Second-to-Fourth Digit Ratio Has a Non-Monotonic Impact on Altruism

Gene-culture co-evolution emphasizes the joint role of culture and genes for the emergence of altruistic and cooperative behaviors and behavioral genetics provides estimates of their relative importance. However, these approaches cannot assess which biological traits determine altruism or how. We analyze the association between altruism in adults and the exposure to prenatal sex hormones, using the second-to-fourth digit ratio. We find an inverted U-shaped relation for left and right hands, which is very consistent for men and less systematic for women. Subjects with both high and low digit ratios give less than individuals with intermediate digit ratios. We repeat the exercise with the same subjects seven months later and find a similar association, even though subjects' behavior differs the second time they play the game. We then construct proxies of the median digit ratio in the population (using more than 1000 different subjects), show that subjects' altruism decreases with the distance of their ratio to these proxies. These results provide direct evidence that prenatal events contribute to the variation of altruistic behavior and that the exposure to fetal hormones is one of the relevant biological factors. In addition, the findings suggest that there might be an optimal level of exposure to these hormones from social perspective.Financial support from the Spanish Ministry of Science and Innovation (ECO2010{17049; ECO2009-09120), the Government of Andalusia Project for Excellence in Research (P07.SEJ.02547), the Government of the Basque Country (IT-223–07) and Fundacion Ramon Areces (I+D-2011)is gratefully acknowledged

Natural disasters and indicators of social cohesion

Do adversarial environmental conditions create social cohesion? We provide new answers to this question by exploiting spatial and temporal variation in exposure to earthquakes across Chile. Using a variety of methods and controlling for a number of socio-economic variables, we find that exposure to earthquakes has a positive effect on several indicators of social cohesion. Social cohesion increases after a big earthquake and slowly erodes in periods where environmental conditions are less adverse. Our results contribute to the current debate on whether and how environmental conditions shape formal and informal institutions

An overview of using small punch testing for mechanical characterization of MCrAlY bond coats

Considerable work has been carried out on overlay bond coats in the past several decades because of its excellent oxidation resistance and good adhesion between the top coat and superalloy substrate in the thermal barrier coating systems. Previous studies mainly focus on oxidation and diffusion behavior of these coatings. However, the mechanical behavior and the dominant fracture and deformation mechanisms of the overlay bond coats at different temperatures are still under investigation. Direct comparison between individual studies has not yet been achieved due to the fragmentary data on deposition processes, microstructure and, more apparently, the difficulty in accurately measuring the mechanical properties of thin coatings. One of the miniaturized specimen testing methods, small punch testing, appears to have the potential to provide such mechanical property measurements for thin coatings. The purpose of this paper is to give an overview of using small punch testing to evaluate material properties and to summarize the available mechanical properties that include the ductile-to-brittle transition and creep of MCrAlY bond coat alloys, in an attempt to understand the mechanical behavior of MCrAlY coatings over a broad temperature range

Achievable tolerances in robotic feature machining operations using a low-cost hexapod

Portable robotic machine tools potentially allow feature machining processes to be brought to large parts in various industries, creating an opportunity for capital expenditure and operating cost reduction. However, robots lack the machining capability of conventional equipment, which ultimately results in dimensional errors in parts. This work showcases a low-cost hexapod-based robotic machine tool and presents experimental research conducted to investigate how the widely researched robotic machining challenges, e.g. structural dynamics and kinematics, translate to achievable tolerance ranges in real-world production to highlight currently feasible applications and provide a context for considering technology improvements. Machining trials assess the total dimensional errors in the final part over multiple geometries. A key finding is error variation which is in the sub-millimetre range, although, in some cases, upper tolerance limits < 100 μm are achieved. Practical challenges are also noted. Most significantly, it is demonstrated that dimensional machining error is mainly systematic in nature and therefore that the total error can be dramatically reduced with in situ measurement and compensation. Potential is therefore found to achieve a flexible, high-performance robotic machining capability despite complex and diverse underlying scientific challenges. Overall, the work presented highlights achievable tolerances in low-cost robotic machining and opportunities for improvement, also providing a practical benchmark useful for process selection

Nano a mikro-formy titanátu vápenatého: syntéza, vlastnosti a použití

Tento článek shrnuje syntetické přístupy, vlastnosti a potenciální využití nano- a mikronových forem částic a povlaků titaničitanu vápenatého CaTiO3 (CT) a jeho kompozitů. Naším cílem je klasifikovat tyto formy podle způsob jejich výroby a článek poskytuje stručný přehled syntetických metod, vlastností a potenciálních aplikací těchto forem, které jsou motivovány luminiscencí, fotokatalytickým a katalytickým účinkem, schopností odstraňovat znečišťující látky, indukcí tvorby biomimetického hydroxylapatitu a využitím v bioinženýrství. Studie se podrobně zabývá formami CT ve vztahu k jejich vlatnostem jako jsou luminiscence, struktura, tvorba biomimetických kalciumfosfátů a a popisuje osseointegraci s kostí tkání.This article reviews synthetic approaches, properties and potential use of nano and micron sized forms of particles and coats of calcium titanate CaTiO3 and its composites. Our aim is to classify these forms according to the way of their fabrication and provide a brief outline of synthetic methods, properties and potential applications of these forms as inspired from luminescence, photocatalytic and catalytic performance, pollutants removal ability, inducement of biomimetic hydroxylapatite formation and bioengineering. The significance of the CT forms in luminescence-structure relationship, biomimetic calcium phosphates formation and osseointegration with bone tissue are dealt with in more detail

Porézní geopolymery: způsoby zpracování a vlastnosti

Keramika s porézní buněčnou strukturou představuje specifickou třídu materiálů obsahující vysokou úroveň pórovitosti (vyšší než 60 objemových %), které se vyznačují trojrozměrným uspořádáním otevřených a / nebo uzavřených buněk. Díky své struktuře vykazuje keramika s otevřenou pórovitostí jedinečnou kombinaci vlastností, jako je nízká hustota, nízká tepelná vodivost, nízkou hmotnost, vysoká propustnost, vysoká odolnost vůči tepelným nárazům a vysokou specifickou povrchovou plochu, což ji činí velmi atraktivní pro různé technické aplikace. Porézní geopolymery vykazují zajímavé vlastnosti v oblasti porézních anorganických materiálů a to díky jedinečné kombinaci dobré tepelné stability a mechanických vlastností. Zajímavým technologickým znakem je to, že jejich kinetika tuhnutí je snadno nastavitelná a díky chemickému složení na bázi keramiky vykazují velmi dobrou stabilitu při zvýšených teplotách. Metody používané pro výrobu porézních geopolymerů lze rozdělit podle technologických přístupů. Bylo zkoumáno mnoho přístupů, jak připravit porézní houby nebo pěny z geopolymerních systémů jako jsou: plynná metoda, rychlé tuhnutí, napěňování, vymrazování anebo jejich kombinace. Pokud jde o makro/mikrostrukturu buněk, může být příprava silně ovlivněna různými charakteristikami, jako jsou: chemické složení, reologické vlastnosti hmot, kinetika tvorby pórů a teplota vytvrzení. Tato studie představuje technologické metody přípravy porézních geopolymerů s ohledem na typy porézních materiálů a experimentální výsledky v této oblasti.Cellular ceramics constitute a specific class of materials containing a high level of porosity, greater than 60 vol%, which are characterized by the presence of three-dimensionally arranged open and/or closed cells. Because of their structure, cellular ceramics exhibit a unique combination of properties such as low density, low thermal conductivity, low thermal mass, high permeability, high thermal shock resistance and high specific surface area, making them essential for various engineering application. Nowadays, porous geopolymers have been the focus of promising research in the field of porous inorganic materials because of their unique combination of good thermal stability and excellent mechanical properties. An interesting technological feature is that their solidification kinetics is easily adjustable and thanks to ceramic-like structure they have significant structural stability at elevated temperatures. The processing methods used for the fabrication of porous geopolymers can be divided into various approaches. Many methods have been explored to synthesize reproducible porous sponges or foams from geopolymer systems, such as gaseous method, rapid solidification, foaming, freeze-casting and/or combination of them. Concerning the macro/micro-structure of cells, the processing can be strongly influenced by various characteristics as a chemical composition, rheological behaviour of the slurries, kinetics of pore formation and hardening behaviour. This study presents methods of processing and manufacturing approaches with respect to types of porous materials and experimental results in this field

The influence of metakaolin substitution by slag in alkali-activated inorganic binders for civil engineering

V této studii byl zkoumán účinek náhrady metakaolínu mletou vysokopecní struskou v alkalickém geopolymerním pojivu z pohledu jejich reologických a mechanických vlastností. Bylo prokázáno, že přidávání strusky do pojiva může zlepšit mechanické vlastnosti konečných produktů. Naše zkoumání bylo zaměřeno na široký interval substituce metakaolinů v rozmezí od 100 do 40 objemových procent metakaolinu, kdy objem pevných látek v konečném pojivu zůstal konstantní. Připravená pojidla byla aktivována alkalickým roztokem křemičitanu draselného s křemičitanovým modulem 1,61. Analýzy velikosti částic byly prováděny pro stanovení distribuce velikosti částic. Reologické vlastnosti byly stanoveny v souladu s průtokovými vlastnostmi měřeními na Fordově výtokovém poháru a oscilačním měřením procesu vytvrzování. Pro zkoumání procesu vytvrzování byla v geometrii rovinných desek použita oscilační reometrie s malou amplitudou řízená deformací. Pro stanovení aplikačních mechanických vlastností byly pojiva plněna keramickým ostřivem v rozmezí zrnitosti 0-1 mm. Plnění bylo udržováno konstantních 275 objemových procent vzhledem k suchému pojivu. Mechanické vlastnosti byly zkoumány po 1, 7 a 28 dnech a mikrostruktura byla dokumentována rastrovací elektronovou mikroskopií. Výsledky ukazují, že přídavek strusky má příznivý účinek nejen na mechanické vlastnosti tvrzeného pojiva, ale také na tokové vlastnosti čerstvé geopolymerní pasty a následné kinetiky vytvrzení alkalicky aktivovaných pojiv.In this study the effect of metakaolin replacement by milled blast furnace slag in alkali-activated geopolymeric binder was investigated in accordance to their rheological and mechanical properties. It was demonstrated that slag addition into the metakaolin binder can improve mechanical properties of final products. Our investigation was focused on broad interval of metakaolin substitution in the range from 100 to 40 volume per cents of metakaolin so that the volume content of solids in final binder was maintained constant. Prepared binders were activated by alkaline solution of potassium silicate with silicate module of 1.61. The particle size analyses were performed for determination of particle size distribution. The rheological properties were determined in accordance to flow properties by measurements on Ford viscosity cup and by oscillatory measurements of hardening process. For the investigation of hardening process, the strain controlled small amplitude oscillatory rheometry was used in plane-plate geometry. For determination of applied mechanical properties were binders filled by ceramic grog in the granularity range 0-1 mm. The filling was maintained constant at 275 volume per cents in accordance to ratio of solids in dry binder. The mechanical properties were investigated after 1, 7 and 28 days and microstructure was documented by scanning electron microscopy. The results indicate that slag addition have beneficial effect not only on mechanical properties of hardened binder but also on flow properties of fresh geopolymer paste and subsequent hardening kinetics of alkali-activated binders

Micro/nano-structured titanium surfaces modified by NaOH–CaCl2-heat-water treatment: Biomimetic calcium phosphate deposition and hMSCs behavior

The unexplored effect of chemical treatment of laser micro/nanostructured titanium surfaces deserves attention due to broadening our knowledge of surface enhancement of biomimetic synthesis of hydroxyapatite and osseointegration of titanium implants. In this study, NaOH-CaCl2-heat-water treatment of titanium is revisited and used to modify porous laser micro/nanostructured oxidic and flat titanium surfaces which are characterized by XRD, electron microscopy, zeta potential and FTIR and Raman spectroscopy. These surfaces are also assessed for their ability to induce biomimetic Ca phosphate deposition from a simulated body fluid (SBF) and to grow human Mesenchymal stem cells (hMSCs). The treatment of titanium surfaces is shown to involve unreported formation of crystalline CaCO3 and the related interpretation of physicochemical changes of the treated titanium surface in soaked SBF raises doubts about the specific role of an intermediary CaTiO3 in the biomimetic formation of apatite on titanium substrates. We show that the biomimetic formation of Ca phosphate in Tas SBF solution occurs both on the surface and in the bulk solution, it is enhanced on the structured surfaces and is affected by a Ca-O(Ti) layer originating on the pristine and chemical treated flat and micro/nanostructured topographies with different delays. These findings are confronted with the pilot results of in vitro analyses showing that the cell growth, shape and osteogenic differentiation of hMSCs are impeded on the surfaces modified by the NaOH-CaCl2-heat-water treatment