High pressure ferroelastic phase transition in SrTiO3.

High pressure measurements of the ferroelastic phase transition of SrTiO3 (Guennou et al 2010 Phys. Rev. B 81 054115) showed a linear pressure dependence of the transition temperature between the cubic and tetragonal phase. Furthermore, the pressure induced transition becomes second order while the temperature dependent transition is near a tricritical point. The phase transition mechanism is characterized by the elongation and tilt of the TiO6 octahedra in the tetragonal phase, which leads to strongly nonlinear couplings between the structural order parameter, the volume strain and the applied pressure. The phase diagram is derived from the Clausius-Clapeyron relationship and is directly related to a pressure dependent Landau potential. The nonlinearities of the pressure dependent strains lead to an increase of the fourth order Landau coefficient with increasing pressure and, hence, to a tricritical-second order crossover. This behaviour is reminiscent of the doping related crossover in isostructural KMnF3.

Absence of pressure-induced amorphization in LiKSO4.

Angle-resolved synchrotron radiation diffraction was used to investigate lithium potassium sulfate (LiKSO(4)) crystals under high pressure. We confirm that the title compound undergoes three phase transitions, α →ß, ß â†’ γ and γ →δ, observed at around 0.8 GPa, 4.0 GPa and 7.0 GPa, respectively. Two competitive structures are proposed for the ß-phase after powder diffraction data Rietveld refinements: an orthorhombic (space group Cmc 2(1)) or a monoclinic (space group Cc) structure. These structures correspond to the models of the low temperature phases. The γ-phase is indexed by a monoclinic structure. Finally, the δ-phase is found to be highly disordered. No evidence of any pressure-induced amorphous phase was observed up to 24 GPa, even under imposed highly non-hydrostatic conditions, contrary to previous propositions.

High-pressure effect on PbTiO3: an investigation by Raman and x-ray scattering up to 63 GPa.

We report a room-temperature high-pressure x-ray and Raman scattering investigation of lead titanate (PbTiO3) up to 63 GPa. Three continuous phase transitions at 13, 20, and 45 GPa between tetragonal-like phases occur. As a result, no evidence is found for a pressure-induced morphotropic phase boundary. Our study provides experimental evidence that PbTiO3 presents a complex sequence of phases accommodating pressure through mechanisms involving oxygen octahedra tilting and reentrance of ferroelectricity.

[The bill of rights for children in sport: a tool to promote the health and protect the child in sport]. / La charte des droits de l'enfant dans le sport: un outil pour promouvoir la santé et protéger l'enfant dans le sport.

The Bill of rights for children in sport was developed in response to the need for prevention and protection of children practicing sport. It is the result of an interdisciplinary approach and is used with young sportsmen, sport clubs and in the education of the professionals involved with children's sport. It is an excellent tool to sensitize people to children's vulnerabilities and to establish the bases for prevention and protection. In complete accordance with the UN Convention on the Rights of the Child, this Bill gives an example of a concrete application in the field of Sports. Used on a regular basis in the field, it contributes to change the adult's vision of children's sport and the approach to coaching;

[Adolescent health: collaborative effort between school health services, medical practitioners and adolescents or specialized clinics]. / Santé des adolescents: te rôle essentiel de la collaboration entre santé scolaire et institutions de soins.

Adolescents have complex health needs, that require consistent answers between the health and education sectors. This article describes the existing structures and collaborations in Geneva, between medical practitioners, specialized clinics and school health. School health doesn't make any routine health screening, but strengthens its role for guidance of adolescents. Priority health activities for school health include protection of victims of abuse, integration of youth living with a chronic condition, and mediation for students with repeated absences. In any of these cases, collaboration between health services and school health services is essential. In the case of drug abuse, collaboration with teachers is necessary.

Ferroelectricity of perovskites under pressure.

Ab initio simulations and experimental techniques are combined to reveal that, unlike what was commonly accepted for more than 30 years, perovskites and related materials enhance their ferroelectricity as hydrostatic pressure increases above a critical value. This unexpected high-pressure ferroelectricity is different in nature from conventional ferroelectricity because it is driven by an original electronic effect rather by long-range interactions.

[Medical certificates for physical education in schools; the situation in Geneva]. / Certificats médicaux de dispense de gymnastique scolaire, la situation à Genève.

The sedentarisation of youth is a major public health issue. Much hope has been placed on school physical education (PE) as a source of regular physical activity and to promote an active life style. A trans-disciplinary group counted the number of medical certificates in secondary school (11339 students), modified the existing excuse form, and generated a debate about PE. In 2000-2001, 15% of students (1688) presented medical certificates: 48% were for >3 months to one year, among which 75% were girls. The proportion of medical certificates varied from school to school (2,3 to 15%). A new form allowing to establish partial incapacity brought a 40% reduction in total medical certificates in 2002-2003.

Migrant children--a challenge for European paediatricians.

UNLABELLED: Each year, tens of thousands of children seek asylum in Europe. Irregular immigration, family reunification programmes and labour migrants contribute additional large populations to the migrant scene in Europe. Paediatricians struggle to find solutions to their needs of health and medical care within different societal and political contexts on a common platform of children's rights and medical ethics. CONCLUSIONS: Migrant children have important health and protection needs. Paediatricians can improve the health and well-being of migrant children by assuring access to paediatric healthcare regardless of the child's legal status. Paediatricians can play an important role in advocating for migrant children in their local community, through concerted activities of national paediatric societies, and through the international paediatric community. National paediatric societies need to put migrant children high on their agenda in discussions with policy and decision makers. Initiatives are needed to create platforms within the international paediatric community where practical strategies to the multitude of issues touched upon by migrant children can be exchanged and international advocacy organized.

Pressure-induced suppression of the diffuse scattering in the model relaxor ferroelectric PbMg(1/3)Nb(2/3)O3.

We report an investigation of the relaxor ferroelectric PbMg(1/3)Nb(2/3)O3 by combining the external parameter high pressure with x-ray diffuse scattering. The observed total suppression of the relaxor-characteristic x-ray diffuse scattering is unusual and points to important pressure-induced changes in the local order. The observed behavior might well be a general feature in relaxor ferroelectrics under high pressure.

Epidemiology of herpes simplex virus in children by detection of specific antibodies in saliva.

OBJECTIVES: To facilitate the study of the prevalence of herpes simplex virus (HSV) infection and its determinants in children, we developed a noninvasive saliva test. METHODS: A capture enzyme-linked immunosorbent assay (ELISA) for the detection of IgG to HSV in saliva was developed, validated against a commercial serum ELISA in 110 children and 187 adults and used in a cross-sectional population-based study including 2,048 children ages 1 to 17 years, recruited in day-care centers and schools of Geneva, Switzerland. Demographic and socioeconomic determinants of HSV prevalence were studied. RESULTS: The sensitivity and specificity of the saliva assay were 94.1 and 95.5%, respectively, compared with the commercial serum ELISA. Participation in the cross-sectional study was 86.6%. The overall prevalence of anti-HSV IgG was 23.91%. It increased with age up to 7 years, reaching a plateau at 35% without evidence for day-care or school transmission. The main determinants of prevalence were region of national origin and parents' professional category. CONCLUSIONS: This new saliva-based assay proved its feasibility in the first population-based study of HSV prevalence in children that uses saliva, confirmed its validity by identifying determinants of prevalence consistent with previous reports and yielded new information, such as the lack of influence of day-care attendance, in the population studied.

What does a single determination of malaria parasite density mean? A longitudinal survey in Mali.

Temporal variations of blood parasite density were evaluated in a longitudinal study of young, asymptomatic men in a village with endemic malaria in Mali (West Africa). Our main intention was to challenge the value of a single measure of parasite density for the diagnosis of malaria, and to define the level of endemicity in any given area. Parasitaemia and body temperature were recorded three times a day in the wet season (in 39 subjects on 12 days) and in the dry season (in 41 subjects on 13 days). Two thousand nine hundred and fifty seven blood smears (98.5% of the expected number) were examined for malaria parasites. We often found 100-fold or greater variations in parasite density within a 6-hour period during individual follow-up. All infected subjects had frequent negative smears. Although fever was most likely to occur in subjects with a maximum parasite density exceeding 10000 parasites/mm3 (P = 0.009), there was no clear relationship between the timing of these two events. Examples of individual profiles for parasite density and fever are presented. These variations (probably due to a 'sequestration-release' mechanism, which remains to be elucidated) lead us to expect a substantial impact on measurements of endemicity when only a single sample is taken. In this study, the percentage of infected individuals varied between 28.9% and 57.9% during the dry season and between 27.5% and 70.7% during the wet season. The highest rates were observed at midday, and there were significant differences between days. Thus, high parasite density sometimes associated with fever can no longer be considered as the gold standard in the diagnosis of malaria. Other approaches, such as decision-making processes involving clinical, biological and ecological variables must be developed, especially in highly endemic areas where Plasmodium infection is the rule rather than the exception and the possible causes of fever are numerous.

Typology and correlates of sexual abuse in children and youth: multivariate analyses in a prevalence study in Geneva.

OBJECTIVE: Child sexual abuse (CSA) encompasses a variety of distinct situations, which should be differentiated. There is a need for a working classification, taking into account various parameters. METHODS: The Geneva CSA prevalence study was based on 1116 randomly selected adolescents aged 14 to 16. Secondary analyses of the 252 reported cases of abuse was carried out using a multivariate approach combining multiple correspondence analysis and automatic classification, leading to descriptive analyses and to a new classification of CSA. RESULTS: Global prevalence of CSA, using a broad definition, was 10.9% for boys, and 33.8% for girls. Classification of cases of abuse differentiated 5 classes: (A) exhibitionism or other abuse without contact, by an adult (proportion of cases in boys: 22%; girls: 32%); (B) abuse of an adolescent boy by a peer without contact (62%); (C) abuse of an adolescent girl by a peer with physical contact (38%); (D) abuse inside the family, repeated (boys: 10%, girls: 16%); (E) child abuse with genital penetration, lasting 2 years or more (boys: 7%; girls: 14%). CONCLUSIONS: CSA is a complex and heterogeneous problem. Reported abuse situations can be classified into five classes, with different degrees of severity, causes, and consequences. Classification is essential in clinical research as well as in the design and conception of prevention programs.

Breast-feeding in Geneva: prevalence, duration and determinants.

A telephone survey was carried out with the objective of measuring the prevalence, duration and determinants of breast-feeding in the canton of Geneva, between August and December 1993. The participants were 278 out of 320 families with a telephone number in Geneva, from a random sample of families in which a child had been born in Geneva in the preceding 15 months. Prevalence of breast-feeding at 1 day of life was 93.3%, at 3 months 62.5%, at 4 months 51.1%, at 6 months 28.1%; median duration was 4.2 months. For complete (exclusive or predominant) breast-feeding, results were: 1 day 87.3%, 3 months 37.5%, 4 months 19.4%, 6 months 3.8%; median duration 2.4 months. Initial prevalence of breast-feeding was significantly higher in girls (97.2%) than in boys (89.4%, p < 0.01). Duration of breast-feeding was shorter in children of women who smoked (p < 0.001). Relative risks for no breast-feeding at 4 months were 1.53 (95% confidence limits 1.20-1.96) for less than 15 cigarettes per day during pregnancy, and 3.65 (2.19-6.09) for 15 cigarettes or more. Duration of breast-feeding was shorter if the mother worked as an employee. Prevalence and duration were higher if the mother was originally from Africa, Asia, Middle-East or Latin American countries. Although the initial prevalence of breast-feeding was relatively high, only half of children were breast-fed at 4 months. Promotive efforts are needed to increase the duration of breast-feeding, in particular by legislation on maternal protection. Further studies are required to clarify gender differences in breast-feeding.

Hemorheology and walking of peripheral arterial occlusive diseases patients during treatment with Ginkgo biloba extract.

AIM: To study the effects of Ginkgo biloba extract 761 (GbE) from the points of view of hemorheology for patients of peripheral arterial occlusive diseases (PAOD). METHODS: The treatment with GbE (240 mg.d-1, po) and the pain-free walking distance (PFWD) were carried out for 24 PAOD patients (12 nondiabetic, ND and 12 diabetic, D) over 48 wk. The parameters erythrocyte stiffness (ES) and relaxation time (RT), the blood plasma viscosity (eta), the plasma fibrinogen concentration (Cf) and the blood sedimentation rate (BSR), the PFWD, and maximal walking distance (MWD) were determined at 6 wk before treatment (-6), at the beginning of the treatment (0), and after 6, 11, 16, and 48 wk of treatment. RESULTS: At wk -6, ES and RT of both the ND- and D-group were not significantly different from a healthy control group. At wk 0, stiffness and RT were significantly higher than healthy control, and the mean PFWD was only 111 m. The eta value was significantly elevated and Cf and BSR were enhanced. Throughout 11 wk of treatment ES, RT, eta, and Cf decreased gradually and PFWD improved. Between 16 and 48 wk, ES, and RT were no longer significantly different from the controls, whereas eta and Cf decreased gradually but remained higher than normal, BSR decreased, and the PFWD improved by a factor of 3.8 times (D) and 3.3 times (ND). CONCLUSION: GbE gives therapeutic effects in PAOD patients.

Seasonality and malaria in a west African village: does high parasite density predict fever incidence?

In this cohort study, the authors studied the effect of blood malaria parasite density on fever incidence in children in an endemic area with 9 days' follow-up of 1- to 12-year-old children during two time periods: the end of the dry season (May 1993: n = 783) and the end of the rainy season (October 1993: n = 841) in Bougoula, West Africa (region of Sikasso, Mali). The cumulative incidence of fever (temperature > 38.0 degrees C) was 2.0% in the dry season and 8.2% in the rainy season (p < 0.0001). In the rainy season, the risk of fever was increased in children of ages 1-3 years (relative risk (RR) = 2.5, 95% confidence interval (CI) 1.6-4.1); in those with an initial parasitemia > 15,000/microliter (RR = 2.7, 95% CI 1.4-5.4); in children with an enlarged spleen (RR = 2.0, 95% CI 1.2-3.3); or in those with anemia (hematocrit < 30%: RR = 1.8, 95% CI 1.1-2.9). In the dry season, anemia was the only predictor of fever incidence. In the rainy season, the best predictors of fever were, in order, age (< 4 years), enlarged spleen, and high parasite density. Even in the higher risk groups, the cumulative incidence was < 20%. The authors conclude that most children with high parasite density do not develop fever subsequently. The association between parasite density and fever varies according to age and season. Since even high levels of parasite density do not reliably predict fever incidence, parasite density should be considered as just one of a group of indicators that increase the probability of a fever of malarial origin.

PIP: In a cohort study, the effect of blood malaria parasite density on fever incidence in children was studied in an endemic area with 9 days' follow-up of children aged 1-12 years during two time periods: the end of the dry season (May 1993: n = 783) and the end of the rainy season (October 1993: n = 841) in Bougoula, West Africa (region of Sikasso, Mali). The number of registered children was 928 in the dry season and 998 in the rainy season. Complete follow-up and information were available for 835 children in the dry season and for 964 children in the rainy season. The 9-day cumulative fever incidence (body temperature above 38.0 degrees Celsius) increased from 2.0% in the dry season to 8.2% in the rainy season (p 0.0001). In the rainy season, the risk of fever increased in children aged 1-3 years (relative risk [RR] = 2.5; 95% confidence interval [CI], 1.6-4.1); in those with an initial parasitemia greater than 15,000/mcl (RR = 2.7; 95% CI, 1.4-5.4); in those with an enlarged spleen (RR = 2.0; 95% CI, 1.2-3.3); or in those with anemia (hematocrit 30%: RR = 1.8; 95% CI, 1.1-2.9). In the dry season, anemia (hematocrit 30%) was the only predictor of fever incidence with a cumulative incidence of 10.0%. In nonanemic children, a parasite count of 2000/mcl was the next best predictor. In the rainy season, the best predictors of fever were age (4 years), enlarged spleen, and high parasite density (1/mcl). Even in the higher risk groups, the cumulative incidence was 20%. Most children with high parasite density do not develop fever subsequently. The association between parasite density and fever varies according to age and season. Since even high levels of parasite density do not reliably predict fever incidence, parasite density should be considered not so much a direct marker of an ongoing attack but as just one indicator of the likelihood of a current or imminent attack or even one just passed.

Seasonality, malaria, and impact of prophylaxis in a West African village I. Effect of anemia in pregnancy.

The importance of malaria as a cause of anemia in pregnancy in endemic areas remains controversial. The prevalence of anemia in pregnant women following the dry (May) and the rainy (November) seasons was compared in two successive years in Bougoula village (region of Sikasso, Mali). Phase I (1992) was observational and included 172 pregnant women and 208 controls. In Phase II (1993, 174 pregnant women and 206 controls), malaria prophylaxis with proguanil (200 mg/day) and chloroquine (300 mg/week) was offered to pregnant women. A strong seasonal variation in the prevalence of moderate to severe anemia in pregnant women (hematocrit < 30%) occurred in Phase I (dry season = 8.7%, rainy season = 41.2%). This variation was present only in women of parity lower than five, and paralleled variation in parasitemia. In Phase II, the seasonal variation of anemia was suppressed in women under malaria prophylaxis (presence of antimalarial metabolites in urine), and the overall prevalence of moderate to severe anemia in pregnancy decreased by 55.5% (22.8-74.3%). We conclude that malaria is the major cause of anemia in pregnancy in this region. A high priority should be given to prevention of malaria in pregnancy.

Seasonality, malaria, and impact of prophylaxis in a West African village. II. Effect on birthweight.

The impact of malaria on low birthweight was investigated in Bougoula village (Sikasso region, Mali). In two successive years, pregnant women were followed until delivery. Phase I (1992) was observational, with 135 complete observations. Phase II (1993) included 126 participants, who were offered malaria prophylaxis with proguanil (200 mg/day) and chloroquine (300 mg/week). The results show that 1) infants of first and second pregnancies had lower birth weights (-382.7 +/- 62.6 g; P < 0.0001) compared with higher rank pregnancies; 2) strong seasonal variation in birthweight was observed in Phase I, with an annual cycle, a nadir in January, and an amplitude of 372.4 g (P = 0.0002); 3) parasitemia measured during pregnancy was associated with lower birthweight in infants from first and second pregnancies, but not from higher parity mothers; and 4) malaria prophylaxis taken for 20 weeks or more in Phase II suppressed the seasonal variation of birthweight and the effect of low parity (+423.4 +/- 118.8 g; P = 0.0004). We conclude that malaria in pregnancy has an important negative impact on birthweight in first and second pregnancies. Prophylaxis with proguanil and chloroquine is an effective prophylaxis when taken for 20 weeks or more.

[Prone sleeping position and other risk factors in sudden infant death syndrome: a prevalence study in Geneva]. / Position ventrale de sommeil et autres facteurs de risque du syndrome de mort subite du nourrisson: une étude de prévalence à Genève.

A survey by telephone interviews has been carried out in 1993 in the canton of Geneva, in order to measure the prevalence of 3 risk factors for the sudden infant death syndrome (SIDS) and to evaluate the potential for SIDS prevention based on these factors: prone sleeping position, tobacco smoking by the parents during pregnancy, and no complete breast-feeding at 8 days of age. 278 families participated to the study, of 320 families who could be contacted by telephone in Geneva, from a random sample of 550 families having had a child in Geneva in the preceding 12 months. 40% of the infants had been put to bed in the prone position on the preceding evening 18% of the mothers had smoked during pregnancy. Prevalence of low birth weight was 4.9% for 0 to 4 cigarettes per day during pregnancy, 17.2% for 5 cigarettes and more. At one week, 16.5% of children were not exclusively breast-fed. On the basis of these results, it can be estimated that an effective prevention programme, centered on prone sleeping position could decrease the incidence of SIDS by 50% or more. An even greater fraction of cases, up to 80%, could be avoided by the prevention of the 3 studied factors. These estimates show the need to develop a mother and child health programme in Switzerland.