226 research outputs found
No alignment of cattle along geomagnetic field lines found
This paper presents a study of the body orientation of domestic cattle on
free pastures in several European states, based on Google satellite
photographs. In sum, 232 herds with 3412 individuals were evaluated. Two
independent groups participated in our study and came to the same conclusion
that, in contradiction to the recent findings of other researchers, no
alignment of the animals and of their herds along geomagnetic field lines could
be found. Several possible reasons for this discrepancy should be taken into
account: poor quality of Google satellite photographs, difficulties in
determining the body axis, selection of herds or animals within herds, lack of
blinding in the evaluation, possible subconscious bias, and, most importantly,
high sensitivity of the calculated main directions of the Rayleigh vectors to
some kind of bias or to some overlooked or ignored confounder. This factor
could easily have led to an unsubstantiated positive conclusion about the
existence of magnetoreception.Comment: Added electronic supplement with source dat
Childhood health motivation and adult cardiometabolic health in the Childhood Determinants of Adult Health (CDAH) study
Objective: This research examined if childhood health motivation was associated with adult health behaviors and objectively measured health outcomes.Method: Data were from the Childhood Determinants of Adult Health study. Children aged 9 to 15 years in 1985 completed a questionnaire with health motivation items. In 2004-2006, when aged 26 to 36, participants completed assessments of health behaviors (smoking, diet, alcohol consumption, and physical activity) and cardiometabolic outcomes (body mass index, carotid intima-media thickness from ultrasound, and HOMA insulin resistance from fasting blood samples). Structural path regression analyses examined pathways from health motivation in childhood to adult cardiometabolic outcomes, mediated via adult health behaviors measured concurrently, controlling for age, sex and socioeconomic position.Results: There were 6,230 (49% female) children with data on health motivation. There were two latent constructs: health motivation (4 items: visiting a dentist, visiting a doctor, knowing about your body, and eating a good diet) and risk motivation (3 items: not being a smoker, not being fat, and not drinking alcohol). Greater health motivation was directly associated with nonsmoking, lower carotid intima-media thickness, and lower body mass index in adulthood. Greater risk motivation was directly associated with smoking, higher alcohol consumption, and poorer diets in adulthood. It was also indirectly associated with higher carotid intima-media thickness and higher HOMA insulin resistance via poorer health behaviors.Conclusions: Health motivation during childhood appears important to maintain health across the life course. It could be a target for interventions to improve cardiovascular health in children and adults
Maternal Exposure to Occupational Solvents and Childhood Leukemia
Many organic solvents are considered probable carcinogens. We carried out a population-based caseâcontrol study including 790 incident cases of childhood acute lymphoblastic leukemia and as many healthy controls, matched on age and sex. Maternal occupational exposure to solvents before and during pregnancy was estimated using the expert method, which involves chemists coding each individualâs job for specific contaminants. Home exposure to solvents was also evaluated. The frequency of exposure to specific agents or mixtures was generally low. Results were generally similar for the period ranging from 2 years before pregnancy up to birth and for the pregnancy period alone. For the former period, the odds ratio (OR), adjusted for maternal age and sex, for any exposure to all solvents together was 1.11 [95% confidence interval (CI), 0.88â1.40]. Increased risks were observed for specific exposures, such as to 1,1,1-trichloroethane (OR = 7.55; 95% CI, 0.92â61.97), toluene (OR = 1.88; 95% CI, 1.01â3.47), and mineral spirits (OR = 1.82; 95% CI, 1.05â3.14). There were stronger indications of moderately increased risks associated with exposure to alkanes (C5âC17; OR = 1.78; 95% CI, 1.11â2.86) and mononuclear aromatic hydrocarbons (OR = 1.64; 95% CI, 1.12â2.41). Risk did not increase with increasing exposure, except for alkanes, where a significant trend (p = 0.04) was observed. Home exposure was not associated with increased risk. Using an elaborate exposure coding method, this study shows that maternal exposure to solvents in the workplace does not seem to play a major role in childhood leukemia
General Relativity and Weyl Geometry
We show that the general theory of relativity can be formulated in the
language of Weyl geometry. We develop the concept of Weyl frames and point out
that the new mathematical formalism may lead to different pictures of the same
gravitational phenomena. We show that in an arbitrary Weyl frame general
relativity, which takes the form of a scalar-tensor gravitational theory, is
invariant with respect to Weyl tranformations. A kew point in the development
of the formalism is to build an action that is manifestly invariant with
respect to Weyl transformations. When this action is expressed in terms of
Riemannian geometry we find that the theory has some similarities with
Brans-Dicke gravitational theory. In this scenario, the gravitational field is
not described by the metric tensor only, but by a combination of both the
metric and a geometrical scalar field. We illustrate this point by, firstly,
discussing the Newtonian limit in an arbitrary frame, and, secondly, by
examining how distinct geometrical and physical pictures of the same phenomena
may arise in different frames. To give an example, we discuss the gravitational
spectral shift as viewed in a general Weyl frame. We further explore the
analogy of general relativity with scalar-tensor theories and show how a known
Brans-Dicke vacuum solution may appear as a solution of general relativity
theory when reinterpreted in a particular Weyl frame. Finally, we show that the
so-called WIST gravity theories are mathematically equivalent to Brans-Dicke
theory when viewed in a particular frame.Comment: LATEX, 22 page
Association of early life factors and brain tumour risk in a cohort study
Using population-based linked birth and cancer registry data, we investigated whether the risk of brain tumour in childhood (n=155) was associated with perinatal risk factors. This population-based cohort showed that being born into a larger family or to a mother with a history of miscarriage may increase childhood brain tumour risk
Infectious diseases in the first year of life, perinatal characteristics and childhood acute leukaemia
The objective of the present study was to investigate the role of early common infections and perinatal characteristics in the aetiology of childhood common leukaemia. A case-control study was conducted from 1995 to 1998 in France, and included 473 incident cases of acute leukaemia (AL) (408 acute lymphoblastic leukaemia (ALL), 65 acute myeloid leukaemia (AML) age-, sex- and region-matched with 567 population-based controls. Data on the medical history of the child and his/her environment were collected using self-administered questionnaires. Analyses were conducted using nonconditional logistic regression. A slight negative association with early infections was observed (OR=0.8; 95% CI (0.6-1.0)). The association was stronger for early gastrointestinal infections. Early day-care was found to be associated with a decreased risk of AL (OR=0.6; 95% CI (0.4-0.8) and OR=0.8; 95% CI (0.5-1.2) for day-care starting before age 3 months and between 3 and 6 months, respectively). No association with breast-feeding was observed, irrespective of its duration. A birth order of 4 or more was associated with a significantly increased risk of AL (OR=2.0; 95% CI (1.1-3.7) with ALL). A history of asthma was associated with a decreased risk of ALL (OR 0.5; 95% CI (0.3-0.90). Although the results regarding birth order and breast-feeding do not fit with Greaves' hypothesis, the study supports the hypothesis that early common infections may play a protective role in the aetiology of childhood leukaemia, although this effect was not more marked for common ALL
Breastfeeding and risk of childhood CNS tumours
We investigated infant feeding habits in relation to risk of childhood central nervous system tumours among 633 cases in the UK Childhood Cancer Study (UKCCS). No significant effect of breastfeeding was detected overall (odds ratio 1.01, confidence interval: 0.85â1.21) nor in any morphological subgroup. Similarly, no effect for the duration of breastfeeding or any other feeding practices was observed
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