Craniofacial and occlusal features of individuals with Turner Syndrome: A cephalometric study.

Craniofacial features of 18 individuals with Turner Syndrome (TS) were compared with age and gender matched healthy individuals. Dental history, panoramic radiograph, dental casts and cephalometric measurements were assessed. The dental casts analysis showed a significantly higher PH/PW ratio in individuals with TS under GH therapy compared to healthy individuals (p=0.004; paired t-test). This data objectively supported the definition of a high-narrow palate. The ANB angle and the Wits index were similar in the two group, showing a skeletal class I malocclusion. The vertical characteristics did not differ between the two groups, showing a mesofacial growth pattern. Our results showed similar cephalometric characteristics in individuals with TS treated with GH and healthy controls.

Time Evolution of the Kondo Resonance in Response to a Quench.

We investigate the time evolution of the Kondo resonance in response to a quench by applying the time-dependent numerical renormalization group (TDNRG) approach to the Anderson impurity model in the strong correlation limit. For this purpose, we derive within the TDNRG approach a numerically tractable expression for the retarded two-time nonequilibrium Green function G(t+t^{'},t), and its associated time-dependent spectral function, A(ω,t), for times t both before and after the quench. Quenches from both mixed valence and Kondo correlated initial states to Kondo correlated final states are considered. For both cases, we find that the Kondo resonance in the zero temperature spectral function, a preformed version of which is evident at very short times t→0^{+}, only fully develops at very long times t≳1/T_{K}, where T_{K} is the Kondo temperature of the final state. In contrast, the final state satellite peaks develop on a fast time scale 1/Γ during the time interval -1/Γ≲t≲+1/Γ, where Γ is the hybridization strength. Initial and final state spectral functions are recovered in the limits t→-∞ and t→+∞, respectively. Our formulation of two-time nonequilibrium Green functions within the TDNRG approach provides a first step towards using this method as an impurity solver within nonequilibrium dynamical mean field theory.

A machine learning tool for re-planning and adaptive RT: A multicenter cohort investigation.

PURPOSE: To predict patients who would benefit from adaptive radiotherapy (ART) and re-planning intervention based on machine learning from anatomical and dosimetric variations in a retrospective dataset. MATERIALS AND METHODS: 90 patients (pts) treated for head-neck cancer (H&N) formed a multicenter data-set. 41 H&N pts (45.6%) were considered for learning; 49 pts (54.4%) were used to test the tool. A homemade machine-learning classifier was developed to analyze volume and dose variations of parotid glands (PG). Using deformable image registration (DIR) and GPU, patients' conditions were analyzed automatically. Support Vector Machines (SVM) was used for time-series evaluation. "Inadequate" class identified patients that might benefit from replanning. Double-blind evaluation by two radiation oncologists (ROs) was carried out to validate day/week selected for re-planning by the classifier. RESULTS: The cohort was affected by PG mean reduction of 23.7±8.8%. During the first 3weeks, 86.7% cases show PG deformation aligned with predefined tolerance, thus not requiring re-planning. From 4th week, an increased number of pts would potentially benefit from re-planning: a mean of 58% of cases, with an inter-center variability of 8.3%, showed "inadequate" conditions. 11% of cases showed "bias" due to DIR and script failure; 6% showed "warning" output due to potential positioning issues. Comparing re-planning suggested by tool with recommended by ROs, the 4th week seems the most favorable time in 70% cases. CONCLUSIONS: SVM and decision-making tool was applied to overcome ART challenges. Pts would benefit from ART and ideal time for re-planning intervention was identified in this retrospective analysis.

Reducing absorbed dose to eye lenses in head CT examinations: the effect of bismuth shielding.

The eye lens is considered to be among the most radiosensitive human tissues. Brain CT scans may unnecessarily expose it to radiation even if the area of clinical interest is far from the eyes. The aim of this study is to implement a bismuth eye lens shielding system for Head-CT acquisitions in these cases. The study is focused on the assessment of the dosimetric characteristics of the shielding system as well as on its effect on image quality. The shielding system was tested in two set-ups which differ for distance ("contact" and "4 cm" Set up respectively). Scans were performed on a CTDI phantom and an anthropomorphic phantom. A reference set up without shielding system was acquired to establish a baseline. Image quality was assessed by signal (not HU converted), noise and contrast-to-noise ratio (CNR) evaluation. The overall dose reduction was evaluated by measuring the CTDIvol while the eye lens dose reduction was assessed by placing thermoluminescent dosimeters (TLDs) on an anthropomorphic phantom. The image quality analysis exhibits the presence of an artefact that mildly increases the CT number up to 3 cm below the shielding system. Below the artefact, the difference of the Signal and the CNR are negligible between the three different set-ups. Regarding the CTDI, the analysis demonstrates a decrease by almost 12 % (in the "contact" set-up) and 9 % (in the "4 cm" set-up). TLD measurements exhibit an eye lens dose reduction by 28.5 ± 5 and 21.1 ± 5 % respectively at the "contact" and the "4 cm" distance. No relevant artefact was found and image quality was not affected by the shielding system. Significant dose reductions were measured. These features make the shielding set-up useful for clinical implementation in both studied positions.

In vivo 3 T MR diffusion tensor imaging for detection of the fibre architecture of the human uterus: a feasibility and quantitative study.

OBJECTIVE: The aim of this study was to investigate the feasibility of depicting fibre architecture of human uteri in vivo using 3 T MR diffusion tensor imaging (MR-DTI) with a three-dimensional (3D) tractography approach. Quantitative results were provided. METHODS: In vivo 3 T MR-DTI was performed on 30 volunteers (9 Caesarean delivery). Main diffusion directions reflecting the fibre orientation were determined using sensitivity-encoding single-shot echo planar imaging with diffusion-sensitised gradients (b=600 mm(2) s(-1)) along 32 directions. A deterministic fibre-tracking algorithm was used to show in vivo fibre architecture, compared with ex vivo histological slides of cadaveric uteri. The number of fibres, the fibre density, the fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) were measured in 13 volunteers. RESULTS: Anisotropy was found in most regions of normal uteri and the preferential order of uterine fibres depicted, consisting of two representative fibre directions: circular and longitudinal, as in ex vivo studies. Two-thirds of uteri with a Caesarean scar did not have the same orientation of fibres in the anterior isthmus when compared with non-scarred myometrium. Quantitative data were obtained from 13 volunteers: Caesarean-scarred uteri (n=5) showed lower fibre number and density in the scarred anterior isthmus than the nulliparous uteri (n=8). No significant differences were found in FA (0.42 ± 0.02, 0.41 ± 0.02; p=0.25) and ADC (1.82 ± 0.18 × 10(-3) mm(2) s(-1), 1.93 ± 0.25 × 10(-3) mm(2) s(-1); p=0.20). CONCLUSION: Fibre architecture of the human uterus can be depicted in vivo using 3 T MR-DTI. Advances in knowledge 3 T MR-DTI can help to provide an in vivo insight of uterine anatomy non-invasively, especially in females with previous Caesarean surgery, in order to provide better management of subsequent deliveries.

Charge Kondo anomalies in PbTe doped with Tl impurities.

We investigate the properties of PbTe doped with a small concentration x of Tl impurities acting as acceptors and described by Anderson impurities with negative onsite correlation energy. We use the numerical renormalization group method to show that the resulting charge Kondo effect naturally accounts for the unusual low temperature and doping dependence of normal state properties, including the self-compensation effect in the carrier density and the nonmagnetic Kondo anomaly in the resistivity. These are found to be in good qualitative agreement with experiment. Our results for the Tl s-electron spectral function provide a new interpretation of point contact data.

Phase Contrast MR as Non-Invasive Tool in the Diagnosis of Benign Intracranial Hypertension.

Idiopathic intracranial hypertension (IIH) is characterized by an increased intracranial pressure in the absence of expansive lesions or cerebrospinal fluid (CSF) circulation obstructions. Its physiopathology is still not fully understood. The diagnosis is currently established on clinical grounds (Dandy criteria) along with an invasive measurement of CSF dynamic parameters through the infusion test. This study compares the invasive pressure measurements with the biomechanical CSF parameters derived from a phase-contrast MR protocol to evaluate the accuracy and reliability of the phase-contrast MR protocol.

Mechanical control of spin states in spin-1 molecules and the underscreened Kondo effect.

The ability to make electrical contact to single molecules creates opportunities to examine fundamental processes governing electron flow on the smallest possible length scales. We report experiments in which we controllably stretched individual cobalt complexes having spin S = 1, while simultaneously measuring current flow through the molecule. The molecule's spin states and magnetic anisotropy were manipulated in the absence of a magnetic field by modification of the molecular symmetry. This control enabled quantitative studies of the underscreened Kondo effect, in which conduction electrons only partially compensate the molecular spin. Our findings demonstrate a mechanism of spin control in single-molecule devices and establish that they can serve as model systems for making precision tests of correlated-electron theories.

Kondo decoherence: finding the right spin model for iron impurities in gold and silver.

We exploit the decoherence of electrons due to magnetic impurities, studied via weak localization, to resolve a long-standing question concerning the classic Kondo systems of Fe impurities in the noble metals gold and silver: which Kondo-type model yields a realistic description of the relevant multiple bands, spin, and orbital degrees of freedom? Previous studies suggest a fully screened spin S Kondo model, but the value of S remained ambiguous. We perform density functional theory calculations that suggest S=3/2. We also compare previous and new measurements of both the resistivity and decoherence rate in quasi-one-dimensional wires to numerical renormalization group predictions for S=1/2, 1, and 3/2, finding excellent agreement for S=3/2.

Metallic and insulating phases of repulsively interacting fermions in a 3D optical lattice.

The fermionic Hubbard model plays a fundamental role in the description of strongly correlated materials. We have realized this Hamiltonian in a repulsively interacting spin mixture of ultracold (40)K atoms in a three-dimensional (3D) optical lattice. Using in situ imaging and independent control of external confinement and lattice depth, we were able to directly measure the compressibility of the quantum gas in the trap. Together with a comparison to ab initio dynamical mean field theory calculations, we show how the system evolves for increasing confinement from a compressible dilute metal over a strongly interacting Fermi liquid into a band-insulating state. For strong interactions, we find evidence for an emergent incompressible Mott insulating phase. This demonstrates the potential to model interacting condensed-matter systems using ultracold fermionic atoms.

Kondo proximity effect: how does a metal penetrate into a Mott insulator?

We consider a heterostructure of a metal and a paramagnetic Mott insulator using an adaptation of dynamical mean-field theory to describe inhomogeneous systems. The metal can penetrate into the insulator via the Kondo effect. We investigate the scaling properties of the metal-insulator interface close to the critical point of the Mott insulator. At criticality, the quasiparticle weight decays as 1/x;{2} with distance x from the metal within our mean-field theory. Our numerical results (using the numerical renormalization group as an impurity solver) show that the prefactor of this power law is extremely small.

Mott transition of fermionic atoms in a three-dimensional optical trap.

We study theoretically the Mott metal-insulator transition for a system of fermionic atoms confined in a three-dimensional optical lattice and a harmonic trap. We describe an inhomogeneous system of several thousand sites using an adaptation of dynamical mean-field theory solved efficiently with the numerical renormalization group method. Above a critical value of the on-site interaction, a Mott-insulating phase appears in the system. We investigate signatures of the Mott phase in the density profile and in time-of-flight experiments.

Quantum phase transition in the two-band hubbard model.

The interaction between itinerant and Mott localized electronic states in strongly correlated materials is studied within dynamical mean field theory in combination with the numerical renormalization group method. A novel nonmagnetic zero temperature quantum phase transition is found in the bad-metallic orbital-selective Mott phase of the two-band Hubbard model, for values of the Hund's exchange which are relevant to typical transition metal oxides.

Scaling of the low-temperature dephasing rate in Kondo systems.

We present phase coherence time measurements in quasi-one-dimensional Ag wires doped with Fe Kondo impurities of different concentrations n_{s}. Because of the relatively high Kondo temperature T_{K} approximately 4.3 K of this system, we are able to explore a temperature range from above T_{K} down to below 0.01T_{K}. We show that the magnetic contribution to the dephasing rate gamma_{m} per impurity is described by a single, universal curve when plotted as a function of T/T_{K}. For T>0.1T_{K}, the dephasing rate is remarkably well described by recent numerical results for spin S=1/2 impurities. At lower temperature, we observe deviations from this theory. Based on a comparison with theoretical calculations for S>1/2, we discuss possible explanations for the observed deviations.

Universal dephasing rate due to diluted Kondo impurities.

We calculate the dephasing rate due to magnetic impurities in a weakly disordered metal as measured in a weak-localization experiment. If the density nS of magnetic impurities is sufficiently low, the dephasing rate 1/tauphi is a universal function, 1/tauphi=(nS/nu)f(T/TK), where TK is the Kondo temperature and nu is the density of states. We show that inelastic vertex corrections with a typical energy transfer DeltaE are suppressed by powers of 1/(tauphiDeltaE) proportional to nS. Therefore, the dephasing rate can be calculated from the inelastic cross section proportional to pinu ImT-/pinuT/2, where T is the T matrix which is evaluated numerically exactly using the numerical renormalization group.

Mott transition and transport crossovers in the organic compound kappa-(BEDT-TTF)2Cu[N(CN)2]Cl.

We have performed in-plane transport measurements on the two-dimensional organic salt kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Cl. A variable (gas) pressure technique allows for a detailed study of the changes in conductivity through the insulator-to-metal transition. We identify four different transport regimes as a function of pressure and temperature (corresponding to insulating, semiconducting, "bad metal," and strongly correlated Fermi-liquid behaviors). Marked hysteresis is found in the transition region, which displays complex physics that we attribute to strong spatial inhomogeneities. Away from the critical region, good agreement is found with a dynamical mean-field calculation of transport properties using the numerical renormalization group technique.

Magnetic correlations and the anisotropic Kondo effect in Ce1-xLaxAl3.

By combining the results of muon spin relaxation and inelastic neutron scattering in the heavy fermion compounds Ce1-xLaxAl3 (0.0