Smooth pursuit eye movements, attention, and schizophrenia

In previous studies, smooth pursuit eye movements (SPEM) have been shown to be disordered in about 70% of schizophrenics and about 45% of their first-degree relatives. In this report, the role of attention in these eye movements is addressed in three experiments (using as subjects schizophrenics, their first-degree relatives, and normals administered chloral hydrate) that recruit focused attention to the task. These studies show that voluntary attention in the form of inattention, "heedless negligence," or failure to cooperate, is not the specific attentional quality that is disordered in SPEM of schizophrenics and their relatives. Rather, the data both indicate that nonvoluntary attending is specifically disordered in these persons, and implicate a neurophysiological substrate that can be described as a failure of inhibitory, synchronizing integrating systems which may be located in the brain stem.     

A television scanner for the ultracentrifuge. II. Multiple cell operation

The "Optical Multichannel Analyzer" (OMA) is a commercially available instrument that with the absorption optical system of the ultracentrifuge, provides an entire 500 channel intensity profile of a cell in real time. With its own analog-todigital converter, the OMA integrates a selectable number of 32.8 msec scans to provide a time-averaged image in digital form. This paper describes an interface-controller for operation of the OMA with single- and double-sector cells in multi-cell rotors, simulating double-beam measurement required for absorbance determinations. The desired sector is selected by "gating" the intensifier stage of a "Silicon Intensified Target" vidicon (SIT) used as the light detector. The cell location in the rotor and the position of the gate relative to the cell centerline is obtained from a phase-locked loop circuit which divides each rotation of the rotor into 3600 parts independent of rotor speed. (This circuit employed with photo-multiplier scanners would select the gate position for integration of photomultiplier pulses.) From examination of appropriate signals with an oscilloscope, it was verified that gate positions and widths are located with an accuracy of 0.1degree or better and with a precision of +/- 0.1 mus. The light intensity profile for any desired cell can be examined in "real time", even during acceleration of the rotor. Additional circuits employing a 10 MHz crystal clock 1) control the automatic collection of data for all sectors in multicell rotors at digitally selected time intervals, 2) display the rotor speed, and 3) indicate the elapsed time of the experiment. Constructed but not tested are additional circuits for pulsing a laser into the absorption or Rayleigh optical system. The accuracy of the pulsed SIT has been demonstrated by measurement of absorbances of solutions and also by sedimentation equilibrium experiments with myoglobin. The estimated error is 0.003 for absorbances ranging from 0 to 1. The interface-controller operates extremely well, but problems related to the pulsed SIT (optimum gate position relative to the sector opening shape of high-voltage pulse, slight pincushion distortion) require more work.     

Residual fertilizer nitrogen as influenced by timing and nitrogen forms in a silty clay soil under sugarcane in Mauritius

A field study was initiated to investigate the influence of application time on the disposition of 100 kg N ha^–1 applied as¹⁵N-labelled NaNO₃ and (NH₄)₂SO₄ to a silty clay soil (a ustic eutropept) under sugarcane (Saccharum hybrid sp.) in Mauritius. The results showed that the vertical and lateral distribution of residual fertilizer N remaining in the soil 2 years after fertilization was not influenced by the chemical nature of N used nor by the time of application. On account of rapid biological immobilization more than 50% of the residual N in the soil remained in the surface 15-cm layer and less than 30% of fertilizer N had moved laterally more than 30 cm away from the zone of fertilization. There was however more residual fertilizer N in the soil when the N was applied in September (23 kg N ha^–1) than in December (16 kg N ha^–1) because fertilizer N applied during the active sugarcane growth in December was used more efficiently than similar applications in September when growth was slow. The present study provides further evidence to substantiate that N leaching is not of significant concern in soils located in a tropical environment similar to that of Mauritius.     

Shear rate and wall slip velocity functions of polyvinyl chloride melts based on slit die viscometry data

Shear stress versus shear rate and wall shear stress versus slip velocity relations of polymer melts are key material property functions needed in the design of polymer processing equipment. These properties are normally measured using capillary or slit viscometers. The presence of slip greatly complicates the processing of the resulting viscometry data. This paper describes the conversion of the viscometry data of a number of polyvinyl chloride melts through slit dies with different gaps into these two material property functions. The conversion procedure, based on Tikhonov regularization, has the advantage that it is independent of rheological constitutive equation and does not require extrapolation of the experimental data. It also has the ability to cope with the unavoidable noise in the experimental data. Consequently, the property functions thus obtained are likely to be closer to true material properties than those from some of the existing methods. For each of the polyvinyl chloride melts investigated, these properties' functions will be compared with published results and their differences discussed.     

Determination of peak expiratory flow

It is still unknown whether peak expiratory flow (PEF) is determined by "wave speed" flow limitation in the airways. To investigate the influences of airway mechanical properties on PEF, five healthy adults performed maximal forced expiratory effort (MFEE) manoeuvres, in the standard manner and following breathholds at total lung capacity (TLC) of 2 s and 10 s. Oesophageal pressure (Poes) was measured as an index of respiratory effort. Subjects also performed a MFEE following a 10 s breathhold during which intrathoracic pressure was voluntarily raised by a Valsalva manoeuvre, which would increase transmural pressure and cross-sectional area of the extrathoracic airway. Additional MFEEs were performed with the neck fully flexed and extended, to change longitudinal tracheal tension. In separate studies, PEF was measured with a spirometer and with a pneumotachograph. Breathholds at TLC (2 s and 10 s), and neck flexion reduced PEF by a mean of 9.8% (SD 2.9%), 9.6% (SD 1.6%), and 8.7% (SD 2.8%), respectively, when measured with the spirometer. The same pattern of results was seen when measured with the pneumotachograph. These reductions occurred despite similar respiratory effort. Voluntarily raising intrathoracic pressure during a 10 s breathhold did not reverse a fall in PEF. MFEE manoeuvre with neck extension did not result in an increase in PEF, the group mean % changes being -3.0% (SD 5.0%). We conclude that these results do not allow the hypothesis that "wave-speed" (Vws) is reached at PEF to be rejected. A breathhold at TLC could increase airway wall compliance by allowing stress-relaxation of the airway, thus reducing the "Vws" achievable.     

Process optimisation of transfer moulding for electronic packages using artificial neural networks and multiobjective optimisation techniques

Transfer moulding is the most common process for the encapsulation of electronic packages in semiconductor manufacturing. Quality of the moulding is affected by a large number of mould design parameters and process parameters. Currently, the parameters setting is performed by experienced engineers in a trial and error manner and often the optimal setting can not be obtained. In the face of global competition, the current practice is inadequate. In this research, a process optimisation system for transfer moulding of electronic packages is described which involves design of experiments (DOE) techniques, artificial neural networks (ANNs), multiple regression analysis and the minimax method. The system is aimed to determine the optimal mould design parameters and process parameter settings of transfer moulding of electronic packages for multiobjective problem. Implementation of the optimisation system has demonstrated that the time for the determination of optimal mould design parameters and process parameters setting can be greatly reduced and the parameters setting recommended by the system can contribute to the good quality of moulded packages without relying on experienced engineers.     

Interactions between iron deficiency and lead poisoning: epidemiology and pathogenesis

Iron deficiency and lead poisoning are common among infants and children in many parts of the world, and often these two problems are associated. Both conditions are known to cause anemia and appear to produce a more severe form of anemia when in combination. Although the nature of their relationship is not completely elucidated, characterization of a common iron-lead transporter and epidemiological studies among children strongly suggest that iron deficiency may increase susceptibility to lead poisoning. Recent human studies suggest that high iron intake and sufficient iron stores may reduce the risk of lead poisoning. Future clinical trials are necessary to assess the effect of iron supplementation in the public health prevention of lead poisoning and the kinetics of lead in the body.     

The actuation behavior and stability of p‐toluene sulfonate doped polypyrrole films formed at different deposition current densities

Free‐standing films of polypyrrole doped with p‐toluene sulfonate (PPy/pTS) were electropolymerized galvanostatically at different deposition current densities and their electrochemomechanical deformation (ECMD) properties were measured in situ during cyclic voltammetry experiments. It was found that films exhibiting a higher cation‐driven actuation strain were generated when a lower current density was used in electropolymerization, which also led to an increase in PPy conductivity and doping level. A decrease in cation‐driven strain with time was observed in all cases due to a loss of pTS anions from the films. Raman, FTIR, and elemental analyses were used to characterize the films grown at different deposition current densities and no sign of excessive overoxidation was found. SEM images revealed that the morphology of the films was affected by the current density during electropolymerization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The baby and the bathwater: research methods in construction management

This note is written in response to Seymour, D., Crook, D. and Rooke, J. (1997) Construction Management and Economics, 15 (1), 117-19. We argue against their narrow focus on the interpretative approach. Also, Seymour et al. are incorrect in implying that the ‘rationalist approach’ is necessarily quantitative. Our contention is that the choice of research approach in construction management depends on the nature of the problem. However, whatever choice of approach is adopted, it is important that the problem and associated key concepts are defined clearly and that the methods used, underlying assumptions and limitations are transparent and defensible. It is difficult to argue in favour of any single approach based purely on epistemological grounds as what constitutes knowledge is still an unsolved philosophical issue. Since construction management is a practical subject, we suggest that the choice of approach should be a pragmatic one: the approach that is likely to generate practical solutions should be adopted. Seymour et al.'s suggestion serves only to limit our choice of research tools. Furthermore, a lot of the research issues in construction management are practical problems which involve generalization of experience and formulation of hypothesis that can generate empirically testable implications. For problems of this nature, testability of hypothesis and reproducibility of results are important, and the naturalist approach (which is labelled ‘rationalist paradigm’ in Seymour et al.) of discovering causal relationship is more likely to produce general practical solutions. However, this does not deny the value of the interpretative approach, as it may be more suitable for certain types of problem. Moreover, in practice, an understanding of human behaviour ‘from within’ often provides useful insights for formulation of empirically testable hypotheses, despite the philosophical incompatibility of the interpretative and naturalist approaches.     

A real-time risk control and monitoring system for incident handling in wine storage

Due to the fact that wine is highly sensitive to storage conditions such as temperature and humidity, it is a challenging task for a regional distribution hub to provide reliable wine storage facilities for maintaining wine quality during storage. This is especially true when an incident occurs unexpectedly that violates the criteria of suitable storage conditions. Improper incident handling and storage conditions may cause damage to the taste of wine, resulting in depreciation of the wine’s value. Therefore, controlling and monitoring risk in real-time during wine storage is critical to providing a quick response to prevent the wine quality from deterioration. In this paper, a RFID-based risk control and monitoring system (RCMS), which integrates radio frequency identification (RFID) technology and case-based reasoning (CBR), is proposed for monitoring real-time physical storage conditions and for formulating an immediate action plan for handling incidents. In the retrieval process of the CBR engine, genetic algorithms (GA) are applied to search for case clusters by considering the best combination of multi-dimensional parameters. With the help of RCMS, a shortlist of critical control actions, possible causes of incidents and corresponding actions can be generated to reduce the risk of deteriorating wine quality and possible compensation costs being incurred, while customer satisfaction can be maintained.