An Improved Forward Scattering Simulation Technique for Microwave Breast Imaging

Abstract-Microwave imaging is a promising alternative to conventional mammography methods. At microwave frequencies, normal and malignant tissues show high contrasts in their electrical properties. Microwave Imaging (MWI) systems can be used to construct three-dimensional profiles of the electrical properties of the body part that is being examined. MWI systems illuminate the body part with electromagnetic radiation of a suitable frequency. Using the measured scattered field at the surface of the body, inverse scattering algorithms reconstruct profiles of the electrical properties of the target. It is therefore of the uttermost importance that the forward scattering set-up is correct so that an inversion algorithm can create accurate profiles of electrical properties. We propose an improvement over the existing integral equation based forward scattering simulation techniques for microwave breast cancer imaging. Early detection of breast cancer is crucial. At this stage, the size of malignant tissue can be in the order of millimeters. For imaging involving such a small malignancy, one must use high-frequency radiation. At such frequencies, in order to overcome the relaxation effect of complex permittivity, we use the Debye model. For solving the forward scattering problem, we use the stabilized bi-conjugate gradient fast Fourier transform method (BI-CGSTAB-FFT). For the scattering domain, we apply the socalled cyclic boundary condition. This reduces the number of FFTs involved thus saving time and memory. For the BI-CGSTAB-FFT iteration method, we choose the initial value of the total field to be the incident electric field. This choice yields better convergence than a random selection of initial condition

Membrane Topology of the Lactococcal Bacteriocin ATP-binding Cassette Transporter Protein LcnC. Involvement of LcnC in Lactococcin A Maturation

Many non-lantibiotic bacteriocins of lactic acid bacteria are produced as precursors with N-terminal leader peptides different from those present in preproteins exported by the general sec-dependent (type II) secretion pathway. These bacteriocins utilize a dedicated (type I) secretion system for externalization. The secretion apparatus for the lactococcins A, B, and M/N (LcnA, B, and M/N) from Lactococcus lactis is composed of the two membrane proteins LcnC and LcnD. LcnC belongs to the ATP-binding cassette transporters, whereas LcnD is a protein with similarities to other accessory proteins of type I secretion systems. This paper shows that the N-terminal part of LcnC is involved in the processing of the precursor of LcnA. By making translational fusions of LcnC to the reporter proteins β-galactosidase (LacZ) and alkaline phosphatase (PhoA*), it was shown that both the N- and C-terminal parts of LcnC are located in the cytoplasm. As the N terminus of LcnC is required for LcnA maturation and is localized in the cytoplasm, we conclude that the processing of the bacteriocin LcnA to its mature form takes place at the cytosolic side of the cytoplasmic membrane.

The Transcriptome of the Nosocomial Pathogen Enterococcus faecalis V583 Reveals Adaptive Responses to Growth in Blood

gains access to the bloodstream and establishes a persistent infection is not well understood.. infections

Comparative Genomic Analysis of Pathogenic and Probiotic Enterococcus faecalis Isolates, and Their Transcriptional Responses to Growth in Human Urine

Urinary tract infection (UTI) is the most common infection caused by enterococci, and Enterococcus faecalis accounts for the majority of enterococcal infections. Although a number of virulence related traits have been established, no comprehensive genomic or transcriptomic studies have been conducted to investigate how to distinguish pathogenic from non-pathogenic E. faecalis in their ability to cause UTI. In order to identify potential genetic traits or gene regulatory features that distinguish pathogenic from non-pathogenic E. faecalis with respect to UTI, we have performed comparative genomic analysis, and investigated growth capacity and transcriptome profiling in human urine in vitro. Six strains of different origins were cultivated and all grew readily in human urine. The three strains chosen for transcriptional analysis showed an overall similar response with respect to energy and nitrogen metabolism, stress mechanism, cell envelope modifications, and trace metal acquisition. Our results suggest that citrate and aspartate are significant for growth of E. faecalis in human urine, and manganese appear to be a limiting factor. The majority of virulence factors were either not differentially regulated or down-regulated. Notably, a significant up-regulation of genes involved in biofilm formation was observed. Strains from different origins have similar capacity to grow in human urine. The overall similar transcriptional responses between the two pathogenic and the probiotic strain suggest that the pathogenic potential of a certain E. faecalis strain may to a great extent be determined by presence of fitness and virulence factors, rather than the level of expression of such traits

Genetic Diversity among Enterococcus faecalis

Enterococcus faecalis, a ubiquitous member of mammalian gastrointestinal flora, is a leading cause of nosocomial infections and a growing public health concern. The enterococci responsible for these infections are often resistant to multiple antibiotics and have become notorious for their ability to acquire and disseminate antibiotic resistances. In the current study, we examined genetic relationships among 106 strains of E. faecalis isolated over the past 100 years, including strains identified for their diversity and used historically for serotyping, strains that have been adapted for laboratory use, and isolates from previously described E. faecalis infection outbreaks. This collection also includes isolates first characterized as having novel plasmids, virulence traits, antibiotic resistances, and pathogenicity island (PAI) components. We evaluated variation in factors contributing to pathogenicity, including toxin production, antibiotic resistance, polymorphism in the capsule (cps) operon, pathogenicity island (PAI) gene content, and other accessory factors. This information was correlated with multi-locus sequence typing (MLST) data, which was used to define genetic lineages. Our findings show that virulence and antibiotic resistance traits can be found within many diverse lineages of E. faecalis. However, lineages have emerged that have caused infection outbreaks globally, in which several new antibiotic resistances have entered the species, and in which virulence traits have converged. Comparing genomic hybridization profiles, using a microarray, of strains identified by MLST as spanning the diversity of the species, allowed us to identify the core E. faecalis genome as consisting of an estimated 2057 unique genes

Macrophage Replication Screen Identifies a Novel Francisella Hydroperoxide Resistance Protein Involved in Virulence

Francisella tularensis is a Gram-negative facultative intracellular pathogen and the causative agent of tularemia. Recently, genome-wide screens have identified Francisella genes required for virulence in mice. However, the mechanisms by which most of the corresponding proteins contribute to pathogenesis are still largely unknown. To further elucidate the roles of these virulence determinants in Francisella pathogenesis, we tested whether each gene was required for replication of the model pathogen F. novicida within macrophages, an important virulence trait. Fifty-three of the 224 genes tested were involved in intracellular replication, including many of those within the Francisella pathogenicity island (FPI), validating our results. Interestingly, over one third of the genes identified are annotated as hypothetical, indicating that F. novicida likely utilizes novel virulence factors for intracellular replication. To further characterize these virulence determinants, we selected two hypothetical genes to study in more detail. As predicted by our screen, deletion mutants of FTN_0096 and FTN_1133 were attenuated for replication in macrophages. The mutants displayed differing levels of attenuation in vivo, with the FTN_1133 mutant being the most attenuated. FTN_1133 has sequence similarity to the organic hydroperoxide resistance protein Ohr, an enzyme involved in the bacterial response to oxidative stress. We show that FTN_1133 is required for F. novicida resistance to, and degradation of, organic hydroperoxides as well as resistance to the action of the NADPH oxidase both in macrophages and mice. Furthermore, we demonstrate that F. holarctica LVS, a strain derived from a highly virulent human pathogenic species of Francisella, also requires this protein for organic hydroperoxide resistance as well as replication in macrophages and mice. This study expands our knowledge of Francisella's largely uncharacterized intracellular lifecycle and demonstrates that FTN_1133 is an important novel mediator of oxidative stress resistance

PERSEPSI PERSEPSI MAHASISWA PGSD TERHADAP PERKULIAHAN ONLINE DI MASA PANDEMIK COVID-19

ABSTRACT   Online learning is a learning system established along the pandemic covid-19 era. This study is aimed at describing students’ perceptions on online learning along covid-19 period. The data was gathered thought the levering questionnaire and interview process. The sample covered 76 students of PGSD study programs STKIP Soe. The result showed that 64% students supported the use online learning science increases students competence in using technology, materials can be accessed easily, anytime, anywhere, the materials are easy to understand and decrease expenses on transportation. There were 68,5% students said that there were hindrances’ related to the system that covered look of internet access, and look of the facilities there were 54% student shared their expectation to have online learning system in the next semester and also face to face learning system especially for math programs strengthen their understanding on the materials. The learning process should also be delivered by implementation of interesting creative and innovative method to create conducive and comfortable learning process. Keywords: Perception, Online Learning, Pandemic Covid-19   ABSTRAK   Perkuliahan online merupakan salah satu kebijakan yang diterapkan dimasa pandemic covid-19. Tujuan penelitian ini adalah untuk mendeskripsikan persepsi mahasiswa mengenai perkuliahan online di masa pandemic covid-19. Data penelitian dikumpulkan melalui kuesioner dan wawancara. Sampel dari penelitian adalah mahasiswa PGSD STKIP Soe sebanyak 76 orang. Hasil penelitian menunjukkan bahwa sebanyak 64% mahasiswa menyatakan adanya kelebihan dalam perkuliahan online yakni peningkatan kemampuan mahasiswa dalam penggunaan teknologi, pembelajaran dapat diakses kapan saja dan dimana saja, materi yang disampaikan dapat dipahami dan adanya pengurangan biaya transportasi ke kampus. Sebanyak 68,5% menyatakan bahwa hambatan perkuliahan online meliputi kurangnya ketersediaan kuota internet, koneksi internet yang tidak stabil, dan sarana prasarana yang kurang, Sebanyak 54%   mahasiswa sangat berharap proses perkuliahan di semester berikut tetap dilakukan perkuliahan online dan perlu diadakanya perkuliahan tatap muka untuk matakuliah matematika agar mahasiswa bisa lebih memahami materinya. Pembelajaran yang dirancang pun juga dapat menggunakan metode yang lebih kreatif dan inovatif sehingga menciptakan suasana pembelajaran yang menyenangkan bagi mahasiswa. Kata Kunci: Persepsi, Perkuliahan Online, Pandemi Covid-19 &nbsp

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Impact of short term use of interdialytic 60% ethanol lock solution on tunneled silicone catheter dysfunction.

International audienceINTRODUCTION: Ethanol lock (EL) is used to reduce catheter infections, but its impact on dialysis catheter dysfunction has not been studied. METHODS: We analyzed the rate of dialysis silicone catheter dysfunction after an interdialytic 60% EL in an open prospective controlled non crossover cohort study, with each patient being his or her own control. The study was divided into three consecutive 2-week periods: the pre- and post-intervention periods, in which interdialytic standard locks (SL) were used, and the intervention period, in which one EL was instilled during the first week, and two consecutively in the second week. We analyzed the rate of catheter dysfunction (exchange, use of fibrinolytic, reversing the lines, difficulty in instilling or withdrawing fluid) after EL or SL. RESULTS: In 30 patients, 90 EL were instilled. The rate of catheter dysfunction increased during the EL period (2 - 13%, p < 0.001), and between the two consecutive dialysis sessions before and after EL (p < 0.05). It decreased between the two consecutive dialysis sessions after EL and the following dialysis session after an SL (p < 0.05). No catheter was removed. The urea reduction ratio did not differ in dialysis after an SL and after an EL (0.77 vs. 0.73, p = 0.17). CONCLUSION: Short term EL is associated with a transient increase in catheter dysfunction, without resulting in catheter removal or decreasing dialysis efficiency