There is an extensive literature discussing how individuals’ marriage behavior changes as a country develops. However, no existing data set allows an explicit investigation of the relationship between marriage and economic development. In this paper, we construct new cross-country panel data on marital statistics for 16 OECD countries from 1900 to 2000, in order to analyze such a relationship. We use this data set, together with cross-country data on real GDP per capita and the value added share of agriculture, manufacturing, and services sectors, to document two novel stylized facts. First, the fraction of a country’s population that is married displays a hump-shaped relationship with the level of real GDP per capita. Second, the fraction of the married correlates positively with the share of manufacturing in GDP. We conclude that the stage of economic development of a country is a key factor that affects individuals’ family formation decisions.

Employing the Kolodner–Coffman method, we show the exact multiplicity of positive solutions for the one-dimensional p-Laplacian that is subject to a Dirichlet boundary condition with a positive convex nonlinearity and an indefinite weight function.

We recently showed that social encounter stimulation induces hyperactivity in mice reared in social isolation from early life and this is associated with the transient activation of prefrontal dopaminergic and serotonergic systems. In the present study, we examined the effect of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor antagonist 2, 3-dioxo-6-nitro-1, 2, 3, 4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide (NBQX) on encounter-induced behavioural and neurochemical changes to study the role of the receptor in abnormal behaviours in isolation-reared mice. The encounter to an intruder mouse induced hyperactivity with transient increases in prefrontal dopamine and serotonin levels in isolation-reared mice. NBQX attenuated the encounter-induced hyperactivity and the associated neurochemical changes in isolation-reared mice. In addition, NBQX reduced aggressive behaviour and cognitive impairment in isolation-reared mice, but did not affect depressive-like behaviour or spontaneous hyper-locomotion in these animals. The AMPA receptor agonist (S)-AMPA increased prefrontal dopamine and serotonin release, and this effect was higher in isolation-reared mice than in the group-reared mice, suggesting higher prefrontal AMPA receptor activity in isolation-reared mice. Furthermore, isolation rearing increased the expression of AMPA receptor subunits (GluR1, GluR2 and GluR3) and GluR1 Ser845 phosphorylation in the prefrontal cortex, but not in the hippocampus or nucleus accumbens. Taken together, these results suggest that an increase in AMPA receptor activity in the prefrontal cortex contributes to some, but not all, abnormal behaviours in isolation-reared mice.

CrB2 possess the hexagonal AlB2 structure which belongs to the spacegroup of P6/mmm. The compound exhibits para- to antiferro-magnetic transition at about 88 K. By using a macroscopic measurement technique, that is, a conventional resonant ultrasound spectroscopy (RUS) with a millimeter size mono-crystal, significant elastic anomalies have been observed just above the magnetic transition temperature. On the other hand, elastic constants determined by a microscopic measurement technique, that is, an inelastic X-ray scattering method (BL35XU of SPring-8, Japan) do not show any elastic anomalies at around the transition temperature. In order to explain the discrepancy, we have introduced a kind of so called ΔE effect resulting from a multidomain structure. If crystal lattice is slightly deformed by a spontaneous magnetostriction in the antiferromagnetic state, the symmetry of crystal lattice is lowered from hexagonal to monoclinic when the symmetry of magnetic structure is taken into account. By the lowering of the symmetry, the crystal consists of six magnetic domains in the antiferro magnetic state. If magnetic domain boundaries move in response to externally applied stresses, the mechanical deformation is absorbed by nonelastic deformations induced by the movement of magnetic domain boundaries. This multidomain model well explains the experimental results obtained by both microscopic (X-ray) and macroscopic (ultrasound) measurements. The microscopic measurement technique is useful to obtain the true elastic properties of crystal lattice without effects coming from a multidomain structure.

Collagen fibril membranes (CFMs) with a high mechanical property were fabricated with a lateral face evaporation method, in which type I atelocollagen extracted from tilapia scales was used. The density and thickness of the CFM obtained were 0.51 ± 0.04 mg/cm3 and 50 ± 5 μm. The collagen fibrils in the CFM had a similar periodic stripped pattern of 67 nm with native collagen fibrils. The CFM was crosslinked in gaseous glutaraldehyde for different duration in order to increase the mechanical property. The crosslinking degrees of the CFMs analyzed by free amino groups gradually increased to 70.3 % against the exposure duration until 6 hours, and reached a plateau. The denaturation temperatures of the CFMs with the crosslinking degrees at 20.4 % to 43% were linearly increased from 49°C to 75°C. The tensile strength of the CFMs was slightly improved until the crosslinking degree at 33.3 % and then the tensile strength rapidly increased to be 68 MPa. It was suggested that a percolation phenomenon took place in the CFMs by crosslinking of collagen fibrils with polymerized GA molecules.

This paper considers the magnitude of the gripping power, i.e., the internal force that depends on the grasping posture or object orientation in a two-dimensional grasp by two contact points with friction. Expressing the effect of variations in the object posture as the direction of an external force, we propose an “internal force diagram.” The internal force necessary to create a statically stable grasp is depicted in the object coordinate frame. Then, a polar coordinate system is introduced in which the orientation represents the direction of the external force, while the distance from the origin represents the minimum necessary internal force. We demonstrate a method based on friction cone configurations to manually draw the internal force diagram, using only a ruler and a compass. The validity of this drawing method is confirmed by a comparison with computer-generated plots. Finally, the characteristics of the internal force diagram are discussed.

Maternal nutritional status during pregnancy is an important determinant of fetal growth. Although the effects of several nutrients and foods have been well examined, little is known about the relationship of overall maternal diet in pregnancy to fetal growth, particularly in non-Western populations. We prospectively examined the relationship of maternal dietary patterns in pregnancy to neonatal anthropometric measurements at birth and risk of small-for-gestational-age (SGA) birth among 803 Japanese women with live-born, singleton, term deliveries. Maternal diet in pregnancy was assessed using a validated, self-administered diet history questionnaire. Dietary patterns from thirty-three predefined food groups (g/4184 kJ) were extracted by cluster analysis. The following three dietary patterns were identified: the ‘meat and eggs’ (n 326), ‘wheat products’, with a relatively high intake of bread, confectioneries and soft drinks (n 303), and ‘rice, fish and vegetables’ (n 174) patterns. After adjustment for potential confounders, women in the ‘wheat products’ pattern had infants with the significantly lowest birth weight (P = 0·045) and head circumference (P = 0·036) among those in the three dietary patterns. Compared with women in the ‘rice, fish and vegetables’ pattern, women in the ‘wheat products’ pattern had higher odds of having a SGA infant for weight (multivariate OR 5·2, 95 % CI 1·1, 24·4), but this was not the case for birth length or head circumference. These results suggest that a diet high in bread, confectioneries, and soft drinks and low in fish and vegetables during pregnancy might be associated with a small birth weight and an increased risk of having a SGA infant.

The effects of water vapor and oxygen on the cyclic fatigue behavior of oxygen-excess La0.8Sr0.2MnO3+δ (LSM) were investigated under three-point bending at 1273 K. Because the fatigue life did not obviously depend on the number of cycles, which also represented the effective time of the applied stress, the fracture was presumed to not be significantly controlled by stress-corrosion cracking. Under a low oxygen partial pressure (), however, wet exposure inhibited both fatigue fracture and permanent deformation, in which the LSM crystal lattice was distorted and the unit cell free volume was reduced. Under a high , on the contrary, the crystal symmetry was increased by the wet exposure. The inhibition of fatigue fracture and deformation at both high and low was probably caused by retardation of lanthanum diffusion through its vacancies.

Although several nutrients and foods are suggested to be preventive against postpartum depression, all previous studies have primarily focused on single nutrients or foods. In contrast, studies on dietary patterns, namely the measurement of overall diet by considering the cumulative effects of nutrient, may provide new insights into the influence of diet on postpartum depression. We prospectively examined the association between dietary patterns during pregnancy and the risk of postpartum depression among 865 Japanese women. Diet was assessed with a validated, self-administered diet history questionnaire. Dietary patterns from thirty-three predefined food groups (energy-adjusted food (g/d)) were extracted by factor analysis. Postpartum depression was defined as present when the subjects had an Edinburgh Postnatal Depression Scale score of ≥ 9 at 2–9 months postpartum. A total of 121 women (14·0 %) were classified as having postpartum depression. Three dietary patterns were identified: ‘Healthy’, ‘Western’ and ‘Japanese’ patterns. After adjustment for potential confounders, neither the ‘Healthy’ nor the ‘Japanese’ pattern was related to the risk of postpartum depression. Compared with the first quartile of the ‘Western’ pattern, only the second quartile was independently related to a decreased risk of postpartum depression (multivariate OR 0·52, 95 % CI 0·30, 0·93), although no evident exposure–response associations were observed (P for trend = 0·36). The present study failed to substantiate clear associations between dietary patterns and the risk of postpartum depression. Further studies with more accurate measurements are warranted to confirm the relationship between dietary patterns and the risk of postpartum depression.

Increased homocysteine levels might accelerate dopaminergic cell death in Parkinson's disease (PD) through neurotoxic effects; thus, increasing intake of B vitamins involved in the regulation of homocysteine metabolism might decrease the risk of PD through decreasing plasma homocysteine. However, epidemiological evidence for the association of dietary B vitamins with PD is sparse, particularly in non-Western populations. We conducted a hospital-based case–control study in Japan to examine associations between dietary intake of folate, vitamin B6, vitamin B12 and riboflavin and the risk of PD. Patients with PD diagnosed using the UK PD Society Brain Bank criteria (n 249) and controls without neurodegenerative diseases (n 368) were recruited. Dietary intake during the preceding month was assessed at the time of study recruitment using a validated, self-administered, semi-quantitative, comprehensive diet history questionnaire. After adjustment for potential dietary and non-dietary confounding factors, intake of folate, vitamin B12 and riboflavin was not associated with the risk of PD (P for trend = 0·87, 0·70 and 0·11, respectively). However, low intake of vitamin B6 was associated with an increased risk of PD, independent of potential dietary and non-dietary confounders. Multivariate OR (95 % CI) for PD in the first, second, third and fourth quartiles of vitamin B6 were 1 (reference), 0·56 (0·33, 0·94), 0·69 (0·38, 1·25) and 0·48 (0·23, 0·99), respectively (P for trend = 0·10). In conclusion, in the present case–control study in Japan, low intake of vitamin B6, but not of folate, vitamin B12 or riboflavin, was independently associated with an increased risk of PD.

The Dirichlet problem

is considered, where B = {x ∈ ℝN : |x| < 1}, N ≥ 3, p > 1, K ∈ C2[0, 1] and K(r) > 0 for 0 ≤ r ≤ 1. A sufficient condition is derived for the uniqueness of radial solutions of (*) possessing exactly k − 1 nodes, where k ∈ ℕ. It is also shown that there exists K ∈ C∞[0, 1] such that (*) has at least three radial solutions possessing exactly k − 1 nodes, in the case 1 < p < (N + 2)/(N − 2).

Buckling of arc discharge made multi-walled carbon nanotubes with various lengths was studied by alternating the length of a multi-walled nanotube by intermittent cutting. Buckling stresses were determined by measuring force-distance curves employing an atomic force microscope and the values were compared with those expected from the Euler's theoretical model. As the length of a nanotube was shortened, its buckling mode changed from elastic compressive bending with Young's modulus of 1.2TPa, to inelastic compressive fracture. The inelastic behavior observed for short nanotubes can be attributed to the buckling mechanism, in which ripple-like distortions develop along the nanotube sidewalls.

We report the preparation and thermoelectric properties of oriented higher manganese silicide (HMS) with a composition of MnSi1.73 bulk. The grain alignment and densification were achieved by rotating high magnetic field and spark plasma sintering (SPS) techniques, respectively. The easy magnetization axis of MnSi1.73 was found to be c-axis, and the applied magnetic field of 2 T was strong enough to rotate the powder with a mean grain size of 1 μm. The c-axis of grains was oriented when applying the magnetic field, and the degree of orientation was further increased after heat treatment. However, a secondary phase that was mono manganese silicide (MnSi) was observed as a result of oxidation on the surface of synthesized powder. The electrical conductivity of the c-axis oriented specimen along the ab-plane was about 40% larger than that for sample processed only by SPS, while the Seebeck coefficient of oriented and nonoriented specimens showed similar values regardless of existence of the second phase. Consequently, the power factor of the c-axis oriented specimen along the ab-plane was enhanced by about 35% compared to the nonoriented one. The proposed approach is found to be very effective not only in obtaining the oriented materials with nonductility but also in enhancing the thermoelectricity.