Combining gradient ascent search and support vector machines for effective autofocus of a field emission–scanning electron microscope

Autofocus is an important issue in electron microscopy, particularly at high magnification. It consists in searching for sharp image of a specimen, that is corresponding to the peak of focus. The paper presents a machine learning solution to this issue. From seven focus measures, support vector machines fitting is used to compute the peak with an initial guess obtained from a gradient ascent search, that is search in the direction of higher gradient of focus. The solution is implemented on a Carl Zeiss Auriga FE-SEM with a three benchmark specimen and magnification ranging from x300 to x160 000. Based on regularized nonlinear least squares optimization, the solution overtakes the literature non-regularized search and Fibonacci search methods: accuracy improvement ranges from 1.25 to 8 times, fidelity improvement ranges from 1.6 to 28 times, and speed improvement ranges from 1.5 to 4 times. Moreover, the solution is practical by requiring only an off-line easy automatic train with cross-validation of the support vector machines

Schätzung der Zahl der Menschen in finanziell schwierigen Lebenslagen knapp oberhalb der Armutsgrenze

Gemäss statistischen Berechnungen lebten in der Schweiz im Jahr 2020 8.5% der ständigen Wohnbevölkerung in Privathaushalten unterhalb der absoluten Armutsgrenze. Dies entspricht rund 722’000 Personen. Mit 15.5% gelten beinahe doppelt so viele als armutsgefährdet (Bundesamt für Statistik, 2022). Dies deutet darauf hin, dass eine beträchtliche Zahl der Haushalte unmittelbar oberhalb der Armutsgrenze lebt. Diese armutsgefährdete Bevölkerungsgruppe droht mit geringen Einkommensausfällen unter die Schwelle des Existenzminimums zu fallen. Vor diesem Hintergrund interessiert sich Caritas Schweiz dafür, wie viele Menschen unmittelbar oberhalb der Armutsschwelle leben sowie ob bestimmte bzw. welche Haushaltsformen stärker davon betroffen sind. Der Berner Fachhochschule stehen in Zusammenhang mit dem SNF-Projekt «Ungleichheit, Armutsrisiken und Wohlfahrtsstaat1» verknüpfte Steuerdaten zur Verfügung, die sich – dank umfassender Fallzahlen – für detaillierte Verteilungsanalysen eignen. Im vorliegenden Dokument wird beschrieben, wie auf dieser Grundlage eine Analyse des Bereiches unmittelbar oberhalb der Armutsschwelle vorgenommen werden kann. Dabei zeigen wir auf, wie viele und welche Haushalte sich in Abhängigkeit unterschiedlich definierter Schwellenwerte in einer finanziell schwierigen Situation befinden

Datenauswertungen kinderleicht gemacht

Sozialdienste verfügen über detaillierte Informationen zur Fall- und Kostenentwicklung. Die Analyse dieser Daten ist jedoch aufwändig und benötigt spezifisches Know-how. Mit einem von der BFH entwickelten Daten-Dashboard lassen sie sich rasch und ohne Vorkenntnisse aufbereiten und präsentieren

Geschlechterunterschiede bei Einkommen und Vermögen

Wie sind in der Schweiz Einkommen und Vermögen zwischen den Geschlechtern verteilt? Basierend auf neuen Daten zeigen wir Unterschiede zwischen Frauen und Männern auf und gehen auf die Gründe dafür ein

Unabhängig, aber arm: Zur Dauer des Nichtbezuges von Sozialhilfe

Es gibt Menschen, die unterhalb des Existenzminimums leben und trotzdem keine Sozialhilfe beziehen. In einer Studie für die Sozialhilfe Basel-Stadt wurde erstmals untersucht, ob es sich beim Nichtbezug um ein kurzfristiges oder länger andauerndes Phänomen handelt. Was bedeuten die Erkenntnisse für die Armutsbekämpfung

Modulation of Cell Surface Receptor Expression by Modified Vaccinia Virus Ankara in Leukocytes of Healthy and HIV-Infected Individuals

Viral vectors are increasingly used as delivery means to induce a specific immunity in humans and animals. However, they also impact the immune system, and it depends on the given context whether this is beneficial or not. The attenuated vaccinia virus strain modified vaccinia virus Ankara (MVA) has been used as a viral vector in clinical studies intended to treat and prevent cancer and infectious diseases. The adjuvant property of MVA is thought to be due to its capability to stimulate innate immunity. Here, we confirmed that MVA induces interleukin-8 (IL-8), and this chemokine was upregulated significantly more in monocytes and HLA-DR(bright)dendritic cells (DCs) of HIV-infected patients on combined antiretroviral therapy (ART) than in cells of healthy persons. The effect of MVA on cell surface receptors is mostly unknown. Using mass cytometry profiling, we investigated the expression of 17 cell surface receptors in leukocytes afterex vivoinfection of human whole-blood samples with MVA. We found that MVA downregulates most of the characteristic cell surface markers in particular types of leukocytes. In contrast, C-X-C motif chemokine receptor 4 (CXCR4) was significantly upregulated in each leukocyte type of healthy persons. Additionally, we detected a relative higher cell surface expression of the HIV-1 co-receptors C-C motif chemokine receptor 5 (CCR5) and CXCR4 in leukocytes of HIV-ART patients than in healthy persons. Importantly, we showed that MVA infection significantly downregulated CCR5 in CD4+ T cells, CD8+ T cells, B cells, and three different DC populations. CD86, a costimulatory molecule for T cells, was significantly upregulated in HLA-(DRDCs)-D-bright after MVA infection of whole blood from HIV-ART patients. However, MVA was unable to downregulate cell surface expression of CD11b and CD32 in monocytes and neutrophils of HIV-ART patients to the same extent as in monocytes and neutrophils of healthy persons. In summary, MVA modulates the expression of many different kinds of cell surface receptors in leukocytes, which can vary in cells originating from persons previously infected with other pathogens

Influence of the live cell DNA marker DRAQ5 on chromatin-associated processes

In the last decade, live cell fluorescence microscopy experiments have revolutionized cellular and molecular biology, enabling the localization of proteins within cellular compartments to be analysed and to determine kinetic parameters of enzymatic reactions in living nuclei to be measured. Recently, in vivo DNA labelling by DNA-stains such as DRAQ5, has provided the opportunity to measure kinetic reactions of GFP-fused proteins in targeted areas of the nucleus with different chromatin compaction levels. To verify the suitability of combining DRAQ5-staining with protein dynamic measurements, we have tested the cellular consequences of DRAQ5 DNA intercalation. We show that DRAQ5 intercalation rapidly modifies both the localization and the mobility properties of several DNA-binding proteins such as histones, DNA repair, replication and transcription factors, by stimulating a release of these proteins from their substrate. Most importantly, the effect of DRAQ5 on the mobility of essential cellular enzymes results in a potent inhibition of the corresponding cellular functions. From these observations, we suggest that great caution must be used when interpreting live cell data obtained using DRAQ5

Coordinated progression through two subtranscriptomes underlies the tachyzoite cycle of Toxoplasma gondii

BACKGROUND: Apicomplexan parasites replicate by varied and unusual processes where the typically eukaryotic expansion of cellular components and chromosome cycle are coordinated with the biosynthesis of parasite-specific structures essential for transmission. METHODOLOGY/PRINCIPAL FINDINGS: Here we describe the global cell cycle transcriptome of the tachyzoite stage of Toxoplasma gondii. In dividing tachyzoites, more than a third of the mRNAs exhibit significant cyclical profiles whose timing correlates with biosynthetic events that unfold during daughter parasite formation. These 2,833 mRNAs have a bimodal organization with peak expression occurring in one of two transcriptional waves that are bounded by the transition into S phase and cell cycle exit following cytokinesis. The G1-subtranscriptome is enriched for genes required for basal biosynthetic and metabolic functions, similar to most eukaryotes, while the S/M-subtranscriptome is characterized by the uniquely apicomplexan requirements of parasite maturation, development of specialized organelles, and egress of infectious daughter cells. Two dozen AP2 transcription factors form a series through the tachyzoite cycle with successive sharp peaks of protein expression in the same timeframes as their mRNA patterns, indicating that the mechanisms responsible for the timing of protein delivery might be mediated by AP2 domains with different promoter recognition specificities. CONCLUSION/SIGNIFICANCE: Underlying each of the major events in apicomplexan cell cycles, and many more subordinate actions, are dynamic changes in parasite gene expression. The mechanisms responsible for cyclical gene expression timing are likely crucial to the efficiency of parasite replication and may provide new avenues for interfering with parasite growth

Synergy of the antibiotic colistin with echinocandin antifungals in Candida species.

International audienceOBJECTIVES: Candida albicans is the most prevalent fungal pathogen of humans, causing a wide range of infections from harmless superficial to severe systemic infections. Improvement of the antifungal arsenal is needed since existing antifungals can be associated with limited efficacy, toxicity and antifungal resistance. Here we aimed to identify compounds that act synergistically with echinocandin antifungals and that could contribute to a faster reduction of the fungal burden. METHODS: A total of 38 758 compounds were tested for their ability to act synergistically with aminocandin, a β-1,3-glucan synthase inhibitor of the echinocandin family of antifungals. The synergy between echinocandins and an identified hit was studied with chemogenomic screens and testing of individual Saccharomyces cerevisiae and C. albicans mutant strains. RESULTS: We found that colistin, an antibiotic that targets membranes in Gram-negative bacteria, is synergistic with drugs of the echinocandin family against all Candida species tested. The combination of colistin and aminocandin led to faster and increased permeabilization of C. albicans cells than either colistin or aminocandin alone. Echinocandin susceptibility was a prerequisite to be able to observe the synergy. A large-scale screen for genes involved in natural resistance of yeast cells to low doses of the drugs, alone or in combination, identified efficient sphingolipid and chitin biosynthesis as necessary to protect S. cerevisiae and C. albicans cells against the antifungal combination. CONCLUSIONS: These results suggest that echinocandin-mediated weakening of the cell wall facilitates colistin targeting of fungal membranes, which in turn reinforces the antifungal activity of echinocandins