Photovoltaic effect in an electrically tunable van der Waals heterojunction

Semiconductor heterostructures form the cornerstone of many electronic and optoelectronic devices and are traditionally fabricated using epitaxial growth techniques. More recently, heterostructures have also been obtained by vertical stacking of two-dimensional crystals, such as graphene and related two- dimensional materials. These layered designer materials are held together by van der Waals forces and contain atomically sharp interfaces. Here, we report on a type- II van der Waals heterojunction made of molybdenum disulfide and tungsten diselenide monolayers. The junction is electrically tunable and under appropriate gate bias, an atomically thin diode is realized. Upon optical illumination, charge transfer occurs across the planar interface and the device exhibits a photovoltaic effect. Advances in large-scale production of two-dimensional crystals could thus lead to a new photovoltaic solar technology.Comment: 26 pages, 14 figures, Nano Letters 201

Test anxiety, working memory, and cognitive performance: Supportive effects of sequential demands

Substantial evidence suggests that test anxiety is associated with poor performance in complex tasks. Based on the differentiation of coordinative and sequential demands on working memory (Mayr & Kliegl, 1993), two studies examined the effects of sequential demands on the relationship between test anxiety and cognitive performance. Both studies found that high sequential demands had beneficial effects on the speed and accuracy of the performance of test-anxious participants. It is suggested that the more frequent memory updates associated with high sequential demands may represent external processing aids that compensate for the restricted memory capacity of individuals with high test anxiet

Fluorescence Fluctuation Spectroscopy on Viral-Like Particles Reveals Variable Gag Stoichiometry

AbstractFluorescence fluctuation spectroscopy determines the brightness, size, and concentration of fluorescent particles from the intensity bursts generated by individual particles passing through a small observation volume. Brightness provides a measure of the number of fluorescently labeled proteins within a complex and has been used previously to determine the stoichiometry of small oligomers in cells. We extend brightness analysis to large macromolecular protein complexes containing thousands of proteins and determine their stoichiometry. This study investigates viral-like particles (VLP) formed from human immunodeficiency virus type 1 (HIV-1) Gag protein expressed in COS-1 cells using fluorescence fluctuation spectroscopy to determine the stoichiometry of HIV-1 Gag within the particles. Control experiments establish that the stoichiometry and size of VLPs are not influenced by labeling of HIV-1 Gag with a fluorescent protein. The experiments further show that the brightness scales linearly with the amount of labeled Gag within the particle. Brightness analysis shows that the Gag stoichiometry of VLPs formed in COS-1 cells is not constant, but varies with the amount of transfected DNA plasmid. We observed HIV-1 Gag stoichiometries ranging from ∼750 to ∼2500, whereas the size of the VLPs remains unchanged. This result indicates that large areas of the VLP membrane are void of Gag protein. Therefore, a closed layer of HIV-1 Gag at the membrane is not required for VLP production. This study shows that brightness analysis has the potential to become an important tool for investigating large molecular complexes by providing quantitative information about their size and composition

Taurolidine reduces the tumor stimulating cytokine interleukin-1beta in patients with resectable gastrointestinal cancer: a multicentre prospective randomized trial

Background The effect of additional treatment strategies with antineoplastic agents on intraperitoneal tumor stimulating interleukin levels are unclear. Taurolidine and Povidone-iodine have been mainly used for abdominal lavage in Germany and Europe. Methods In the settings of a multicentre (three University Hospitals) prospective randomized controlled trial 120 patients were randomly allocated to receive either 0.5% taurolidine/2,500 IU heparin (TRD) or 0.25% povidone-iodine (control) intraperitoneally for resectable colorectal, gastric or pancreatic cancers. Due to the fact that IL-1beta (produced by macrophages) is preoperatively indifferent in various gastrointestinal cancer types our major outcome criterion was the perioperative (overall) level of IL-1beta in peritoneal fluid. Results Cytokine values were significantly lower after TRD lavage for IL-1beta, IL-6, and IL-10. Perioperative complications did not differ. The median follow-up was 50.0 months. The overall mortality rate (28 vs. 25, p = 0.36), the cancer-related death rate (17 vs. 19, p = .2), the local recurrence rate (7 vs. 12, p = .16), the distant metastasis rate (13 vs. 18, p = 0.2) as well as the time to relapse were not statistically significant different. Conclusion Reduced cytokine levels might explain a short term antitumorigenic intraperitoneal effect of TRD. But, this study analyzed different types of cancer. Therefore, we set up a multicentre randomized trial in patients undergoing curative colorectal cancer resection. Trial registration : ISRCTN6647853

New Insights into HTLV-1 Particle Structure, Assembly, and Gag-Gag Interactions in Living Cells

Human T-cell leukemia virus type 1 (HTLV-1) has a reputation for being extremely difficult to study in cell culture. The challenges in propagating HTLV-1 has prevented a rigorous analysis of how these viruses replicate in cells, including the detailed steps involved in virus assembly. The details for how retrovirus particle assembly occurs are poorly understood, even for other more tractable retroviral systems. Recent studies on HTLV-1 using state-of-the-art cryo-electron microscopy and fluorescence-based biophysical approaches explored questions related to HTLV-1 particle size, Gag stoichiometry in virions, and Gag-Gag interactions in living cells. These results provided new and exciting insights into fundamental aspects of HTLV-1 particle assembly—which are distinct from those of other retroviruses, including HIV-1. The application of these and other novel biophysical approaches promise to provide exciting new insights into HTLV-1 replication

Biophysical analysis of HTLV-1 particles reveals novel insights into particle morphology and Gag stoichiometry

<p>Abstract</p> <p>Background</p> <p>Human T-lymphotropic virus type 1 (HTLV-1) is an important human retrovirus that is a cause of adult T-cell leukemia/lymphoma. While an important human pathogen, the details regarding virus replication cycle, including the nature of HTLV-1 particles, remain largely unknown due to the difficulties in propagating the virus in tissue culture. In this study, we created a codon-optimized HTLV-1 Gag fused to an <it>EYFP </it>reporter as a model system to quantitatively analyze HTLV-1 particles released from producer cells.</p> <p>Results</p> <p>The codon-optimized Gag led to a dramatic and highly robust level of Gag expression as well as virus-like particle (VLP) production. The robust level of particle production overcomes previous technical difficulties with authentic particles and allowed for detailed analysis of particle architecture using two novel methodologies. We quantitatively measured the diameter and morphology of HTLV-1 VLPs in their native, hydrated state using cryo-transmission electron microscopy (cryo-TEM). Furthermore, we were able to determine HTLV-1 Gag stoichiometry as well as particle size with the novel biophysical technique of fluorescence fluctuation spectroscopy (FFS). The average HTLV-1 particle diameter determined by cryo-TEM and FFS was 71 ± 20 nm and 75 ± 4 nm, respectively. These values are significantly smaller than previous estimates made of HTLV-1 particles by negative staining TEM. Furthermore, cryo-TEM reveals that the majority of HTLV-1 VLPs lacks an ordered structure of the Gag lattice, suggesting that the HTLV-1 Gag shell is very likely to be organized differently compared to that observed with HIV-1 Gag in immature particles. This conclusion is supported by our observation that the average copy number of HTLV-1 Gag per particle is estimated to be 510 based on FFS, which is significantly lower than that found for HIV-1 immature virions.</p> <p>Conclusions</p> <p>In summary, our studies represent the first quantitative biophysical analysis of HTLV-1-like particles and reveal novel insights into particle morphology and Gag stochiometry.</p

Anthracycline-Induced Cardiotoxicity: Cardiac Monitoring by Continuous Wave-Doppler Ultrasound Cardiac Output Monitoring and Correlation to Echocardiography

Background: Anthracyclines are agents with a well-known cardiotoxicity. The study sought to evaluate the hemodynamic response to an anthracycline using real-time continuous-wave (CW)-Doppler ultrasound cardiac output monitoring (USCOM) and echocardiography in combination with serum biomarkers. Methods: 50 patients (26 male, 24 female, median age 59 years) suffering from various types of cancer received an anthracycline-based regimen. Patients' responses were measured at different time points (T0 prior to infusion, T1 6 h post infusion, T2 after 1 day, T3 after 7 days, and T4 after 3 months) with CW-Doppler ultrasound (T0-T4) and echocardiography (T1, T4) for hemodynamic parameters such as stroke volume (SV; SVUSCOM ml) and ejection fraction (EF; EFechocardiography%) and with NT-pro-BNP and hs-Troponin T (T0-T4). Results: During the 3-month observation period, the relative decrease in the EF determined by echocardiography was -2.1% (Delta T0-T4, T0 71 +/- 7.8%, T4 69.5 +/- 7%, p = 0.04), whereas the decrease in SV observed using CW-Doppler was -6.5% (Delta T0-T4, T0 54 +/- 19.2 ml, T4 50.5 +/- 20.6 ml, p = 0.14). The kinetics for serum biomarkers were inversely correlated. Conclusions: Combining real-time CW-Doppler USCOM and serum biomarkers is feasible for monitoring the immediate and chronic hemodynamic changes during an anthracycline-based regimen; the results obtained were comparable to those from echocardiography

The Actin Targeting Compound Chondramide Inhibits Breast Cancer Metastasis via Reduction of Cellular Contractility

Background: A major player in the process of metastasis is the actin cytoskeleton as it forms key structures in both invasion mechanisms, mesenchymal and amoeboid migration. We tested the actin binding compound Chondramide as potential anti-metastatic agent. Methods: In vivo, the effect of Chondramide on metastasis was tested employing a 4T1-Luc BALB/c mouse model. In vitro, Chondramide was tested using the highly invasive cancer cell line MDA-MB-231 in Boyden-chamber assays, fluorescent stainings, Western blot and Pull down assays. Finally, the contractility of MDA-MB-231 cells was monitored in 3D environment and analyzed via PIV analysis. Results: In vivo, Chondramide treatment inhibits metastasis to the lung and the migration and invasion of MDA-MB-231 cells is reduced by Chondramide in vitro. On the signaling level, RhoA activity is decreased by Chondramide accompanied by reduced MLC-2 and the stretch induced guanine nucleotide exchange factor Vav2 activation. At same conditions, EGF-receptor autophosphorylation, Akt and Erk as well as Rac1 are not affected. Finally, Chondramide treatment disrupted the actin cytoskeleton and decreased the ability of cells for contraction. Conclusions: Chondramide inhibits cellular contractility and thus represents a potential inhibitor of tumor cell invasion

Mindestlohn : Für und Wider ; Schutz vor Niedriglöhnen oder Arbeitsplatzvernichter ; Für und Wider die Festsetzung eines gesetzlichen Mindestlohns ; Aufruf der Präsidenten und Direktoren der Wirtschaftsforschungsinstitute

Bietet ein allgemeiner Mindestlohn Schutz vor ausländischer Niedriglohnkonkurrenz, und sorgt er für existenzsichernde Einkommen? Oder vernichtet er Arbeitsplätze und verhindert, dass existenzsichernde Einkommen erzielt werden können? Gibt es belastbare empirische Studien, und was kann die deutsche Politik aus den Erfahrungen der europäischen Nachbarn und den USA mit Mindestlöhnen lernen? Ist die Sicherung von Mindesteinkommen durch Zuschüsse eine Alternative? Das ifo Institut hat bedeutende und bekannte Ökonomen im deutschsprachigen Raum gebeten, zu diesen Fragen kurz Stellung zu nehmen. Mit der Sammlung von Argumenten, die für oder gegen die staatliche Festsetzung eines Mindestlohns sprechen und die neben arbeitsmarkttheoretischen und verhaltensökonomischen auch juristische Aspekte berücksichtigen, soll zur Versachlichung der Diskussion um den Mindestlohn beigetragen werden.Neben Mitgliedern des Sachverständigenrates zur Begutachtung der gesamtwirtschaftlichen Entwicklung und den Präsidenten und Direktoren einiger Wirtschaftsforschungsinstitute kommen ehemalige und gegenwärtige Vorsitzende wichtiger wirtschaftspolitischer Beratungsgremien sowie international anerkannte Wissenschaftler zu Wort.Mindestlohn, Niedriglohn, Arbeitsplatz, Beschäftigungseffekt, Schwarzarbeit, Schattenwirtschaft, Ordnungspolitik, Arbeitslosigkeit, Arbeitsmarkt, Reform, Dumping, Arbeitnehmer, Armut, Humankapital, Arbeitsangebot, Sozialstaat, Deutschland