Brownian motion in a non-homogeneous force field and photonic force microscope

The Photonic Force Microscope (PFM) is an opto-mechanical technique based on an optical trap that can be assumed to probe forces in microscopic systems. This technique has been used to measure forces in the range of pico- and femto-Newton, assessing the mechanical properties of biomolecules as well as of other microscopic systems. For a correct use of the PFM, the force field to measure has to be invariable (homogeneous) on the scale of the Brownian motion of the trapped probe. This condition implicates that the force field must be conservative, excluding the possibility of a rotational component. However, there are cases where these assumptions are not fulfilled Here, we show how to improve the PFM technique in order to be able to deal with these cases. We introduce the theory of this enhanced PFM and we propose a concrete analysis workflow to reconstruct the force field from the experimental time-series of the probe position. Furthermore, we experimentally verify some particularly important cases, namely the case of a conservative or rotational force-field

Biochar-based wastewater treatment to combat antimicrobial resistance

Antimicrobial resistance (AMR) is driven in part by environmental reservoirs of antimicrobial-resistant organisms and genes, as well as antimicrobials themselves, which drive resistance via selective pressure. According to the UN, 80% of all wastewater flows into the environment untreated. When wastewater is treated, treatment plants can act as hotspots of horizontal gene transfer from resistant to non-resistant organisms. There is therefore an urgent need to filter wastewater from sources rich in resistant bacteria and antimicrobials, like hospitals and pharmaceutical plants, before they reach environmental reservoirs where resistance can spread. Biochars produced from waste lignocellulosic biomass are ideal for this purpose, as they are highly adsorbent, affordable, and sustainable, with morphologies and surface chemistries that are tunable by choice of production conditions. Here, we link peak pyrolysis temperatures and alkaline pretreatment of walnut shell biochars to their filtration performance, showing these materials are suitable for in-line filtration of wastewater to combat AMR

Balanço de energia em amendoim irrigado.

O presente estudo utilizou o método do balanço de energia através da razão de Bowen para estimar os fluxos de calor latente (LE) e sensível (H) a partir de medidas do saldo de radiação (Rn), fluxo do calor do solo (G) e gradientes psicométricos (com termopares) em dois cultivares amendoim (Arachis hypogaea L.) irrigado. Os resultados indicam que a partição de Rn em fluxos de LE, H e G varia durante o ciclo, principalmente em função do desenvolvimento vegetativo da cultura. O método da razão de Bowen propiciou medidas de consumo hídrico coerentes com a cultura do amendoim (valores médios de 6 mm.dia-1 para ambos os cultivares).CBA 2009

Hyperglycemia selectively increases the expression of cycloxygenase-2 in human aortic endothelial cells

The conversion of arachidonic acid to vasoactive prostanoids including prostacyclin, prostaglandins and tromboxanes is mediated by cycloxygenase (COX). Two isoforms of enzyme have been shown: a constitutive (COX-1) and an inducible form (COX-2). Products of the arachidonic acid metabolism may be involved in the impairment of endothelium-dependent vasodilatation observed both in experimental models and in patients with diabetes mellitus. To determine the effect of hyperglycemia on COX-1 and COX-2 expression, human aortic endothelial cells (HAEC) were exposed to normal (5.5mM) and high (22.2mM) concentrations of glucose for 5 days. Cells were also treated with mannitol (22.2 mM) to rule out an effect due to osmolality changes. COX-1 and COX-2 mRNA and protein expressions were analyzed by Southern and Western blotting, respectively. Treatment with high glucose was associated with a two-fold increase of both COX-2 mRNA (P<0.05) and protein levels (P<0.05), whereas no changes were observed for COX-1. Moreover high concentration of mannitol did not exert any significant effect. The present study demonstrates that both isoforms of COX are normally expressed in HAEC, but only COX-2 was stimulated after exposure to high glucose. The results of the present study may provide molecular basis to understand hyperglycemia-induced endothelial dysfunctio

Thermophoresis of Brownian particles driven by coloured noise

The Brownian motion of microscopic particles is driven by the collisions with the molecules of the surrounding fluid. The noise associated with these collisions is not white, but coloured due, e.g., to the presence of hydrodynamic memory. The noise characteristic time scale is typically of the same order as the time over which the particle's kinetic energy is lost due to friction (inertial time scale). We demonstrate theoretically that, in the presence of a temperature gradient, the interplay between these two characteristic time scales can have measurable consequences on the particle long-time behaviour. Using homogenization theory, we analyse the infinitesimal generator of the stochastic differential equation describing the system in the limit where the two characteristic times are taken to zero; from this generator, we derive the thermophoretic transport coefficient, which, we find, can vary in both magnitude and sign, as observed in experiments. Furthermore, studying the long-term stationary particle distribution, we show that particles can accumulate towards the colder (positive thermophoresis) or the warmer (negative thermophoresis) regions depending on the dependence of their physical parameters and, in particular, their mobility on the temperature.Comment: 9 pages, 4 figure

PINK1 homozygous W437X mutation in a patient with apparent dominant transmission of parkinsonism.

We analyzed the PINK1 gene in 58 patients with early-onset Parkinsonism and detected the homozygous mutation W437X in 1 patient. The clinical phenotype was characterized by early onset (22 years of age), good re- sponse to levodopa, early fluctuations and dyskinesias, and psychiatric symptoms. The mother, heterozygote for W437X mutation, was affected by Parkinson’s disease and 3 further relatives were reported affected, according to an autosomal dominant transmission

A Barrier to Exclusive Breastfeeding for Wic Enrollees: Limited Use of Exclusive Breastfeeding Food Package for Mothers

Background: In the first 2 weeks of life, most breastfeeding mother–infant dyads in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) receive infant formula from WIC, instead of a larger food package designed for exclusively breastfeeding mothers. This study was designed to explore reasons for high rates of formula supplementation of breastfeeding newborns enrolled in WIC and the limited use of the WIC expanded food package. Methods: We conducted in-depth interviews with 29 mothers who either partially or exclusively breastfed for at least 2 months. Interviews were transcribed verbatim, analyzed, coded, and organized into 10 themes. Results: Participants view the WIC program in a contradictory manner. They see it as highly supportive of breastfeeding, but also as a promoter of infant formula. The expanded food package for mothers is not valued, but free supplemental formula is highly valued. Misinformation about breastfeeding pervades the healthcare system, and exclusive breastfeeding is not promoted as an important health goal. Lack of access to breast pumps, the unacceptability of pumping in the workplace, and difficulties with nursing in public all contribute to formula supplementation. Conclusions: The healthcare system, the WIC program, and demands of daily life all contribute to low rates of exclusive breastfeeding in the WIC program. The available expanded food package for mothers who are exclusively breastfeeding is both disliked and underutilized, while free supplemental formula is rarely discouraged

Correlations between structure and dynamics in complex networks

Previous efforts in complex networks research focused mainly on the topological features of such networks, but now also encompass the dynamics. In this Letter we discuss the relationship between structure and dynamics, with an emphasis on identifying whether a topological hub, i.e. a node with high degree or strength, is also a dynamical hub, i.e. a node with high activity. We employ random walk dynamics and establish the necessary conditions for a network to be topologically and dynamically fully correlated, with topological hubs that are also highly active. Zipf's law is then shown to be a reflection of the match between structure and dynamics in a fully correlated network, as well as a consequence of the rich-get-richer evolution inherent in scale-free networks. We also examine a number of real networks for correlations between topology and dynamics and find that many of them are not fully correlated.Comment: 16 pages, 7 figures, 1 tabl