to estimate the extent to which poverty spell beginnings and endings are associated with changes in income or changes in family structure. Less than 40 percent of poverty spell beginnings seem to be caused by a drop in the heads earnings,while 60 percent of endings occur when the head's earnings increase. As a result we argue that to understand the causes and potential remedies for poverty, researchers must focus on household formation decisions and on the behavior of so called secondary family members.

Spangolite: an s=1/2 maple leaf lattice antiferromagnet?

Spangolite, Cu6Al(SO4)(OH)12Cl.3H2O, is a hydrated layered copper sulphate mineral. The Cu2+ ions of each layer form a systematically depleted triangular lattice which approximates a maple leaf lattice. We present details of the crystal structure, which suggest that in spangolite this lattice actually comprises two species of edge linked trimers with different exchange parameters. However, magnetic susceptibility measurements show that despite the structural trimers, the magnetic properties are dominated by dimerization. The high temperature magnetic moment is strongly reduced below that expected for the six s=1/2 in the unit cell.Comment: Accepted for JPCM Frustrated Magnetism special issue, added reference [5] in replacemen

Reconstructing (super)trees from data sets with missing distances: Not all is lost

The wealth of phylogenetic information accumulated over many decades of biological research, coupled with recent technological advances in molecular sequence generation, present significant opportunities for researchers to investigate relationships across and within the kingdoms of life. However, to make best use of this data wealth, several problems must first be overcome. One key problem is finding effective strategies to deal with missing data. Here, we introduce Lasso, a novel heuristic approach for reconstructing rooted phylogenetic trees from distance matrices with missing values, for datasets where a molecular clock may be assumed. Contrary to other phylogenetic methods on partial datasets, Lasso possesses desirable properties such as its reconstructed trees being both unique and edge-weighted. These properties are achieved by Lasso restricting its leaf set to a large subset of all possible taxa, which in many practical situations is the entire taxa set. Furthermore, the Lasso approach is distance-based, rendering it very fast to run and suitable for datasets of all sizes, including large datasets such as those generated by modern Next Generation Sequencing technologies. To better understand the performance of Lasso, we assessed it by means of artificial and real biological datasets, showing its effectiveness in the presence of missing data. Furthermore, by formulating the supermatrix problem as a particular case of the missing data problem, we assessed Lasso's ability to reconstruct supertrees. We demonstrate that, although not specifically designed for such a purpose, Lasso performs better than or comparably with five leading supertree algorithms on a challenging biological data set. Finally, we make freely available a software implementation of Lasso so that researchers may, for the first time, perform both rooted tree and supertree reconstruction with branch lengths on their own partial datasets

The active microbial community more accurately reflects the anaerobic digestion process: 16S rRNA (gene) sequencing as a predictive tool

Background: Amplicon sequencing methods targeting the 16S rRNA gene have been used extensively to investigate microbial community composition and dynamics in anaerobic digestion. These methods successfully characterize amplicons but do not distinguish micro-organisms that are actually responsible for the process. In this research, the archaeal and bacterial community of 48 full-scale anaerobic digestion plants were evaluated on DNA (total community) and RNA (active community) level via 16S rRNA (gene) amplicon sequencing. Results: A significantly higher diversity on DNA compared with the RNA level was observed for archaea, but not for bacteria. Beta diversity analysis showed a significant difference in community composition between the DNA and RNA of both bacteria and archaea. This related with 25.5 and 42.3% of total OTUs for bacteria and archaea, respectively, that showed a significant difference in their DNA and RNA profiles. Similar operational parameters affected the bacterial and archaeal community, yet the differentiating effect between DNA and RNA was much stronger for archaea. Co-occurrence networks and functional prediction profiling confirmed the clear differentiation between DNA and RNA profiles. Conclusions: In conclusion, a clear difference in active (RNA) and total (DNA) community profiles was observed, implying the need for a combined approach to estimate community stability in anaerobic digestion

Legal and Contractual Conditions: Implications on contructors' solvency

Often legal and contractual conditions stipulate payment terms for contracts which could impact on constructors’ solvency. Evidence from different countries suggests that legal and contractual conditions have evolved or are evolving to cater for cash flow problems that could lead to insolvencies. However the review shows that in most countries payment terms specified in legislation are applicable only where contractual conditions have not been specified, while in some countries contract conditions become void if they violate legislative provisions. The UK Act requires fair payment regimes and adjudication to be in the contracts. Similarly, NSW and other Acts voids contract provisions that exclude payment rights. Some of the legislation provides distinct features which could be considered upon contracting. For example the Queensland Act provides different payment due time for head contractors (within 25 business days of claim served) and subcontractors (within 15 business days of claim served). The Act of Western Australia and Northern Territory prohibits existing contract provisions of payment within 50 days of a served claim. Similarly, the latest Tasmanian Act prohibits the right to suspend the work if the party fails to make the adjudication within the stipulated time. The paper suggests that appropriate provisions of legislation need to be incorporated into contractual conditions since legislative provisions stand secondary to contract and available by default

Observation of Conduction Band Satellite of Ni Metal by 3p-3d Resonant Inverse Photoemission Study

Resonant inverse photoemission spectra of Ni metal have been obtained across the Ni 3$p$ absorption edge. The intensity of Ni 3$d$ band just above Fermi edge shows asymmetric Fano-like resonance. Satellite structures are found at about 2.5 and 4.2 eV above Fermi edge, which show resonant enhancement at the absorption edge. The satellite structures are due to a many-body configuration interaction and confirms the existence of 3$d^8$ configuration in the ground state of Ni metal.Comment: 4 pages, 3 figures, submitted to Physical Review Letter

Weibull-type limiting distribution for replicative systems

The Weibull function is widely used to describe skew distributions observed in nature. However, the origin of this ubiquity is not always obvious to explain. In the present paper, we consider the well-known Galton-Watson branching process describing simple replicative systems. The shape of the resulting distribution, about which little has been known, is found essentially indistinguishable from the Weibull form in a wide range of the branching parameter; this can be seen from the exact series expansion for the cumulative distribution, which takes a universal form. We also find that the branching process can be mapped into a process of aggregation of clusters. In the branching and aggregation process, the number of events considered for branching and aggregation grows cumulatively in time, whereas, for the binomial distribution, an independent event occurs at each time with a given success probability.Comment: 6 pages and 5 figure

Polarization Switching Dynamics Governed by Thermodynamic Nucleation Process in Ultrathin Ferroelectric Films

A long standing problem of domain switching process - how domains nucleate - is examined in ultrathin ferroelectric films. We demonstrate that the large depolarization fields in ultrathin films could significantly lower the nucleation energy barrier (U*) to a level comparable to thermal energy (kBT), resulting in power-law like polarization decay behaviors. The "Landauer's paradox": U* is thermally insurmountable is not a critical issue in the polarization switching of ultrathin ferroelectric films. We empirically find a universal relation between the polarization decay behavior and U*/kBT.Comment: 5 pages, 4 figure

The effects of different preservation methods on the quality of nunu, a locally fermented Nigerian dairy product

Biochemical and microbial analyses were carried out on fresh and preserved nunu for seven days. Fresh nunu contained protein, carbohydrates, lipids, calcium and other nutrients. Fresh samples had an initial pH of 4.4, microbial load of 4.2 x 103 cfu/ml and free fatty acid level of 2.21 mg/g of sample. Unpreserved sample showed appreciable degree of lipolysis, proteolysis and lactose fermentation. Preservation was by physical and chemical means. Physical methods included pasteurization and refrigeration. Pasteurization proved to be the least effective method of preservation. There was an appreciable level of increase in microbial count and biochemical changes. The chemical preservatives used were sodium benzoate and benzoic acid (1% concentration, w/v of sample). Sodium benzoate proved to be the most effective of all methods of preservation. The microbial count was significantly reduced (p < 0.05) and there were very slight biochemical changes. Benzoic acid was also effective, but less than sodium benzoate. Nunu, if well preserved, can thus be a very refreshing and nourishing beverage that is affordable to many