Core–periphery dynamics in the Portland, Oregon, region: 1982–2006

The relative strength of positive and negative spillovers of urban development is a long-standing and contested issue in regional and development economics, and the search for spread and backwash effects of development in urban core economies goes back at least 50 years. Using data from IMPLAN and the Bureau of Economic Analysis to develop multiregional input–output models, we developed estimates of core–periphery economic interdependence (sales and purchases of goods and services and commuting of workers between the core and the periphery) of the Portland, Oregon, region for 1982 and 2006. We explored whether the changing flows of sales and purchases, spillovers and commuting between 1982 and 2006 suggested a dominance of spread effects or backwash effects. We found increased commuting between periphery and core, decreased core–periphery transactions, and smaller core-to-periphery spillovers and periphery-to-core spillovers in both goods and services. Our findings do not point to a clear dominance of spread or backwash effects. Results showing smaller core-to-periphery and periphery-to-core multipliers/spillovers suggest that spread effects related to trade in goods and services weakened between 1982 and 2006. Our findings of increased commuting are consistent with enhanced spread effects in labor markets.     

Charge Density Influences C1 Domain Ligand Affinity and Membrane Interactions

The C1 domain, which represents the recognition motif on protein kinase C for the lipophilic second messenger diacylglycerol and its ultrapotent analogues, the phorbol esters, has emerged as a promising therapeutic target for cancer and other indications. Potential target selectivity is markedly enhanced both because binding reflects ternary complex formation between the ligand, C1 domain, and phospholipid, and because binding drives membrane insertion of the C1 domain, permitting aspects of the C1 domain surface outside the binding site, per se, to influence binding energetics. Here, focusing on charged residues identified in atypical C1 domains which contribute to their loss of ligand binding activity, we showed that increasing charge along the rim of the binding cleft of the protein kinase C δ C1 b domain raises the requirement for anionic phospholipids. Correspondingly, it shifts the selectivity of C1 domain translocation to the plasma membrane, which is more negatively charged than internal membranes. This change in localization is most pronounced in the case of more hydrophilic ligands, which provide weaker membrane stabilization than do the more hydrophobic ligands and thus contributes an element to the structure–activity relations for C1 domain ligands. Coexpressing pairs of C1‐containing constructs with differing charges each expressing a distinct fluorescent tag provided a powerful tool to demonstrate the effect of increasing charge in the C1 domain.     

A brief review of hardware for catheter tracking in magnetic resonance imaging.

Magnetic resonance imaging (MRI) has traditionally been used exclusively in a role for patient diagnosis. However, it is unlikely that this role is sufficient for its continued prominence in medical imaging. Instead, the more ambitious role in diagnosis and also therapy/intervention will occur as demand for minimally invasive procedures increases. Fortunately, with recent improvement in technical specifications and creative pulse sequence design, MRI systems can now provide high quality near-real-time images that facilitate a variety of image-guided procedures, many based around delivery via catheters. While X-ray opacity is not available as a means for detecting the progression of the catheter in MRI systems today, a variety of novel hardware devices have been designed and used for MRI catheter tracking. This report provides a brief review of some fundamental methods for catheter tracking in MRI.     

Comparison of on-line partial discharge detection methods for HV cable joints

The capacitive coupler, acoustic emission (AE) sensor and radio frequency current transducer (RFCT) have been used to detect partial discharge (PD) activity within a 132 kV prefabricated cable joint containing a known defect. Although each of the three methods has been applied individually under different situations, a comprehensive investigation and comparison of these three methods has not yet been made. Results obtained were compared to measurements made using the conventional electrical detection method. The quantification of the capacitive coupler measured signal in mV with a discharge apparent quantity in pC has been investigated and an on-line quantification method proposed. The capacitive coupler has good detection sensitivity and PD location can be realised by studying the time of Right between signals from two sensors. The difference in pulse shape, spectrum and time of flight between an internal discharge and external interference has been investigated. The AE approach has the advantage of being free from electrical interference. However, investigation indicated that AE signals were significantly attenuated within the cable joint. RFCTs were used to detect the discharge current flowing through the cable sheath. Where the detection sensitivity was low, a wavelet de-noising method was applied to process the RFCT signals and proved to tie effective in increasing the measurement signal to noise ratio.     

A novel method for determining calibration and behavior of PVDF ultrasonic hydrophone probes in the frequency range up to 100 MHz

A new calibration technique for PVDF ultrasonic hydrophone probes is described. Current implementation of the technique allows determination of hydrophone frequency response between 2 and 100 MHz and is based on the comparison of theoretically predicted and experimentally determined pressure-time waveforms produced by a focused, circular source. The simulation model was derived from the time domain algorithm that solves the non linear KZK (Khokhlov-Zabolotskaya-Kuznetsov) equation describing acoustic wave propagation. The calibration technique data were experimentally verified using independent calibration procedures in the frequency range from 2 to 40 MHz using a combined time delay spectrometry and reciprocity approach or calibration data provided by the National Physical Laboratory (NPL), UK. The results of verification indicated good agreement between the results obtained using KZK and the above-mentioned independent calibration techniques from 2 to 40 MHz, with the maximum discrepancy of 18% at 30 MHz. The frequency responses obtained using different hydrophone designs, including several membrane and needle probes, are presented, and it is shown that the technique developed provides a desirable tool for independent verification of primary calibration techniques such as those based on optical interferometry. Fundamental limitations of the presented calibration method are also examined.     

Obliquity factor for radiation from solid-state laser

The radiated field consists of forward radiation at an angle ? and backward radiation at ? ? ? reflected from the dielectric-air interface into an additional component of field at angle ?. The total radiation contains a factor that simplifies into an expression recently obtained by more sophisticated methods, and which is here interpreted as the Huygens obliquity factor for the arrangement. A small correction to the expression is also obtained.     

Polarisation degeneracy in bent optical fibre

It is shown that the previously established polarisation degeneracy for propagation round a bent optical fibre obtains only in the limit of equality of core and cladding permittivities. Unequal permittivities produce differential attenuations in the components parallel to and perpendicular to the plane of the bend.     

Further results on the experimental evaluation of iterative learning control algorithms for non-minimum phase plants

This paper builds on previous work in which simple structure ILC algorithms were experimentally evaluated on a non-minimum phase plant. The phase-lead update law, the most promising of those implemented, is examined using an established performance criterion. The use of a forgetting factor is found to overcome the problem of instability, but at the expense of increased final error. This is verified through experimentation. The phase-lead algorithm is improved using additional phase-leads to remove the instability and improve convergence and final error. This technique is generalized to produce an optimization routine which leads to greatly improved results. The learning law utilizing the plant adjoint is found to fit naturally into this framework and practical results are presented to compare their respective performance. This algorithm, which requires a model of the plant, is reformulated into one which does not. Results are presented using this technique and practical guidelines are produced and tested to improve its performance. A simple method of increasing the learning at higher frequencies is proposed and practical limitations are addressed and verified experimentally. All the algorithms tested are compared with respect to their performance, practicality and robustness.