The Feminisation U, Cultural Norms, and the Plough

The feminisation U describes the tendency of female labour force participation (FLFP) to first decline and then rise in the process of development. Long considered to be a ‘stylised fact’, the feminisation U is actually supported by mixed evidence. This research identifies an important source of heterogeneity in the shape of the feminisation U across countries – the cultural norms and values engendered by the adoption of the plough in pre-industrial times. In line with existing theoretical accounts of the U-curve, which suggest that initial conditions are critical, we find evidence that a tradition of plough use intensifies the U-shaped path of FLFP. Based on a dynamic panel-data estimator, we find evidence of a significantly U-shaped path of FLFP in countries with a history of ancestral plough use, but no such relationship in ‘non-plough countries’. We also explore, and rule out, other potential drivers of heterogeneity (e.g. the timing of the Neolithic revolution), and investigate empirically the causal mechanisms that generate the feminisation U in plough countries. Our results address the empirical controversy surrounding the feminisation U, while shedding new light on the long-run effects of plough adoption

Exploring the material properties of small scale folded structures

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (page 21).make robotics more readily available to the average person. Although designs for a number of successful printable robots have already been produced, there has been little formal exploration into the materials properties of these structures. Three point bending tests were performed on beams made of the materials and cross-sectional geometries of current designs to determine the bending stiffness of the printable beams currently found in printable robots, particularly the printable quad-rotor frame. As expected the composite acrylic and PEEK triangular beam had the highest bending stiffness El at 4.15 ± 1.67 N*m2. The lowest El was the triangular PEEK beam in its weak configuration at 0.02 ± 0.005 N*m2. 3D printed ABS beams had an unreliable result, with El in the range of 11.7 ± 8.05 N*m2. Overall our experimentally calculated values for El were generally consistent with the theoretically calculated values, providing useful information to inform future design choices and understanding the limitations of printable robot structures.by Megan E. Uberti.S.B

BFACF-style algorithms for polygons in the body-centered and face-centered cubic lattices

In this paper the elementary moves of the BFACF-algorithm for lattice polygons are generalised to elementary moves of BFACF-style algorithms for lattice polygons in the body-centred (BCC) and face-centred (FCC) cubic lattices. We prove that the ergodicity classes of these new elementary moves coincide with the knot types of unrooted polygons in the BCC and FCC lattices and so expand a similar result for the cubic lattice. Implementations of these algorithms for knotted polygons using the GAS algorithm produce estimates of the minimal length of knotted polygons in the BCC and FCC lattices

Screen-Printed Biosensors for the Early Detection of Biomarkers Related to Alzheimer Disease: Preliminary Results

Abstract Alzheimer disease (AD), despite representing the most common type of dementia in elderly, is still lacking reliable methodologies for early diagnosis. A potential biomarker associated to AD development has been recently identified in the open isoform of p53, redox sensitive protein, currently quantified using a specific blood-based enzyme-linked immunosorbent assay (ELISA). In order to overcome ELISA limitations (level of detection, standardization and reliability), this study aimed to realize a low cost highly sensitive portable point-of-care (PoC) testing system based on screen printed electrochemical sensors (SPES). The study specifically reported the design of the platform, including the sensing probe and the electronic circuit devoted to the conditioning of the electric signal. Preliminary results were obtained from circuit testing by using controlled concentrations of electrolytic solutions and from an initial calibration stage by using Anodic Stripping Voltammetry (ASV) measurements. Future works will address the quantification of unknown concentration of unfolded p53 in peripheral blood samples, thus to validate the here-presented low cost, easy to use and highly precise platform

Landmark Optimization Using Local Curvature for Point-Based Nonlinear Rodent Brain Image Registration

Purpose. To develop a technique to automate landmark selection for point-based interpolating transformations for nonlinear medical image registration. Materials and Methods. Interpolating transformations were calculated from homologous point landmarks on the source (image to be transformed) and target (reference image). Point landmarks are placed at regular intervals on contours of anatomical features, and their positions are optimized along the contour surface by a function composed of curvature similarity and displacements of the homologous landmarks. The method was evaluated in two cases (n = 5 each). In one, MRI was registered to histological sections; in the second, geometric distortions in EPI MRI were corrected. Normalized mutual information and target registration error were calculated to compare the registration accuracy of the automatically and manually generated landmarks. Results. Statistical analyses demonstrated significant improvement (P < 0.05) in registration accuracy by landmark optimization in most data sets and trends towards improvement (P < 0.1) in others as compared to manual landmark selection

Nanoscale friction of biomimetic hair surfaces

We investigate the nanoscale friction between biomimetic hair surfaces using chemical colloidal probe atomic force microscopy experiments and nonequilibrium molecular dynamics simulations. In the experiments, friction is measured between water-lubricated silica surfaces functionalised with monolayers formed from either octadecyl or sulfonate groups, which are representative of the surfaces of virgin and ultimately bleached hair, respectively. In the simulations, friction is monitored between coarse-grained model hair surfaces with different levels of chemical damage, where a specified amount of grafted octadecyl groups are randomly replaced with sulfonate groups. The sliding velocity dependence of friction in the simulations can be described using an extended stress-augmented thermally activation model. As the damage level increases in the simulations, the friction coefficient generally increases, but its sliding velocity-dependence decreases. At low sliding velocities, which are closer to those encountered experimentally and physiologically, we observe a monotonic increase of the friction coefficient with damage ratio, which is consistent with our new experiments using biomimetic surfaces and previous ones using real hair. This observation demonstrates that modified surface chemistry, rather than roughness changes or subsurface damage, control the increase in nanoscale friction of bleached or chemically damaged hair. We expect the methods and biomimetic surfaces proposed here to be useful to screen the tribological performance of hair care formulations both experimentally and computationally