North Atlantic climate far more predictable than models imply.

Quantifying signals and uncertainties in climate models is essential for the detection, attribution, prediction and projection of climate change1-3. Although inter-model agreement is high for large-scale temperature signals, dynamical changes in atmospheric circulation are very uncertain4. This leads to low confidence in regional projections, especially for precipitation, over the coming decades5,6. The chaotic nature of the climate system7-9 may also mean that signal uncertainties are largely irreducible. However, climate projections are difficult to verify until further observations become available. Here we assess retrospective climate model predictions of the past six decades and show that decadal variations in North Atlantic winter climate are highly predictable, despite a lack of agreement between individual model simulations and the poor predictive ability of raw model outputs. Crucially, current models underestimate the predictable signal (the predictable fraction of the total variability) of the North Atlantic Oscillation (the leading mode of variability in North Atlantic atmospheric circulation) by an order of magnitude. Consequently, compared to perfect models, 100 times as many ensemble members are needed in current models to extract this signal, and its effects on the climate are underestimated relative to other factors. To address these limitations, we implement a two-stage post-processing technique. We first adjust the variance of the ensemble-mean North Atlantic Oscillation forecast to match the observed variance of the predictable signal. We then select and use only the ensemble members with a North Atlantic Oscillation sufficiently close to the variance-adjusted ensemble-mean forecast North Atlantic Oscillation. This approach greatly improves decadal predictions of winter climate for Europe and eastern North America. Predictions of Atlantic multidecadal variability are also improved, suggesting that the North Atlantic Oscillation is not driven solely by Atlantic multidecadal variability. Our results highlight the need to understand why the signal-to-noise ratio is too small in current climate models10, and the extent to which correcting this model error would reduce uncertainties in regional climate change projections on timescales beyond a decade.

Ultrasmall Moment Incommensurate Spin Density Wave Order Masking a Ferromagnetic Quantum Critical Point in NbFe_{2}.

In the metallic magnet Nb_{1-y}Fe_{2+y}, the low temperature threshold of ferromagnetism can be investigated by varying the Fe excess y within a narrow homogeneity range. We use elastic neutron scattering to track the evolution of magnetic order from Fe-rich, ferromagnetic Nb_{0.981}Fe_{2.019} to approximately stoichiometric NbFe_{2}, in which we can, for the first time, characterize a long-wavelength spin density wave state burying a ferromagnetic quantum critical point. The associated ordering wave vector q_{SDW}=(0,0,l_{SDW}) is found to depend significantly on y and T, staying finite but decreasing as the ferromagnetic state is approached. The phase diagram follows a two-order-parameter Landau theory, for which all of the coefficients can now be determined. Our findings suggest that the emergence of spin density wave order cannot be attributed to band structure effects alone. They indicate a common microscopic origin of both types of magnetic order and provide strong constraints on related theoretical scenarios based on, e.g., quantum order by disorder.

Interaction driven subgap spin exciton in the Kondo insulator SmB6.

Using inelastic neutron scattering, we map a 14 meV coherent resonant mode in the topological Kondo insulator SmB6 and describe its relation to the low energy insulating band structure. The resonant intensity is confined to the X and R high symmetry points, repeating outside the first Brillouin zone and dispersing less than 2 meV, with a 5d-like magnetic form factor. We present a slave-boson treatment of the Anderson Hamiltonian with a third neighbor dominated hybridized band structure. This approach produces a spin exciton below the charge gap with features that are consistent with the observed neutron scattering. We find that maxima in the wave vector dependence of the inelastic neutron scattering indicate band inversion.

Basal-body-associated macromolecules: a continuing debate.

Controversy over the possibility that centrioles/basal bodies contain nucleic acids has overshadowed results demonstrating other macromolecules in the lumen of these organelles. Glycogen particles, which are known to be present within the lumen of the centriole/basal body of sperm cells, have now been found in basal bodies of protists belonging to three different groups. Here, we extend the debate on a role for RNA in basal body/centriole function and speculate on the origin and the function of centriolar glycogen.

Screened moments and extrinsic in-gap states in samarium hexaboride.

Samarium hexaboride (SmB6) is a Kondo insulator, with a narrow gap due to hybridization between localized and conduction electrons. Despite being an insulator, many samples show metal-like properties. Rare-earth purification is exceedingly difficult, and nominally pure samples may contain 2% or more of impurities. Here to determine the effects of rare-earth doping on SmB6, we synthesized and probed a series of gadolinium-doped samples. We found a relationship between specific heat and impurity moment screening which scales systematically. Consistent with this finding, our neutron scattering experiments of a high purity sample of doubly isotopic 154Sm11B6 show no intrinsic excitations below the well-established 13 meV spin-exciton. The result of introducing impurities into a Kondo insulator is incompletely understood, but it is clear from our measurements that there is a systematic relationship between rare-earth impurities and metal-like properties in SmB6.

Magnetic moments induce strong phonon renormalization in FeSi.

The interactions of electronic, spin and lattice degrees of freedom in solids result in complex phase diagrams, new emergent phenomena and technical applications. While electron-phonon coupling is well understood, and interactions between spin and electronic excitations are intensely investigated, only little is known about the dynamic interactions between spin and lattice excitations. Noncentrosymmetric FeSi is known to undergo with increasing temperature a crossover from insulating to metallic behaviour with concomitant magnetic fluctuations, and exhibits strongly temperature-dependent phonon energies. Here we show by detailed inelastic neutron-scattering measurements and ab initio calculations that the phonon renormalization in FeSi is linked to its unconventional magnetic properties. Electronic states mediating conventional electron-phonon coupling are only activated in the presence of strong magnetic fluctuations. Furthermore, phonons entailing strongly varying Fe-Fe distances are damped via dynamic coupling to the temperature-induced magnetic moments, highlighting FeSi as a material with direct spin-phonon coupling and multiple interaction paths.

Fine-structural study of mitosis in the testacean Arcella vulgaris Ehrbg.

The two nuclei of Arcella vulgaris divide synchronously by closed intranuclear orthomitosis during the formation and deployment of the thecagenous cytoplasmic bud. In prophase, the two nuclei are stacked one behind the other in front of the pseudostome, and markedly flattened, which brings the chromosomes near the equatorial plane. The nucleolus disperses, the nuclear lamina gradually disappears, and non-oriented microtubule bundles grow from intranuclear MTOCs. The condensing chromosomes already show attachment sites for one or more microtubules. In prometaphase, the nuclei are still stacked; the chromosomes further condense, the microtubules are oriented but short, leaving large polar regions of the nucleus filled with diffuse nucleolar material. At metaphase, the nucleus elongates to become spherical to barrelshaped; the spindle microtubules are longer but do not reach the nuclear envelope at the poles. In the polar regions, the nucleolar material aggregates into globular masses. The nuclear envelope remains continuous and devoid of lamina, but becomes sinuous. The kinetochores are improminent, associated with up to 6 microtubules. There are no nuclear pole bodies or extranuclear microtubules. At telophase, the nuclear envelope becomes very convoluted, suggesting that portions of the daughter nuclei bud off into the cytoplasm. Annulate lamellae occur inside the nuclei. The chromosomes decondense and the nuclear lamina is reformed, simultaneously with the appearance of new nucleoli which then fuse into one. Post-telophase nuclei undergo shuttle migrations with the cytoplasm between daughter cells.

New ultrastructural data on the morphogenesis of the test in the testacean Arcella vulgaris.

Transmission electron microscopic studies of dividing Arcella vulgaris Ehrbg. have shown that:

Nuclear fine structure at interphase and during encystment in two forms of the testacean Arcella vulgaris.

Arcella vulgaris and A. vulgaris var. multinucleata have two and seven vesicular nuclei, respectively. In early interphase, the nuclei are spherical, with a main central nucleolus and several small peripheral nucleoli. The main nucleolus has mixed fibrillar and granular components and no apparent chromatin bodies in the nucleolus-organizing regions (NORs). The nuclear chromatin is dispersed except for small heterochromatin lumps. Nuclear bodies of fibrous structure occur outside the main nucleolus. The nuclear envelope shows an internal lamina and an external layer of tangential fibres. In middle interphase, the nuclei become irregular in shape and adjacent to the plasma membrane at the dorsolateral cell surface. The condensation of the chromatin increases. The nucleolus is often eccentric and its NORs show conspicuous bodies of condensed chromatin surrounded by a halo and a fibrous transcription zone. By the end of interphase, the main nucleolus becomes polymorphic and segregated into a fibrillar basal part which contains a vacuolar area with dense inclusions, and a fibro-granular cap which contains many fibrous electron dense bodies. These are likely to be the nuclear chromatin elements. In early resting cysts, the nuclei detach from the cell membrane and approach one another. The main nucleolus segregates into large, mainly peripheral fibrillar blocks inside a granular mass. The NORs consist of condensed chromatin bodies without a transcription zone around them. The nuclear chromatin is condensed. Conspicuous intranuclear annulate lamellae bearing pore complexes occur only in cysts.

Efficacy of Daflon 500 mg in venous leg ulcer healing: a double-blind, randomized, controlled versus placebo trial in 107 patients.

The objective of this study was to evaluate the efficacy of Daflon 500 mg (Dios)* in venous ulcers. A multicenter, double-blind, randomized, controlled versus placebo (Plac) trial was conducted, with stratification according to the size of ulcer (< or = 10 cm and > 10 cm). The protocol called for a two-month treatment with Dios (one tablet = 450 mg micronized purified Diosmin) or a placebo, two tablets/day, in addition to compression therapy. Evaluations were performed every fifteen days, from D0 to D60. The primary endpoint, in accordance with Alexander House group requirements were: percentage of patients with complete ulcer healing, ie, comparison between Dios and Plac group at D60, and comparison of survival curves in each group between D0 and D60 (log rank test). Secondary endpoints included ulcer surface area assessed by computerized planimetric measurements, qualitative evaluation of ulcers, and symptoms. The patients were 105 men and women ranging in age from eighteen to eighty-five years, with standard compression stocking, who were undergoing standardized local care of ulcer and had no significant arterial disease (ankle/arm systolic pressure index > 0.8). Fifty-three patients received Dios, and 52 received Plac. The 2 groups were well matched for age (m +/- 1 SD = seventy-one +/- eleven years), gender, ulcer size, and associated disorders. Among patients with ulcer size < or = 10 cm (Dios = 44, Plac = 47) a significantly larger number of patients had a complete ulcer healing at two months in the Dios group (n = 14) in comparison with the Plac group (n = 6) (32% vs 13%, P = 0.028) with a significantly shorter time duration of healing (P = 0.037). No difference was shown for the secondary criteria, except for sensation of heavy legs (P = 0.039) and a less atonic aspect of ulcer (P = 0.030) in favor of Dios. Among the 14 patients with ulcer size > 10 cm (Dios = 9, Plac = 5), subjected to a descriptive analysis only, no ulcer healed. This study showed that a two-month course of Daflon 500 mg at a daily dose of two tablets, in addition to conventional treatment, is of benefit in patients with venous ulcer < or = 10 cm by accelerating complete healing.

Quick method of measuring the furrows distribution on skin surface replicas.

A fast method of measuring the distribution of furrows can be obtained via the analysis of TV camera images of skin replicas. These replicas are either negative (or direct) or positive. Reflected or transmitted light is used, depending on the type of replica. Each point of the matrix (256 x 256 pixels) is digitised over 6 bits (64 levels) and treated by a personal computer (IBM AT or PC). With such an image, it is not possible to obtain significant results without eliminating noise and enhancing the furrows. Specific software is written in processor language 8086 to obtain a real time system. The distribution of skin furrows is quantified for several interesting cases such as the ageing of the skin or the effect of stress.

[Changes of the cutaneous micro-relief in superficial radiation-induced fibrosis: a qualitative study]. / Modifications du microrelief cutané dans la fibrose radio-induite superficielle: étude qualitative.

Cutaneous radiation-induced fibrosis (RIF) is characterized by a skin retraction or atrophy, toughness to the palpation and often entails functional limitation. Its clinical evaluation remains poorly quantified. The aim of this study was to propose an analytical method to quantify RIF skin surface with the replica technique. In this preliminary study, we report the qualitative and quantitative evaluation of the cutaneous microrelief in 44 healthy controls and in four patients presenting a superficial RIF, 3 to 20 years after radiotherapy for cancer. The microrelief of these RIF presented an abnormal anisotropy with a parallel reorganization of cutaneous valleys in three cases out of four, suggesting a premature radiation-induced ageing of the skin. Each subject being his own control, the relative vertical amplitude of the skin microrelief was +/-15% in control skin. Vertical amplitude was respectively increased by 84% in one inflammatory fibrosis (3 years after RT), decreased by 18% in one evolutive fibrosis (6 years after RT), decreased by 26% in one voluminous stabilized fibrosis (8 years after RT) and decreased by 53% in one atrophic fibrosis (20 years after RT). The present study suggests that the variations of the microrelief parameters could reflect the RIF evolution. This technique requires a validation in a larger series of patients, including patients with telangiectasia.

Rectification of distorted chromosome image: automatic determination of density profiles.

In this study, we present a new method of the rectification of distorted chromosome image allowing a more accurate description of the chromosome by obtaining density profiles with a large choice of scan axes, and an automatic centromere localisation and determination of the centromeric index.

[Measurement of the vascular mass of the human radial artery by ultrasonics]. / Mesure de la masse vasculaire de l'artère radiale humaine par méthode ultrasonique.

OBJECTIVE: To determine the reproducibility of radial artery mass (RAM), in hypertensive patients. DESIGN AND METHODS: In 49 patients, RAM was measured using a high resolution echotracking device (Nius-02) which allows noninvasive measurement of diameter and wall thickness of the radial artery. RAM was validated in vitro by comparing weight of arterial segments to ultrasonographic measurement and determined as RAM = r (pi Re2-pi Ri2) where r is the arterial wall density (1.06 g/cm3), and Re and Ri are values of internal and external radii, respectively. Repeatability coefficient (RC2 = SDi2/n) was 1.3 mg. RESULTS: Blood pressure was (mean +/- SD) 146 +/- 19/85 +/- 15 mmHg, radial arterial diameter was 2,449 +/- 376 microns, radial wall thickness was 302 +/- 68 microns, RAM was 28 +/- 9 mg (range 13-43 mg). CONCLUSION: These results indicate that radial artery mass can be measured using a high resolution echotracking device.

Three-dimensional measurements of skin surface topography by triangulation with a new laser profilometer.

The fast measurement of furrows or wrinkles requires the use of a non-contact device. We have chosen a laser detector based on a triangulation principle, using position-sensitive detectors. This apparatus has a sensitivity of about 2-3 microns for a vertical range > 1 mm; this vertical range can reach 8 mm. There is no contact between the detector and the surface and this reduces the measurement time because, while data are being transmitted, there is no decrease in the scanning speed as with earlier methods. We describe the device and its technical characteristics. The limits of use are shown in the measurement of low-amplitude defects (> 3-4 microns) and of wide defects of < or = 8 mm. Examples of software possibilities and practical applications related to skin microrelief, wrinkles and pathological cases, are also described.

[Histological morphometric methods. II. Automatic analysers (author's transl)]. / Méthodes histomorphométriques. II - Méthodes automatiques.

Histological morphometric methods can be divided into three groups depending on their automation degree: manual methods, semi-automatic methods, fully automatic methods. Among fully automated image analysers, one can separate devices into three main subgroups: 1 - general purpose systems controlled by software can be programmed to undertake an infinite variety of tasks. 2 - general purpose systems with limited repertoire of analysis, controlled by hardware programs. 3 - simple task instruments controlled by hardware programs (e.g. Hematrak, Leitz). Whichever instrument is used, three steps take place in an automated image analysis procedure: 1 - image numeration. 2 - parameters extraction. 3 - parameters interpretation. The NS 2000 image analyser belonged to the 2nd subgroup of the above mentioned systems. Its built-in hardware algorithm works just like successive erosions on images. An example (breast carcinoma tissue section) is given in order to illustrate performances of this peculiar image analyser.

[Histological morphometric methods. I. Semi-automatic methods on graphic tables (author's transl)]. / Méthodes histomorphométriques. I. Méthodes semi-automatiques: applications des tables à digitiser.

Two kinds of parameters are accessible by histological morphometric methods: --actual quantitative ones (e.g. length, area) --discontinuous ones (e.g. cells, nucleus or mitochondrium counting). Measures were all achieved by manual methods in past. Nowadays, apparatus are existing that can solve semi-automatically histomorphometric problems. These apparatus are variously named digitizer, digitizing table, digitalizing table, graphic table and so on. Two histomorphometric examples are described one concerning breast carcinoma the other myocardial vascularization in rats. They both have been treated on a graphic table. Problems and their solutions are developed.

[Histomorphometric study of lymphocyte population in thyroid in Graves' disease after treatment (author's transl)]. / Etude histomorphométrique de la population lymphoïde présente dans les thyroïdes de maladie de Basedow traitée.

The degree of lymphocyte infiltration in subtotal thyroidectomy specimens from patients with treated Graves' disease varies greatly from one case to another. A morphometric study, employing standard and immunofluorescent slides was conducted to evaluate possible statistical correlations between clinical and morphological findings. Quantitative lymphoplasmocytic cellularity differences appeared to be related to the course of the disease. Lymphocyte infiltration was greater in patients with long-standing disease and/or relapses.

Dynamic non-invasive measurements of arterial diameter and wall thickness.

AIM: Non-invasive measurements of arterial diameter and wall thickness are critical in characterizing the onset and development of vascular disease. A precise dynamic method was proposed and tested for this purpose. DESIGN: A non-invasive method of measuring the variations in diameter and thickness of human arteries throughout the cardiac cycle was developed, using a high-precision ultrasonic echo-tracking system. An adaptive filtering technique was used to suppress artefacts caused by the layered tissue structure of the vessel wall. RESULTS: Based on decorrelation of microstructure noise, this technique improved the detectability of the wall interfaces, which allowed a determination of thickness and diameter. The accuracy and reproducibility of the method were tested by measurements of plastic films with known thicknesses. The discrepancies between standard micrometer and pulse-echo measurement were consistently less than 5 microns for film thicknesses ranging from 220 to 800 microns. The difference between two successive measurements was less than 2 microns. The identity of the measured vascular interfaces was checked in two ways. First, experiments on fixed bovine carotid arteries showed that the identified echogenic interfaces corresponded to the actual anatomical structure, as obtained by acoustic microscopy. Second, the radial artery thickness and diameter were extrapolated to obtain the change in wall volume over one cardiac cycle. The volume was found to be nearly constant, indicating incompressibility. CONCLUSION: This method will make it possible to obtain new information on atherogenesis and other vascular diseases.

Interplay of low-energy phonons and magnetic excitations in the Kondo insulator YbB12.

Peculiarities in the lattice dynamics of the Kondo insulator Y bB(12) have been studied by inelastic neutron scattering. Selected phonon modes were traced above and below the temperature region (T ~ 50 K) where the gap opens in the electron density of states. The intensities of some low-energy modes exhibit an anomalous temperature dependence for q vectors close to the Brillouin zone boundary, suggesting a renormalization of the phonon eigenvectors. This effect is thought to arise from a coupling with magnetic excitations of the same symmetry, which exist at nearby energies. It is argued that this magnetovibrational coupling may in turn play a role in the steep temperature crossover existing in Y bB(12) between the low-temperature (Kondo insulator) and high-temperature (incoherent spin-fluctuation) regimes, which is rapidly suppressed by lighter Zr substitution.