A quantitative study of the orientation bias of some edge detector schemes

The evaluation of a particular set of edge detection schemes is described. The results obtained are compared with those obtained from an edge detection scheme using a texture oriented approach. The orientational bias of these schemes is emphasized. Improved qualitative observations are reported and a comparison of the evaluation method with another edge detection evaluation method is presented

Across Bacterial Phyla, Distantly-Related Genomes with Similar Genomic GC Content Have Similar Patterns of Amino Acid Usage

The GC content of bacterial genomes ranges from 16% to 75% and wide ranges of genomic GC content are observed within many bacterial phyla, including both Gram negative and Gram positive phyla. Thus, divergent genomic GC content has evolved repeatedly in widely separated bacterial taxa. Since genomic GC content influences codon usage, we examined codon usage patterns and predicted protein amino acid content as a function of genomic GC content within eight different phyla or classes of bacteria. We found that similar patterns of codon usage and protein amino acid content have evolved independently in all eight groups of bacteria. For example, in each group, use of amino acids encoded by GC-rich codons increased by approximately 1% for each 10% increase in genomic GC content, while the use of amino acids encoded by AT-rich codons decreased by a similar amount. This consistency within every phylum and class studied led us to conclude that GC content appears to be the primary determinant of the codon and amino acid usage patterns observed in bacterial genomes. These results also indicate that selection for translational efficiency of highly expressed genes is constrained by the genomic parameters associated with the GC content of the host genome

Gene expression caused by alkylating agents and cis-diamminedichloroplatinum(II) in Escherichia coli

Previous work has demonstrated heterogeneous effects of methylating agents on induction of DNA damage inducible genes in Escherichia coli. These studies employed E. coli mutants that have fusions of the lac operon to genes induced by treatment with sublethal levels of alkylating agents. These mutants were selected from random insertions of the Mu-dl (Apr lac) phage by screening for induction of beta-galactosidase activity in the presence of methylmethanesulfonate or N-methyl-N\u27-nitro-N-nitrosoguanidine. The current report extends these findings by analyzing gene expression caused by mechlorethamine, chloroethylnitrosoureas and cis-diamminedichloroplatinum(II) (cis-DDP). The results demonstrate heterogeneous effects by these agents on gene expression. While 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea induces alkA, other nitrosoureas, mechlorethamine, and cis-DDP do not cause expression of this gene. Further, while all nitrosoureas caused expression of aidC, mechlorethamine and cis-DDP did not. Lastly, cis-DDP caused marked expression of a sulA fusion mutant while not inducing any of the other E. coli fusion mutants

Solar warming of near-bottom water over a fringing reef

The Kilo Nalu Observatory is located on the foreslope of a fringing reef on the south shore of Oahu, Hawaii. A cabled node at 12-m depth has enabled continuous real-time temperature observations from a thermistor chain extending from 1 to 7 m above bottom. Data from a 27-month deployment in 2007–2009 reveal repeated instances of subsurface temperature inversions. The usual diurnal pattern shows increases in temperature throughout the water column after sunrise, peaking in the early afternoon. Bottom waters typically warm faster than those at mid-depth, driving an inversion in the thermal profile. The onset and evolution of the inversions are consistent with an analytical model of radiation absorption and the contribution to bottom temperature from solar warming of the seafloor. The maximum size, duration and seasonal distribution of the inversions indicate that salinity compensation is a major limiting factor. In the absence of salinity compensation, the implication is that bottom heating destabilizes the water column and convective transport results. In addition, recurring afternoon onshore bottom currents contribute to the termination of inversions. Although radiative heating may exacerbate coral heat stress, radiation-driven thermal convection and exposure to the open ocean modulate temperatures over the reef

Survivorship, complications, and outcomes following distal femoral arthroplasty for non-neoplastic indications.

AIMS: Endoprosthetic reconstruction with a distal femoral arthroplasty (DFA) can be used to treat distal femoral bone loss from oncological and non-oncological causes. This study reports the short-term implant survivorship, complications, and risk factors for patients who underwent DFA for non-neoplastic indications. METHODS: We performed a retrospective review of 75 patients from a single institution who underwent DFA for non-neoplastic indications, including aseptic loosening or mechanical failure of a previous prosthesis (n = 25), periprosthetic joint infection (PJI) (n = 23), and native or periprosthetic distal femur fracture or nonunion (n = 27). Patients with less than 24 months\u27 follow-up were excluded. We collected patient demographic data, complications, and reoperations. Reoperation for implant failure was used to calculate implant survivorship. RESULTS: Overall one- and five-year implant survivorship was 87% and 76%, respectively. By indication for DFA, mechanical failure had one- and five-year implant survivorship of 92% and 68%, PJI of 91% and 72%, and distal femur fracture/nonunion of 78% and 70% (p = 0.618). A total of 37 patients (49%) experienced complications and 27 patients (36%) required one or more reoperation. PJI (n = 16, 21%), aseptic loosening (n = 9, 12%), and wound complications (n = 8, 11%) were the most common complications. Component revision (n = 10, 13.3%) and single-stage exchange for PJI (n = 9, 12.0 %) were the most common reoperations. Only younger age was significantly associated with increased complications (mean 67 years (SD 9.1)) with complication vs 71 years (SD 9.9) without complication; p = 0.048). CONCLUSION: DFA is a viable option for distal femoral bone loss from a range of non-oncological causes, demonstrating acceptable short-term survivorship but with high overall complication rates

Superconductivity from correlated hopping

We consider a chain described by a next-nearest-neighbor hopping combined with a nearest-neighbor spin flip. In two dimensions this three-body term arises from a mapping of the three-band Hubbard model for CuO$_2$ planes to a generalized $t-J$ model and for large O-O hopping favors resonance-valence-bond superconductivity of predominantly $d$-wave symmetry. Solving the ground state and low-energy excitations by analytical and numerical methods we find that the chain is a Luther-Emery liquid with correlation exponent $K_{\rho} = (2-n)^2/2$, where $n$ is the particle density.Comment: 10 pages, RevTeX 3.0 + 2 PostScript figs. Accepted for publication in Phys.Rev.

Miniature thermistor chain for determining surficial sediment porewater advection

A miniature thermistor chain (mTc) was developed to measure the subdiurnal variability of temperature in the upper layers of subtidal coastal permeable (sandy) sediments and across the sediment-water interface (SWI). The mTc has 15 precision thermistors (0.002°C accuracy) attached by narrow tines to a stainless steel backbone that connects to an electronics module, all of which is buried in the top 20 cm of the sediment. Instrument performance was tested by deploying the mTc in nearshore permeable sediment at the Kilo Nalu Observatory, Oahu, Hawaii over an 80-d period. The mTc reached thermal equilibrium with the adjoining sediment within a few days after deployment and then recorded the advective propagation of the sub-daily water-column temperature variation into the sediment. The data produced are consistent with predicted effects of surface waves on advective porewater transport: transport rate increased with wave height and decreased with depth below the SWI, and temperature time lag increased with depth below the SWI. Data from an independent, more deeply buried thermistor are in good agreement with the mTc time-series data, showing attenuated temperature variability and similar (but longer, as expected) thermal time lags. Because thermal variations in surficial sediments is dominated by advection in wavy environments, mTc subdiurnal temperature propagation data can be used to calculate advective transport across the SWI and as deep as 20 cm into the sediment (i.e., over depths where advection dominates over thermal diffusion).This is the publisher’s final pdf. The published article is copyrighted by the American Society of Limnology and Oceanography, Inc. and can be found at: http://aslo.org/lomethods/index.html

Theorising variation in engagement in professional and curriculum development: performativity, capital, systems and purpose

Increasingly, policymakers seek to improve the quality of teaching through curriculum innovations and continuing professional development (CPD) programmes. However, engagement by schools and teachers varies due to mediating influences of neoliberal policies. In this article, we contribute to understanding how these tendencies affect participation. Problematising the notion of context, we examine ways in which systemic influences interacted with participation in a government-funded mathematics professional and curriculum development programme and also with participants’ purposes. A 3-level clustered Randomised Controlled Trial (RCT) and an implementation and process evaluation were augmented by in-depth case studies, cross-case analysis and the application of theoretical constructs to interpret findings. Theories of capital, figured worlds and systemic coupling are utilised to theorise context. Different levels of engagement are partly explainable by: the interaction of schools' relative systemic advantage and disadvantage; their orientation and coupling to performativity regimes; and the alignment or dissonance between continuing professional development or change programmes and the pedagogical and CPD cultures and purposes of the ‘actors’ (schools, departments and teachers). Performativity concerns restricted what were considered legitimate outcomes in some case study schools. This depended on teachers and schools' positioning in terms of relative degrees of systemic privilege or disadvantage - understood as economic, cultural, social and symbolic capital - and also in terms of figured worlds and system coupling. The case studies provide insights into how collaborative professional learning can be fostered more productively. Methodologically, we demonstrate the power of combining methodologies and applying explanatory social theory to augment quasi-experimental paradigms

Managing lifestyle change to reduce coronary risk: a synthesis of qualitative research on peoples’ experiences

Background Coronary heart disease is an incurable condition. The only approach known to slow its progression is healthy lifestyle change and concordance with cardio-protective medicines. Few people fully succeed in these daily activities so potential health improvements are not fully realised. Little is known about peoples’ experiences of managing lifestyle change. The aim of this study was to synthesise qualitative research to explain how participants make lifestyle change after a cardiac event and explore this within the wider illness experience. Methods A qualitative synthesis was conducted drawing upon the principles of meta-ethnography. Qualitative studies were identified through a systematic search of 7 databases using explicit criteria. Key concepts were identified and translated across studies. Findings were discussed and diagrammed during a series of audiotaped meetings. Results The final synthesis is grounded in findings from 27 studies, with over 500 participants (56% male) across 8 countries. All participants experienced a change in their self-identity from what was ‘familiar’ to ‘unfamiliar’. The transition process involved ‘finding new limits and a life worth living’ , ‘finding support for self’ and ‘finding a new normal’. Analyses of these concepts led to the generation of a third order construct, namely an ongoing process of ‘reassessing past, present and future lives’ as participants considered their changed identity. Participants experienced a strong urge to get back to ‘normal’. Support from family and friends could enable or constrain life change and lifestyle changes. Lifestyle change was but one small part of a wider ‘life’ change that occurred. Conclusions The final synthesis presents an interpretation, not evident in the primary studies, of a person-centred model to explain how lifestyle change is situated within ‘wider’ life changes. The magnitude of individual responses to a changed health status varied. Participants experienced distress as their notion of self identity shifted and emotions that reflected the various stages of the grief process were evident in participants’ accounts. The process of self-managing lifestyle took place through experiential learning; the level of engagement with lifestyle change reflected an individual’s unique view of the balance needed to manage ‘realistic change’ whilst leading to a life that was perceived as ‘worth living’. Findings highlight the importance of providing person centred care that aligns with both psychological and physical dimensions of recovery which are inextricably linked

The importance of interocean exchange south of Africa in a numerical model

A fine resolution numerical model of the Southern Ocean (the Fine Resolution Antarctic Model (FRAM)) has been used to investigate the way in which heat is supplied to the South Atlantic. The heat budget in the model is compared with other estimates and is found to be broadly realistic. The temperature structure in the Atlantic, and therefore the meridional heat transport, depend heavily on the input of heat from the Indian Ocean via the Agulhas Retroflection region. FRAM is compared with three models which do not exhibit a significant input of heat from the Indian Ocean. These models also have a lower equatorward heat transport in the South Atlantic. Horizontal resolution affects the amount of Agulhas transfer with coarser resolution leading to lower heat transport in the Atlantic, a result which has implications for ocean models used in climate simulations