Low-temperature magnetization in geometrically frustrated Tb2Ti2O7

The nature of the low temperature ground state of the pyrochlore compound Tb2Ti2O7 remains a puzzling issue. Dynamic fluctuations and short-range correlations persist down to 50 mK, as evidenced by microscopic probes. In parallel, magnetization measurements show irreversibilities and glassy behavior below 200 mK. We have performed magnetization and AC susceptibility measurements on four single crystals down to 57 mK. We did not observe a clear plateau in the magnetization as a function of field along the [111] direction, as suggested by the quantum spin ice model. In addition to a freezing around 200 mK, slow dynamics are observed in the AC susceptibility up to 4 K. The overall frequency dependence cannot be described by a canonical spin-glass behavior.Comment: 5 pages, 4 figures + Supp. Mat (3 pages, 5 figures

Effect of Oral and Maxillofacial Injuries on the Development of Post-Traumatic Stress Disorder: A Cross-Sectional Study

Objective: To assess the influence of oral and maxillofacial trauma on the development of Post-Traumatic Stress Disorder (PTSD) and to determine the efficiency of the Impact of Event Scale-Revised (IES-R) as a diagnostic tool for detecting PTSD in patients with Oral and Maxillofacial injuries. Material and Methods: PTSD was assessed one month postoperatively by the diagnostic instrument, IES-R, to arrive at a provisional diagnosis. A structured clinician-administered PTSD Scale then assessed the patients for the Diagnostic and Statistical Manual of Mental Disorders-5th edition (CAPS-5) to establish a final diagnosis. The assessment of the severity of PTSD was done based on various types of oral and maxillofacial injuries. Results: The IES-R scale provisionally diagnosed 54 subjects with PTSD, out of which 42 were diagnosed to have PTSD by the CAPS-5 scale. Subjects with injuries involving the ‘orbital complex,’ those presenting with a perceptible scar in the maxillofacial region and with multiple avulsed/ luxated anterior teeth, showed a higher affinity to develop PTSD, and this was statistically significant. Conclusion: Higher levels of PTSD in patients with injuries to the maxillofacial region warrants correct diagnosis and detection, and hence the maxillofacial surgeon plays a vital role in this regard. The IES-R is a useful diagnostic tool to detect PTSD early

Exploratory Boosted Feature Selection and Neural Network Framework for Depression Classification

Depression is a burdensome psychiatric disease common in low and middle income countries causing disability, morbidity and mortality in late life. In this study, we demonstrate a novel approach for detection of depression using clinical data obtained from the on-going Mysore Studies of Natal effects on Ageing and Health (MYNAH), in South India where the members have undergone a comprehensive assessment for cognitive function, mental health and cardiometabolic disorders. The proposed model is developed using machine learning approach for classification of depression using Meta-Cognitive Neural Network (McNN) classifier with Projection-based learning (PBL) to address the self-regulating principles like how, what and when to learn. XGBoost is used for feature selection on the available data of assessments with improved confidence. To improve the efficiency of McNN-PBL classifier the best parameters are found using Particle Swarm Optimization (PSO) algorithm. The results indicate that the McNNPBL classifier selects appropriate records to learn and remove repetitive records which improve the generalization performance. The study helps the clinician to identify the best parameters to analyze the patient

Low temperature crystal structure and local magnetometry for the geometrically frustrated pyrochlore Tb2Ti2O7

We report synchrotron radiation diffraction and muon spin rotation (muSR) measurements on the frustrated pyrochlore magnet Tb2Ti2O7. The powder diffraction study of a crushed crystal fragment does not reveal any structural change down to 4 K. The muSR measurements performed at 20 mK on a mosaic of single crystals with an external magnetic field applied along a three-fold axis are consistent with published a.c. magnetic-susceptibility measurements at 16 mK. While an inflection point could be present around an internal field intensity slightly above 0.3 T, the data barely support the presence of a magnetization plateau.Comment: To appear in the proceedings of the 13th International Conference on Muon Spin Rotation, Relaxation and Resonance, Grindelwald, Switzerland, 1-6 June 201

Magnetic chirality of the spin triplet in the spin-ladder compound Sr14Cu24O41 as seen via polarized inelastic neutron scattering

International audienceWe report the direct observation by polarized inelastic neutron scattering experiments at low fields (3.5 T) of the splitting of the spin triplet of magnetic excitations in the response associated with the ladders in the composite cuprate Sr14Cu24O41. By conveniently choosing the magnetic field configuration and by making use of the spin chirality of the excitations, the splitting can be observed at relatively low fields. In this way, resonant excitations can be separated from the remainder of magnetic and phonon excitations at high temperatures. In Sr14Cu24O41, the 32-meV gapped mode vanishes above ∼200 K, close to the hole-crystal melting temperature previously observed by resonant x-ray and neutron diffraction

Allergic and immunologic response of the oral mucosa: An overview

Allergic and immunologic diseases very often manifest oral lesions in their earliest stages, an early diagnosis, which may be spurred by a dental examination, is a key for improved outcomes. After systemic diagnosis, oral lesions benefi t from special care by dentists in alliance with the medical team. This review aims to highlight the most relevant allergic and immunologic conditions of the oral cavity, their pathogenesis, and their pathognomonic diagnostic features, which will navigate the clinicians to arrive at a prompt diagnosis and subsequent management

Macroscopic Quantum Coherence of the Spin Triplet in the Spin-Ladder Compound Sr14Cu24O41

International audienceWe report the direct observation by inelastic neutron scattering experiments of a spin triplet of magnetic excitations in the response associated with the ladders in the composite cuprate Sr14Cu24O41. This appears as a peak at q_{Q1D}=\pi and energy \Delta_1=32.5 meV, and we conjecture that all the triplets making up this conspicuous peak have the same phase and therefore interpret it as the signature of the occurrence of quantum coherence along the ladder direction between entangled spin pairs. From the comparison with previous neutron and x-ray data, we conclude that the temperature evolution of this mode is driven by the crystallization of holes into a charge density wave in the ladder sublattic

Exotic transition in the three-dimensional spin-liquid candidate Tb2Ti2O7

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Collective spin excitations in a quantum spin ladder probed by high-resolution Resonant Inelastic X-ray Scattering

We investigate magnetic excitations in the spin-ladder compound Sr$_{14}$Cu$_{24}$O$_{41}$ using high-resolution Cu $L_3$-edge Resonant Inelastic X-ray Scattering (RIXS). Our findings demonstrate that RIXS couples to collective spin excitations from a quantum spin-liquid ground state. In contrast to Inelastic Neutron Scattering (INS), the RIXS cross section changes only moderately over the entire Brillouin Zone (BZ), revealing a high sensitivity also at small momentum transfers. The two-triplon energy gap is found to be $100\pm 30$ meV. Our results are supported by calculations within an effective Hubbard model for a finite-size cluster.Comment: 10 pages, 4 figures, revised versio