Discounts on fruit and vegetables combined with a space management intervention increased sales in supermarkets.

BACKGROUND/OBJECTIVES: To examine the effects of two interventions on consumer purchases of fruits and vegetables (F&V) on the Danish island of Bornholm: a 20% discount on F&V combined with improved shelf-space allocation, and improved shelf-space allocation alone. SUBJECTS/METHODS: A space management intervention to promote F&V sales was performed in two large discount supermarkets on Bornholm in Denmark for 3 months (September-November 2012). In addition, a 20% discount on F&V was introduced for 3 months in one of the supermarkets ('space + price'). The effect was evaluated using sales data from the two intervention supermarkets and three control supermarkets from the same supermarket chain but in Odsherred, Denmark (control area). Both the effect on sales of fresh F&V and potential unhealthy substitution effects were evaluated using multi-level regression analyses. RESULTS: During the price intervention period, the index number for sales of fresh vegetables increased by 22.2% (P=0.001) in the 'space + price' intervention supermarket compared with the control supermarkets. Furthermore, the index number for the sale of organic fresh fruit and vegetables increased by 12.1% (P=0.04) and the sale of the total amount of fruit and vegetables (fresh, frozen, dried and canned) increased by 15.3% (P=0.01) compared with the control supermarkets. In the 'space only' intervention supermarket no significant increase in the sale of fruit and vegetables was found. No unhealthy substitution effects were found. CONCLUSIONS: In conclusion, a 20% price reduction on F&V significantly increased sales of F&V. The effect was most pronounced on vegetables and no negative/unhealthy substitution effects were found.

Distribution of human Oesophagostomum bifurcum, hookworm and Strongyloides stercoralis infections in northern Ghana.

A cross-sectional study was carried out in 216 randomly selected, representative rural villages in the northeastern part of Ghana from March 1995 to May 1998. Inhabitants of randomly selected households, stratified by age and gender, were included. The geographical position of villages was recorded with a global positioning system (GPS). The prevalence of Oesophagostomum, hookworm and Strongyloides stercoralis infections in a study population of 20250 people was determined by microscopic examination of larvae in stool cultures. The overall prevalence was 10.2, 50.6 and 11.6% for the three nematodes, respectively. Hookworm infections were seen in all but one (99.5%) and S. stercoralis in 88.4% of the 216 villages, while Oesophagostomum infections were found to be common in a limited area with prevalences varying from 0 to 75%. An association was found between Oesophagostomum and hookworm infection, both at the individual and at the village level. Spatial analysis of the prevalence data indicated that the endemic area is relatively clearly demarcated to the south of the study area.

Initiation of multi-leaf collimator conformal radiation therapy.

Clinical studies have been initiated in conformal radiotherapy using a computer controlled multi-leaf collimator. Quantitative dosimetry and treatment planning studies comparing field shaping by lead alloy blocks and the multi-leaf collimator demonstrate the clinical acceptability of the multi-leaf collimator. Sixteen patients with tumors in multiple sites have received some part of their treatments with both blocking systems. Studies of dosimetry and field shaping show that the multi-leaf collimator produces clinically acceptable blocking for most field shapes and disease sites. The 80-20% penumbra was characterized for a wide range of shaped beams. For straight edges perpendicular to the leaf travel, the penumbra of measured dose distributions from the multi-leaf collimator is equal to conventional divergent blocking. When the multi-leaf collimator leaves approach a contour at an angle, the penumbra increases. At forty-five degrees, the maximum angle of approach, the penumbra is approximately 4 mm wider than that for divergent blocks. Three-dimensional treatment planning demonstrates that equivalent dose distributions can be obtained from the two field shaping systems. The multi-leaf collimator can be used effectively and efficiently to treat a variety of disease sites. Its optimal utility may be in treating complex fields--five or more shaped coplanar or non-coplanar beams. It is well suited for conformal therapy applications.

Temperature cycler evaluation: what do you need to know?

Which of the 20 different, commercially available, temperature cyclers adequately fulfill all functional requirements? How can an investigator analyze instrument function? This report describes in detail, for the first time, the characteristics of Ericomp temperature cyclers. The data show that the temperature uniformity, accuracy and maximum overshoot is +/- 0.34 degree C, less than 0.5 degree C and 0.17 degree C, respectively. Cycling temperature reproducibility is 0.1%, and cycling time reproducibility is 0.4%. These data compare very favourably to published data describing other temperature cyclers. The techniques used to obtain these data serve as a model for evaluating instruments for well-to-well uniformity, temperature accuracy and within-run reproducibility.

Effect of small amounts of 131I on 99mTc detection by the scintillation camera.

A patient who had recently received a therapeutic dose of Na131I showed no 99mTc activity on the scintillation camera when a pertechnetate brain scan was attempted. Subsequent experiments showed that, when even small amounts of 131I are present in the field of view of a scintillation camera equipped with a collimator designed for low-energy photons, counting rates from 99mTc are markedly affected.

Technetium-99m stannous phytate as an imaging agent for lymph nodes.

This report describes preliminary results using technetium-99m stannous phytate as a lymph-node imaging agent in animals. After the subcutaneous administration there is good visualization of the draining nodes, best obtained 2-4 hr from the time of injection. There is also visualization of the liver, spleen, kidneys, and bladder. This agent appears suitable for lymph-node imaging in areas where the extranodal concentration does not interfere.

Calculation of the dose in the build-up region for high energy photon beam. Treatment planning when beam spoilers are employed.

Recoil electrons from a polystyrene sheet (beam spoiler) placed in a photon beam were used to modulate the dose in the build-up region. The effects of the beam spoiler on the dosimetry in simple phantoms were studied for both 6 MV and 15 MV photon beams at 100 cm source-to-surface distance (SSD) as a function of (1) the thickness of the spoiler, (2) the spoiler-to-surface distance (SD) and (3) the field size. A radiotherapy treatment planning (RTP) algorithm was used that employs pencil beam dose deposition kernels to evaluate the three-dimensional (3D) dose distribution due to photons and electrons in the build-up region. To determine the energy deposition kernels for the recoil electrons emanating from the spoiler, their energy spectrum needs to be known. Monte Carlo simulations were performed to derive the spectrum of electrons from the beam spoiler. The recoil electron spectrum was found to be nearly independent of field size, SD, and spoiler thickness. The pencil beam energy deposition kernel was calculated for the recoil electrons from the spoiler and inserted in the treatment planning algorithm. The dose calculation algorithm permits merging the photon and recoil electron dose components. In all cases the calculation agrees to within 3% of the measured results.

Practice of 3-dimensional treatment planning at the Fox Chase Cancer Center, University of Pennsylvania.

The use of 3-dimensional (3-D) dose distributions and dose-volume histograms in radiation therapy treatment planning is illustrated on a patient with a head and neck tumor. The patient was immobilized in a rectangular tissue compensation bolus box. The treatment was planned with a 14 MeV D-T derived fast neutron therapy beam. The isodose distributions and the dose-volume histograms at multiple adjacent levels are used to evaluate the adequacy of coverage of target volumes and the doses to the normal tissues. Such dose-volume histograms are useful and practical in summarizing the dose distribution throughout the irradiated volume, assessing the degree of uniformity of the dose distribution within the target volume, quantifying the amount of normal tissue irradiated, and evaluating rival treatment plans for both particle and nonparticle beams.

Tolerance of the human liver to prolonged normothermic ischemia. A biological study of 20 patients submitted to extensive hepatectomy.

To evaluate the biological tolerance of the human liver to prolonged warm ischemia, two groups of extensive hepatic resection for tumor were compared. Group 1 (11 patients) performed with short hepatic inflow occlusion (7 [mean] +/- 2 [SEM] minutes), and group 2 (nine patients) operated with use of complete hepatic vascular exclusion and prolonged warm liver ischemia (38 [mean] +/- 5 [SEM] minutes). Comparison of biological values, such as transaminase, bilirubin, total protein, albumin, and fibrinogen levels, the platelet count, prothrombin complex, and proaccelerin level, did not show statistically significant differences between the two groups. Therefore, the hepatic warm ischemia period may be, if needed, safely extended beyond the classical 15 minutes. It lasted 65 minutes in one case without adverse effect. These clinical observations parallel recent experimental work and should destroy the myth of the high sensitivity of the liver to warm ischemia.

The effect of antibiotic- and hydrocortisone-containing ointments in preventing secondary infections in guinea worm disease.

A randomized, single-blind, controlled study comparing the efficacy of an ointment containing two antibiotics, one containing one antibiotic plus hydrocortisone, and no treatment in reducing secondary infections in patients with patent Guinea worm was undertaken in the northern region of Ghana. Seventy-seven patients were included. Time to complete healing was significantly shorter in the treatment groups compared with the controls (P = 0.044 and P = 0.003, respectively). Secondary infections occurred more often in the controls (P = 0.00014). Ointments containing antibiotics are recommended for application at the early stage of patent Guinea worm infection.

Immunoepidemiology of Dracunculus medinensis infections I. Antibody responses in relation to infection status.

The specific serum IgG1, IgG4, and IgE responses to Dracunculus medinensis and the level of total IgE of individuals living in a highly endemic area of northern Ghana were measured by ELISA. Sera were obtained in the high transmission season from individuals with prepatent, patent, or postpatent infection as well as from individuals from the same endemic area who claimed to have never had a patent infection (i.e., endemic normal individuals). Individuals with prepatent or postpatent infections responded with a significantly lower mean level of specific IgG1 and IgG4 compared with individuals with a patent infection, and with a significantly higher mean level of specific IgG1 and IgG4 compared with endemic normal individuals. For specific IgE, no differences were found in the mean antibody level between the infection status categories. Individuals with a patent infection had a significantly lower mean serum level of total IgE compared with prepatent, postpatent, and endemic normal individuals. Endemic normal individuals had the highest mean level of total IgE. Furthermore, in all clinical categories, high responders for specific IgG1 and IgG4 generally had low levels of total IgE, whereas low responders for specific IgG1 and IgG4 generally had high levels of total IgE. A similar dichotomy, although less distinct, was observed between specific IgG1 and IgG4 on the one hand and specific IgE on the other. Thus, similar to what has been suggested for schistosomiasis and lymphatic filariasis, the relationship between the IgG subclasses and IgE appears to play a role in, or at least to reflect, a mechanism for protective immunity in dracunculiasis.

Immunoepidemiology of Dracunculus medinensis infections II. Variation in antibody responses in relation to transmission season and patency.

The serum antibody responses (specific IgG1, IgG4, and IgE, and total IgE) to Dracunculus medinensis infection in humans from a highly endemic area of northern Ghana were examined regularly by ELISA over a period of one year in cohorts of individuals who developed a patent D. medinensis infection during the study period (actively infected category), or who claimed to have never had a patent infection (endemic normal category). The results were analyzed in relation to seasonality and time of patency of infection. For individuals in the actively infected category, a clear seasonal variation in the mean levels of specific IgG1 and IgG4 was found, with the highest levels late in the dry season and early in the rainy season, when transmission is high, and the lowest levels late in the rainy season and early in the dry season. Endemic normal individuals responded with low and fluctuating levels of specific IgG1 and with low and nonfluctuating levels of specific IgG4. For specific and total IgE, no seasonal variation was observed in any of the two infection status categories. In relation to time of patency of infection (only involving the category of actively infected individuals), the mean levels of specific IgG1 and IgG4 increased from two months before patency of infection, peaked during patency, and then gradually decreased for four months until a constant level was reached. No significant fluctuations in the levels of specific and total IgE were observed in relation to time of patency. The present study thus showed extensive variation in levels of D. medinensis-specific IgG1 and IgG4 (but not IgE) over time. Seasonal variations in antibody responses may also occur in other helminth infections, especially those with seasonal transmission, and these should be taken into consideration when interpreting the results of immunologic studies.

Computer generated scatter dose distributions for 6-MV radiotherapy photon beams.

The time required for accurate computer dose distributions is of major concern in radiation therapy. Isodose distributions were obtained by calculating the primary and scatter radiation reaching a point. A description of the primary dose distribution, especially at the edge of the beam, requires the calculation of the dose on a finely spaced grid. However, the scatter dose distributions can be described on a much coarser grid. The primary and scatter dose distribution calculations were separated into two computer subroutines which permitted choosing the appropriate grid spacing for each dose component. A more rational partition of the computing time for the primary and scatter dose was obtained. In addition, the separation of the calculation of the scatter dose from the total dose allows one to examine the calculated scatter dose distribution as the radial and angular increments used in the Clarkson-Cunningham summation are varied. Accurate scatter dose distributions were generated with a tenfold time reduction by optimization of grid spacing and radial and angular increments.

Extraction of the photon spectra from measured beam parameters.

Knowledge of the photon spectrum of a radiotherapy beam is often needed for three-dimensional (3-D) dose calculations using Monte Carlo methods and/or algorithms employing energy deposition kernels. Direct measurement of the x-ray energy fluence spectrum is not feasible for the high-energy photon beams used clinically. In this paper, the spectrum is extracted from basic beam data that are readily obtained for a clinical beam. We describe the photon spectrum using just two parameters. One parameter, which determines the high-energy part of the spectrum, is obtained using the measured dose in the buildup region for a small field, where electron contamination of the beam can be neglected. The other parameter is extracted from the photon beam attenuation in water. The results compare favorably to spectra generated from Monte Carlo simulations.

Theoretical considerations of effects of x-ray film-screen characteristics on threshold detectability of small low-contrast objects.

An expression is derived for visual contrast of a radiographed small object that takes into account the proportion of scattered radiation as well as the shape of the sensitometric curve of the film-screen combination. Based on this expression for visual contrast applied to two different film-screen systems, predictions are made for threshold perceptability of low-contrast objects radiographed with the two imaging systems in the presence of scattered radiation and at different points on the sensitometric curves.

Measurements of the effects of x-ray film--screen characteristics on threshold detectability of small low-contrast objects.

Experiments were performed to test threshold detectability of a small nylon bead radiographed with two different image receptors and under different scattering conditions. In another paper, the present authors predicted, on theoretical grounds, the visibility of small low-contrast objects radiographed in the presence of scattered radiation. The experiments discussed in this paper tested these predictions using an observer-testing method resulting in Receiver Operating Characteristic (ROC) curves. In addition to the rigidly controlled experiments from which the ROC curves were obtained, another experiment was performed in which a human phantom was used and the radiographs rated as to the visibility of small artificial lesions. By and large, the experiments confirmed the predictions made from the theoretical analysis, using visual contrast as a measure of detectability.

Static multileaf collimator for fast-neutron therapy.

This paper describes a multileaf collimator, designed to obtain irregularly shaped neutron fields, that fits into an existing fixed field-size collimator system. The shape of the desired portal field is obtained by appropriately setting the position of each leaf of the collimator. The collimator consists of 40 polyethylene leaves to produce fields of irregular shape of up to 400 cm2. The leaves are interlaced with grooves to prevent neutron leakage. The measured penumbra defined by the multileaf collimator is similar to that defined by the same length fixed field-size water extended polyester (WEP) collimator. The multileaf collimator has a lower neutron transmission due to its higher hydrogen concentration.

An x-ray fluorescence technique to measure the mercury burden of dentists in vivo.

Mercury exposure in dental offices may represent a health hazard. Previous studies evaluated mercury exposure through blood, urine or hair analysis. The mercury content of body fluids in hair depends on the time since mercury exposure, mode of intake and its excretion, and sequestration by different tissues. Utilizing an x-ray fluorescence technique, the mercury burden in bone, liver, lung, spleen, and kidney was measured in vitro. The x-ray fluorescence, XRF, and chemical assays of the mercury content of these samples correlated. The XRF technique was used to assay the mercury content of tissues irradiated in vivo. It was found that the mercury signal arising at a depth in tissue was reduced as the thickness of overlying material increased. Thus, the XRF assay for tissues in vivo is confined to organs near the surface. The mercury content of the superficial layers of the head and wrist were determined in situ for a dental population. Concentrations as low as 20 micrograms/g could be detected with an exposure of 60 mR. Of the 298 dentists evaluated, 28% had greater than 20 micrograms/g of mercury in the head.

The use of lead-lined cones to improve the beam characteristics of a 50-kVp contact therapy x-ray beam.

Measurements were made to calibrate a Philips RT-50 contact therapy unit using an EG&G extrapolation chamber. The measured half-value layer of 0.27 mm in aluminum agrees closely with published data. Exposure rates in air for 4-cm source-to-surface distance (SSD) cones fall off faster than can be explained by the inverse square law alone. Lining the cone with lead results in exposure rates that follow the inverse square law at all distances from the cone end. Depth dose measurements made for 2- and 4-cm SSD cones produced the anomalous result of greater depth dose for the shorter SSD. This is due to a low-energy component arising from the end of the 4-cm SSD cone, producing an artificially high surface dose. Lining the cone with lead reduces the component and significantly increases the depth dose. The low-energy component is believed to be 6-8 keV characteristic x rays that arise from the stainless-steel cone. Lining the cone with lead either absorbs these x rays or prevents their production.

Determination of scatter factor parameters and electron disequilibrium for monoenergetic photon beams.

The tissue-phantom-ratio (TPR) is expressed as the product of the phantom scatter factor (SF), an electron disequilibrium factor, and an attenuation factor, equal to the zero-area TPR. The scatter factor, as a function of depth d and field size s, has been described by two parameters a and w, SF(d,s) = 1 + asd/(ws + d). We have determined the parameters a and w for 20 monoenergetic photon beams between 1 and 20 MeV. Pencil-beam energy-deposition kernels were obtained using Monte Carlo simulations. The kernels were used to calculate broad-beam depth-dose data, which were converted to TPR and fitted to the equation above using an iterative search over a-w space. The parameter a is nearly equal to the attenuation coefficient for all energies while the parameter w increases with energy. The resulting a and w compare favorably to values determined for clinical photon beams, as a function of the measured attenuation coefficient. With the scatter factor determined, we isolated the electron disequilibrium factor for each monoenergetic beam. It can be characterized as a quadratic function of the depth. The coefficients of the quadratic function can be related to the range of the most energetic secondary electron produced.