Statistical Gain Characteristics of Radar Antennas at Very Short Fresnel Zone Distances

This paper extends the existing knowledge of statistical gain characteristics of radar antennas to include very short Fresnel zone ranges. The data indicate that the median gain and the standard deviation remain essentially the same as those observed in the Fraunhofer zone until the range begins to approach the physical dimensions of the antenna; however, as the range is decreased closer toward physical contact, the median gain decreases and the standard deviation increases. The site-effects tests which were conducted in the Fresnel zone indicate that the geometrical configuration of an object, the position of an object, and the clear-site median gain of an antenna help to determine the magnitude of the effects of objects on the clear-site statistical gain characteristics.     

Potential antitumor agents. 19. Multiply substituted 4'-(9-acridinylamino)methanesulfonanilides

A series of 42 multiply substituted 4'-(9-acridinylamino)methanesulfonanilides has been prepared and evaluated in the L1210 system. In addition to biologic activity changes resulting from altered agent lipophilic-hydrophilic balance variants containing both acridine 4-CH3 and 3-NH2, NHCOCH3 or NO2 substituents have reduced activity. Variants 3,6-disubstituted, using functions of differing electronic character, have depressed activity, suggesting that there is limited site bulk tolerance. Asymmetric 3,5-disubstitution should then be the preferred pattern; the 3-ND-5CH-3'-OCH variant is the most dose potent (optimum dose qd 1-5, 1.25 mg/kg/day) of the high activity agents of this series so far prepared.     

Controlled ultrasound tissue erosion

The ability of ultrasound to produce highly controlled tissue erosion was investigated. This study is motivated by the need to develop a noninvasive procedure to perforate the neonatal atrial septum as the first step in treatment of hypoplastic left heart syndrome. A total of 232 holes were generated in 40 pieces of excised porcine atrial wall by a 788 kHz single-element transducer. The effects of various parameters [e.g., pulse repetition frequency (PRF), pulse duration (PD), and gas content of liquid] on the erosion rate and energy efficiency were explored. An Isppa of 9000 W/cm2, PDs of 3, 6, 12, and 24 cycles; PRFs between 1.34 kHz and 66.7 kHz; and gas saturation of 40-55% and 79-85% were used. The results show that very short pulses delivered at certain PRFs could maximize the erosion rate and energy efficiency. We show that well-defined perforations can be precisely located in the atrial wall through the controlled ultrasound tissue erosion (CUTE) process. A preliminary in vivo experiment was conducted on a canine subject, and the atrial septum was perforated using CUTE.     

Dose-reducing strategies in combination offers substantial potential benefits to females requiring X-ray examination

This work, using an adult anthropomorphic phantom, aimed to establish an optimised technique for ladies of child-bearing age undergoing antero-posterior (AP) pelvis and AP and lateral lumbar spine examinations. Phase one of the work involved introducing the following dose-reducing measures individually: increased kVp, increased focus-film distances, a carbon fibre cassette, a faster film/screen combination. The second phase established an optimised technique based on a combination of the parameters listed above. Radiation dose was measured using thermoluminescent dosimeters and image quality was evaluated using anatomical criteria. All dose-reducing methods were compared with a standard technique, currently being used in a Dublin hospital. The results demonstrated that the optimised procedure reduced effective dose by 77, 62 and 66% for AP pelvis and AP and lateral lumbar spine respectively (p < 0.05) compared with the standard technique, with no significant changes in image quality. Dose-reducing measures used in combination offer substantial potential for optimisation of radiological procedures.     

Statistical Prediction Model for EMC. Analysis of Out-of-Band Phased Array Antennas

A statistical model was developed for predicting and describing the out-of-band pattern characteristics of phased arrays containing ferrite phase shifters. Statistical analysis techniques are necessary because experimental investigations showed that the propagation of higher-order modes at out-of-band frequencies cause phased arrays containing ferrite phase shifters not only to respond differently at out-of-band frequencies but also to exhibit random behavior. Equations were derived which relate the out-of-band pattern scanning properties, relative gain levels, median gain, and standard deviation to the in-band scan angle and the ferrite phase shifter statistics. Computer algorithms were written to both compute and graphically display the out-of-band antenna patterns. Experimentally derived phase-shift data were used as inputs to the model. The results of these investigations show that statistical analysis techniques are potentially very useful in an EMC context for characterizing out-of-band responses of phased array antennas     

Modeling and reconfiguring intelligent holonic manufacturing systems with Internet-based mobile agents

A holonic manufacturing system (HMS) represents a new breed of intelligent shop-floor management technology for the production of artifacts that satisfy unique customer requirements. Flexibility is an essential characteristic of the HMS in order to manufacture high-variety low-volume artifacts. Autonomous smart entities called holons interact, via cooperation protocols, within a HMS to support the runtime reconfiguration demanded by such an agile shop-floor. This paper presents a framework to model and reconfigure, in real-time, the holons' abstract behavioral specifications through the application of Internet-based mobile agents. A tool is also described to convert these specifications into a corresponding implementation model (based on the IEC 61499 function block architecture) that holons can execute across an open network of controller devices.     

Microbubble-enhanced cavitation for noninvasive ultrasound surgery

Experiments were conducted to explore the potential of stabilized microbubbles for aiding tissue ablation during ultrasound therapy. Surgically exteriorized canine kidneys were irradiated in situ using single exposures of focused ultrasound. In each experiment, tip to eight separate exposures were placed in the left kidney. The right kidney was then similarly exposed, but while an ultrasound contrast agent was continually infused. Kidneys were sectioned and examined for gross observable tissue damage. Tissue damage was produced more frequently, by lower intensity and shorter duration exposures, in kidneys irradiated with the contrast agent present. Using 250-ms exposures, the minimum intensity that produced damage was lower in kidneys with microbubbles than those without (controls) in 10 of 11 (91%) animals. In a separate study using /spl sim/3200 W/cm/sup 2/ exposures, the minimum duration that produced damage was shorter after microbubbles were introduced in 11 of 12 (92%) animals. With microbubbles, gross observable tissue damage was produced with exposure intensity /spl ges//spl sim/800 W/cm/sup 2/ and exposure duration /spl ges/10 /spl mu/s. The overall intensity and duration tissue damage thresholds were reduced by /spl sim/2/spl times/ and /spl sim/100/spl times/, respectively. Results indicate that acoustic cavitation is a primary damage mechanism. Lowering in vivo tissue damage thresholds with stabilized microbubbles acting as cavitation nuclei may make acoustic cavitation a more predictable, and thus practical, mechanism for noninvasive ultrasound surgery.     

Electroporation of single cells and tissues with an electrolyte-filled capillary

We show how an electrolyte-filled capillary (EFC) coupled to a high-voltage power supply can be used as a versatile electroporation tool for the delivery of dyes, drugs, and biomolecules to the cytoplasm of single cells and cells in tissues. A large-voltage pulse applied across the EFC (fused silica, 30 cm long, 375-microm o.d., 30-microm i.d.) gives rise to a small electric field outside the terminus of the EFC, which causes pore formation in cell membranes and induces an electroosmotic flow of electrolyte. When the EFC contains cell-loading agents, then the electroosmotic flow delivers the agents at the site of pore formation. The combination of pore formation and delivery enables loading of materials into the cytoplasm. By patch-clamp and fluorescence microscopy, formation of pores was observed at estimated transmembrane voltages of <85 mV with half-maximum values around 206 mV. The electroporation protocol was demonstrated by introduction of fluorogenic dyes into single NG108-15 cells, cellular processes, and small populations of cells in organotypic hippocampal cultures. Preliminary results are shown in which this protocol was employed for in vivo electroporation of ventral mesencephalon in rat brains. The technique was also used to access organelle-based detection systems inside cells. As a demonstration, 1,4,5-inositoltriphosphate was added to the electrolyte and detected by intracellular organelles in electroporated cells.     

Modelling consumer behavioural intentions towards food with implications for marketing quality low-input and organic food

The paper is based upon a study of European consumers’ behavioural intentions towards food purchase for four food products in six countries. The analytical method employs a structural equation model within the marketing framework of the quality-value-satisfaction-loyalty (QVSL) paradigm. The paper focuses on country-based versions of the model. The sample consists of 5072 regular consumers of the four products and includes consumers of conventional foods, quality low-input foods and organic foods. The model establishes the determinants of behavioural intentions towards foods that consumers purchase regularly. In addition, it provides the facility to examine the potential of quality low-input foods and organic foods. The results reveal the contribution of satisfaction, perceived value and perceived quality to improving behavioural intentions and how these constructs could contribute to the improved effectiveness of marketing conventional, quality low-input and organic foods to existing and potential consumers.     

Iron deficiency – is there a role for the food industry?

Iron deficiency is one of the most common nutritional deficiencies worldwide, in both developing and developed regions. Although the aetiology of iron deficiency and resultant anaemia may be multifaceted, inadequate iron intakes, poor iron absorption and disease status may all be underlying causes. Whilst nutrition and supplement interventions may go some way towards improving iron status in ‘at‐risk’ populations, their efficacy can be questioned. New approaches, including food‐based strategies, may be an alternative means of improving the iron status and health of the public sectors. Economically, food‐based approaches may also be more cost‐effective than iron supplements. This paper aims to discuss how the food industry may play an important role in improving the iron status of public sectors, helping to prevent iron deficiency and need for tablet‐based iron supplements.