Magnetism of the LTT phase of Eu doped La_{2-x}Sr_xCuO_4

The ESR signal of Gd spin probes (0.5 at %) as well as the static normal state susceptibility of Eu (J(Eu^{3+})=0) doped La_{2-x-y}Sr_xEu_yCuO_4 reveal pronounced changes of the Cu magnetism at the structural transition from the orthorhombic to the low temperature tetragonal phase for all non-superconducting compositions. Both a jumplike decrease of \chi as well as the ESR data show an increase of the in-plane magnetic correlation length in the LTT phase. From the Gd^{3+} ESR linewidth we find that for specific Eu and Sr concentrations in the LTT phase the correlation length increases up to more than 100 lattice constants and the fluctuation frequency of the CuO_2 spin system slows down to 10^{10}- 10^{11}sec^{-1}. However, there is no static order above T ~ 8K in contrast to the LTT phase of Nd doped La_{2-x}Sr_xCuO_4 with pinned stripe correlations.Comment: 7 pages, RevTex, 3 eps figures. To appear in the Proceedings of the International Conference "Stripes, Lattice Instabilities and High Tc Superconductivity", (Rome, Dec. 1996

Low Energy Singlets in the Excitation Spectrum of the Spin Tetrahedra System Cu_2Te_2O_5Br_2

Low energy Raman scattering of the s=1/2 spin tetrahedra system Cu_2Te_2O_5Br_2 is dominated by an excitation at 18 cm^{-1} corresponding to an energy E_S=0.6\Delta, with \Delta the spin gap of the compound. For elevated temperatures this mode shows a soft mode-like decrease in energy pointing to an instability of the system. The isostructural reference system Cu_2Te_2O_5Cl_2 with a presumably larger inter-tetrahedra coupling does not show such a low energy mode. Instead its excitation spectrum and thermodynamic properties are compatible with long range Neel-ordering. We discuss the observed effects in the context of quantum fluctuations and competing ground states.Comment: 5 pages, 2 figures, ISSP-Kashiwa 2001, Conference on Correlated Electron

Serotonin-3 Receptors in the Posterior Ventral Tegmental Area Regulate Ethanol Self-Administration of Alcohol-Preferring (P) Rats

Several studies indicated the involvement of serotonin-3 (5-HT 3 ) receptors in regulating alcohol- drinking behavior. The objective of this study was to determine the involvement of 5-HT 3 receptors within the ventral tegmental area (VTA) in regulating ethanol self-administration by alcohol-preferring (P) rats. Standard two-lever operant chambers were used to examine the effects of 7 consecutive bilateral micro-infusions of ICS205-930 (ICS), a 5-HT 3 receptor antagonist, directly into the posterior VTA on the acquisition and maintenance of 15% (v/v) ethanol self- administration. P rats readily acquired ethanol self-administration by the 4 th session. The three highest doses (0.125, 0.25 and 1.25 ug) of ICS prevented acquisition of ethanol self- administration. During the acquisition post-injection period, all rats treated with ICS demonstrated higher responding on the ethanol lever, with the highest dose producing the greatest effect. In contrast, during the maintenance phase, the 3 highest doses (0.75, 1.0 and 1.25 ug) of ICS significantly increased responding on the ethanol lever; following the 7-day dosing regimen, responding on the ethanol lever returned to control levels. Micro-infusion of ICS into the posterior VTA did not alter the low responding on the water lever, and did not alter saccharin (0.0125% w/v) self-administration.. Micro-infusion of ICS into the anterior VTA did not alter ethanol self- administration. Overall, the results of this study suggest that 5-HT 3 receptors in the posterior VTA of the P rat may be involved in regulating ethanol self-administration. In addition, chronic operant ethanol self-administration, and/or repeated treatments with a 5-HT 3 receptor antagonist may alter neuronal circuitry within the posterior VTA

Effects of Alcohol and Saccharin Deprivations on Concurrent Ethanol and Saccharin Operant Self-Administration by Alcohol-Preferring (P) Rats

Consumption of sweet solutions has been associated with a reduction in withdrawal symptoms and alcohol craving in humans. The objective of the present study was to determine the effects of EtOH and saccharin (SACC) deprivations on operant oral self-administration. P rats were allowed to lever press concurrently self-administer EtOH (15% v/v) and SACC (0.0125% g/v) for 8 weeks. Rats were then maintained on daily operant access (non-deprived), deprived of both fluids (2 weeks), deprived of SACC and given 2 ml of EtOH daily, or deprived of EtOH and given 2 ml of SACC daily. All groups were then given two weeks of daily operant access to EtOH and SACC, followed by an identical second deprivation period. P rats responded more for EtOH than SACC. All deprived groups increased responding on the EtOH lever, but not on the SACC lever. Daily consumption of 2 ml EtOH decreased the duration of the ADE. Home cage access to 2 ml SACC also decreased the ADE but to a lesser extent than access to EtOH. A second deprivation period further increased and prolonged the expression of an ADE. These results show EtOH is a more salient reinforcer than SACC. With concurrent access to EtOH and SACC, P rats do not display a saccharin deprivation effect. Depriving P rats of both EtOH and SACC had the most pronounced effect on the magnitude and duration of the ADE, suggesting that there may be some interactions between EtOH and SACC in their CNS reinforcing effects

Dzyaloshinsky-Moriya Spin Canting in the LTT Phase of La2-x-yEuySrxCuO4

The Cu spin magnetism in La2-x-yEuySrxCuO4 (x<=0.17; y<=0.2) has been studied by means of magnetization measurements up to 14 T. Our results clearly show that in the antiferromagnetic phase Dzyaloshinsky-Moriya (DM)superexchange causes Cu spin canting not only in the LTO phase but also in the LTLO and LTT phases. In La1.8Eu0.2CuO4 the canted DM-moment is about 50% larger than in pure La2CuO4 which we attribute to the larger octahedral tilt angle. We also find clear evidence that the size of the DM-moment does not change significantly at the structural transition at T_LT from LTO to LTLO and LTT. The most important change induced by the transition is a significant reduction of the magnetic coupling between the CuO2 planes. As a consequence, the spin-flip transition of the canted Cu spins which is observed in the LTO phase for magnetic field perpendicular to the CuO2 planes disappears in the LTT phase. The shape of the magnetization curves changes from the well known spin-flip type to a weak-ferromagnet type. However, no spontaneous weak ferromagnetism is observed even at very low temperatures, which seems to indicate that the interlayer decoupling in our samples is not perfect. Nonetheless, a small fraction (<15%) of the DM-moments can be remanently magnetized throughout the entire antiferromagnetically ordered LTT/LTLO phase, i.e. for T<T_LT and x<0.02. It appears that the remanent DM-moment is perpendicular to the CuO2 planes. For magnetic field parallel to the CuO2 planes we find that the critical field of the spin-flop transition decreases in the LTLO phase, which might indicate a competition between different in-plane anisotropies. To study the Cu spin magnetism in La2-x-yEuySrxCuO4, a careful analysis of the Van Vleck paramagnetism of the Eu3+ ions was performed.Comment: 22 pages, 27 figure

Common genetic and environmental contributions to post-traumatic stress disorder and alcohol dependence in young women

BACKGROUND: The few genetically informative studies to examine post-traumatic stress disorder (PTSD) and alcohol dependence (AD), all of which are based on a male veteran sample, suggest that the co-morbidity between PTSD and AD may be attributable in part to overlapping genetic influences, but this issue has yet to be addressed in females. METHOD: Data were derived from an all-female twin sample (n=3768) ranging in age from 18 to 29 years. A trivariate genetic model that included trauma exposure as a separate phenotype was fitted to estimate genetic and environmental contributions to PTSD and the degree to which they overlap with those that contribute to AD, after accounting for potential confounding effects of heritable influences on trauma exposure. RESULTS: Additive genetic influences (A) accounted for 72 % of the variance in PTSD ; individual-specific environmental (E) factors accounted for the remainder. An AE model also provided the best fit for AD, for which heritability was estimated to be 71 %. The genetic correlation between PTSD and AD was 0.54. CONCLUSIONS: The heritability estimate for PTSD in our sample is higher than estimates reported in earlier studies based almost exclusively on an all-male sample in which combat exposure was the precipitating traumatic event. However, our findings are consistent with the absence of evidence for shared environmental influences on PTSD and, most importantly, the substantial overlap in genetic influences on PTSD and AD reported in these investigations. Additional research addressing potential distinctions by gender in the relative contributions of genetic and environmental influences on PTSD is merited

Green Production of Anionic Surfactant Obtained from Pea Protein

A pea protein isolate was hydrolyzed by a double enzyme treatment method in order to obtain short peptide sequences used as raw materials to produce lipopeptides-based surfactants. Pea protein hydrolysates were prepared using the combination of Alcalase and Flavourzyme. The influence of the process variables was studied to optimize the proteolytic degradation to high degrees of hydrolysis. The average peptide chain lengths were obtained at 3–5 amino acid units after a hydrolysis of 30 min with the mixture of enzymes. Then, N-acylation in water, in presence of acid chloride (C12 and C16), carried out with a conversion rate of amine functions of 90%, allowed to obtain anionic surfactant mixtures (lipopeptides and sodium fatty acids). These two steps were performed in water, in continuous and did not generate any waste. This process was therefore in line with green chemistry principles. The surface activities (CMC, foaming and emulsifying properties) of these mixtures were also studied. These formulations obtained from natural renewable resources and the reactions done under environmental respect, could replace petrochemical based surfactants for some applications

Assessment of information resources for people with hypodontia

Aim: To assess the adequacy of patient information to support understanding and decision-making for people affected by hypodontia. Methods: 1) Questionnaire to understand the provision of patient information by dentists; 2) Systematic search to identify online open-access patient information; 3) Quality assessment of written patient information. Results: Questionnaire response rate was 49% (319/649); 91% examined and/or treated people with hypodontia. Most general dentists referred patients to specialist services without providing written hypodontia information. The majority of dental specialists provide patient leaflets but less than a third used web-resources. Only 19% of respondents felt current resources were fit-for-purpose. Thirty-one patient resources (18 leaflets and 13 online) were assessed against quality criteria. The aim of the resource was seldom explicit, the content was often incomplete and variation in readability scores indicated high levels of literacy were required. Discussion: Access to, and quality of, patient information for hypodontia is inadequate. Current resources are not sufficiently comprehensive to prepare young patients to engage in shared dental care decisions with their parents and/or dental professionals. Conclusion: There is a need for improved access to, and provision of, information about hypodontia if dental professionals want to meet best practice guidance and involve patients in shared decision-making

Development of the Tilburg Pregnancy Distress Scale: the TPDS

Contains fulltext : 96807.pdf (publisher's version ) (Open Access)ABSTRACT: BACKGROUND: Pregnant women with high levels of stress, depression and/or anxiety are at increased risk for adverse perinatal outcomes and impaired neurologic and emotional development of the offspring. Pregnancy specific instruments to measure psychological functioning during gestation are scarce and do not define items based on in-depth interviews of pregnant and recently delivered women. The current study developed a pregnancy specific scale that measures psychological functioning using in-depth interviews. METHODS: Three focus groups were formed to discuss issues most relevant to pregnancy distress; 22 candidate items were derived for pilot testing (study I, n = 419) its psychometric properties by means of explorative factor analyses (EFA). This resulted in a 17-item TPDS which was further explored by confirmatory factor analyses (CFA) and concurrent and construct validity assessment (study II, n = 454). RESULTS: EFA in study I suggested a two component solution (negative affect (NA) and partner involvement (PI)). CFA in study II resulted in a higher order model of the NA subscale into three more subscales: NA regarding confinement, delivery and general health. TPDS, EPDS and GAD-7 were all significantly correlated. CONCLUSIONS: The TPDS constitutes a valid and user friendly instrument to assess pregnancy distress. In addition to its proven ability to pick up pregnancy specific negative affect it also includes an important sub-scale measuring perceived partner involvement