Snow metamorphism: a fractal approach

Snow is a porous disordered medium consisting of air and three water phases: ice, vapour and liquid. The ice phase consists of an assemblage of grains, ice matrix, initially arranged over a random load bearing skeleton. The quantitative relationship between density and morphological characteristics of different snow microstructures is still an open issue. In this work, a three-dimensional fractal description of density corresponding to different snow microstructure is put forward. First, snow density is simulated in terms of a generalized Menger sponge model. Then, a fully three-dimensional compact stochastic fractal model is adopted. The latter approach yields a quantitative map of the randomness of the snow texture, which is described as a three-dimensional fractional Brownian field with the Hurst exponent H varying as continuous parameter. The Hurst exponent is found to be strongly dependent on snow morphology and density. The approach might be applied to all those cases where the morphological evolution of snow cover or ice sheets should be conveniently described at a quantitative level

Effects of switching to PI monotherapy on measures of lipoatrophy: meta-analysis of six randomized HIV clinical trials

Background: Switching from triple combination treatment to protease inhibitor (PI) monotherapy may prevent or reverse adverse events related to long-term nucleoside analogues. Lipoatrophy is associated with long-term use of thymidine analogues (zidovudine and stavudine). Methods: A detailed MEDLINE search was conducted to identify randomised clinical trials of triple combination treatment versus PI monotherapy. Summary results from analysis of changes in body composition (DEXA analysis) were collected: the mean change in limb fat and trunk fat to Week 48 or 96, and the percentage of patients with lipoatrophy (20% reduction from baseline in limb fat) or lipohypertrophy (20% rise from baseline in trunk fat). Results: Six randomised trials of PI monotherapy versus triple therapy with data on body composition changes, measured by DEXA scanning at baseline and Week 48 or 96, were identified: Abbott-613 (LPV/r vs ZDV/3TC/EFV, induction-maintenance trial, n=105), Monark (LPV/r vs ZDV/3TC/LPV/r, first-line trial, n=63), Kalesolo (LPV/r vs LPV/r +2NRTIs, switch trial, n=42), MONOI (DRV/r vs DRV/r + 2NRTIs, switch trial, n=156), MONARCH (DRV/r vs DRV/r + 2NRTIs, switch trial, n=30) and KRETA (LPV/r vs LPV/r + ABC/3TC, switch trial, n=74). In the meta-analysis, there were greater rises in limb fat in the PI monotherapy arms than the triple therapy arms (mean difference =277g, 95% CI=+36 to+517g, p=0.024). The percentage of patients with lipoatrophy was significantly lower in the PI monotherapy arms (4%) than the triple therapy arms (20%), (p=0.0005). There was no difference between PI monotherapy and triple therapy for mean change in trunk fat (mean difference=−73g, 95% CI = −621 to +475g, p=ns). There was also no significant difference in the risk of lipohypertrophy between the PI monotherapy arms (32%) and the triple therapy arms (27%) (p=ns). In each of the four analyses, there was no evidence for heterogeneity of treatment effects between the trials (Cochran's Q tests, p=ns for each comparison). Conclusions: In this meta-analysis, the risk of lipoatrophy was significantly lower for patients taking PI monotherapy, compared to triple therapy. There was no significant difference between the arms for lipohypertrophy. However, several of the trials included zidovudine in the control arm, which carries a higher risk of lipoatrophy than tenofovir and abacavir, which are now more widely used

Predação de lagartas desfolhadoras do dendezeiro por Alcaeorrhynchus grandis (Hemiptera: Pentatomidae).

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Primeira ocorrência de Alcaeorrhynchus grandis (Dallas) (Hemiptera: Pentatomidae) predando lagartas desfolhadoras do dendezeiro no estado do Pará.

O dendezeiro ou palma africana (Elaeis guineensis) é considerado a principal atividade agroindustrial em regiões tropicais úmidas, semelhantes à Amazônia, como a Malásia, Indonésia, parte amazônica do Equador, Colômbia e alguns países africanos. É uma cultura perene e de vida útil econômica entre 25 e 30 anos, o que garante maior estabilidade ambiental e a caracteriza como uma das mais importantes oleaginosas. Destaca-se pela alta rentabilidade, geração de emprego, fixação do homem ao campo e redução de impactos ambientais além de ser uma fonte de óleo vegetal, principalmente, para a fabricação do "biodíesel

Derivation of a Non-Local Interfacial Hamiltonian for Short-Ranged Wetting II: General Diagrammatic Structure

In our first paper, we showed how a non-local effective Hamiltionian for short-ranged wetting may be derived from an underlying Landau-Ginzburg-Wilson model. Here, we combine the Green's function method with standard perturbation theory to determine the general diagrammatic form of the binding potential functional beyond the double-parabola approximation for the Landau-Ginzburg-Wilson bulk potential. The main influence of cubic and quartic interactions is simply to alter the coefficients of the double parabola-like zig-zag diagrams and also to introduce curvature and tube-interaction corrections (also represented diagrammatically), which are of minor importance. Non-locality generates effective long-ranged many-body interfacial interactions due to the reflection of tube-like fluctuations from the wall. Alternative wall boundary conditions (with a surface field and enhancement) and the diagrammatic description of tricritical wetting are also discussed.Comment: (14 pages, 2 figures) Submitted J. Phys. Condens. Matte

Predação de lagartas desfolhadoras em cultivos comerciais de dendê (Elaeis guineensis) por Alcaeorrhynchus grandis (Dallas) (Hemiptera: Pentatomidae), no Município de Tailândia, Pará.

SICONBIOL. ID - 152

RETRACTED ARTICLE: Painful os intermetatarseum in athletes: a literature review of this condition is presented

Painful os intermetatarseum is a very rare condition. Gruber et al. first described os intermetatarseum in 1877. This condition is usually asymptomatic. One should consider painful os intermetatarseum as being a possible cause of dorsal foot pain in athletes. Surgical excision of the os intermetatarseum should be considered for those patients failing conservative treatment. Here, a literature review of this condition is presented

Million-fold sensitivity enhancement in proteopathic seed amplification assays for biospecimens by Hofmeister ion comparisons

Recent work with prion diseases and synucleinopathies indicates that accurate diagnostic methods for protein-folding diseases can be based on the ultrasensitive, amplified measurement of pathological aggregates in biospecimens. A better understanding of the physicochemical factors that control the seeded polymerization of such aggregates, and their amplification in vitro, should allow improvements in existing assay platforms, as well as the development of new assays for other proteopathic aggregates. Here, we systematically investigated the effects of the ionic environment on the polymerization of tau, α-synuclein, and the prion protein (PrP) induced by aggregates in biospecimens. We screened salts of the Hofmeister series, a relative ordering of strongly and weakly hydrated salts that tend to precipitate or solubilize proteins. We found that sensitivities of tau-based assays for Alzheimer’s seeds and PrP-based assays for prions were best in weakly hydrated anions. In contrast, we saw an inverse trend with different tau-based assays, improving detection sensitivity for progressive supranuclear palsy seeds by ≈106. Hofmeister analysis also improved detection of sporadic Creutzfeldt–Jakob disease prions in human nasal brushings and chronic wasting disease prions in deer-ear homogenates. Our results demonstrate strong and divergent influences of ionic environments on the amplification and detection of proteopathic seeds as biomarkers for protein-folding diseases

On the Radiative Impact of Biomass-Burning Aerosols in the Arctic: The August 2017 Case Study

Boreal fires have increased during the last years and are projected to become more intense and frequent as a consequence of climate change. Wildfires produce a wide range of effects on the Arctic climate and ecosystem, and understanding these effects is crucial for predicting the future evolution of the Arctic region. This study focuses on the impact of the long-range transport of biomass-burning aerosol into the atmosphere and the corresponding radiative perturbation in the shortwave frequency range. As a case study, we investigate an intense biomass-burning (BB) event which took place in summer 2017 in Canada and subsequent northeastward transport of gases and particles in the plume leading to exceptionally high values (0.86) of Aerosol Optical Depth (AOD) at 500 nm measured in northwestern Greenland on 21 August 2017. This work characterizes the BB plume measured at the Thule High Arctic Atmospheric Observatory (THAAO; 76.53° N, °68.74° W) in August 2017 by assessing the associated shortwave aerosol direct radiative impact over the THAAO and extending this evaluation over the broader region (60° N-80° N, 110° W-0° E). The radiative transfer simulations with MODTRAN6.0 estimated an aerosol heating rate of up to 0.5 K/day in the upper aerosol layer (8-12 km). The direct aerosol radiative effect (ARE) vertical profile shows a maximum negative value of -45.4 Wm-2 for a 78° solar zenith angle above THAAO at 3 km altitude. A cumulative surface ARE of -127.5 TW is estimated to have occurred on 21 August 2017 over a portion (3.1 10^6 km2) of the considered domain (60° N-80° N, 110° W-0° E). ARE regional mean daily values over the same portion of the domain vary between -65 and -25 Wm-2. Although this is a limited temporal event, this effect can have significant influence on the Arctic radiative budget, especially in the anticipated scenario of increasing wildfires

[(11)C]PiB PET in Gerstmann-Sträussler-Scheinker disease

Gerstmann-Sträussler-Scheinker Disease (GSS) is a familial neurodegenerative disorder characterized clinically by ataxia, parkinsonism, and dementia, and neuropathologically by deposition of diffuse and amyloid plaques composed of prion protein (PrP). The purpose of this study was to evaluate if [(11)C]Pittsburgh Compound B (PiB) positron emission tomography (PET) is capable of detecting PrP-amyloid in PRNP gene carriers. Six individuals at risk for GSS and eight controls underwent [(11)C]PiB PET scans using standard methods. Approximately one year after the initial scan, each of the three asymptomatic carriers (two with PRNP P102L mutation, one with PRNP F198S mutation) underwent a second [(11)C]PiB PET scan. Three P102L carriers, one F198S carrier, and one non-carrier of the F198S mutation were cognitively normal, while one F198S carrier was cognitively impaired during the course of this study. No [(11)C]PiB uptake was observed in any subject at baseline or at follow-up. Neuropathologic study of the symptomatic individual revealed PrP-immunopositive plaques and tau-immunopositive neurofibrillary tangles in cerebral cortex, subcortical nuclei, and brainstem. PrP deposits were also numerous in the cerebellar cortex. This is the first study to investigate the ability of [(11)C]PiB PET to bind to PrP-amyloid in GSS F198S subjects. This finding suggests that [(11)C]PiB PET is not suitable for in vivo assessment of PrP-amyloid plaques in patients with GSS