20,458 research outputs found
Union learning representatives: facilitating professional development for Scottish teachers
In the United Kingdom, teachers' professional associations and labor organizations, notably in the form of trade unions have historically been involved in education and training in the workplace. Recently, in the United Kingdom this activity has gained greater credence and importance due to the emergence of trade union learning representatives who are a new category of unpaid lay representation with statutory rights who operate within the workplace. They are part of the present UK government's drive to expand and improve lifelong learning and continuing professional development (CPD) in order to create the new learning society within the UK. In Scotland, a constituent part of the UK with its own distinctive education system, the McCrone Report (2000), particularly its CPD recommendations and the subsequent 21st Century Agreement (Scottish Executive Education Department [SEED], 2001) has added impetus to the role of these learning representatives within the Scottish teaching profession. This article examines how the Educational Institute of Scotland, a professional trade union, which represents the overwhelming majority of teachers in Scotland, has launched a learning representatives initiative with the aim that the representatives work to advise, broker, and facilitate improved CPD opportunities for their colleagues, particularly in relation to Chartered Teacher status (O'Brien and Hunt, 2005)
Shor's quantum factoring algorithm on a photonic chip
Shor's quantum factoring algorithm finds the prime factors of a large number
exponentially faster than any other known method a task that lies at the heart
of modern information security, particularly on the internet. This algorithm
requires a quantum computer a device which harnesses the `massive parallelism'
afforded by quantum superposition and entanglement of quantum bits (or qubits).
We report the demonstration of a compiled version of Shor's algorithm on an
integrated waveguide silica-on-silicon chip that guides four single-photon
qubits through the computation to factor 15.Comment: 2 pages, 1 figur
An XMM-Newton observation of the Narrow Line Seyfert 1 Galaxy, Markarian 896
XMM-Newton observations of the NLS1 Markarian 896 are presented. Over the
2-10 keV band, an iron emission line, close to 6.4 keV, is seen. The line is
just resolved and has an equivalent width of ~170 eV. The broad-band spectrum
is well modelled by a power law slope of gamma ~ 2.03, together with two
blackbody components to fit the soft X-ray excess. Using a more physical
two-temperature Comptonisation model, a good fit is obtained for an input
photon distribution of kT ~ 60eV and Comptonising electron temperatures of ~0.3
and 200 keV. The soft excess cannot be explained purely through the
reprocessing of a hard X-ray continuum by an ionised disc reflector.Comment: 6 pages, 4 figures, accepted by MNRA
Improving wafer-scale Josephson junction resistance variation in superconducting quantum coherent circuits
Quantum bits, or qubits, are an example of coherent circuits envisioned for
next-generation computers and detectors. A robust superconducting qubit with a
coherent lifetime of (100 s) is the transmon: a Josephson junction
functioning as a non-linear inductor shunted with a capacitor to form an
anharmonic oscillator. In a complex device with many such transmons, precise
control over each qubit frequency is often required, and thus variations of the
junction area and tunnel barrier thickness must be sufficiently minimized to
achieve optimal performance while avoiding spectral overlap between neighboring
circuits. Simply transplanting our recipe optimized for single, stand-alone
devices to wafer-scale (producing 64, 1x1 cm dies from a 150 mm wafer)
initially resulted in global drifts in room-temperature tunneling resistance of
30%. Inferring a critical current variation from this
resistance distribution, we present an optimized process developed from a
systematic 38 wafer study that results in 3.5% relative standard deviation
(RSD) in critical current () for 3000 Josephson junctions (both single-junctions and
asymmetric SQUIDs) across an area of 49 cm. Looking within a 1x1 cm moving
window across the substrate gives an estimate of the variation characteristic
of a given qubit chip. Our best process, utilizing ultrasonically assisted
development, uniform ashing, and dynamic oxidation has shown = 1.8% within 1x1 cm, on average,
with a few 1x1 cm areas having 1.0% (equivalent to 0.5%). Such stability would drastically improve the yield of
multi-junction chips with strict critical current requirements.Comment: 10 pages, 4 figures. Revision includes supplementary materia
The Distance to Nova V959 Mon from VLA Imaging
Determining reliable distances to classical novae is a challenging but
crucial step in deriving their ejected masses and explosion energetics. Here we
combine radio expansion measurements from the Karl G. Jansky Very Large Array
with velocities derived from optical spectra to estimate an expansion parallax
for nova V959 Mon, the first nova discovered through its gamma-ray emission. We
spatially resolve the nova at frequencies of 4.5-36.5 GHz in nine different
imaging epochs. The first five epochs cover the expansion of the ejecta from
2012 October to 2013 January, while the final four epochs span 2014 February to
2014 May. These observations correspond to days 126 through 199 and days 615
through 703 after the first detection of the nova. The images clearly show a
non-spherical ejecta geometry. Utilizing ejecta velocities derived from 3D
modelling of optical spectroscopy, the radio expansion implies a distance
between 0.9 +/- 0.2 and 2.2 +/- 0.4 kpc, with a most probable distance of 1.4
+/- 0.4 kpc. This distance implies a gamma-ray luminosity much less than the
prototype gamma-ray-detected nova, V407 Cyg, possibly due to the lack of a red
giant companion in the V959 Mon system. V959 Mon also has a much lower
gamma-ray luminosity than other classical novae detected in gamma-rays to date,
indicating a range of at least a factor of 10 in the gamma-ray luminosities for
these explosions.Comment: 11 pages, 8 figures, 3 tables, submitted to ApJ 2015-01-21, under
revie
Lasers incorporating 2D photonic bandgap mirrors
Semiconductor lasers incorporating a 2D photonic lattice as a one end mirror in a Fabry-Perot cavity are demonstrated. The photonic lattice is a 2D hexagonal close-packed array with a lattice constant of 220 nm. Pulsed threshold currents of 110 mA were observed from a 180 μm laser
Two-dimensional photonic band-gap mirrors at 850 and 980 nm
Summary form only given. Photonic band-gap (PBG) crystals can be fabricated in semiconductor devices through the etching of patterns of holes in the device, resulting in a periodic dielectric structure. One of the more practical uses of photonic crystals in optoelectronic devices is for thin, high-reflectivity mirrors. The use of hexagonal arrays of etched circular holes results in a 2-D photonic band-gap mirror that can be tuned to a specific wavelength by varying the hole radius and the lattice spacing. 2-D mirror characterization is performed by evaluating the light emission from an active waveguide
Spectral evolution and the onset of the X-ray GRB afterglow
Based on light curves from the Swift Burst Analyser, we investigate whether a
`dip' feature commonly seen in the early-time hardness ratios of Swift-XRT data
could arise from the juxtaposition of the decaying prompt emission and rising
afterglow. We are able to model the dip as such a feature, assuming the
afterglow rises as predicted by Sari & Piran (1999). Using this model we
measure the initial bulk Lorentz factor of the fireball. For a sample of 23
GRBs we find a median value of Gamma_0=225, assuming a constant-density
circumburst medium; or Gamma_0=93 if we assume a wind-like medium.Comment: 4 pages, 3 figures. To appear in the proceedings of GRB 2010,
Annapolis November 2010. (AIP Conference proceedings
- …