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Introduction: Several common breast cancer genetic susceptibility variants have recently been identified. We aimed to determine how these variants combine with a subset of other known risk factors to influence breast cancer risk in white women of European ancestry using case-control studies participating in the Breast Cancer Association Consortium.Methods: We evaluated two-way interactions between each of age at menarche, ever having had a live birth, number of live births, age at first birth and body mass index (BMI) and each of 12 single nucleotide polymorphisms (SNPs) (10q26-rs2981582 (FGFR2), 8q24-rs13281615, 11p15-rs3817198 (LSP1), 5q11-rs889312 (MAP3K1), 16q12-rs3803662 (TOX3), 2q35-rs13387042, 5p12-rs10941679 (MRPS30), 17q23-rs6504950 (COX11), 3p24-rs4973768 (SLC4A7), CASP8-rs17468277, TGFB1-rs1982073 and ESR1-rs3020314). Interactions were tested for by fitting logistic regression models including per-allele and linear trend main effects for SNPs and risk factors, respectively, and single-parameter interaction terms for linear departure from independent multiplicative effects.Results: These analyses were applied to data for up to 26,349 invasive breast cancer cases and up to 32,208 controls from 21 case-control studies. No statistical evidence of interaction was observed beyond that expected by chance. Analyses were repeated using data from 11 population-based studies, and results were very similar.Conclusions: The relative risks for breast cancer associated with the common susceptibility variants identified to date do not appear to vary across women with different reproductive histories or body mass index (BMI). The assumption of multiplicative combined effects for these established genetic and other risk factors in risk prediction models appears justified. © 2010 Milne et al.; licensee BioMed Central Ltd.

Background : Biological materials have a complex, hierarchical structure, with vital structural features present at all size scales, from the nanoscale to the macroscale. A method that can connect information at multiple length scales has great potential to reveal novel information. This article presents one such method with an application to the bamboo culm wall. Moso (Phyllostachys edulis) bamboo is a commercially important bamboo species. At the cellular level, bamboo culm wall consists of vascular bundles embedded in a parenchyma cell tissue matrix. The microfibril angle (MFA) in the bamboo cell wall is related to its macroscopic longitudinal stiffness and strength and can be determined at the nanoscale with wide-angle X-ray scattering (WAXS). Combining WAXS with X-ray microtomography (XMT) allows tissue-specific study of the bamboo culm without invasive chemical treatment. Results : The scattering contribution of the fiber and parenchyma cells were separated with spatially-localized WAXS. The fiber component was dominated by a high degree of orientation corresponding to small MFAs (mean MFA 11 degrees). The parenchyma component showed significantly lower degree of orientation with a maximum at larger angles (mean MFA 65 degrees). The fiber ratio, the volume of cell wall in the fibers relative to the overall volume of cell wall, was determined by fitting the scattering intensities with these two components. The fiber ratio was also determined from the XMT data and similar fiber ratios were obtained from the two methods, one connected to the cellular level and one to the nanoscale. X-ray diffraction tomography was also done to study the differences in microfibril orientation between fibers and the parenchyma and further connect the microscale to the nanoscale. Conclusions : The spatially-localized WAXS yields biologically relevant, tissue-specific information. With the custommade bench-top set-up presented, diffraction contrast information can be obtained from pl

Background Biological materials have a complex, hierarchical structure, with vital structural features present at all size scales, from the nanoscale to the macroscale. A method that can connect information at multiple length scales has great potential to reveal novel information. This article presents one such method with an application to the bamboo culm wall. Moso (Phyllostachys edulis) bamboo is a commercially important bamboo species. At the cellular level, bamboo culm wall consists of vascular bundles embedded in a parenchyma cell tissue matrix. The microfibril angle (MFA) in the bamboo cell wall is related to its macroscopic longitudinal stiffness and strength and can be determined at the nanoscale with wide-angle X-ray scattering (WAXS). Combining WAXS with X-ray microtomography (XMT) allows tissue-specific study of the bamboo culm without invasive chemical treatment. Results The scattering contribution of the fiber and parenchyma cells were separated with spatially-localized WAXS. The fiber component was dominated by a high degree of orientation corresponding to small MFAs (mean MFA 11°). The parenchyma component showed significantly lower degree of orientation with a maximum at larger angles (mean MFA 65°). The fiber ratio, the volume of cell wall in the fibers relative to the overall volume of cell wall, was determined by fitting the scattering intensities with these two components. The fiber ratio was also determined from the XMT data and similar fiber ratios were obtained from the two methods, one connected to the cellular level and one to the nanoscale. X-ray diffraction tomography was also done to study the differences in microfibril orientation between fibers and the parenchyma and further connect the microscale to the nanoscale. Conclusions The spatially-localized WAXS yields biologically relevant, tissue-specific information. With the custom-made bench-top set-up presented, diffraction contrast information can be obtained from plant tissue

Bamboo is an underutilized resource widely available in countries with rapidly developing economies. Structural bamboo products, analogous to wood products, allow flexibility in the shape and dimensions of bamboo structural members. Here, the ultrastructure, microstructure, cell wall properties and flexural properties of three species of bamboo (Moso, Guadua and Tre Gai) are compared. At a given density, the axial modulus of elasticity of Guadua is higher than that of Moso or Tre Gai, which are similar; ultrastructural results suggest that Guadua has a higher solid cell wall stiffness. At a given density, their moduli of rupture are similar., National Science Foundation (U.S.) (OISE-1258574)

The flexural properties in the longitudinal direction for natural and thermo-hydro-mechanically densified Moso bamboo (Phyllostachys pubescens Mazel) culm wall material are measured. The modulus of elasticity (MOE) and modulus of rupture (MOR) increase with densification, but at the same density, the natural material is stiffer and stronger than the densified material. This observation is primarily attributed to bamboo’s heterogeneous structure and the role of the parenchyma in densification. The MOE and MOR of both the natural and densified bamboo appear linearly related to density. Simple models are developed to predict the flexural properties of natural bamboo. The structure of the densified bamboo is modelled, assuming no densification of bamboo fibers, and the flexural properties of densified bamboo are then predicted using this structure and the same cell wall properties of that of the natural material modelling. The results are then compared with those for two analogous structural bamboo products: Moso bamboo glulam and scrimber., National Science Foundation (U.S.) (Grant 1258574)

The modulus of elasticity (MOE) of three-layer moso bamboo (Phyllostachys pubescens Mazel) Oriented Strand Board (OSB) was modelled using a multiscale approach proposed for wood OSB. The modelling approach for wood OSB was adapted to bamboo OSB by accounting for the different structures of wood and bamboo tissue. The MOE of moso bamboo OSB was measured previously in bending; the strands in the surface layer had a preferred orientation and were either from the internode region of the culm or contained node tissue. The model for loading parallel to the preferred orientation of the surface strands gives a good description of the measured values of MOE for boards with internode surface strands (8.6 GPa modelled compared to 8.1 GPa previously measured), but overpredicts that for boards with surface strands containing nodes (8.8 GPa modelled compared to 6.7 previously measured). The model for loading perpendicular to the preferred orientation of the surface strands gives a good description of the MOE data if the core layer moduli are estimated using compliance averaging, for specimens with and without nodes (1.5 GPa modelled compared to 1.5 GPa previously measured).

Balsa wood is one of the preferred core materials in structural sandwich panels, in applications ranging from wind turbine blades to boats and aircraft. Here, we investigate the mechanical behavior of balsa as a function of density, which varies from roughly 60 to 380 kg/m3. In axial compression, bending, and torsion, the elastic modulus and strength increase linearly with density while in radial compression, the modulus and strength vary nonlinearly. Models relating the mechanical properties to the cellular structure and to the density, based on deformation and failure mechanisms, are described. Finally, wood cell-wall properties are determined by extrapolating the mechanical data for balsa, and are compared with the reduced modulus and hardness of the cell wall measured by nanoindentation.

Hierarchical cellular structures are ubiquitous in nature because of their low-density, high-specific properties, and multifunctionality. Inspired by these systems, we created lightweight ceramic architectures composed of closed-cell porous struts patterned in the form of hexagonal and triangular honeycombs by direct foam writing. The foam ink contains bubbles stabilized by attractive colloidal particles suspended in an aqueous solution. The printed and sintered ceramic foam honeycombs possess low relative density (∼6%). By tailoring their microstructure and geometry, we created honeycombs with different modes of deformation, exceptional specific stiffness, and stiffness values that span over an order of magnitude. This capability represents an important step toward the scalable fabrication of hierarchical porous materials for applications, including lightweight structures, thermal insulation, tissue scaffolds, catalyst supports, and electrodes., National Science Foundation (U.S.) (Grant DMR 1305284)

We investigate the elastic behavior of periodic hexagonal honeycombs over a wide range of relative densities and cell geometries, using both analytical and numerical approaches. Previous modeling approaches are reviewed and their limitations identified. More accurate estimates of all nine elastic constants are obtained by modifying the analysis of Gibson and Ashby (1997) to account for the nodes at the intersection of the vertical and inclined members. The effect of the nodes becomes significant at high relative densities. We then compare the new analytical equations with previous analytical models, with a numerical analysis based on a computational homogenization technique and with data for rubber honeycombs over a wide range of relative densities and cell geometries. The comparisons show that both the new analytical equations and numerical solutions give a remarkably good description of the data. The results provide new insights into understanding the mechanics of honeycombs and designing new cellular materials in the future.

Background: Biological materials have a complex, hierarchical structure, with vital structural features present at all size scales, from the nanoscale to the macroscale. A method that can connect information at multiple length scales has great potential to reveal novel information. This article presents one such method with an application to the bamboo culm wall. Moso (Phyllostachys edulis) bamboo is a commercially important bamboo species. At the cellular level, bamboo culm wall consists of vascular bundles embedded in a parenchyma cell tissue matrix. The microfibril angle (MFA) in the bamboo cell wall is related to its macroscopic longitudinal stiffness and strength and can be determined at the nanoscale with wide-angle X-ray scattering (WAXS). Combining WAXS with X-ray microtomography (XMT) allows tissue-specific study of the bamboo culm without invasive chemical treatment. Results: The scattering contribution of the fiber and parenchyma cells were separated with spatially-localized WAXS. The fiber component was dominated by a high degree of orientation corresponding to small MFAs (mean MFA 11°). The parenchyma component showed significantly lower degree of orientation with a maximum at larger angles (mean MFA 65°). The fiber ratio, the volume of cell wall in the fibers relative to the overall volume of cell wall, was determined by fitting the scattering intensities with these two components. The fiber ratio was also determined from the XMT data and similar fiber ratios were obtained from the two methods, one connected to the cellular level and one to the nanoscale. X-ray diffraction tomography was also done to study the differences in microfibril orientation between fibers and the parenchyma and further connect the microscale to the nanoscale. Conclusions: The spatially-localized WAXS yields biologically relevant, tissue-specific information. With the custom-made bench-top set-up presented, diffraction contrast information can be obtained from plant tissue (1) f

Monolithic silica aerogels are well known for their low thermal conductivity (approximately 15 mW/(m K)) (Aegerter et al. (Eds.), 2011. Aerogels Handbook, first ed., Springer-Verlag New York, LLC, New York, NY). Their low relative density (typically less than 5%) reduces conduction through the solid and their small pore size, typically less than one hundred nanometers, on the order of the mean free path of air, reduces conduction through air, as well as convection and radiation. As they are fragile and brittle, they are often used in a granular form in thermal insulation, with some increase in their thermal conductivity from the air between the granules. Here, we describe a technique for compacting a bed of granular silica aerogel that reduces the thermal conductivity from 24 mW/(m K) (when uncompacted) to 13 mW/(m K) (after compaction). We find that there is an optimum level of compaction to minimize the thermal conductivity: at higher levels of compaction, the contact area between the granules increases and the granules densify, increasing conduction through the solid., DuPont MIT Alliance

Within the general framework of developing a cement‐based sandwich panel for housing construction, wood‐cement composites were identified as a promising facing material. Five commercially available wood‐cement and natural‐fiber‐cement board products were studied in an experimental program. The modulus of elasticity, the limit of proportionality stress, the modulus of rupture, and the post‐cracking behavior were measured in three‐point bending. The compressive strength and failure mode were characterized from uniaxial compression tests on small cubic specimens. The microstructure of these composites was characterized using a scanning electron microscope. The effect of the fiber reinforcement on the mechanical properties was related to the observed behavior.

Monolithic silica aerogels provide exceptional thermal insulation but have low mechanical properties. For instance, their flexural strength is typically 0.03–0.08 MPa. Here, we report on the development of a truss-core sandwich panel filled with compacted aerogel granules, designed to provide both mechanical support and thermal insulation. Mechanical and thermal properties of the sandwich panel prototype were measured and compared with theoretical models available in the literature. The models give a good description of the properties of aerogel-filled truss-core sandwich panels., DuPont MIT Alliance

Bamboo has been used structurally for thousands of years. Recently, structural bamboo products analogous to wood products have become of interest both commercially and academically. This file contains original experimental results of an investigation of both the microstructure and mechanical properties of natural Moso bamboo (Phyllostachys pubescens). One of the primary aims of the investigation is to contribute data and knowledge in order to facilitate the design of products and structures with bamboo. The authors of the dataset hope making the data available allows for easy comparison and combination with others’ results, thusly furthering this goal. The raw experimental data contained in this file is the dataset presented in the article “The Structure and Mechanics of Moso Bamboo Material” in Journal of the Royal Society Interface, with which the dataset shares a name. The data is also used in “Understanding the Structural Properties of Moso Bamboo to Engineer Sustainable Structural Bamboo Products” in the 2014 World Conference Engineering Timber Engineering Proceedings. Bamboo is known to have radial and longitudinal density gradients in the tissue. In this study, the microstructural and mechanical aspects of these gradients are the primary focus. Internodes from a single culm of Moso bamboo, obtained from Bamboo Craftsman Company (Portland, Oregon), are used. Microstructural images obtained with scanning electron microscopy (SEM) are used to determine volume fractions and solid fractions of the parenchyma and vascular bundles. These images are given in this dataset. The mechanical properties measured are: the axial Young's modulus in bending, axial modulus of rupture (in bending), axial compressive strength, and radial and tangential compressive strengths. Small mechanical test specimens (for every test type) are cut at different longitudinal (internodes) and radial positions to assess the gradients’ effects on mechanical properties. Raw data from these tests w, This dataset is based upon work supported by the National Science Foundation OISE: 1258574.

Background: The presence of perfluoroalkyl acids (PFAAs) in breast milk has been documented, but their lactational transfer has been rarely studied. Determination of the elimination rates of, these chemicals during breastfeeding is important and critical for assessing exposure in mothers, and infants., O b jectives: We aimed to investigate the association between breastfeeding and maternal serum, concentrations of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoic, acid (PFNA), and perfluorohexane sulfonate (PFHxS). For a subset of the population, for, whom we also have their infants' measurements, we investigated associations of breastfeeding with, infant serum PFAA concentrations., Methods: The present analysis included 633 women from the C8 Science Panel Study who had, a child < 3.5 years of age and who provided blood samples and reported detailed information on, breastfeeding at the time of survey. PFAA serum concentrations were available for all mothers and, 8% (n=49) of the infants. Maternal and infant serum concentrations were regressed on duration of, breastfeeding. R esults: Each month of breastfeeding was associated with lower maternal serum concentrations, of PFOA (-3%, 95% CI:-5, -2%), PFOS (-3%, 95% CI:-3, -2%), PFNA (-2%, 95% CI, -2, -1%), and PFHxS (-1%, 95% CI:-2, 0%). The infant PFOA and PFOS serum concentrations, were 6% (95% CI: 1, 10%) and 4% (95% CI: 1, 7%) higher per month of breastfeeding., C onclusions: Breast milk is the optimal food for infants, but is also a PFAA excretion route for, lactating mothers and exposure route for nursing infants.

Background: The single-nucleotide polymorphism (SNP) 5p12-rs10941679 has been found to be associated with risk of breast cancer, particularly estrogen receptor (ER)-positive disease. We aimed to further explore this association overall, and by tumor histopathology, in the Breast Cancer Association Consortium. Methods: Data were combined from 37 studies, including 40,972 invasive cases, 1,398 cases of ductal carcinoma in situ (DCIS), and 46,334 controls, all of white European ancestry, as well as 3,007 invasive cases and 2,337 controls of Asian ancestry. Associations overall and by tumor invasiveness and histopathology were assessed using logistic regression. Results: For white Europeans, the per-allele OR associated with 5p12-rs10941679 was 1.11 (95% CI = 1.08-1.14, P = 7 x 10(-18)) for invasive breast cancer and 1.10 (95% CI = 1.01-1.21, P = 0.03) for DCIS. For Asian women, the estimated OR for invasive disease was similar (OR 1.07, 95% CI = 0.99-1.15, P = 0.09). Further analyses suggested that the association in white Europeans was largely limited to progesterone receptor (PR)positive disease (per-allele OR = 1.16, 95% CI = 1.12-1.20, P = 1 x 10(-18) vs. OR = 1.03, 95% CI = 0.99-1.07, P = 0.2 for PR-negative disease; P-heterogeneity 2 x 10(-7)); heterogeneity by ER status was not observed (P = 0.2) once PR status was accounted for. The association was also stronger for lower grade tumors [per-allele OR (95% CI) 1.20 (1.14-1.25), 1.13 (1.09-1.16), and 1.04 (0.99-1.08) for grade 1, 2, and 3/4, respectively; Ptrend 5 x 10(-7)]. Conclusion: 5p12 is a breast cancer susceptibility locus for PR-positive, lower grade breast cancer. Impact: Multicenter fine-mapping studies of this region are needed as a first step to identifying the causal variant or variants. Cancer Epidemiol Biomarkers Prev; 20(10); 2222-31. (C) 2011 AACR.

Introduction Several common breast cancer genetic susceptibility variants have recently been identified. We aimed to determine how these variants combine with a subset of other known risk factors to influence breast cancer risk in white women of European ancestry using case-control studies participating in the Breast Cancer Association Consortium. Methods We evaluated two-way interactions between each of age at menarche, ever having had a live birth, number of live births, age at first birth and body mass index (BMI) and each of 12 single nucleotide polymorphisms (SNPs) (10q26-rs2981582 (FGFR2), 8q24-rs13281615, 11p15-rs3817198 (LSP1), 5q11-rs889312 (MAP3K1), 16q12-rs3803662 (TOX3), 2q35-rs13387042, 5p12-rs10941679 (MRPS30), 17q23-rs6504950 (COX11), 3p24-rs4973768 (SLC4A7), CASP8-rs17468277, TGFB1-rs1982073 and ESR1-rs3020314). Interactions were tested for by fitting logistic regression models including per-allele and linear trend main effects for SNPs and risk factors, respectively, and single-parameter interaction terms for linear departure from independent multiplicative effects. Results These analyses were applied to data for up to 26,349 invasive breast cancer cases and up to 32,208 controls from 21 case-control studies. No statistical evidence of interaction was observed beyond that expected by chance. Analyses were repeated using data from 11 population-based studies, and results were very similar. Conclusions The relative risks for breast cancer associated with the common susceptibility variants identified to date do not appear to vary across women with different reproductive histories or body mass index (BMI). The assumption of multiplicative combined effects for these established genetic and other risk factors in risk prediction models appears justified.

Why are things in nature shaped the way they are? How do birds fly? Why do bird nests look the way they do? How do woodpeckers peck? These are the types of questions Dr. Lorna Gibson's freshman seminar at MIT has been investigating. We invite you to explore with us. Questions such as these are the subject of biomimetic research. When engineers copy the shapes found in nature we call it Biomimetics. The word biomimic comes from bio, as in biology and mimetic, which means to copy. Join us as we explore and look for answers to why similar shapes occur in so many natural things and how physics change the shape of nature.

Phenomenology of mechanical behavior of materials at the macroscopic level. Relationship of mechanical behavior to material structure and mechanisms of deformation and failure. Topics include: elasticity, viscoelasticity, plasticity, creep, fracture, and fatigue. Case studies and examples drawn from a variety of classes of materials including: metals, ceramics, polymers, thin films, composites, and cellular materials.

Why are things in nature shaped the way they are? Why can't trees grow taller than they are? Why is grass skinny and hollow? Why are some leaves full of holes? These are the types of questions Dr. Lorna Gibson's freshman seminar at MIT has been investigating. We invite you to explore with us. Questions such as these are the subject of biomimetic research. When engineers copy the shapes found in nature we call it Biomimetics. the word biomimic comes from bio, as in biology and mimetic, which means to copy. Join us as we explore and look for answers to why similar shapes occur in so many natural things and how physics change the shape of nature.

Phenomenology of mechanical behavior of materials at the macroscopic level. Relationship of mechanical behavior to material structure and mechanisms of deformation and failure. Topics include: elasticity, viscoelasticity, plasticity, creep, fracture, and fatigue. Case studies and examples drawn from a variety of classes of materials including: metals, ceramics, polymers, thin films, composites, and cellular materials.

Electrical, optical, magnetic, and mechanical properties of metals, semiconductors, ceramics and polymers. Discussion of roles of bonding, structure (crystalline, defect, energy band and microstructure) and composition in influencing and controlling physical properties. Case studies drawn from a variety of applications including semiconductor diodes, optical detectors, sensors, thin films, biomaterials, composites, and cellular materials.

Structural sandwich panels are composed of two thin, stiff skins separated by a light weight core. The faces are typically strong materials such as aluminum fiber reinforced composites, while honeycombs or foams are used in the core. The separation of the faces increase the moment of inertia of the panel with minimum increase in weight. Because of this, these panels are extremely efficient in bending and are used in applications where the weight of the member is critical: aircraft, marine, and land vehicles; portable structures; construction in remote areas; roofing shells; and some types of sports equipment (e.g., modern downhill skis). In all of these, the mechanical behavior of the sandwich panel depends on the strength and stiffness of the face and the core, on the geometry of the panel (the core and face thicknesses), and on the bond strength between the faces and the core. The goal of this research is to determine the core density as well as the core and face thicknesses that minimize the weight of a sandwich panel for given structural requirements. This will improve the minimum design of structural sandwich panels in a manner not previously possible.

This report contains a software program for the optimum design of sandwich panels. This program calculates the minimum weight design of sandwich beams and plates subject to stiffness and/or strength constraints. The program has been designed to run on an IBM PC compatible computer. The analysis performed by the program is described together with a complete listing of program. The program is available on diskette which interested users may obtain from Professor Lorna Gibson at MIT. Keywords: Advanced construction materials; Structural composites; Sandwich panels; Building materials; Composite materials.

We conducted a systematic review to assess the effectiveness of Community Based Rehabilitation (CBR) for people with physical and mental disabilities in low- and middle-income countries, and/or their family/carers, and community. We identified 15 eligible studies, 10 of which were randomised controlled studies. Overall, the studies suggested that CBR may be effective in improving the clinical outcomes and enhancing functioning and quality of life of the person with disabilities and his/her carer. However, this conclusion must be interpreted with caution due to the small number of studies, concerns about study quality, and lack of information on cost-effectiveness of the interventions.