Household Structures and Savings: Evidence from Household Surveys

This paper examines the relationship between household structures, the institutions that shape them and physical and human capital accumulation using household and individual data from China, Indonesia, Côte d'Ivoire and Ghana. Household structures differ greatly across countries and are very diverse within countries. In the two African countries studied a large share of the population live in extended households and/or polygamous ones. Such household structures are the exception or even absent in the Asian cases, where nuclear monogamous households prevail. This paper finds that polygamy is negatively related to capital accumulation. Wealth per capita is significantly lower in polygamous households even after controlling for income, age and literacy of the household head. A first analysis of the possible channels suggests that the larger size of polygamous households plays an important role. A similar result is found for education: enrolment rates are never higher but frequently lower in these households. The diversity across countries demonstrates that polygamy has very different meanings across societies. Extended households are also examined. The analysis shows that those households that accommodate inactive members of the extended kin group are wealthier than other, comparable households. This result is consistent with accommodation of kin group members acting as a vehicle for solidarity that could also be regarded as a private "tax on success". The implicit transfers embedded in such mechanisms, including fostering, are very high compared to monetary and in-kind transfers and have often been overlooked in the analysis of social relations. --household structure,saving,polygamy,fostering,Africa,capital accumulation

Highly-efficient noise-assisted energy transport in classical oscillator systems

Photosynthesis is a biological process that involves the highly-efficient transport of energy captured from the sun to a reaction center, where conversion into useful biochemical energy takes place. Even though one can always use a quantum perspective to describe any physical process, since everything follows the laws of Quantum Mechanics, is the use of quantum theory imperative to explain this high efficiency? Making use of the quantum-classical correspondence of electronic energy transfer recently introduced by Eisfeld and Briggs [Phys. Rev. E 85, 046118 (2012)], we show here that the highly-efficient noise-assisted energy transport described by Rebentrost et al. [New J. Phys. 11, 033003 (2009)], and Plenio and Huelga [New J. Phys. 10, 113019 (2008)], as the result of the interplay between the quantum coherent evolution of the photosynthetic system and noise introduced by its surrounding environment, it can be found as well in purely classical systems. The wider scope of applicability of the enhancement of energy transfer assisted by noise might open new ways for developing new technologies aimed at enhancing the efficiency of a myriad of energy transfer systems, from information channels in micro-electronic circuits to long-distance high-voltage electrical lines.Comment: 4 pages, 3 figure

Modelling monetary transmission in UK manufacturing industry

This paper studies the transmission of monetary policy to industrial output in the UK. In order to capture asymmetries, a system of threshold equations is considered. However, unlike previous research, endogenous threshold parameters are allowed to be different for each equation. This approach is consistent with economic intuition and is shown to be of tangible importance after suitable econometric evaluation. Results show evidence of cross-sectional differences across industries and asymmetries in some sectors. These findings contribute to the debate about the importance of alternative economic theories to explain these asymmetries and support the use of a sectorally disaggregated approach to the analysis of monetary transmission

Atmospheric monitoring in the mm and sub-mm bands for cosmological observations: CASPER2

Cosmological observations from ground at millimetre and sub-millimetre wavelengths are affected by atmospheric absorption and consequent emission. The low and high frequency (sky noise) fluctuations of atmospheric performance imply careful observational strategies and/or instrument technical solutions. Measurements of atmospheric emission spectra are necessary for accurate calibration procedures as well as for site testing statistics. CASPER2, an instrument to explore the 90-450 GHz (3-15 1/cm) spectral region, was developed and verified its operation in the Alps. A Martin-Puplett Interferometer (MPI) operates comparing sky radiation, coming from a field of view (fov) of 28 arcminutes (FWHM) collected by a 62-cm in diameter Pressman-Camichel telescope, with a reference source. The two output ports of the interferometer are detected by two bolometers cooled down to 300 mK inside a wet cryostat. Three different and complementary interferometric techniques can be performed with CASPER2: Amplitude Modulation (AM), Fast-Scan (FS) and Phase Modulation (PM). An altazimuthal mount allows the sky pointing, possibly co-alligned to the optical axis of the 2.6-m in diameter telescope of MITO (Millimetre and Infrared Testagrigia Observatory, Italy). Optimal timescale to average acquired spectra is inferred by Allan variance analysis at 5 fiducial frequencies. We present the motivation for and design of the atmospheric spectrometer CASPER2. The adopted procedure to calibrate the instrument and preliminary performance of the instrument are described. Instrument capabilities were checked during the summer observational campaign at MITO in July 2010 by measuring atmospheric emission spectra with the three different procedures.Comment: 11 pages, 9 figures, 2 tables, Accepted for publication in MNRA

Low-temperature anomalies of a vapor deposited glass

We investigate the low temperature properties of two-dimensional Lennard-Jones glass films, prepared in silico both by liquid cooling and by physical vapor deposition. We identify deep in the solid phase a crossover temperature $T^*$, at which slow dynamics and enhanced heterogeneity emerge. Around $T^*$, localized defects become visible, leading to vibrational anomalies as compared to standard solids. We find that on average, $T^*$ decreases in samples with lower inherent structure energy, suggesting that such anomalies will be suppressed in ultra-stable glass films, prepared both by very slow liquid cooling and vapor deposition.Comment: 10 pages including appendices, 8 figures. Version accepted for Physical Review Material

Ideal isotropic auxetic networks from random networks

Auxetic materials are characterized by a negative Poisson's ratio, $\mathrm{\nu}$. As the Poisson's ratio becomes negative and approaches the lower isotropic mechanical limit of $\mathrm{\nu = -1}$, materials show enhanced resistance to impact and shear, making them suitable for applications ranging from robotics to impact mitigation. Past experimental efforts aimed at reaching the $\mathrm{\nu = -1}$ limit have resulted in highly anisotropic materials, which show a negative Poisson's ratio only when subjected to deformations along specific directions. Isotropic designs have only attained moderately auxetic behavior, or have led to structures that cannot be manufactured in 3D. Here, we present a design strategy to create isotropic structures from disordered networks that leads to Poisson's ratios as low as $\mathrm{\nu = -0.98}$. The materials conceived through this approach are successfully fabricated in the laboratory and behave as predicted. The Poisson's ratio $\mathrm{\nu}$ is found to depend on network structure and bond strengths; this sheds light on the structural motifs that lead to auxetic behavior. The ideas introduced here can be generalized to 3D, a wide range of materials, and a spectrum of length scales, thereby providing a general platform that could impact technology.Comment: 16 pages, 6 figure

Strengthening measurements from the edges: application-level packet loss rate estimation

Network users know much less than ISPs, Internet exchanges and content providers about what happens inside the network. Consequently users cannot either easily detect network neutrality violations or readily exercise their market power by knowledgeably switching ISPs. This paper contributes to the ongoing efforts to empower users by proposing two models to estimate -- via application-level measurements -- a key network indicator, i.e., the packet loss rate (PLR) experienced by FTP-like TCP downloads. Controlled, testbed, and large-scale experiments show that the Inverse Mathis model is simpler and more consistent across the whole PLR range, but less accurate than the more advanced Likely Rexmit model for landline connections and moderate PL

Microstructure and corrosion evolution of additively manufactured aluminium alloy AA7075 as a function of ageing

Additively manufactured high strength aluminium alloy AA7075 was prepared using selective laser melting. High strength aluminium alloys prepared by selective laser melting have not been widely studied to date. The evolution of microstructure and hardness, with the attendant corrosion, were investigated. Additively manufactured AA7075 was investigated both in the as-produced condition and as a function of artificial ageing. The microstructure of specimens prepared was studied using electron microscopy. Production of AA7075 by selective laser melting generated a unique microstructure, which was altered by solutionising and further altered by artificial ageing - resulting in microstructures distinctive to that of wrought AA7075-T6. The electrochemical response of additively manufactured AA7075 was dependent on processing history, and unique to wrought AA7075-T6, whereby dissolution rates were generally lower for additively manufactured AA7075. Furthermore, immersion exposure testing followed by microscopy, indicated different corrosion morphology for additively manufactured AA7075, whereby resultant pit size was notably smaller, in contrast to wrought AA7075-T6.Comment: 37 pages, includes 4 Tables and 11 Figure