This paper investigates various aspects of the links between exporting and productivity for a large sample of firms in the United Kingdom. We find evidence to support the proposition that sunk costs are important. Self selection takes place, with larger and more productive firms entering export markets, and firms have to become more productive in order to enter. Industry characteristics also af...

The harmonic map heat flow is a model for nematic liquid crystals and also has origins in geometry. We present an analysis of the asymptotic behaviour of singularities arising in this flow for a special class of solutions which generalises a known (radially symmetric) reduction. Specifically, the rate at which blowup occurs is investigated in settings with certain symmetries using the method of...

Improving digital images of carbon nanotubes is an important task for characterizing nanotube structures in Nanoscience and Nanotechnology. A two-step algorithm is proposed for enhancing the information of carbon nanotube images, which are obtained by a scanning electron microscopy. In the first step it is carried out the characterization of the intensity profile of the nanotube by using the fi...

Background: Nowadays, image de-noising plays a very important role in medical analysis applications and pre-processing step. Many filters were designed for image processing, assuming a specific noise distribution, so the images which are acquired by different medical imaging modalities must be out of the noise. Objectives: This study has focused on the sequence filters which are selected ...

Spectral shaping of an all-fiber torsional acousto-optic (AO) tunable filter is studied. The technique is based on the axial modulation of AO coupling strength along a highly birefringent optical fiber, which is achieved by tailoring the outer diameter of the fiber along its propagation axis. Two kinds of filter spectral shaping schemes-Gaussian apodization and matched filtering with triple res...

1) Introduction One of the most serious problems that limits the capacity of CDMA systems is the multi-access interference (MAI), caused by the cross-correlation between spreading sequences of active users. The undesirable impact of the MAI becomes more remarkable and sometimes disastrous when the number of active users becomes large or when the power level of certain users is significantly hig...

In this paper, a multiscale line filter is proposed which is integrated with phase congruency to detect the network of vessels in retinal images. The proposed line filter can reduces the influence of step edges compared with Gaussian matched filter, and the post process use the phase congruency demonstrated a substantial improvement in detecting vessels which have low contrast or minor width. T...

The sensitivity of gravitational wave searches is reduced by the presence non-Gaussian noise in detector data. These non-Gaussianities often match well with template waveforms used matched filter searches, and require signal-consistency tests to distinguish them from astrophysical signals. However, empirically tuning these for maximum efficacy time consuming limits complexity tests. In this wor...

Searches for binary inspiral signals in data collected by interferometric gravitational wave detectors utilize matched filtering techniques. Although matched filtering is optimal in the case of stationary Gaussian noise, data from real detectors often contains “glitches” and episodes of excess noise which cause filter outputs to ring strongly. We review the standard χ statistic which is used to...