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Since ancient times, lubricants have been used to reduce friction and wear problems of mechanical systems. However, nowadays, there is a constant effort to improve their performance through additives so that they can accomplish properly in this modern world. In that sense, in this study, it was proposed the use of Poly(ε-Caprolactone) (PCL) as a biodegradable additive in Castor oil. The effect that this additive has on the tribological properties of AISI 4140 steel/Al2O3 tribosystem was analyzed. For this purpose, PCL was dissolved in Castor oil at 65 °C for 15 minutes. Later, once the lubricant formulations got into room temperature, friction tests were conducted with a ball-on-disk configuration. Several experiments were systematically carried out in order to study the factors that could influence the performance of the tribological system, for instance: additive concentration, velocity, temperature, and wear track radius. The kinetic friction coefficient was used to analyze the results as an output variable. The parameters in which the best friction behavior was observed were employed again to compare the efficiency of the polymeric additive by profoundly analyzing and comparing the wear response of the system. The PCL additive showed great results by decreasing friction up to 30% compared to the neat Castor oil. Nevertheless, as the opposite effect, this additive increased the steel wear to almost half an order of magnitude. Given the above, this investigation showed that, with further studies, Poly(ε-Caprolactone) could be used as an additive in vegetable oil-based lubricants for the improvement of friction performance.
The purpose of this study was to analyse the reliability and validity of a semi-quantitative FFQ to assess food group consumption in South American children and adolescents.
The SAYCARE (South American Youth/Child cARdiovascular and Environmental) study is an observational, multicentre, feasibility study performed in a sample of 3- to 18-year-old children and adolescents attending private and public schools from six South American countries. Participants answered the FFQ twice with a two-week interval and three 24-h dietary recalls. Intraclass and Spearman’s correlations, weighted Cohen’s kappa (κw), percentage of agreement and energy-adjusted Pearson’s correlation coefficients were calculated.
Seven cities in South America (Buenos Aires, Lima, Medelin, Montevideo, Santiago, Sao Paulo and Teresina).
A sample of 200 children and 244 adolescents for reliability analyses and 252 children and 244 adolescents for validity analyses were included.
Depending on the food group, for children and adolescents, reliability analyses resulted in Spearman’s coefficients from 0·47 to 0·73, intraclass correlation coefficients from 0·66 to 0·99, κw coefficients from 0·35 to 0·63, and percentage of agreement between 72·75 and 83·52 %. In the same way, validity analyses resulted in Spearman’s coefficients from 0·17 to 0·37, energy-adjusted Pearson’s coefficients from 0·17 to 0·61, κw coefficients from 0·09 to 0·24, and percentages of agreement between 45·79 and 67·06 %.
The SAYCARE FFQ achieved reasonable reliability and slight-moderate validity for almost all food groups intakes. Accordingly, it can be used for the purpose of ranking the intake of individuals within a population.
We consider de Finetti’s problem for spectrally one-sided Lévy risk models with control strategies that are absolutely continuous with respect to the Lebesgue measure. Furthermore, we consider the version with a constraint on the time of ruin. To characterize the solution to the aforementioned models, we first solve the optimal dividend problem with a terminal value at ruin and show the optimality of threshold strategies. Next, we introduce the dual Lagrangian problem and show that the complementary slackness conditions are satisfied, characterizing the optimal Lagrange multiplier. Finally, we illustrate our findings with a series of numerical examples.
Consumption of fruits and vegetables (F&V) among adolescents falls below recommendations in many Western countries. The impact of social and emotional aspects of family life on adolescent dietary behaviour may contribute to this, yet remains under-investigated. The present study examines the association between adolescents’ perceptions of emotional home atmosphere (EHA) and their F&V consumption frequency.
An FFQ was used to assess F&V consumption frequency. EHA was assessed by an eight-item measure with three subscales: perceived home warmth, strictness and relational tension. EHA subscales were used as binary variables: a score equal to or above the median value was considered as a higher perception, while a score below the median was considered as a lower perception of the EHA in question. Country differences in meeting the European 5-a-day recommendations were described. Further, the association between EHA and F&V consumption frequency was investigated using multiple linear regression.
Regional examination centres in eight European countries.
Adolescents (n 3196) aged 12–18 years.
The mean F&V consumption frequency was 3·27 (sd 2·84) times/d. Only 16·1 % of boys and 18 % of girls in our study sample met the recommendation of five F&V daily. After controlling for age, sex, education level of the parents and country of origin, perceived home warmth was associated with a 16 (95 % CI 9, 22) % higher F&V consumption frequency (P < 0·001).
F&V consumption frequency was suboptimal in the survey areas. Interventions targeting perceived warmth as a component of EHA could potentially have a positive effect on adolescents’ dietary behaviour.
To investigate whether adherence to the adapted Mediterranean Diet Score for Adolescents (MDS_A) and the adapted Mediterranean Diet Quality Index for Adolescents (KIDMED_A) is associated with better food/nutrient intakes and nutritional biomarkers.
The Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study is a cross-sectional study aiming to obtain comparable data on a variety of nutritional and health-related parameters in European adolescents aged 12·5–17·5 years.
Nine European countries.
European adolescents (n 2330) recruited to the HELENA study. Dietary intake was obtained with 24 h dietary recalls, an FFQ and a Food Choices and Preferences questionnaire. MDS_A was calculated as a categorical variable using cut-offs (MDS_A), as a continuous variable (zMDS_A) and with energy adjustments (zEnMDS_A). The KIDMED_A score was also calculated.
Multilevel linear regression analysis showed positive associations for zMDS_A and KIDMED_A with serum levels of vitamin D, vitamin C, plasma folate, holo-transcobalamin, β-carotene and n-3 fatty acids, while negative associations were observed with trans-fatty acid serum levels. For categorical indices, blood biomarkers showed few significant results. zMDS_A and KIDMED_A showed positive associations with vegetables and fruits intake, and negative associations with energy-dense and low-nutritious foods. zMDS_A and KIDMED_A were positively associated with all macronutrients, vitamins and minerals (all P < 0·0001), except with monosaccharides and PUFA for KIDMED_A and cholesterol for both indices (P < 0·05).
zMDS_A and KIDMED_A have shown the strongest associations with the dietary indicators and biomarkers that have been associated with the Mediterranean diet before, and are therefore considered the most appropriate and valid Mediterranean diet scores for European adolescents.
One of the job resources most strongly associated with nurses’ well-being and motivation is social support. However, the psychosocial mechanisms that would explain this relationship have not been sufficiently researched. Thus, the main aim of this study was analyze whether this relationship could be mediated by two variables: role ambiguity and psychological flexibility. A total of 196 nurses from various Spanish hospitals and primary health care centers participated in this cross-sectional study. A multiple mediation analysis was run using the “PROCESS” macro script in SPSS 23.0. The results showed that co-worker support was related to higher levels of vigor and vitality through role ambiguity (Estimate = .158, 95% CI [.050, .298], and Estimate = .212, 95% CI [.076, .390], respectively). The same applied to supervisor support, (Estimate = .197, 95% CI [.059, .378], and Estimate = .212, 95% CI [.076, .390], respectively). Co-worker support was also related to higher levels of vigor and vitality through psychological flexibility, (Estimate = .132, 95% CI [.048, .271], and Estimate = .216, 95% CI [.086, .394], respectively). The same applied to supervisor support (Estimate = .092, 95% CI [.024, .208], and Estimate = .157, 95% CI [.035, .333], respectively). However, in the relationships between co-worker, supervisor support and exhaustion, only psychological flexibility played a mediating role. In conclusion, social support in nursing is a job resource that is associated with high levels of energy and motivation among nurses through the mediating role of certain job demands and personal resources.
To assess the reliability and validity of body weight (BW) and body image (BI) perception reported by parents (in children) and by adolescents in a South American population.
Cross-sectional study. BW perception was evaluated by the question, ‘Do you think you/your child are/is: severely wasted, wasted, normal weight, overweight, obese?’ BI perception was evaluated using the Gardner scale. To evaluate reliability, BW and BI perceptions were reported twice, two weeks apart. To evaluate validity, the BW and BI perceptions were compared with WHO BMI Z-scores. Kappa and Kendall’s tau-c coefficients were obtained.
Public and private schools and high schools from six countries of South America (Argentina, Peru, Colombia, Uruguay, Chile, Brazil).
Children aged 3–10 years (n 635) and adolescents aged 11–17 years (n 400).
Reliability of BW perception was fair in children’s parents (κ=0·337) and substantial in adolescents (κ=0·709). Validity of BW perception was slight in children’s parents (κ=0·176) and fair in adolescents (κ=0·268). When evaluating BI, most children were perceived by parents as having lower weight. Reliability of BI perception was slight in children’s parents (κ=0·124) and moderate in adolescents (κ=0·599). Validity of BI perception was poor in children’s parents (κ=−0·018) and slight in adolescents (κ=0·023).
Reliability of BW and BI perceptions was higher in adolescents than in children’s parents. Validity of BW perception was good among the parents of the children and adolescents with underweight and normal weight.
In this paper, the feedback linearization approach is used to introduce a motion controller for unicycle-type wheeled mobile robots (UWMRs). The output function is defined as a linear combination of the error state. The novel scheme is firstly tested in numerical simulation and compared with its corresponding experimental result. Three controllers are taken from the literature and compared to the proposed approach by means of experiments. The gains of the experimentally tested controllers are selected to obtain identical energy consumption. The Optitrack commercial vision system and Pioneer P3-DX UWMR are used in real-time experimental tests. In addition, two sets of experimental results for different motion tasks are provided. The results show that the proposed controller presents the best tracking accuracy.
Poly (methyl methacrylate)/hydroxyapatite (PMMA/HAp) nanocomposites with HAp nanoparticles content of 12 wt.% were obtained by free-radical polymerization synthesis. Three different concentrations of benzoyl peroxide (PBO) of 3, 6, and 12 wt.% were studied. The results showed that the concentration of PBO has an effect on the performance of composites. In particular, the nanocomposite with the highest concentration of PBO presented the best mechanical and tribological behavior, as well as the lowest values of water absorption and porosity percent.
To analyse the Nutritional Knowledge Test (NKT) using Item Response Theory (ITR) analysis and to assess the construct validity of the Nutritional Knowledge Scale (NKTS) and its associations with adolescent food group consumption and nutritional biomarkers.
Multicentre investigation conducted in ten European cities.
Adolescents aged 12·5–17·5 years (n 3215) who completed over 75 % of the NKT.
Factor analysis indicated that the NKT can be analysed with a one-dimensional model. Eleven out of twenty-three items from the NKT presented adequate parameters and were selected to be included in the NKTS. Nutrition knowledge was positively associated with consumption of fruits, cereals, dairy products, pulses, meat and eggs, and fish, as well as with blood concentrations of vitamin C, β-carotene, n-3 fatty acids, holo-transcobalamin, cobalamin and folate; nutrition knowledge was negatively associated with intake of olives and avocado, alcohol and savoury snacks.
The NKTS assessed nutritional knowledge adequately and it is proposed as a new tool to investigate this subject in future studies.
The present study aimed to explore the mediating role of family-related determinants on the effects of the ToyBox-intervention on pre-school children’s consumption of healthy and unhealthy snacks.
The ToyBox-intervention was a kindergarten-based, family-involved intervention with a cluster-randomized design, aiming to promote healthy lifestyle behaviours to prevent obesity at pre-school age.
Kindergartens (n 309) in six European countries.
A total of 6290 pre-schoolers and their families participated in the ToyBox-intervention in 2012–2013 and data from 5212 pre-schoolers/families were included in the current analyses.
Even though the total effect of the ToyBox-intervention on healthy and unhealthy snacking was not significant, the ToyBox-intervention significantly improved parental rule setting on children’s unhealthy snack consumption (i.e. restriction of snacking while watching television and permission only at certain occasions) and parental consumption of unhealthy snacks, while it increased parental knowledge on snacking recommendations. Regarding healthy snacking, the ToyBox-intervention improved children’s attitude towards fruit and vegetables (F&V). All previously mentioned family-related determinants mediated the intervention effects on pre-schoolers’ consumption of healthy and unhealthy snacks. Almost all family-related determinants examined in the study were independently associated with pre-schoolers’ consumption of healthy and unhealthy snacks.
The intervention was effective in improving relevant family-related determinants. Interventions aiming to promote F&V consumption and limit the consumption of unhealthy snacks in pre-schoolers should target on these mediators, but also identify new family-, school- or peer-related determinants, to enhance their effectiveness.
The aim of this research was to investigate the influence of substrate roughness on the adhesion and tribological performance of thin TiN coatings obtained by physical vapor deposition. For that purpose, substrates of AISI H13 steel with surface finishes of 0.06, 0.28 and 0.90 μm in Ra were coated with TiN under the same coating conditions. The chemical composition of the steel, as well as that of the TiN coating, were obtained using EDS analysis. Adhesion tests were carried out following the procedure of BSi 1071-8 standard while hardness was evaluated by ASTM C 1327-03. On the other hand, dry sliding friction tests were conducted with a pin-on-disk tribometer, according to the ASTM G 99-05 standard. This study showed that the roughness of the coating increases as the substrate roughness increases. Regarding adhesion and hardness, all the samples showed an adhesion class 1 according to the standard and a hardness value of 14.51 GPa. Nevertheless, the highest substrate roughness produced the best adhesion. On the other hand, the lowest values for the friction coefficient and wear behavior were obtained by the sample with the lowest substrate roughness of 0.06 µm. In addition, it was found that friction and wear increase when the substrate roughness increases.
To describe the design of the Feel4Diabetes-intervention and the baseline characteristics of the study sample.
School- and community-based intervention with cluster-randomized design, aiming to promote healthy lifestyle and tackle obesity and obesity-related metabolic risk factors for the prevention of type 2 diabetes among families from vulnerable population groups. The intervention was implemented in 2016–2018 and included: (i) the ‘all-families’ component, provided to all children and their families via a school- and community-based intervention; and (ii) an additional component, the ‘high-risk families’ component, provided to high-risk families for diabetes as identified with a discrete manner by the FINDRISC questionnaire, which comprised seven counselling sessions (2016–2017) and a text-messaging intervention (2017–2018) delivered by trained health professionals in out-of-school settings. Although the intervention was adjusted to local needs and contextual circumstances, standardized protocols and procedures were used across all countries for the process, impact, outcome and cost-effectiveness evaluation of the intervention.
Primary schools and municipalities in six European countries.
Families (primary-school children, their parents and grandparents) were recruited from the overall population in low/middle-income countries (Bulgaria, Hungary), from low socio-economic areas in high-income countries (Belgium, Finland) and from countries under austerity measures (Greece, Spain).
The Feel4Diabetes-intervention reached 30 309 families from 236 primary schools. In total, 20 442 families were screened and 12 193 ‘all families’ and 2230 ‘high-risk families’ were measured at baseline.
The Feel4Diabetes-intervention is expected to provide evidence-based results and key learnings that could guide the design and scaling-up of affordable and potentially cost-effective population-based interventions for the prevention of type 2 diabetes.
Few previous studies in Latin America (LA) have provided data on dietary intake composition with a standardized methodology. The present study aimed to characterize energy intake (EI) and to describe the main food sources of energy in representative samples of the urban population from eight LA countries from the Latin American Study in Nutrition and Health (ELANS).
Cross-sectional study. Usual dietary intake was assessed with two non-consecutive 24 h dietary recalls.
Urban areas from eight countries (Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Peru, Venezuela), September 2014 to July 2015.
Adolescents and adults aged 15–65 years. Final sample comprised 9218 individuals, of whom 6648 (72·1 %) were considered plausible reporters.
Overall, mean EI was 8196 kJ/d (1959 kcal/d), with a balanced distribution of macronutrients (54 % carbohydrate, 30 % fat, 16 % protein). Main food sources of energy were grains, pasta and bread (28 %), followed by meat and eggs (19 %), oils and fats (10 %), non-alcoholic homemade beverages (6 %) and ready-to-drink beverages (6 %). More than 25 % of EI was provided from food sources rich in sugar and fat, like sugary drinks, pastries, chips and candies. Meanwhile, only 18 % of EI was from food sources rich in fibre and micronutrients, such as whole grains, roots, fruits, vegetables, beans, fish and nuts. No critical differences were observed by gender or age.
Public health efforts oriented to diminish consumption of refined carbohydrates, meats, oils and sugar and to increase nutrient dense-foods are a priority in the region to drive to a healthier diet.
Physical activity (PA) levels and dietary habits are considered some of the most important factors associated with obesity. The present study aimed to examine the association between PA level and food and beverage consumption in European children (2–10 years old).
A sample of 7229 children (49·0 % girls) from eight European countries participating in the IDEFICS (Identification and prevention of Dietary and lifestyle induced health EFfects In Children and infantS) study was included. Moderate-to-vigorous PA (MVPA) was assessed objectively with accelerometers. FFQ was used to register dietary habits. ANCOVA and binary logistic regression were applied.
Boys who spent less time in MVPA reported lower consumption of vegetables, fruits, cereals, yoghurt, milk, bread, pasta, candies and sugar-sweetened beverages (SSB) than boys who spent more time in MVPA (P<0·05). Moreover, boys who spent less time in MVPA were more likely to consume fast foods and water than those in the highest MVPA tertile (P<0·05). Girls who spent less time in MVPA reported lower consumption frequencies of vegetables, pasta, bread, yoghurt, candies, jam/honey and SSB than girls in the highest MVPA tertile (P<0·05). Also, girls in the lowest MVPA tertile were more likely to consume fast foods and water than those with high levels of MVPA (P<0·05).
Food intake among European children varied with different levels of daily MVPA. Low time spent in MVPA was associated with lowest consumption of both high- and low-energy-dense foods and high fast-food consumption.
Metamaterials offer the possibility to control and manipulate electromagnetic radiation. Spoof surface plasmon metamaterials are the focus of this Element of the Metamaterials Series. The fundamentals of spoof surface plasmons are reviewed, and advances on plasmonic metamaterials based on spoof plasmons are presented. Spoof surface plasmon metamaterials on a wide range of geometries are discussed: from planar platforms to waveguides and localized modes, including cylindrical structures, grooves, wedges, dominos or conformal surface plasmons in ultrathin platforms. The Element closes with a review of recent advances and applications such as Terahertz sensing or integrated devices and circuits.
Energy balance-related behaviours (EBRB) are established in childhood and seem to persist through to adulthood. A lower parental educational level was associated with unhealthy behavioural patterns. The aim of the study is to identify clusters of EBRB and examine their association with preschool children’s BMI and maternal, paternal and parental education. A subsample of the ToyBox study (n 5387) conducted in six European countries was used. Six behavioural clusters (‘healthy diet and low activity’, ‘active’, ‘healthy lifestyle’, ‘high water and screen time; low fruits and vegetables (F&V) and physical activity (PA)’, ‘unhealthy lifestyle’ and ‘high F&V consumers’) emerged. The healthiest group characterised by high water and F&V consumption and high PA z scores (‘healthy lifestyle’) was more prevalent among preschool children with at least one medium- or higher-educated parent and showed markedly healthier trends for all the included EBRB. In the opposite, the ‘unhealthy lifestyle’ cluster (characterised by high soft drinks and screen time z scores, and low water, F&V and PA z scores) was more prevalent among children with lower parental, paternal and maternal education levels. OR identified that children with lower maternal, paternal and parental education levels were less likely to be allocated in the ‘healthy lifestyle’ cluster and more likely to be allocated in the ‘unhealthy lifestyle’ cluster. The ‘unhealthy lifestyle’ cluster was more prevalent among children with parents in lower parental educational levels and children who were obese. Therefore, parental educational level is one of the key factors that should be considered when developing childhood obesity prevention interventions.