New frequency/voltage converters for ac-electrogravimetric measurements based on fast quartz crystal microbalance

A better understanding of the mechanisms located at the solid/electrolyte interface is becoming essential to the development of new applications in the electrochemical fields. The fast quartz crystal microbalance is an attractive and powerful gravimetric sensor which can be used in the dynamic regime to determine a mass/potential transfer function. The principle is equivalent to classical electrochemical impedance measurements; the only difference is the determination of mass changes given by the quartz crystal microbalance rather than current changes following sine wave modulations of the applied potential. This function appears very well adapted to characterize ionic exchanges at the electrochemical interface. Frequency/voltage converters are the key devices in translating the microbalance frequency response in terms of a continuous voltage change. The latter allows the transfer function to be obtained via a frequency response analyzer. Different converters were tested in this work in order to improve the performances of the experimental setup.

Has the WIC incentive to formula-feed led to an increase in overweight children?

We explored the relationship between the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) and overweight status in children, with a focus on WIC's provision of infant formula, through secondary analyses and review of existing literature. Because of the complexity involved and the lack of previous research on the combined link between WIC, breast-feeding, and overweight status, we considered evidence for each of these relations separately. Using food-cost data from the WIC's 1996 Participant and Program Characteristics Survey, we found that the state-level average for 1 y of program benefits for women who formula-fed was over twice the value of program benefits for those who breast-fed (BF). This difference in benefit levels, or formula incentive, was negatively associated with both the in-hospital and 6-mo BF rates in state-level multiple regression models. Despite WIC's efforts to promote BF, other large-scale studies have found a negative association of program participation with BF rates. An inverse association of BF on subsequent overweight in children also has been shown in a number of studies. Despite this accumulating evidence for the protective effect of BF, it has not been seen in African American or Latino populations. In sum, there is reason to be concerned that WIC's incentive to formula-feed may have led to an increase in overweight children; yet there is too much uncertainty about the issue to conclude that this is so. Further research is needed to understand this relationship, as is the development of applied interventions to increase BF rates.

Household food insecurity and overweight status in young school children: results from the Early Childhood Longitudinal Study

OBJECTIVE

Recent work on the determinants of obesity has shown a positive association between household food insecurity and overweight status in adult women, yet research exploring this issue in children has been inconclusive. In this study we examine the association between food insecurity and overweight status in young school children by using a large, nationally representative sample.

METHODS

Data from the Early Childhood Longitudinal Study-Kindergarten Cohort (ECLS-K) were analyzed. Replicate heights and weights were measured on kindergarten children (N = 16889) in the spring of 1999. Children with a body mass index > or = 95th percentile of their gender-specific BMI-for-age chart were considered overweight. Food-insecurity status was assessed by using the full 18-question US Department of Agriculture Household Food Security Scale. Multivariate logistic regression was used to assess the relationship between overweight and food-insecurity status while controlling for potential demographic, socioeconomic, and behavioral confounders.

RESULTS

Overall, 11.2% of the girls and 11.8% of the boys were overweight. Children from food-insecure households were 20% less likely to be overweight than their food-secure counterparts. Similar results on the food-insecurity/overweight link were found across a range of different models and expressions for key variables. Positive predictors of overweight status included low physical activity, television watching for > 2 hours/day, high birth weight, black or Latino ethnicity, and low income.

CONCLUSIONS

There are strong arguments for reducing food insecurity among households with young children. This research suggests that these arguments would be based on reasons other than a potential link to obesity. Low activity levels and excessive television watching, however, were strongly related to overweight status, a finding that supports continued efforts to intervene in these areas.

Who decides what evidence is? Developing a multiple perspectives paradigm in mental health

OBJECTIVE

To compare different perspectives on evidence in relation to mental health care.

METHOD

The method and materials constitute a selective literature review comparing key elements of evidence-based medicine and evidence-based policy with perspectives on evidence from users, carers and professionals. The aim was to develop an argument concerning these comparisons.

RESULTS

What constitutes evidence from the perspectives of different stakeholders is a field of contestation.

CONCLUSION

It is timely for a multiple perspective paradigm on evidence in science to be developed and this paper initiates this process in relation to mental health care.

Staff in services for people with intellectual disabilities: the impact of stress on attributions of challenging behaviour

BACKGROUND

There is a lack of a conceptual framework as to how stress and attribution variables interact and influence staff behaviour in response to challenging behaviour. To address this, a model is tested examining the impact of stress on attributions of challenging behaviour within Weiner's model of helping.

METHOD

A total of 107 staff working in community homes for people with intellectual disabilities completed a self-report questionnaire that measured stress, burnout, attributions, emotions, optimism and helping behaviour in response to challenging behaviour.

RESULTS

Partial support was found for the role of attributions and emotions. However, although staff reported high stress levels and moderate burnout, this did not appear to relate to their reporting of thoughts and feelings regarding challenging behaviour predicted by Weiner's helping model. It was not possible to fully test the helping model, as the 'help' variable was not normally distributed.

CONCLUSIONS

There was little evidence to suggest that stress has a primary role in determining staff responses when examined within Weiner's model of helping. Limited support in general was offered for Weiner's helping model. Potential conceptual difficulties and clinical implications are explored and alternative models for future research are discussed.

Oxygen consumption and PEEPe in ventilated COPD patients

The intrinsic positive-end-expiratory pressure (PEEPi) increases the inspiratory load, the cost of breathing and thus oxygen consumption (V(O2)). It has been shown that applying an extrinsic positive-end-expiratory pressure (PEEPe) reduces the inspiratory threshold load but the optimal PEEPe level is still in debate. We hypothesize that the best level of PEEPe could induce a decrease in V(O2) by reducing the V(O2) demands from PEEPi. Nine mechanically ventilated COPD patients were included. The level of PEEPe was determined in accordance with the static PEEPi. V(O2) was measured using an automatic gas analyser during synchronized intermittent mandatory ventilation (SIMV): without PEEPe, with a PEEPe equal to 50% of static PEEPi and with a PEEPe equal to 100% of static PEEPi. Static PEEPi appeared to be significantly correlated with the degree of airflow obstruction (FEV1) (P<0.05). Applying a PEEPe equal to static PEEPi resulted in a significant decrease in V(O2) (P<0.05) whereas the change in V(O2) proved to be unpredictable for a PEEPe level of 50% of static PEEPi. In conclusion, V(O2) decreases progressively when increasing PEEPe up to a level equal to 100% of static PEEPi. Thus, in mechanically ventilated COPD patients with a FEV1 < or = 1000 ml, applying a PEEPe of 5 cmH2O should be recommended.

Limits on gravitational-wave emission from selected pulsars using LIGO data

We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10(-5) for the four closest pulsars.

Food store access and household fruit and vegetable use among participants in the US Food Stamp Program

OBJECTIVE

Recent research on access to food among low-income populations in industrialised countries has begun to focus on neighbourhood food availability as a key determinant of dietary behaviour. This study examined the relationship between various measures of food store access and household fruit and vegetable use among participants in the Food Stamp Program, America's largest domestic food assistance programme.

DESIGN

A secondary data analysis was conducted using the 1996-97 National Food Stamp Program Survey. The survey employed a 1-week food inventory method, including two at-home interviews, to determine household food use. Separate linear regression models were developed to analyse fruit and vegetable use. Independent variables included distance to store, travel time to store, ownership of a car and difficulty of supermarket access. All models controlled for a full set of socio-economic variables.

SUBJECTS

A nationally representative sample of participants (n=963) in the Food Stamp Program.

RESULTS

After controlling for confounding variables, easy access to supermarket shopping was associated with increased household use of fruits (84 grams per adult equivalent per day; 95% confidence interval 5, 162). Distance from home to food store was inversely associated with fruit use by households. Similar patterns were seen with vegetable use, though associations were not significant.

CONCLUSIONS

Environmental factors are importantly related to dietary choice in a nationally representative sample of low-income households, reinforcing the importance of including such factors in interventions that seek to effect dietary improvements.

Use of two torque absorbers in a trans-femoral prosthesis of an amputee golfer

This single case study reports the successful trial of the use of 2 torque absorbers in a single trans-femoral prosthesis. The adapted prosthesis enabled a greater degree of rotation on a vertical axis which can be a significant advantage to amputee golfers.

Predicting dietary intakes with simple food recall information: a case study from rural Mozambique

OBJECTIVE

Improving dietary status is an important development objective, but monitoring of progress in this area can be too costly for many low-income countries. This paper demonstrates a simple, inexpensive technique for monitoring household diets in Mozambique.

DESIGN

Secondary analysis of data from an intensive field survey on household food consumption and agricultural practices, known as the Nampula/Cabo Delgado Study (NCD).

SUBJECTS

In total, 388 households in 16 villages from a stratified random sample of rural areas in Nampula and Cabo Delgado provinces in northern Mozambique.

METHODS

The NCD employed a quantitative 24-h food recall on two nonconsecutive days in each of the three different seasons. A dietary intake prediction model was developed with linear regression techniques based on NCD nutrient intake data and easy-to-collect variables, such as food group consumption and household size The model was used to predict the prevalence of low intakes among subsamples from the field study using only easy-to-collect variables.

RESULTS

Using empirical data for the harvest season from the original NCD study, 40% of the observations on households had low-energy intakes, whereas rates of low intake for protein, vitamin A, and iron, were 14, 94, and 39, respectively. The model developed here predicted that 42% would have low-energy intakes and that 12, 93, and 35% would have low-protein, vitamin A, and iron intakes, respectively. Similarly, close predictions were found using an aggregate index of overall diet quality.

CONCLUSIONS

This work demonstrates the potential for using low-cost methods for monitoring dietary intake in Mozambique.

Comparison of morphologic features of intact and ruptured aneurysms of infrarenal abdominal aorta

INTRODUCTION

Endovascular aneurysm repair (EVAR) has been suggested as a technique to improve outcome of ruptured abdominal aortic aneurysm (AAA). Whether this technique becomes an established treatment will depend, in part, on the anatomy of ruptured AAA.

METHODS

The anatomy of intact and ruptured AAA seen in a university department of vascular surgery over 5 years was reviewed. Aneurysm anatomy was assessed with spiral computed tomographic angiography. Suitability for EVAR was assessed from the dimensions of the proximal neck and common iliac arteries. Neck length less than 15 mm, neck width greater than 30 mm, and common iliac artery diameter greater than 22 mm were declared unsuitable for EVAR.

RESULTS

Three hundred sixty-three patients with intact AAA and 46 with ruptured AAA were identified. Larger intact aneurysms were significantly associated with longer renal artery-bifurcation distance and more complex proximal neck architecture. In this sample, patients with ruptured AAA were more likely to have larger aneurysms with shorter and narrower proximal necks. Significantly more intact aneurysms were morphologically suitable for endovascular repair compared with ruptured AAA (78% vs 43%; P <.001).

CONCLUSIONS

Ruptured AAA are less likely to be suitable for endovascular repair than are intact AAA, most probably because of larger diameter at presentation. Open repair will likely remain the treatment of choice in most patients with ruptured AAA, because of current morphologic constraints of endovascular repair.

Injuries in a modern dance company: effect of comprehensive management on injury incidence and time loss

BACKGROUND

Professional dancers experience high rates of musculoskeletal injuries.

OBJECTIVE

To analyze the effect of comprehensive management (case management and intervention) on injury incidence, time loss, and patterns of musculoskeletal injury in a modern dance organization.

STUDY DESIGN

Retrospective/prospective cohort study.

METHODS

Injury data were analyzed over a 5-year period, 2 years without intervention and 3 years with intervention, in a modern dance organization (42 dancers). The number of workers' compensation cases and number of dance days missed because of injury were compared across a 5-year period in a factorial design.

RESULTS

Comprehensive management significantly reduced the annual number of new workers' compensation cases from a high of 81% to a low of 17% and decreased the number of days lost from work by 60%. The majority of new injuries occurred in younger dancers before the implementation of this program. Most injuries involved overuse of the lower extremity, similar to patterns reported in ballet companies. Benefits of comprehensive management included early and effective management of overuse problems before they became serious injuries and triage to prevent overutilization of medical services.

CONCLUSIONS

This comprehensive management program effectively decreased the incidence of new cases and lost time. Both dancers and management strongly support its continuance.

Poly(D,L-lactic acid)-poly(ethylene glycol)-monomethyl ether diblock copolymers control adhesion and osteoblastic differentiation of marrow stromal cells

Biodegradable polymers, such as poly(lactic acid) (PLA) and poly(lactic-coglycolic acid) (PLGA), are attractive materials for tissue engineering because of their degradative and mechanical properties, which permit scaffolds to be tailored to the individual requirements of different tissues. Although these materials support tissue development, their chemical properties offer no control of cell adhesion or function because their surfaces become immediately masked by adsorbing serum proteins when the materials come into contact with body fluids. Furthermore, adhesion proteins undergo conformational changes and a decrease in bioactivity when adsorbed to hydrophobic materials, such as PLA. To overcome these limitations, we modified the properties of PLA by synthesizing a diblock copolymer with poly(ethylene glycol) (PEG), which is known to reduce the amount of adsorbed proteins and to modify their conformation. By altering the PEG content of these diblock copolymers we were able to control the adsorption of adhesion proteins and, because cell adhesion takes place only in the presence of serum proteins, to control cell adhesion and cell shape. Marrow stromal cell differentiation to the osteoblastic phenotype was strongly improved on PEG-PLA compared with PLA, PLGA and tissue culture polystyrene and led to a 2-fold increase in alkaline phosphatase activity and mineralization.

Quantitative indicators from a food expenditure survey can be used to target the food insecure in South Africa

Recent work on assessing household food insecurity has focused mainly on experiential-based measures using qualitative survey questions. In this paper, we employed two quantitative measures to estimate prevalence rates for household food insecurity in South Africa. One measure, termed food poverty, assessed whether the amount spent by a household on food was inadequate to purchase a low cost food plan. Low energy availability assessed whether the food energy available to a household, through its purchases and home production, was less than the sum of its members' recommended energy intakes. The 1995 Income and Expenditure Survey, a large representative survey of South African households (n = 28,704), was used for this secondary data analysis. Results showed that 43% of households were in food poverty in October 1995, and 55% had a low energy availability. These indicators allowed classification of households into four groups: food poverty only; low energy availability only; food insecure on both measures; and food secure. These groups differed on various aspects of household food consumption, suggesting that these indicators can be used to target different types of interventions to meet specific needs. Both bivariate and multivariate analyses showed that households that were food insecure on both measures were more likely to be in rural areas, have low incomes or large household sizes, and be headed by Africans or individuals of mixed ancestry. These patterns of food insecurity were corroborated by previous research on income poverty and nutritional status, suggesting that food poverty and low energy availability are useful, quantitative indicators for assessing food insecurity in South Africa.

Prevalence of household food poverty in South Africa: results from a large, nationally representative survey

OBJECTIVES

Household food insecurity is a major determinant of undernutrition, yet there is little information on its prevalence in the South African population. This paper assesses household food insecurity in South Africa using a quantitative and objective measure, known as food poverty, and provides prevalence estimates by geographic area and socio-economic condition.

DESIGN

Secondary data analysis combining two sources: Statistics South Africa's household-based 1995 Income and Expenditure Survey; and the University of Port Elizabeth's Household Subsistence Level series, a nationally-conducted, market-based survey.

SETTING

South Africa.

SUBJECTS

A nationally representative sample of the entire country - stratified by race, province, and urban and non-urban areas - consisting of 28 704 households.

RESULTS

A household is defined to be in food poverty when monthly food spending is less than the cost of a nutritionally adequate very low-cost diet. The prevalence of food poverty in South Africa in 1995 was 43%. Food poverty rates were highest among households headed by Africans, followed by coloureds, Indians and whites. Higher food poverty rates were found with decreasing income, increasing household size, and among households in rural areas or those headed by females.

CONCLUSIONS

The widespread nature of household food insecurity in South Africa is documented here. Prevalence rates by geographic and socio-economic breakdown provide the means for targeting of nutritional interventions and for monitoring progress in this field. The corroboration of these findings with both internal validation measures and external sources suggests that food poverty is a useful, objective measure of household food insecurity.

Evaluation of a rapid field tool for assessing household diet quality in Mozambique

The Nutrition Section of the Mozambican Ministry of Health recently implemented a low-cost, rapid field tool for assessing the quality of household diets. Such tools can play an important part in targeting development assistance in countries where resources are scarce. This paper evaluates how well the tool performs at describing household dietary intakes in northern Mozambique and explores ways to improve it. The food-group classification and scoring system that form the core of the tool were applied to household data (n = 1,140) collected in a previous quantitative diet study in Nampula and Cabo Delgado Provinces. Using mean intakes as a criterion, the diet assessment tool performed well on all nutrients studied, except vitamin A. Those classified by the tool into the top group of diet quality had the highest mean intakes of energy, protein, and iron as well as the highest mean scores on the Mozambican Diet Quality Index, whereas those classified in the bottom group had the lowest intakes. Sensitivity rates for the diet assessment tool could be substantially improved by raising the cutoff point for an acceptable diet from the current threshold of 20 points to 23 points. Regression analysis was used to suggest other possible improvements. Such improvements were only marginal and do not justify field implementation, given the added complexity in classifying and scoring. This paper provides evidence that, with some minor changes, the Ministry of Health diet assessment method can be a useful tool in describing the dietary situation of groups of Mozambican households. Since this tool is both inexpensive and simple to use, there may be interest in adapting it for use in other low-income countries. A series of steps for doing so is outlined at the end of this paper.

Reflexive shifts of covert attention operate in an egocentric coordinate frame

Covert shifts of attention have been shown to improve detection and discrimination thresholds for a range of visual stimuli. Although there is some evidence to suggest that the allocation of attention to a particular region of interest occurs in a retinotopic frame of reference, the importance of an allocentric, or object-based, framework has gained widespread empirical support. The current experiment investigates the nature of the spatial representation in which covert shifts of attention occur in response to a reflexive prime. Primes and targets were presented in four conditions designed to vary systematically the validity of the spatial relationship between the prime and target in egocentric or allocentric coordinate frameworks. A significant advantage, in terms of reaction time and correct identification, was found for targets located in positions previously primed in an egocentric (but not allocentric) framework whereas there was no advantage for locations primed in an allocentric (but not egocentric) framework. These results suggest that the allocation of covert spatial attention within an egocentric framework may be more important than previously thought.