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Planetary bodies with a sufficiently energetic origin are likely to begin their evolution in largely liquid state. Cooling and crystallization at the surface of a mostly liquid magma ocean (MO) is expected to produce a sedimented partially crystallized cumulate of melt and denser mineral grains at its base. The rate of crystallization and cumulate sedimentation are controlled by radiation through an atmosphere devolatilized from the vigorously convecting MO. Melt retained in the cumulate is initially isolated from the overlying MO and atmosphere; but through compaction and buoyant migration in permeable cumulates, retained melt may be discharged into the overlying MO and its dissolved volatiles contributed to the growing atmosphere. The rates of cumulate compaction and radiative cooling though the atmosphere may thus play interacting and competing roles governing the time scale of MO evolution.We explore these effects using a thermal evolution model similar to that described by Elkins-Tanton (2008; doi.org/10.1016/j.epsl.2008.03.062). In the current study, the top of the cumulate layer is defined by a depositional melt fraction (~50%) and temperature at which a liquid of MO composition behaves like a viscous solid. Heat flux from the MO surface is limited by radiation through a gray H2O-CO2 rich atmosphere (Abe and Matsui, 1988; doi.org/10.1175/1520-0469(1988)0452.0.CO;2). We consider Mars and Earth-like bodies with initial bulk H2O-CO2 concentrations 0.5%-0.1% and 0.05%-0.01% and vary the prescribed amount of retained melt in the cumulate from 0% (instantaneous compaction) to 50% (no compaction). For the Mars-sized body increasing retained melt fraction over this range reduces MO freezing time by nearly one order of magnitude (from ~1 Myr to The melt fraction retained in compacting cumulate deposited at constant, prescribed sedimentation rate is determined by the rate of buoyant melt migration (Shirley 1986; doi.org/10.1086/629088). For reasonable values of cumulate grainsize (~1 mm; Solomatov and Stevenson, 1993; doi.org/10.1029/92JE02839) and interstitial melt viscosity (~0.1 Pa-s). Cumulates in a Mars-sized, 1000 km deep MO solidifying in 0.1 Myr (cumulate thickening rate ~ 104 km/Myr) should retain melt fractions in the range of 10 to 30%, consistent with values the above thermal model shows are needed to produce this solidification rate. Nearly an order of magnitude reduction in freezing time due to retained melt can be expected.Ongoing work integrates the thermal evolution and migration of retained melt into a unified self-consistent model in which the variation of cumulate sedimentation rate with time is determined by the heat flux through the evolving atmosphere. Our results thus far indicate that volatiles contained in melt retained within cumulates, rather than being added to a growing atmospheric mass, could significantly reduce the time scale of MO solidification. Exploring this for small planetesimal-sized bodies will be particularly interesting since smaller gravity will reduce the rate of cumulate melt segregation while atmospheric escape may limit the mass of a growing atmosphere.

Solidification of magma oceans (MOs) formed early in the evolution of planetary bodies sets the initial condition for their evolution on much longer time scales. Ideal fractional crystallization would generate an unstable chemical stratification that subsequently overturns to form a stably stratified mantle. The simplest model of overturn assumes that cumulates remain immobile until the end of MO solidification. However, overturning of cumulates and thermal convection during solidification may act to reduce this stratification and introduce chemical heterogeneity on scales smaller than the MO thickness. We explore overturning of cumulates before the end of MO crystallization and the possible consequences for mantle structure and composition. In this model, increasingly dense iron-rich layers, crystallized from the overlying residual liquid MO, are deposited on a thickening cumulate layer. Overturn during solidification occurs if the dimensionless parameter, R c , measuring the ratio of the MO time of crystallization τ M O to the timescale associated with compositional overturn τ o v = μ / Δ ρ g H exceeds a threshold value. If overturn did not occur until after solidification, this implies that the viscosity of the solidified mantle must have been sufficiently high (possibly requiring efficient melt extraction from the cumulate) for a given rate of solidification. For the lunar MO, possible implications for the generation of the Mg-suites and mare basalt are suggested.

Lunar cumulate mantle overturn and the subsequent upwelling of overturned mantle cumulates provides a potential framework for understanding the first-order thermochemical evolution of the Moon. Upwelling of ilmenite-bearing cumulates (IBC) after the overturn has a dominant influence on the dynamics and long-term thermal evolution of the lunar mantle. An important parameter determining the stability and convective behaviour of the IBC is its viscosity, which was recently constrained through rock-deformation experiments. To examine the effect of IBC viscosity on the upwelling of overturned lunar cumulate mantle, here we conduct three-dimensional mantle convection models with an evolving core superposed by an IBC-rich layer, which resulted from mantle overturn after magma ocean solidification. Our modelling shows that a reduction of mantle viscosity by one order of magnitude, due to the presence of ilmenite, can dramatically change convective planform and long-term lunar mantle evolution. Our model results suggest a relatively stable partially molten IBC layer that has surrounded the lunar core to the present day.

The New Horizons spacecraft has found evidence for geologic activity on the surface of Pluto, including extensional tectonic deformation of its water ice bedrock see Moore et al. (2016). One mechanism that could drive extensional tectonic activity is global surface expansion due to the partial freezing of an ocean. We use updated physical properties for Pluto and simulate its thermal evolution to understand the survival of a possible subsurface ocean. For thermal conductivities of rock less than 3 W m−1 K−1, an ocean forms and at least partially freezes, leading to recent extensional stresses in the ice shell. In scenarios where the ocean freezes and the ice shell is thicker than 260 km, ice II forms and causes global volume contraction. Since there is no evidence for recent compressional tectonic features, we argue that ice II has not formed and that Pluto's ocean has likely survived to present day.

Many studies show that neonicotinoid insecticides cause toxicity to aquatic invertebrates. Some studies report that insecticide toxicity may differ in combination with other agrochemicals under realistic field conditions. To explore such altered toxicity further, we aimed to determine the single and combined effects of environmentally relevant levels of the neonicotinoid thiacloprid and nutrients on different endpoints of 4 aquatic invertebrate species. Animals were exposed to these agrochemicals using a caged experiment within experimental ditches. We observed thiacloprid‐induced toxicity for 2 crustaceans, Daphnia magna and Asellus aquaticus, and for 1 out of 2 tested insect species, Cloeon dipterum. We observed no toxic effects for Chironomus riparius at the time‐weighted average test concentration of 0.51 μg thiacloprid/L. For D. magna, the observed toxicity, expressed as the lowest‐observed‐effect concentration (LOEC), on growth and reproduction was present at thiacloprid concentrations that were 2456‐fold lower than laboratory‐derived LOEC values. This shows that these species, when exposed under natural conditions, may exhibit neonicotinoid‐induced toxic stress. Contrary to the low nutrient treatment, such toxicity was often not observed under nutrient‐enriched conditions. This was likely attributable to the increased primary production that allowed for compensatory feeding. These findings warrant the inclusion of different feeding regimes in laboratory experiments to retrieve the best estimates of neonicotinoid‐induced toxicity in the natural environment. Environ Toxicol Chem 2018;37:1907–1915. © 2018 SETAC

Background Anti-cytokine therapies such as adalimumab, tocilizumab, and the small molecule JAK inhibitor tofacitinib have proven that cytokines and their subsequent downstream signaling processes are important in the pathogenesis of rheumatoid arthritis. Tofacitinib, a pan-JAK inhibitor, is the first approved JAK inhibitor for the treatment of RA and has been shown to be effective in managing disease. However, in phase 2 dose-ranging studies tofacitinib was associated with dose-limiting tolerability and safety issues such as anemia. Upadacitinib (ABT-494) is a selective JAK1 inhibitor that was engineered to address the hypothesis that greater JAK1 selectivity over other JAK family members will translate into a more favorable benefit:risk profile. Upadacitinib selectively targets JAK1 dependent disease drivers such as IL-6 and IFNγ, while reducing effects on reticulocytes and natural killer (NK) cells, which potentially contributed to the tolerability issues of tofacitinib. Methods Structure-based hypotheses were used to design the JAK1 selective inhibitor upadacitinib. JAK family selectivity was defined with in vitro assays including biochemical assessments, engineered cell lines, and cytokine stimulation. In vivo selectivity was defined by the efficacy of upadacitinib and tofacitinib in a rat adjuvant induced arthritis model, activity on reticulocyte deployment, and effect on circulating NK cells. The translation of the preclinical JAK1 selectivity was assessed in healthy volunteers using ex vivo stimulation with JAK-dependent cytokines. Results Here, we show the structural basis for the JAK1 selectivity of upadacitinib, along with the in vitro JAK family selectivity profile and subsequent in vivo physiological consequences. Upadacitinib is ~ 60 fold selective for JAK1 over JAK2, and > 100 fold selective over JAK3 in cellular assays. While both upadacitinib and tofacitinib demonstrated efficacy in a rat model of arthritis, the increased selectivity of upadacitinib for JAK1 resulted in a reduced effect on reticulocyte deployment and NK cell depletion relative to efficacy. Ex vivo pharmacodynamic data obtained from Phase I healthy volunteers confirmed the JAK1 selectivity of upadactinib in a clinical setting. Conclusions The data presented here highlight the JAK1 selectivity of upadacinitinib and supports its use as an effective therapy for the treatment of RA with the potential for an improved benefit:risk profile. Electronic supplementary material The online version of this article (10.1186/s41927-018-0031-x) contains supplementary material, which is available to authorized users.

High-porosity dunite channels produced by orthopyroxene dissolution may provide pathways for orthopyroxene-undersaturated melt generated in the deep mantle to reach shallower depth without extensive chemical reequilibration with surrounding mantle. Previous studies have considered these high-porosity channels and melt localization in the presence of a uniform upwelling mantle flow through the process of melt-rock reaction as well as shear deformation, but not both simultaneously. In this Part 2 of a numerical study of high-porosity melt and dunite channel formation during reactive dissolution, we considered the effect of shear deformation on channel distribution and channel geometry in an upwelling and viscously compacting mantle column. We formulated a high-order numerical experiment using conditions similar to those in Part 1, but with an additional prescribed horizontal shearing component in the solid matrix, as could be present in flowing mantle beneath spreading centers. Our focus was to examine orthopyroxene dissolution to determine the behavior of dunite formation and its interaction with melt flow field, by varying the upwelling and shear rate, orthopyroxene solubility gradient, and domain height. Introduction of shearing tilts the developing dunite, causing asymmetry in the orthopyroxene gradient between the dunite channels and the surrounding harzburgite. The downwind gradient is sharp, nearly discontinuous, whereas the upwind gradient is more gradual. For higher shear rates, a wave-like pattern of alternating high and low-porosity bands form on the downwind side of the channel. The band spacing increases with increasing shear rate, relative melt flow rate, and orthopyroxene solubility gradient, whereas the band angle is independent of solubility gradient and increases with increasing shear rate and decreasing relative melt flow rate. Such features could be observable in the field and provide evidence for mantle shearing. Standing wave-like patterns of melt fraction also develop on the downwind side with possible implications for the interpretation of seismic velocities in upwelling mantle.

In poplar, the CO/FT regulatory module mediates seasonal growth cessation. Although FT interacts with the basic leucine zipper transcription factor FD, surprisingly little is known about the possible role of FD in bud development and growth cessation in trees. In this study, we examined the expression and localization of the poplar FD homolog, PtFD1, during short-day (SD)-induced bud development, and the consequences of overexpressing PtFD1 on bud development and shoot growth. PtFD1 was primarily expressed in apical and axillary buds and exhibited a transient increase in expression during the initial stages of SD-induced bud development. This transient increase declined with continued SD treatment. When PtFD1 was overexpressed in poplar, SD-induced growth cessation and bud formation were abolished. PTFD1 overexpression also resulted in precocious flowering of juvenile plants in long-day (LD) photoperiods. Because the phenotypes associated with overexpression of PtFD1 are similar to those observe when poplar FT1 is overexpressed (Science, 312, 2006, 1040), the expression and diurnal patterns of expression of both poplar FT1 and FT2 were characterized in PtFD1 overexpression poplars and found to be altered. DNA microarray analysis revealed few differences in gene expression between PtFD1 overexpressing poplars in LD conditions while extensive levels of differential gene expression occur in SD-treated plants. These results enforce the connection between the regulation of flowering and the regulation of growth cessation and bud development in poplar.

Recently detected converted phases in upwelling mantle have been attributed to seismic velocity gradients at the onset of melting. In this study, we investigate conditions required to generate a melting onset phase by combining melt migration models with synthetic receiver functions. We find that increasing upwelling velocity, increasing mantle viscosity, and decreasing water content in the mantle source increases the predicted strength of a melting onset phase. Differences in these parameters between study regions may explain observed variations in converted phase magnitude. For a wet mantle source, the amplitude of synthetic receiver functions, calculated using a standard relationship for dependence of seismic velocity on melt fraction, is lower than observed amplitudes. One possibility is that the observed receiver functions indicate a heterogeneous mantle source in which wet and dry components melt independently. Alternatively, the dependence of seismic velocity on melt fraction at very low melt fractions may be much stronger than that used here, as suggested in recent studies.

[1] Gravity anomalies derived from recent Gravity Recovery and Interior Laboratory data suggest the presence of early volume expansion of the Moon. The absence of identifiable thrust faults limits the total net contraction that has occurred. These observations provide constraints on the lunar thermal evolution which raise questions for giant impact origin of the Moon. To study the lunar expansion/contraction history, we perform 3-D thermochemical mantle evolution models, with solidifying core overlain by a layer of ilmenite-bearing cumulates (IBCs) resulting from mantle overturn after magma ocean solidification. Our models focus on the effects of the overturn-produced density stratification with a deep heat-producing element (HPE) distribution and a top insulating megaregolith layer. The deep HPE can cause an early expansion up to 1.5 km radius due to the heating of thedeep mantle. This HPE distribution also reduces the present-day contraction by ~7 km. Compared to the models without overturn, an end-member model with a stable IBC-rich layer on the core-mantle boundary shows an overall present-day contraction as small as 1.1 km. The low thermal conductivity of megaregolith also affects the present-day contraction, reducing it by ~3 km.

This study examines the combined effects of melt migration by porous flow in the asthenosphere and dike propagation in the lithosphere. Melt collecting at the base of the lithosphere forms a decompacting boundary layer (DBL), in which the overpressure is sufficient to nucleate dikes that propagate buoyantly upward into the lithosphere. The asthenosphere melt flux determines the excess pressure and melt accumulation rate in the DBL, which together with the state of lithospheric stress, control dike growth rate, dike recurrence interval and the height to which dikes propagate. The vertical propagation and subsequent freezing of melt filled dikes heats and thins the lithosphere. Our model couples fundamental aspects of dike propagation and porous flow that are commonly treated separately. Our model allows us to estimate conditions under which vertically propagating dikes can thin the lithosphere, given a melt flux determined by the rate of melt production in the asthenosphere. The model also provides an estimate of the amount of melt present at the base of the lithosphere. We find that a steady state high-porosity boundary layer at the lithosphere–asthenosphere boundary, with a melt fraction about 2.5–4 times higher than the asthenosphere melt fraction. Diking occurs at melt fractions much less than the disaggregation limit, so dikes are only a few km tall and about 1 cm wide. Though dikes are small, their recurrence on the order of days can lead to lithosphere erosion rates on the order of a few km/Myr with a melt fraction of a few percent at the base of the lithosphere. The steady state boundary layer melt fraction is controlled by differences in lithospheric stress state and or asthenosphere melt flux, indicating that seismic discontinuities associated with melt accumulation at the lithosphere–asthenosphere boundary should vary systematically with variations in asthenosphere melt generation and tectonic setting.

SUMMARY Compaction–dissolution waves in porosity and melt pressure form spontaneously in numerical simulations of melt migration in an upwelling, viscously compacting, porous column in a solubilitygradient.Themeltfractionisassumedtobesmallandthesolidcomprisesolivineand orthopyroxene. The solubility of orthopyroxene in the melt is assumed to increase linearly with height and induces a gradient reaction, assumed to be at local equilibrium. Approximations for the vertical, 1-D, steady-state solutions are derived assuming negligible resistance to compaction. The linear stability of the steady-state solutions is characterized by complex eigenvalues and an oscillatory instability with strong wavenumber selection. This instability leads to the formation of checkerboard compaction–dissolution waves observed in the nonlinear numerical simulations. The phase velocity of these waves is larger than the solid velocity but smaller than the melt velocity. The oscillatory instability is realized over a range of parameters and the variation in wave properties is explored. A power-law bulk-viscosity formulation, ξ = η/φ m , is shown to decrease growth rates linearly in the exponent, m. For small perturbations, the growth rates and phase velocities measured from high-resolution numerical simulations are predicted by the linear theory as well as the dominant wavenumber in the non-linear regime. We present a regime diagram for reaction infiltration instabilities in viscouslycompacting porousmediaandshowthatcompaction–dissolutionwaves arefavoured by increasing solid upwelling and small solubility gradients relative to high-porosity channels. The regime diagram suggests that the formation of compaction–dissolution waves is a feasible new physical mechanism for melt transport beneath mid-ocean ridges.

Dear Editor, No specific treatment exists for Lhermitte's sign or an electric shock-like sensation that extends down the spine and shoots into the limbs lasting just a few seconds elicited during movement of cervical spine, particularly flexion of the neck. This symptom has been reported in various medical-like cervical spondylosis, multiple sclerosis, vitamin B12 deficiency, and pernicious anemia ⇓. Many times, this transient symptom is self-limiting and will resolve over a period of 6 months. However, for those patients whose symptoms are not so fortunate, few options are available. Pharmacological treatment is initially analgesics, short-course opioid medications, muscle relaxants, and tapering doses of oral steroids. Persistent symptoms may be improved with neuropathic pain medications like gabapentin, pregabalin, tricyclic antidepressants, clonazepam, baclofen, carbamazepine, amitriptyline, and phenytoin ⇓. The following case report utilizes neuromodulation after all other conservative methods failed to provide pain relief for this patient. The patient is a 60-year-old man with a history of worsening chronic neck pain without incident and reported “electricity running down my back and legs” when turning his head downward. A magnetic resonance imaging (MRI) scan demonstrated severe spondylosis at C5-6, a moderate degree of cervical stenosis, and a concern for development of myelopathy. As the thoracic and lumbar MRI was absent of disease, the patient's neurosurgeon diagnosed the traveling electric shock pain down the patient's legs as …

Solid-state thermal convection, as a model for the internal dynamics of planetary mantles, is generated both by volumetric heating and heating from below. A series of 2D and 3D numerical experiments is described where a bottom heat flux is prescribed as well as a constant fraction of volumetric heating with either free-slip or no-slip conditions for the two horizontal boundaries. The assumption that hot plumes rising in the interior of the layer act as a volumetric heat source leads to a first order scaling of thermal boundary layers. Cases with a no-slip boundary agree well with this scaling while cases with free-slip systematically deviate: a decrease of 20–30% is observed for the temperature difference across the boundary layer when the fraction of heating from below is increased from 0 to 1. These differences are attributable to a velocity structure near the boundary varying with the fraction of volumetric heating. The main planetary implications are that (i) the average thermal structure of the bulk mantle and lithosphere are not good indicators of the distribution of heat sources between the interior (e.g. radioactive heating, secular cooling) and the lower interface (e.g. core cooling); (ii) in contrast, the nature of volcanism (whether it is localized, hot spot like or widespread) reflect this distribution and should thus help to constrain the global thermal structure as well as the existence of a magnetic dynamo.

In this paper, a new membrane separation process is presented. This process is based on a multiple chamber cell that allows the separation of oil from water by placing two membranes of different hydrophobicity in contact with the emulsion. Further chemical modifications of the membranes have been performed in order to vary their hydrophobicity in the perspective of optimizing the fractionation process via specific interactions between membrane and emulsion components. For this purpose, methylcellulose was modified with 1,2-epoxydodecane and incorporated in the membrane elaboration process. The modification of membrane surface chemical structure was demonstrated by ATR-FTIR and XPS experiments. Preliminary filtration tests are presented as well as future perspectives to optimize the membrane modification procedure.

Annales Francaises d'Oto-Rhino-Laryngologie et de pathologie cervico-faciale - Vol. 124 - N° 2 - p. 90-94

The recent developments in gamma cameras have lead to significant improvements of intrinsic spatial resolution in radioisotopic imaging. Especially, using smaller photodetectors (PSPMT, photodiodes) enables to build more compact devices which permits to place the detector very near from the organ under study and thus to enhance the global spatial resolution. However, these improvements need to reduce image pixel size which worsens the signal to noise ratio in every pixel. Moreover, many clinical examinations, such as scintimammography will be all the more useful since small nodules can be detected. In this work, we present a method combining a denoising wavelet filtering method with watershed determination, both leading to hot nodule enhancement. This method was applied to Monte Carlo simulations of a 64 mm high volume containing hot nodules of various sizes with a tumor to background ratio equal to 5. Although nodules were not visible in raw images corresponding to 10 min acquisitions, the described process allowed the detection of 88% of 6 mm nodules and more than 97 % of nodules whose diameter was greater or equal to 8 mm. Results obtained on phantoms without hot spheres permit to assess the pertinence of the proposed method. Furthermore, the whole process runs very fast.

Although gamma cameras have emerged in the 1960s, their spatial resolution is still not sufficient to detect small tracer concentration abnormalities. Examinations like mammo-scintigraphy requires high spatial resolution and then the possibility to position the detector as close to the explored organ as possible. Diagnostic accuracy in nuclear medicine imaging has seen a notable advancement with the emergence of the new position-sensitive photomultiplier tube (PSPMT). This component allows to develop a compact gamma detector which fulfils these requirements. This study investigates the feasibility and the characteristics of a medium field of view high spatial resolution gamma ray detector based on R8520 PSPMT array coupled to a pixelated NaI(Tl) crystal array. As first results, a photocathode uniformity variation of 1–3 was observed on the whole field of view. Energy resolution obtained is better than 10% FWHM at 140 keV in PSPMT centers. Concerning spatial linearity, it depends on the uniformity of the PSPMT used. Consequently, it will be necessary to develop linearity and energy correction methods.

Resume Les metastases osseuses sont la cause la plus frequente de douleur chez les patients atteints de cancer. Leur prise en charge sur le plan antalgique est un challenge therapeutique. La composante douloureuse ne repond pas toujours aux antalgiques majeurs, a la chimiotherapie et a la radiotherapie. Quand ces traitements sont depasses, la vertebroplastie, la cimentoplastie, la radiofrequence par voie percutanee et la radiotherapie metabolique sont des methodes elegantes et efficaces venant en complement des traitement classiques.

Significant and perhaps complete melting of the young terrestrial planets is expected from their heat of accretion and core formation. The process of subsequent magma ocean fractional solidification creates a cumulate mantle unstable to gravitational overturn. Overturn should be fast (≤ 1 to 10 Ma) and result in increasing mantle density with depth. This stable stratification inhibits later thermal convection, preserving geochemical heterogeneities. Overturn places cold cumulates against the core–mantle boundary, which creates sufficient heat flux to drive a core dynamo, producing a brief, strong magnetic field. During overturn, hot cumulates rise from depth and melt adiabatically, creating an early crust to record this field and leaving behind mantle reservoirs with isotopic fractionations dating from the early evolution of the planet.

Needs in medical diagnosis, especially for early and reliable breast cancer detection, lead us to consider developments in scintillation crystals and position sensitive photomultiplier tubes (PSPMT) in order to develop a high-resolution medium field γ -ray imaging device. However the ideal detector for γ -rays represents a compromise between many conflicting requirements. In order to optimize different parameters involved in the detection process, we have developed a Monte Carlo simulation software. Its aim was to study the light distribution produced by a gamma photon interacting with a pixellated scintillation crystal coupled to a PSPMT array. Several crystal properties were taken into account as well as the intrinsic response of PSPMTs. Images obtained by simulations are compared with experimental results. Agreement between simulation and experimental results validate our simulation model.

Resume L’escalade est un sport particulierement bien adapte aux enfants IMC. Avec cette activite, l’enfant experimente de facon ludique et intense les exercices faits en reeducation. Ce sport apprehende deux aspects, l’escalade et l’assurance. Compte tenu de la disposition de notre structure artificielle d’escalade, nous avons propose cette activite a des enfants non marchants, capables de se tenir en position assise et ayant des troubles praxiques. Afin de stabiliser la position assise de ces enfants lorsqu’ils assurent leur partenaire, nous avons realise une installation s’adaptant sur un banc suedois et permettant de les fixer au moyen d’une degaine. Ce systeme simple a montre une efficacite remarquable et nous a permis de nous degager des contraintes liees au maintien d’une position correcte et pouvoir se consacrer a l’apprentissage des praxies.

The convective instability of a viscous fluid with strongly temperature-dependent viscosity cooled from above provides a basis for better understanding the thermal evolution of the Earth and other planets. The role of temperature-dependent viscosity in the initiation of thermal convection is important since thermally activated creep is strongly temperature dependent. This study introduces a criterion for convective instability based on the ratio of the Rayleigh–Taylor (R-T) growth rate of the thermal density stratification due to conductive cooling and the rate of conductive smoothing of convectively generated temperature variations. This definition of a critical boundary layer Rayleigh number that must be reached for the onset of convection is consistent with numerical experiments reported here as well as earlier theoretical and experimental studies. The length and temperature scales appearing in this Rayleigh number provide valuable physical insight into the behavior of the fluid at the onset of convection. A consistently defined viscosity ratio across the convecting thermal boundary layer leads to a characteristic temperature difference (ΔTc) across this layer. The viscosity ratio inferred from the onset times in numerical experiments reported here (≈10) is similar to that seen in laboratory experiments [Geophys. Res. 99 (1994) 19853] and is consistent with the linearized R-T analysis. Calculation of the onset time of convection and the conductive lid thickness at onset, based on laboratory-derived rheological parameters, provides a better basis to assess the convective instability of the oceanic upper mantle and the possible formation of a thick cratonic lithosphere by the cooling of continental mantle.

In an attempt to improve pulmonary CT scan reading, a computerized model of lung has first been elaborated. The secondary lobule was used as structuring lung element. The entire organ was composed of several lobule layers and of broncho-vascular trees. As pulmonary nodule distribution modes may turn the diagnostic onto specific pathology type, it is very important to define them as precisely as possible. Seven nodule distributions have been modeled: homogenous, peripheral, centrolobular, pleural, lymphatic, and broncho-vascular. A software tool was developed which allows the radiologist to spread nodules either in the whole lung or in anatomical lung areas, using one or more defined distribution modes until the simulated images mimic the CT scans under analysis. First results show a good agreement between scans and synthesized slices. The software tool described here help the physician to determine the true underlying nodule distribution involved in the pulmonary CT under analysis and lead then to a more precise diagnosis. Moreover, it can be used for radiologist education and training.

Crystallization of a magma ocean on a large terrestrial planet that is significantly melted by the energy of accretion may lead to an unstable cumulate density stratification, which may overturn to a stable configuration. Overturn of the initially unstable stratification may produce an early basaltic crust and differentiated mantle reservoirs. Such a stable compositional stratification can have important implications for the planet's subsequent evolution by delaying or suppressing thermal convection and by influencing the distribution of radiogenic heat sources. We use simple models for fractional crystallization of a martian magma ocean, and calculate the densities of the resulting cumulates. While the simple models presented do not include all relevant physical processes, they are able to describe to first order a number of aspects of martian evolution. The models describe the creation of magma source regions that differentiated early in the history of Mars, and present the possibility of an early, brief magnetic field initiated by cold overturned cumulates falling to the core- mantle boundary. In a model that includes the density inversion at about 7.5 GPa, where olivine and pyroxene float in the remaining magma ocean liquids while garnet sinks, cumulate overturn sequesters alumina in the deep martian interior. The ages and compositions of source regions are consistent with SNC meteorite data.

The pulp aroma composition of untreated, boiled and roasted Dacryodes edulis (G. Don) H.J. Lam (Burseraceae) fruits from Cameroon was investigated by headspace solid phase microextraction (HS-SPME) coupled with gas chromatographic-spectroscopic (GC/FID and GC/MS) and olfactoric methods to identify those volatiles responsible for the characteristic aroma of these different samples. In particular, monoterpenes, such as α-pinene (untreated/boiled/roasted fruits: 60.3%/44.9%/37.1%), β-pinene (8.2%/21.1%/16.2%), myrcene (15.0%/7.3%/20.9%), limonene (3.6%/6.3%/3.4%) and sabinene (1.4%/3.8%/1.1%) were found to be main compounds of these essential oils. In addition, dimethyl sulfide (4.1%/7.0%) and hexanal (4.6%/8.1%) could be identified in the pulp headspace of boiled and roasted D. edulis fruits. A correlation of the identified constituents of these three pulp headspace samples of this commonly known “African pear” from Cameroon with their single odor impressions is also given.

We characterize two single elements consisting of 10×10×5 and 5×5×5 mm3 scintillator crystals read out by 10×10 mm2 PIN silicon photodiode. The photodiode signal is amplified by an ultra-low-noise preamplifier and a pulse shape amplifier. The photodiode has a low leakage current (

Models for the evolution of the Moon must explain a number of important characteristics of its magmatic history. Primary among them is the emplacement of mare basalts primarily on one side of the Moon, and in a region of the surface roughly correlating with that containing high subsurface concentrations of KREEP. It is thus important to explore mechanisms which will regionally concentrate a KREEP layer early in lunar evolution and which ∼400–500 Myr later give rise to mare basalt generation beneath the same region. Gravitational instability of a chemically dense, ilmenite-rich cumulate created during the fractionation of an anorthositic crust is one candidate model. If so, gravitational instability must occur at long wavelength to explain the hemispheric asymmetry. We examine the Rayleigh–Taylor instability of a dense layer near the surface of a sphere, representing the lunar mantle, in which the viscosity varies with depth. Our results show that spherical harmonic degree 1 is the fastest growing wavelength of instability if the viscosity of the dense layer is sufficiently low relative to that of the deeper mantle or if the viscosity of the mantle increases with depth. However, the viscosity increase cannot be distributed over a depth that is too large. We explore whether a residual KREEP-like layer near the base of anorthositic crust might give rise to these needed conditions.

The mantle electromagnetic and tomography (MELT) experiment found a surprising degree of asymmetry in the mantle beneath the fast-spreading, southern East Pacific Rise (MELT Seismic Team, Science 280 (1998) 1215–1218; Forsyth et al., Science 280 (1998) 1235–1238; Toomey et al., Science 280 (1998) 1224–1227; Wolfe and Solomon, Science 280 (1998) 1230–1232; Scheirer et al., Science 280 (1998) 1221–1224; Evans et al., Science 286 (1999) 752–756). Pressure-release melting of the upwelling mantle produces magma that migrates to the surface to form a layer of new crust at the spreading center about 6 km thick (Canales et al., Science 280 (1998) 1218–1221). Seismic and electromagnetic measurements demonstrated that the distribution of this melt in the mantle is asymmetric (Forsyth et al., Science 280 (1998) 1235–1238; Toomey et al., Science 280 (1998) 1224–1227; Evans et al., Science 286 (1999) 752–756) at depths of several tens of kilometers, melt is more abundant beneath the Pacific plate to the west of the axis than beneath the Nazca plate to the east. MELT investigators attributed the asymmetry in melt and geophysical properties to several possible factors: asymmetric flow passively driven by coupling to the faster moving Pacific plate; interactions between the spreading center and hotspots of the south Pacific; an off-axis center of dynamic upwelling; and/or anomalous melting of an embedded compositional heterogeneity (MELT Seismic Team, Science 280 (1998) 1215–1218; Forsyth et al., Science 280 (1998) 1235–1238; Toomey et al., Science 280 (1998) 1224–1227; Wolfe and Solomon, Science 280 (1998) 1230–1232; Evans et al., Science 286 (1999) 752–756). Here we demonstrate that passive flow driven by asymmetric plate motion alone is not a sufficient explanation of the anomalies. Asthenospheric flow from hotspots in the Pacific superswell region back to the migrating ridge axis in conjunction with the asymmetric plate motion can create many of the observed anomalies.

Cell cultures of highbush blueberry cultivar ‘Gulfcoast’ ( Vaccinium corymbosum L. x Vaccinium darrowi Camp) were used to determine if tissue cultures could be used as a surrogate for whole plants in studying dehydrin expression. Cell clusters in liquid medium were subjected to treatments known to induce dehydrins in whole plants, and dehydrin protein and RNA levels were monitored. Two dehydrins of 65 and 30 kDa were detected with a polyclonal antibody raised against the 65 kDa dehydrin of blueberry. Using a full-length cDNA clone of blueberry dehydrin 1 as a probe, one mRNA of 0.75 kb, an appropriate size to encode the 30 kDa dehydrin, was detected on RNA blots. When cells were grown at 4 °C, abundance of the 30 kDa dehydrin increased, but the 65 kDa dehydrin did not. Level of the 0.75 kb message increased temporarily then decreased with cold treatment. Disparities between protein and transcript levels suggested that post-transcriptional mechanisms were involved in regulation of dehydrin expression. Some of the abscisic acid (ABA) concentrations tested induced expression of both dehydrins. Polyethylene glycol in the cultures repressed expression of both dehydrins and of the 0.75 kb mRNA. Results obtained from cell culture differed in too many ways from those on whole plants to make cell culture suitable for studying dehydrin expression in blueberry.