Family History as an Important Factor for Stratifying Participants in Genetic Studies of Major Depression.

Depression is estimated to affect 350 million people worldwide. The World Mental Health Survey conducted in 17 countries found that, on average, about one in 20 people reported having an episode of depression in the previous year. Although depression has been shown to be moderately heritable by studies conducted in the past, the search for its so-called missing heritability has so far been unsuccessful. The difficulty in identifying common genetic variants predisposing to depression could be due to large sample sizes needed to detect small effects on genetic risk and the heterogeneous nature of major depressive disorder (MDD). The aim of our study was to determine whether there was a connection between a family history of depression in MDD patients and the presence of putative risk variants in the well-studied SLC6A4, COMT and PCLO genes. We analyzed 133 patients with MDD (30.0% with a positive family history for MDD and 70.0% sporadic cases) and compared them to 279 healthy controls. When comparing all the depressed patients to controls, no significant differences in genotype and allele distributions were detected. After stratifying patients according to their family history, the PCLO rs2522833 C allele was shown to be significantly less common in patients with a positive family history (p = 0.001), indicating a possible difference in the genetic structure of MDD between familial and sporadic cases and a less important role of the common genetic risk variants for the development of MDD in familial cases.

Deuteron NMR resolved mesogen vs. crosslinker molecular order and reorientational exchange in liquid single crystal elastomers.

Differences in the temperature behaviour of orientational ordering of structurally equivalent side-chain liquid single crystal elastomers (LSCEs) with (2)H-labelled crosslinker and mesogen have been studied by deuteron quadrupole-perturbed NMR. The impact of nematic director reorientations on the deuteron NMR spectral shapes was analyzed in terms of a discrete reorientational exchange model. This provided for the determination of the degree of nematic director alignment and for the quantification of the influence of the reorientational exchange on the (2)H NMR spectra in terms of two parameters, the nematic director orientational dispersion parameter σθ and the motional effectiveness parameter α. A comparative analysis of model simulations and experimental spectra reveals that mesogenic molecules in LSCEs exhibit faster reorientational dynamics as compared to crosslinker molecules and that mesogens and crosslinkers exhibit a similar and rather substantial static director orientational disorder.

Size effects in a relaxor: further insights into PMN.

Dielectric measurements of PbMg1/3Nb2/3O3 (PMN) powder and dense ceramics with grain sizes between 15 nm and two microns were carried out in a broad frequency range (20 Hz-1 GHz). Clear grain size dependence of relaxor behavior was evidenced. A progressive transformation from Vogel-Fulcher behavior towards the Arrhenius process in the PMN with reduction of grain size in both ceramics and powder was observed. In the case of ceramics we were able to extract deeper information from the distributions of relaxation times and an analysis using the Vogel-Fulcher law, revealing two main contributions: a fast part of distribution of relaxation times with a maximum close to 10(-11) s, which is almost grain-size independent and has a non-polar origin; whereas, a process with long relaxation times (in the time range of 10(-8) to 10(-5) s) is associated with the dynamics of the polar nanoregions and is strongly suppressed with reduction of grain size. The results of dielectric investigations are confirmed by Nuclear Magnetic Resonance experiments.

Photoisomerization-controlled phase segregation in a submicron confined azonematic liquid crystal.

Deuteron nuclear magnetic resonance is used to study the phase segregation behavior of photoisomerizable liquid crystal diheptylazobenzene (7AB) confined into cylindrical pores of Anopore membranes. It is demonstrated that the concentration of both components in a binary trans-7AB and cis-7AB mixture can be controlled dynamically using UV-illumination stimulated trans-to-cis photoisomerization and thermally induced cis-to-trans backisomerization. The so far elusive temperature-concentration phase diagram of such system is determined by comparative analysis of the behavior in bulk, thin-planar, and Anopore-confining geometry.

(39)K NMR and EPR study of multiferroic K(3)Fe(5)F(15).

(39)K NMR spectra and relaxation times of polycrystalline K(3)Fe(5)F(15) have been used as a microscopic detector of the local magnetic fields at the magnetic transition at T(N) = 123 K. The NMR lineshape widens abruptly upon crossing T(N) due to the onset of internal magnetic fields, while we find no significant lineshift. The paraelectric to ferroelectric transition at T(c) = 490 K and the magnetic transition at T(N) have also been studied using X-band EPR (electron paramagnetic resonance). An increase and subsequent decrease in the EPR susceptibilities is observed on approaching T(N) from above. There is also a significant increase in the linewidth. At the same time the g-factor first decreases and then increases with decreasing temperature. The local magnetic field is different at different K sites and is much smaller than the magnetic field around the Fe sites. This seems to be consistent with the behaviour of a weak ferrimagnet. The ferrimagnetism does not seem to be due to spin canting as the lattice is disordered, but may arise from thermal blocking of superparamagnetic percolation clusters. The ferroelectric transition at T(c) shows no electronic anomaly, demonstrating that we are dealing with a classical phonon anomaly as found in conventional oxides rather than an electronic transition.

Evidence of supercritical behavior in liquid single crystal elastomers.

Temperature profiles of the first and the second moment of the nematic order parameter distribution function, as determined from the deuteron nuclear magnetic resonance line shapes, as well as heat capacity response, provide support for the supercritical scenario of the nematic-paranematic phase transition in liquid single crystal elastomers. The relative strength of the locked-in internal mechanical field with respect to the critical field can be decreased by swelling the elastomer samples with low molecular mass nematogen. By increasing the concentration of the dopant, critical and below-critical behavior is promoted.

Anchoring and structural transitions as a function of molecular length in confined liquid crystals.

Using deuteron nuclear magnetic resonance to study liquid crystals confined to cylindrical pores, an anchoring transition has been found. The transition exhibits an unexpected sharp dependence of the anchoring strength on cyanobiphenyl liquid crystal molecular length. A structural transition from a parallel axial to a planar radial configuration occurs due to an anchoring transition from planar to weakly homeotropic orientation at the walls. The anchoring strength is at a minimum near the decylcyanobiphenyl (10CB) liquid crystal length. Long chain liquid crystal configurations depend on thermal cycling and on the equilibrium atmosphere leading to a bistable SmA structure. Orientational order wetting in the isotropic phase also depends on molecular length.

Field cooled and zero field cooled 207Pb NMR of the relaxor ferroelectric PMN.

A 2.8 kV/cm electric field has been applied parallel to the external magnetic field along the [111] direction of a PMN single crystal and the 207Pb NMR spectra were measured at 9.1 T. Whereas the zero field cooled (ZFC) spectrum exhibits a Gaussian-like line shape, the FC spectrum clearly shows a two peak structure. One of the two peaks coincides with the ZFC spectrum. The other peak is shifted by about 100 kHz towards lower frequencies with respect to the ZFC peak and seems to be characteristic for the ferroelectric state. The ferroelectric shift agrees with the predictions of the spherical random bond-random field model.

Low-frequency proton NMR relaxometry of a polymer dispersed liquid crystal above TNI.

Using proton NMR relaxometry in the kilohertz frequency range, we study dynamics of 5CB liquid crystal molecules dispersed in the form of spherical microdroplets in a PDLC material. The focus of the study is the spin-lattice relaxation in the rotating frame, T1rho(-1), measured above the nematic-isotropic transition TNI. We show that the relaxation rate T1rho(-1)--when induced by uniform molecular translational diffusion in a spherical cavity--depends on the strength of the rotating magnetic field as T1rho(-1) proportional to omega1(-alpha) where alpha varies between 0.7 and 1, depending on the thickness of the ordered surface layer. This relaxation mechanism governs mainly the transverse spin relaxation, whereas the measurements of the frequency and temperature dependence of T1rho(-1) indicate a strong effect of slowing-down of molecular translational diffusion in contact with the polymer surface and yield the average dwell-time of molecules at the surface of the order 10(-5) s.

Surface-induced order and diffusion in 5CB liquid crystal confined to porous glass.

Liquid crystals confined into small cavities are known to have a weak orientational order even above the nematic-isotropic transition temperature. The surface-induced order and molecular dynamics in this temperature range are studied with the aid of deuteron NMR spectra, spin relaxation times T(1) and T(2,) proton dipolar-correlation effect, and direct measurements of the effective diffusion coefficient for the liquid crystal 5CB confined to controlled-pore glasses. Our results show that an arrangement of molecules parallel to the wall is induced by local molecular interactions between the liquid crystal and solid, resulting in a weak and temperature independent surface order parameter, S(0) approximately 0.02 +/- 0.01. There is no indication of a significant slowing-down of molecular diffusion at the wall, neither rotational nor translational. In cavities of nanometer size, where the nematic order evolves gradually upon cooling, a broadening of the NMR linewidths due to dynamic effects should be taken into account.

Smoking in relation to psychosocial risk factors in adolescents.

OBJECTIVE: The study investigated which psychosocial factors distinguish adolescent smokers from non-smokers, and examined the most important factors correlated with smoking. METHOD: A cross-sectional survey carried out by means of a questionnaire which, in addition to items on family, school, healthy habits, drug abuse and suicidal behaviour, also included a scale of depression (Zung's SDS) and of self-esteem (Rosenberg's SES). Sample. Two thousand one hundred and eleven high school students aged from 17.0 to 18.11 (1,083 girls and 1,028 boys), of whom 221 girls and 239 boys were smokers. RESULTS: The smokers of both sexes differed significantly from the non-smokers in frequency of substance abuse, family dysfunction, suicidal ideation and suicide attempts, attitude towards the harmful effects of smoking, truancy from school, and lesser involvement in sports. With regard to smoking behaviour, the most important predictive factors for adolescents of both sexes proved to be substance abuse, truancy, suicide attempts, a lower estimate of the harmfulness of smoking, and infrequent engagement in sports. Among the girls, predictive factors were also sexual and physical abuse, and binge eating. CONCLUSIONS: Smoking behaviour in adolescence may be part of a pattern of problematic behaviour and may be linked to various psychopathological disturbances.

Gender differences in psychosocial risk factors among Slovenian adolescents.

This study investigated psychosocial risk factors in adolescents and assessed gender differences in the frequency of their occurrence. A specially designed questionnaire, which included validated scales for the evaluation of depression (Zung Self-rating Depression Scale) and self-esteem (Rosenberg Self-Esteem Scale), was administered to a representative sample of Slovenian adolescents. The final sample consisted of 4,590 high school students of both sexes, aged 14 to 19 years. Data analysis revealed several significant gender differences. Girls more often than boys reported family conflict, personal problems, physical inactivity, attempts to control body weight, use of psychoactive drugs, suicidal ideation, and suicide attempts. Their level of depression was higher and self-esteem lower when compared with their male counterparts. Boys more often than girls indicated that they watched a great deal of television, were the victims of peer violence, and drank alcohol.

Interlayer molecular exchange in an anticlinically ordered chiral liquid crystal

The interlayer molecular exchange has been determined in the antiferroelectric smectic-C(*)(A) phase of alphad(2) deuterated 4-(1-methylheptyloxycarbonyl)phenyl4(')-octyloxybiphenyl-4-carboxylat e via quadrupolar deuteron NMR self-diffusion in the spatially varying electric field gradient produced by the anticlinic smectic layer structure. The interlayer self-diffusion coefficient is here by two orders of magnitude smaller than in synclinically ordered smectic phases. The results support the entropic suppression model of the origin of anticlinic smectic ordering. The applied technique could possibly allow for a new insight into the local structure of the intermediate "clock" phases.

Deuteron NMR investigation of a photomechanical effect in a smectic-A liquid crystal

Deuteron quadrupole-perturbed NMR is used to study the perturbation of orientational order in a smectic-A liquid crystal (octylcyanobiphenyl or 8CB) caused by photoinduced trans-to-cis isomerization of a photosensitive dopant (diheptylazobenzene or 7AB). The time and temperature dependences of the orientational order were independently studied for 8CB, 7AB, and their mixtures. Upon UV irradiation that causes trans-to-cis isomerization of 7AB, the orientational order parameter of the smectic-A phase is reduced. Relaxation in the dark exponentially restores the equilibrium value of the order parameter. The characteristic time for this process closely matches the lifetimes of the 7AB excited state. While in the 8CB smectic-A matrix, the cis-isomerized 7AB molecules retain a uniaxial orientational order with the director oriented along the normal to the smectic layers. The highly bent 7AB cis molecules act as a disorienting factor, decreasing the orientational order in the layers and causing a small increase in layer spacing. This disorder-induced increase in layer spacing is much smaller than the actual increase as observed by in situ x-ray experiments on UV-irradiated mixtures of 8CB:7AB. Concomitant with the experimental observation that only a fraction of 7AB molecules are converted to the cis state, this work provides indirect evidence for a nanophase segregation with the 7AB cis-isomers arranged within the interlayer space, thus significantly increasing the smectic layer spacing.

Characteristics of suicide attempters in a Slovenian high school population.

The study was carried out on a representative sample of Slovenian high school students (n = 3687) of whom 238 (137 girls and 101 boys) have already attempted suicide. Both suicide attempters and nonattempters were assessed by a questionnaire consisting of Zung's (1965) Depression Scale, Rosenberg's (1965) Self-Esteem Scale, sociodemographic data, information on suicide attempt, suicide ideation, family relations, and substance abuse. Statistical analyses indicated that groups differed in the levels of self-esteem, emotional reaction to family problems, running away from home, and substance abuse. The differences in the level of depression, frequency of suicide ideation, family suicide occurrence, smoking, and alcohol use were significant.

Deuteron NMR study of monolayer thick films of nematogenic molecules

We present a deuteron NMR study of molecular thickness films of a nematogenic material in cylindrical pores. Compared to liquid crystal in bulk or completely filling the pores, a reduced quadrupole splitting is found. It strongly depends on thickness, but only weakly on temperature, even crossing the bulk nematic-isotropic transition. This demonstrates the presence of a 2D-like film that eventually coexists with a bulklike phase suggesting a dewetting behavior. Motionally averaged angular patterns with biaxiallike features reveal unexpectedly fast surface molecular diffusion.

Measurement of the surface-induced order in polymer dispersed liquid crystals: an approach by NMR relaxometry.

A method based on NMR relaxometry is introduced to study surface-induced order in the isotropic phase of confined liquid crystals. We show that the magnitude of the surface order parameter S0 can be obtained from an increase in the deuteron transverse relaxation rate T-12. The increase originates in the molecular diffusion between the weakly ordered surface region and disordered area in the rest of the cavity. No assumptions concerning the residence time of molecules at the surface are needed. We apply the approach to a polymer dispersed liquid crystal and find a temperature independent S0 of magnitude congruent with 0.08. This indicates that short range interactions at the interface dominate the behavior of S0, and that only a partial orientational wetting occurs.

Effects of quenched disorder on the orientational order of the octylcyanobiphenyl liquid crystal.

Deuteron NMR (DNMR) measurements were performed with high-temperature and spectral resolution on the octylcyanobiphenyl (8CB) liquid crystal confined to the randomly interconnected pores of silica aerogel as a function of temperature and silica density. The aerogel density was varied by one order of magnitude and the temperature spanned the isotropic (I), nematic (N), and smectic-A (SmA) phases of 8CB. For all samples, the liquid crystal was confined to pores smaller than the micron-sized magnetic coherence length. Thus the observed line shapes reflect the director pattern, n(r-->), and the orientational order, Q, as dictated by the porous host. The DNMR spectral patterns are consistent with powder line shapes representative of a randomized n(r-->) characterized by a single Q. The nematic domains formed are of finite dimension that likely exceeds the confining size. The weakly first-order nematic-to-isotropic phase transition becomes less discontinuous with decreasing pore size, eventually becoming continuous at an aerogel density between 0.36 and 0.5 g/cm(3). In the most severe confinement, no phase transitions are observed with only a continuous evolution of Q present. The orientational order is suppressed from the bulk's with no enhancement upon the onset of the SmA phase. This indicates a decoupling of nematic and smectic order parameters and a severe suppression of the SmA phase by this porous media.