It has been suggested that main risk factors for development of allergic diseases operate already during pregnancy and in early childhood. To study the association between gestational age, birth weight, parity and parental farming with the risk of atopy and asthma in young adults. In a prospective birth cohort study, 5192 subjects born in Northern Finland in 1966 were followed up at the age of 31. Skin prick tests were done to three of the most common allergens in Finland and to house dust mite. Data on doctor-diagnosed asthma was obtained from questionnaires. Perinatal data had already been collected during pregnancy. The risk of atopy increased linearly with increasing length of pregnancy among babies born in the 35th weak of gestation or later. Gestational age equal to, or over 40 weeks compared with less than 36 weeks was associated with an increased risk of atopy (multivariate odds ratio 1.65, 95% CI 1.16, 2.34). The association was stronger among farmers' children (P for interaction 0.01). High parity and being a farmer's child (multivariate odds ratio 0.50, 95% CI 0.42–0.60) was associated with decreased risk of atopy. In contrast, no associations were observed for doctor-diagnosed asthma. The results underline the importance of pregnancy and very early childhood in the development of atopy, and suggest that timing of the environmental exposure is of importance for the immune system. No association was observed for asthma, which may be due to the multifactorial origins of asthma.
These prospective data indicate that brisk walking and vigorous exercise are associated with substantial and similar reductions in the incidence of coronary events among women.
Nanoscience offers the promise of producing revolutionary advances in many areas of technology, ranging from electronics and computing to biology and medicine, and thus may impact in a substantial way our future lives. This presentation will provide an overview to the bottom-up paradigm for nanotechnology enabled using nanowire building blocks. First, the growth of nanowires, with composition controlled down to the atomic scale, their fundamental electronic properties, and the assembly of integrated structures will be described. Second, studies of nanowire based electronic circuits and nanocomputing systems will be critically examined. Third, nanowire devices configured as electrically-based biosensors will be discussed with an emphasis on disease detection and ultimate sensitivity limits of these nanodevices, as well as the potential linkage to biological information processing. Challenges and goals that must be met to realize these and other nanotechnologies in the future will be discussed.
Model equations governing the debonding and the pushout phases of the fiber pushout test are presented and are then evaluated for accuracy by comparing them with detailed numerical analyses of some specific examples. It is assumed that a residual compressive stress acts across the fiber/matrix interface and residual axial stress in the fiber is taken into account. The interface is characterized by a mode 2 debond toughness Λ and is assumed to develop a frictional stress upon sliding according to τ = τ 0 − μπ r, corresponding to a constant stress contribution and a Coulomb term. The model applies either to pushout of a single fiber embedded in a homogeneous matrix or to a fiber selected for pushout from a specimen sliced from a fiber reinforced composite. The effect of redistribution of residual stress due to slicing the composite in preparation of the specimen is addressed in numerical examples. The detailed numerical work establishes that the debond crack advancing down the fiber becomes unstable and breaks through to the bottom of the specimen when the debond tip reaches a distance about one and one half fiber radii from the bottom. The model equations provide a reasonably accurate description of the dependence of the pushout test on its many parameters.
This letter describes a method for producing chaotic transport trajectories in planar, microfluidic networks prepared by standard, single-step lithography and operated with a steady-state inflow of the fluids into the device. Gaseous slugs flowing through the network produce temporal variation of pressure distribution and lead to stretching and folding of the continuous fluid. Stabilization of the bubbles by surface-active agents is not necessary, and the method is compatible with the wide range of reactions performed in on-chip bioassays.
By means of an approach that employs alkali-metal alloys, bulk single-phase (RbxK1-x)(3)C(6O) superconductors have been prepared for all x between 0 and 1. For x = 1 it is shown that the maximum superconducting fraction, which approaches 100% in sintered pellets, occurs at a Rb to C(60) ratio of 3:1. More importantly, single-phase superconductors are formed at all intermediate values of x, and it is shown that the transition temperature (T(c)) increases linearly with x in this series of materials. The formation of a continuous range of solid solutions demonstrates that the rubidium- and potassium-doped C(60) superconducting phases must be isostructural, and furthermore, suggests that the linear increase in T(c) with x results from a chemical pressure effect.
This Account summarizes techniques for fabrication and applications in biomedicine of microfluidic devices fabricated in poly(dimethylsiloxane) (PDMS). The methods and applications described focus on the exploitation of the physical and chemical properties of PDMS in the fabrication or actuation of the devices. Fabrication of channels in PDMS is simple, and it can be used to incorporate other materials and structures through encapsulation or sealing (both reversible and irreversible).
