The effect of the substitution for Mn with Al in the magnetoresistive perovskite La 2/3 Ca 1/3 MnO 3 has been studied by preparing the series La 2/3 Ca 1/3 Mn 1Ϫx Al x O 3 (xр0.2). A careful study of the magnetic, structural, and transport properties has been carried out by means of electrical resistance, magnetoresistance, ac magnetic susceptibility, x-ray-diffraction, and neutron-diffraction techniques. Up to xϭ0.05 the Curie temperature ͑and the associated metal-insulator transition͒ decreases drastically with Al doping and the magnetoresistive properties do not change very much. For xу0.1 the lattice spontaneously begins to lose oxygen atoms and for xϭ0.2, 3% of oxygen vacancies are present. This fact along with the random distribution of the Al atoms makes these compounds rather disordered from a structural and magnetic point of view. However, the magnetoresistance is enhanced, reaching colossal values of 10 7 % at Hϭ12 T at low temperatures for xϭ0.2.

has been studied by means of a.c. magnetic susceptibility, x-ray and neutron diffraction from 1.5 up to 330 K. This compound shows a structural transition at 299.7 K. Below this temperature a charge ordering state was observed by both x-ray and neutron diffraction measurements. The structure is orthorhombic at temperatures higher than 300 K, but at lower temperatures the patterns show new reflection peaks that can be accounted for in a monoclinic unit cell with stripes of and in the ac-plane. Moreover, the system orders antiferromagnetically at around 120 K giving rise to a magnetic structure of CE type. The magnetic susceptibility measurement clearly shows an anomalous behaviour at both transition temperatures. The charge ordering temperature for the compound is the highest reported in the series (RE = rare earth). This is argued to be a consequence of the larger orthorhombic distortion produced in the unit cell by the lower size of ion.

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La,Nd,Sm͒ oxides with the perovskite structure have been studied. All of these compounds show a spin-glass behavior at low temperatures. Isostructural compounds in which Ni or Co are replaced by a nonmagnetic element do not show spin-glass behavior. Therefore, simultaneous presence of Ni and Co is needed to develop competitive ferro-and antiferromagnetic interactions in the ͑RE͒Ni 0.3 Co 0.7 O 3 compounds. Moreover, large negative magnetoresistance below freezing temperature is observed in these samples. We conclude the existence of an electronic transfer between Ni 31 and Co 31 ions in these compounds which gives rise to ferromagnetic interactions.[S0031-9007 (98)05513-6] PACS numbers: 71.30. + h, 75.10.Nr, 75.70.PaThe ͑RE͒MO 3 oxides with perovskite structure, RE being a trivalent rare-earth ion and M being a 3d transition metal, have generated a great deal of interest due to the variety of the magnetic and electrical behavior [1,2]. This interest has grown due to the high temperature superconductivity in related copper perovskites and the recent discovery of the colossal magnetoresistance in manganese perovskites [3][4][5]. The electronic ͑RE͒NiO 3 phase diagram is composed of a paramagnetic insulator, an antiferromagnetic insulator, and paramagnetic metal phases depending on the temperature and the RE ionic radius [6,7]. The perovskite lattice distortions, in particular the Ni -O-Ni angle, are related to the RE 31 ionic size. Therefore, a systematic change of the transfer integral between Ni-3d and O-2p orbitals (p-d mixing) is observed in ͑RE͒NiO 3 perovskites. When the Ni-O-Ni angle is close to 180 ± , a metallic phase is favored while the insulator phase is stabilized when this angle decreases [8]. Then, LaNiO 3 is a metallic compound while NdNiO 3 and SmNiO 3 show a metal-insulator transition at 220 and at 400 K, respectively. In addition, NdNiO 3 and SmNiO 3 develop an antiferromagnetic ordering at 220 K. On the other hand, ͑RE͒CoO 3 perovskites [9-14] show a semiconductor behavior below room temperature. Their ground state is a nonmagnetic Co 31 ͑S 0, t 6 2g ͒. This low spin state changes to a higher spin configuration with increasing temperature but the exact transformation is still an open question; some authors [10] claim a change from the low spin to the high spin state ͑S 2, t 4 2g e 2 g ͒ while other authors [13] suggest the formation of the intermediate spin configuration ͑S 1, t 5 2g , e 1 g ͒. The magnetic and electrical behavior of ͑RE͒Ni 12x -Co x O 3 mixed perovskites have been studied by several authors [14 -18]. LaNi 12x Co x O 3 shows metallic behavior below room temperature up to x 0.6 and semiconductor behavior for higher Co content. In the Nd and Sm compounds, the main effect of Ni replacement by Co is the suppression of the temperature-driven metal-insulator transition, stabilizing the metallic phase for x # 0.2. Higher Co content leads to semiconducting samples as occurs in the La compounds. Earlier magnetic measurements have shown the presence of ferromagnetic interactions in the se...

We used national surveys to study how older persons' changing household patterns influence the gender balance of caregiving in two countries with distinct household structures and cultures, Spain and Sweden. In both countries, men and women provide care equally often for their partner in couple-only households. This has become the most common household type among older persons in Spain and prevails altogether in Sweden. This challenges the traditional dominance of young or middle-aged women as primary caregivers in Spain. In Sweden, many caregivers are old themselves. We focus attention to partners as caregivers and the consequences of changing household structures for caregiving, which may be on the way to gender equality in both countries, with implications for families and for the public services.

A survey was conducted during 2015 to monitor psychoactive substance use in a sample of drivers in Spanish roads and cities. Traffic police officers recruited drivers at sites carefully chosen to achieve representativeness of the driver population. A brief questionnaire included the date, time, and personal and driving patterns data. Alcohol use was ascertained through ethanol breath test at the roadside and considered positive if concentrations >0.05mg alcohol/L were detected. Four drug classes were assessed on-site through an oral fluid screening test that, if positive, was confirmed through a second oral fluid sample at a reference laboratory. Laboratory confirmation analyses screened for 26 psychoactive substances. To evaluate the association between drug findings and age, sex, road type (urban/interurban), and period of the week (weekdays, weeknights, weekend days, weekend nights), logistic regression analyses were done (overall, and separately for alcohol, cannabis and cocaine). A total of 2744 drivers, mean age of 37.5 years, 77.8% men, were included. Overall, 11.6% of the drivers had at least one positive finding to the substances assessed. Substances more frequently testing positive were cannabis (7.5%), cocaine (4.7%) and alcohol (2.6%). More than one substance was detected in 4% of the subjects. The proportion of positive results decreased with age, and was more likely among men and on urban roads. The pattern for alcohol use was similar but did not change with age and increased among drivers recruited at night. Cannabis was more likely to be detected at younger ages and cocaine was associated with night driving. Alcohol use before driving has decreased over the last decade; however, the consumption of other illegal drugs seems to have increased. The pattern of illegal psychoactive substance observed is similar to that declared in surveys of the general population of adults.

The perovskite oxides NdNi 1−x Cu x O 3 have been synthesized for 0 x 0.2 under high oxygen pressure using a sol-gel method. Their structural, electrical, magnetic and calorimetric properties have been measured over a wide temperature range (4-300 K). All of the samples have an orthorhombic unit cell which does not change with Cu content. Nevertheless, their electrical properties change drastically with x from the very lowest values of x. The metal-insulator transition temperature decreases as x increases, up to x = 0.03; for x 0.03 the system is metallic for all temperatures. Moreover, the replacing of Ni with Cu atoms leads to magnetic disorder in the Ni sublattice.

In the last three decades, disability and dependence in old age have become major political and social issues. The World Health Organization and the scientific community have made strenuous efforts to reach a global consensus and to unify concepts and classifications; statistical institutions focus on the creation of sources to enable the study of disability, and society is looking for a healthier aging process, better environment, and appropriate health policies. Spain has followed the pace of this global movement. The National Statistics Institute has conducted three major surveys on disability and dependency (1986, 1999 and 2008). Analysis of their objectives, methodologies, frameworks and applications on the one hand, and data related to older people on the other, confirm the quantitative burden of disability and dependence and also reveals a change in the social and political significance of both old age and disability. Therefore, there is a gradual shift in statistical and policy interests from the causes of disability to their consequences-mainly dependence-and the set of personal and environmental factors that interact with this state.