A pre-enrichment step is essential for detection of Campylobacter sp in turbid pond water

This work aimed to detect Campylobacter species from naturally contaminated turbid pond water by PCR. A total of 16 water samples were collected from a turbid village pond. Four methods of DNA extraction were applied to centrifuge pellets from eight 100 ml pond water samples prior to attempted detection of Campylobacter by PCR without an enrichment step. These methods were (1) Tris-HCl and sodium dodecyl sulfate followed by phenol:chloroform:isoamylalcohol extraction followed by treatment with DNA clean up kit, (2) proteinase K, (3) Chelex® 100, and (4) boiling. The other eight pond water samples (10 ml and 100 ml) were filtered and filters were incubated overnight in Preston enrichment broth. The centrifuge pellets obtained from enrichment cultures were treated by proteinase K for DNA extraction. Primers CF03 and CF04 for the flagellin genes (fla A and fla B) of Campylobacter jejuni and Campylobacter coli were used for amplifying the extracted DNA. The DNA extracted from eight-100 ml pond water samples that were not subject to selective enrichment was never amplified with primers CF03 and CF04, hence Campylobacter was not detected. In contrast, the DNA that was from samples that were subjected to a selective enrichment step in Preston broth prior to PCR assay always gave amplified bands of 340-380 bp, therefore the presence of Campylobacter was confirmed. Detection of campylobacters from naturally contaminated, turbid, environmental water may not be feasible by direct PCR assay because of low numbers and the presence of high concentration of humic matter and other PCR inhibitors. The enrichment of water samples in selective broth, however, facilitated PCR detection of Campylobacter probably by increasing cell number and by diluting PCR inhibitors

Keys from the past: Unlocking the power of eighteenth-century contrapuntal pedagogies

How did eighteenth-century musicians learn to compose, and how were they able to produce musical works with such comparative ease and fluency? What were the strategies at play that enabled even the most workman-like of composers to produce vast amounts of competent music, and how was it possible for almost any professional keyboard player to improvise a passable fugue? It is only recently that scholars have sought the answers to such questions. Groundbreaking work by Gjerdigen (1988; 2007a), Porter (2000; 2002), Renwick (1995), and others, provides a fascinating glimpse of the working methods of eighteenth-century musicians, and also offers implications for contemporary music theory teaching. Historically, training musicians in the art of composition has been one of theory’s primary goals, and it could be argued that the ability to replicate a musical style is a true litmus test of deep understanding. Theory instruction in Australia, however, often falls short in this regard, confining itself instead to drilling rudiments, basic voice-leading tasks, and superficial analysis such as labeling chords. This paper aims to show how theory teaching can be reenvisioned to include style composition as a pedagogically powerful and rewarding activity. It also highlights the key usefulness of eighteenth-century pedagogies in unlocking windows into the common-practice idiom

Local Manipulation of Nuclear Spin in a Semiconductor Quantum Well

The shaping of nuclear spin polarization profiles and the induction of nuclear resonances are demonstrated within a parabolic quantum well using an externally applied gate voltage. Voltage control of the electron and hole wave functions results in nanometer-scale sheets of polarized nuclei positioned along the growth direction of the well. RF voltages across the gates induce resonant spin transitions of selected isotopes. This depolarizing effect depends strongly on the separation of electrons and holes, suggesting that a highly localized mechanism accounts for the observed behavior.Comment: 18 pages, 4 figure

‘.he was excluded for the kind of behaviour that we thought he needed support with…’ A qualitative analysis of the experiences and perspectives of parents whose children have been excluded from school

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordExclusion from school is associated with adverse outcomes for young people. There is limited research that explores parents’ perspectives, particularly in relation to the exclusion of primary school aged children. The present study used semi-structured interviews with 35 parents of 37 children aged 5–12 years from the Southwest of England. Parents experiences were captured in a conceptual model through three main themes. Exclusion was described as part of a complex journey of difficulties reflected by a continuum of coping. The child’s place on the continuum was determined by an interaction between the child, family, and school with communication a key determinant. The study also highlighted the wider implications of exclusion, including emotional and functional impacts on the child and parent and highlighted the importance of the parents voice in the identification and support of their child’s needs. It also presents many complexities surrounding exclusion from school and limited support parents felt their child was offered.This article presents independent research funded by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care (CLAHRC) for the South West Peninsula

Photoassisted tunneling from free-standing GaAs thin films into metallic surfaces

The tunnel photocurrent between a gold surface and a free-standing semiconducting thin film excited from the rear by above bandgap light has been measured as a function of applied bias, tunnel distance and excitation light power. The results are compared with the predictions of a model which includes the bias dependence of the tunnel barrier height and the bias-induced decrease of surface recombination velocity. It is found that i) the tunnel photocurrent from the conduction band dominates that from surface states. ii) At large tunnel distance the exponential bias dependence of the current is explained by that of the tunnel barrier height, while at small distance the change of surface recombination velocity is dominant

Fowler-Nordheim-like local injection of photoelectrons from a silicon tip

Tunneling between a photo-excited p-type silicon tip and a gold surface is studied as a function of tip bias, tip/sample distance and light intensity. In order to extend the range of application of future spin injection experiments, the measurements are carried out under nitrogen gas at room temperature. It is found that while tunneling of valence band electrons is described by a standard process between the semiconductor valence band and the metal, the tunneling of photoelectrons obeys a Fowler-Nordheim-like process directly from the conduction band. In the latter case, the bias dependence of the photocurrent as a function of distance is in agreement with theoretical predictions which include image charge effects. Quantitative analysis of the bias dependence of the dark and photocurrent spectra gives reasonable values for the distance, and for the tip and metal work functions. For small distances image charge effects induce a vanishing of the barrier and the bias dependence of the photocurrent is exponential. In common with many works on field emission, fluctuations in the tunneling currents are observed. These are mainly attributed to changes in the prefactor for the tunneling photocurrent, which we suggest is caused by an electric-field-induced modification of the thickness of the natural oxide layer covering the tip apex.Comment: 12 pages, 11 figures. Submitted to Phys. Rev.

Single-chain factor XII exhibits activity when complexed to polyphosphate

© 2014 The Authors. Journal of Thrombosis and Haemostasis published by Wiley Periodicals, Inc. on behalf of International Society on Thrombosis and Haemostasis.Peer reviewedPublisher PD

170 Nanometer Nuclear Magnetic Resonance Imaging using Magnetic Resonance Force Microscopy

We demonstrate one-dimensional nuclear magnetic resonance imaging of the semiconductor GaAs with 170 nanometer slice separation and resolve two regions of reduced nuclear spin polarization density separated by only 500 nanometers. This is achieved by force detection of the magnetic resonance, Magnetic Resonance Force Microscopy (MRFM), in combination with optical pumping to increase the nuclear spin polarization. Optical pumping of the GaAs creates spin polarization up to 12 times larger than the thermal nuclear spin polarization at 5 K and 4 T. The experiment is sensitive to sample volumes containing $\sim 4 \times 10^{11}$ $^{71}$Ga$/\sqrt{Hz}$. These results demonstrate the ability of force-detected magnetic resonance to apply magnetic resonance imaging to semiconductor devices and other nanostructures.Comment: Submitted to J of Magnetic Resonanc