New head models extracted from thermal infrared (IR) images for dosimetry computations

In electromagnetic dosimetry, anatomical human models are commonly obtained by segmentation of magnetic resonance imaging or computed tomography scans. In this paper, a human head model extracted from thermal infrared images is examined in terms of its applicability to specific absorption rate (SAR) calculations. Since thermal scans are two-dimensional (2D) representation of surface temperature, this allows researchers to overcome the extensive computational demand associated with 3D simulation. The numerical calculations are performed using the finite-difference time-domain method with mesh sizes of 2 mm at 900 MHz plane wave irradiation. The power density of the incident plane wave is assumed to be 10 W/m². Computations were compared with a realistic anatomical head model. The results show that although there were marked differences in the local SAR distribution in the various tissues in the two models, the 1 g peak SAR values are approximately similar in the two models.     

Virtual screening of LPXTG competitive SrtA inhibitors targeting signal transduction mechanism in Bacillus anthracis: a combined experimental and theoretical study

Abstract

Members of the sortase enzyme super family decorate the surfaces of Bacillus anthracis cell wall with proteins that play key roles in microbial pathogenesis and its biofilm formation. Bacillus anthracis Sortase-A (Ba-SrtA) is a potential target for new therapeutics as it is required for B. anthracis survival and replication within macrophages. An understanding of the binding site pocket and substrate recognition mechanism by SrtA enzymes may serve to be beneficial in the rational development of sortase inhibitors. Here, the LPXTG signal peptide-based competitive inhibitors are screened against the Ba-SrtA and compounds with reasonable inhibition, specificity, and mechanisms of inactivation of SrtA have been covered. The screened compounds are experimentally validated against the phylogenetically similar Gram-positive pathogen B. cereus. In situ microscopic visualizations suggest that these screened compounds showed the microbial and biofilm inhibitory activity against B. cereus. It facilitates the further development of these molecules into useful anti-infective agents to treat infections caused by B. anthracis and other Gram-positive pathogens. These results provide insight into basic design principles for generating new clinically relevant lead molecules. It also provides an alternative strategy where a screened ligand molecule can be used in combination to battle increasingly against the Gram-positive pathogens.     

“What Dr Venter did on his holidays”: exploration,hacking, entrepreneurship in the narratives of the Sorcerer II expedition

The Sorcerer II is the highly mediatized and spectacular Venter Institute's ship that circumnavigated the planet between 2003 and 2006 to collect and classify marine microbial genomes. We analyze Craig Venter's public communication activities and strategies especially focusing on the images of science and scientist he proposes: that of an eighteenth-century “savant” and nineteenth-century naturalist devoted to the exploration of new worlds, and that of the hacker, hero of informational capitalism. Emphasizing his independence from both academy and industry, but building strong alliances with both spheres and with the media, Craig Venter sails the oceans of the contemporary biotechnologies' market, interpreting a specific typology of the relationship between science and society, enterprises, universities.     

Prolongation of Life in Anephric Rats following de novo Renal Organogenesis

One solution to the shortage of human organs available for transplantation envisions growing new organs in situ. This can be accomplished by transplantation of developing organ anlagen/primordia. Allotransplantation of embryonic day 15 metanephroi into the omentum of adult hosts is followed by differentiation, growth, vascularization and function of the implants. Here we show that survival of rats with all native renal mass removed can be increased by prior metanephros transplantation and ureteroureterostomy. Excretion of urine formed by metanephroi is prerequisite for enhanced survival. This is the first demonstration that life can be extended following de novo renal organogenesis.     

On the identity of Riccia teneriffae S.W.Arnell (Marchantiophyta: Ricciaceae) and a note on R. cavernosa Hoffm. in the Canary Islands

Abstract

We revised both the holotype and an isotype of Riccia teneriffae S.W.Arnell 1962 and additionally revised our own collections of Riccia cavernosa Hoffm. 1795 from the Canary Islands. Since the types of R. teneriffae represent R. cavernosa, and the latter name precedes the former, R. teneriffae should be treated as a synonym of R. cavernosa. In the Canary Islands, R. cavernosa appears to be rare. It has been found on La Gomera, Gran Canaria, Lanzarote, and Tenerife. We report it as new to Fuerteventura. R. cavernosa inhabits ephemeral, thin layers of mud. Very rarely it occurs on basaltic pyroclasts. SEM images of spores are presented. The local distribution is mapped.     

Flow cytometry and live confocal analysis for the evaluation of the uptake and intracellular distribution of FITC-ODN into HaCaT cells

In this study, the mechanism of the internalization and the cellular distribution of 59 fluorescein conjugated PS-ODN (FITC-ODN) after transfection with different mixed lipidic vesicles/oligo complexes (lipoplexes) have been investigated. Mixed lipidic vesicles were prepared with one of the most used cationic lipid (DOTAP) and different amounts of a cholic acid (UDCA) to release the oligo into HaCaT cells. Using flow cytometry, the cellular uptake of the oligo was studied with and without different inhibitors able to block selectively the different pathways involved in the internalization mechanism. The intracellular distribution of the oligo was analyzed by confocal laser scanning microscopy (CLSM), treating the cells with the lipoplexes and directly observing without any fixing procedure. To better carry out the colocalization studies, fluorescent-labeled markers, specific for the different cellular compartments, were coincubated with 59 fluorescein-conjugated 29-mer phosphorotioate oligonucleotide (FITC-ODN). The different lipidic vesicles affect the internalization mechanism of FITC-ODN. After using the inhibitors, the uptake of complexes involved a different internalization mechanism. The live CLSM analysis demonstrated that, after 1 hour from the complex incubation, the oligo was transferred into cells and localized into the endosomes; after 24 hours, the oligo was intracellularly localized close to the nuclear structure in a punctuate pattern. However, the results from fusion experiments showed also a binding of a quite low amount of oligo with the cell membranes.     

Ruminations on twenty-five years of Patricia Hill Collins's Black Feminist Thought: Knowledge,Consciousness and the Politics of Empowerment

My review focuses on the impact that Black Feminist Thought has had on my personal and professional life. I weave together lessons I have learned from Patricia Hill Collins with reflections on my own lived experience – from my family of origin to college experiences to my work as the founding director of the Collegium of Black Women Philosophers.     

一种基于视网膜主血管方向的视盘定位及提取方法

为分割出眼底图像中的视盘,构建基于眼底图像的计算机辅助诊断系统,提出了一种基于视网膜主血管方向的视盘定位及提取方法。首先,利用Otsu阈值分割眼底图像R通道获取视盘候选区域;然后利用彩色眼底图像的HSV空间的H通道提取视网膜主血管并确定主血管方向;在此基础上,通过在方向图内寻找出对加权匹配滤波器响应值最高的点确定视盘中心位置;最后,利用该位置信息从视盘候选区域中"挑选"出真正的视盘。利用该方法对100幅不同颜色、不同亮度的眼底图像进行视盘分割,得到准确率98%,平均每幅图像处理时间1.3 s。结果表明:该方法稳定可靠,能快速、有效分割出眼底图像中的视盘。