Torus orbits on homogeneous varieties and Kac polynomials of quivers

In this paper we prove that the counting polynomials of certain torus orbits in products of partial flag varieties coincides with the Kac polynomials of supernova quivers, which arise in the study of the moduli spaces of certain irregular meromorphic connections on trivial bundles over the projective line. We also prove that these polynomials can be expressed as a specialization of Tutte polynomials of certain graphs providing a combinatorial proof of the non-negativity of their coefficients

Maximum Torque Per Ampere Control Strategy of a 5-phase PM Generator in healthy and faulty modes for tidal marine turbine application

The work presented in this paper aims to propose a control strategy being able to extract efficiently energy from a fixed-pitch marine current turbine associated with a 5–phase Permanent Magnet Synchronous Generator (PMSG) in healthy mode and in faulty mode. The considered faults are opened phases. For each tidal current speed, the control strategy aims to extract the maximum power with respect of the maximum values of currents and voltages related to the converter. The maximum power is directly related to the Maximum Torque per Ampere (MTPA) control strategy characteristics (all the points which are below the MTPA torque VS rotating speed characteristic can be reached by the converter/generator set). This paper proposes a methodology to establish MTPA characteristics and calculate the corresponding current references in healthy mode and in faulty mode (one or two opened phases) for a 5-phase generator. The studied strategy includes flux weakening operations in the both modes.financement CIFRE Jeumont-Electric Altawes

ENDODONTIC RESIDENTS’ UNDERSTANDING OF BIOSTATISTICS: A 2010 SURVEY OF ENDODONTIC RESIDENTS IN THE UNITED STATES

Endodontic residents must keep current with clinical information to practice evidence- based dentistry. To do so, endodontic residents must access research papers and interpret results. This requires a knowledge of biostatistics. However, the biostatistical knowledge of endodontic residents is relatively unknown. The purpose of the study was to assess the biostatistical knowledge of endodontic residents using a survey instrument to prove or reject the hypothesis that there exists a lack of understanding of biostatistic principles among endodontic residents. A survey consisting of 29 questions querying attitudes and biostatistical knowledge was distributed to 230 endodontic residents and returned with a 32% response rate. The overall mean resident knowledge score was 42.3% (SD, 17.5%; range, 10% to 90%). Only 39% stated they understood all of the statistical terms encountered in journal articles. This data supports the hypothesis that there exists a lack of understanding of biostatistical principles and would suggest that more effective training in biostatistics in residency education is desirable

Performances comparison of different concentrated-winding configurations for 5-phase PMSG in normal and faulty modes in flux weakening operation for fixed pitch tidal turbines

This paper aims to evaluate some configurations of windings for low speed high power 5-phase permanent magnet synchronous generators (PMSG) associated to fixed pitch tidal turbines. Several Fractional-Slot Concentrated- Windings has been considered and compared for these specifications. The proposed structures are compared in terms of torque VS speed characteristics, including flux weakening operation, in healthy and faulty modes. In fault mode, the failure of one and two phases is considered. The results show that concentrated windings can be particularly useful for these particular specifications

Relationship Between Irrigation Thresholds and Potato Tuber Depth in Sandy Soil

Soil disturbance resulting from tuber crop harvesting is a major threat to soil health. The depth of soil intervention is a critical factor that further strengthens the effects of such disturbance and makes harvest one of the most harmful cropping operations. In the case of potato, soil moisture is a determining factor for root and stolon development, hence, a deeper soil intervention may be required at harvest. While potato ranks as the fourth most cultivated crop worldwide, the impact of soil moisture on potato tuber vertical and horizontal distribution has received very little attention. The objective of this study was to evaluate the effects of four soil matric potential thresholds (SMPTs; –10, –20, –30, and –45 kPa) on the spatial (vertical and horizontal) distribution of potato tubers grown in plastic containers filled with sandy soil using an X-ray computed tomography scanner. The results of the experiments conducted in a greenhouse environment suggest that the horizontal distribution of the tubers did not differ significantly across the irrigation treatments. However, a linear relationship between SMPT, and therefore irrigation threshold, and potato tuber depth was observed. In addition, the deepest tuber position was observed under the –10 kPa SMPT, while the tubers were closer to the soil surface under the –45 kPa SMPT, which could lead to a greater preponderance of tuber diseases such as late blight or greening. Thus, potato irrigation events implementing a SMPT between –20 and –30 kPa could reduce the harvest depth, hence, decreasing the negative impacts of soil disturbance on soil structural stability and soil organic carbon degradation while mitigating the impacts of disease as well as reducing fuel costs, greenhouse gas emissions, soil loss and erosion

Kinase inhibitor library screening identifies synergistic drug combinations effective in sensitive and resistant melanoma cells

Background: Melanoma is the most aggressive and deadly form of skin cancer with increasing case numbers worldwide. The development of inhibitors targeting mutated BRAF (found in around 60% of melanoma patients) has markedly improved overall survival of patients with late-stage tumors, even more so when combined with MEK inhibitors targeting the same signaling pathway. However, invariably patients become resistant to this targeted therapy resulting in rapid progression with treatment-refractory disease. The purpose of this study was the identification of new kinase inhibitors that do not lead to the development of resistance in combination with BRAF inhibitors (BRAFi), or that could be of clinical benefit as a 2nd line treatment for late-stage melanoma patients that have already developed resistance. Methods: We have screened a 274-compound kinase inhibitor library in 3 BRAF mutant melanoma cell lines (each one sensitive or made resistant to 2 distinct BRAFi). The screening results were validated by dose-response studies and confirmed the killing efficacies of many kinase inhibitors. Two different tools were applied to investigate and quantify potential synergistic effects of drug combinations: the Chou-Talalay method and the Synergyfinder application. In order to exclude that resistance to the new treatments might occur at later time points, synergistic combinations were administered to fluorescently labelled parental and resistant cells over a period of > 10 weeks. Results: Eight inhibitors targeting Wee1, Checkpoint kinase 1/2, Aurora kinase, MEK, Polo-like kinase, PI3K and Focal adhesion kinase killed melanoma cells synergistically when combined with a BRAFi. Additionally, combination of a Wee1 and Chk inhibitor showed synergistic killing effects not only on sensitive cell lines, but also on intrinsically BRAFi- and treatment induced-resistant melanoma cells. First in vivo studies confirmed these observations. Interestingly, continuous treatment with several of these drugs, alone or in combination, did not lead to emergence of resistance. Conclusions: Here, we have identified new, previously unexplored (in the framework of BRAFi resistance) inhibitors that have an effect not only on sensitive but also on BRAFi-resistant cells. These promising combinations together with the new immunotherapies could be an important step towards improved 1st and 2nd line treatments for late-stage melanoma patients

A simple and rapid approach for screening of SARS-coronavirus genotypes: an evaluation study

BACKGROUND: The Severe Acute Respiratory Syndrome (SARS) was a newly emerged infectious disease which caused a global epidemic in 2002–2003. Sequence analysis of SARS-coronavirus isolates revealed that specific genotypes predominated at different periods of the epidemic. This information can be used as a footprint for tracing the epidemiology of infections and monitor viral evolution. However, direct sequencing analysis of a large number of clinical samples is cumbersome and time consuming. We present here a simple and rapid assay for the screening of SARS-coronavirus genotypes based on the use of fluorogenic oligonucleotide probes for allelic discrimination. METHODS: Thirty SARS patients were recruited. Allelic discrimination assays were developed based on the use of fluorogenic oligonucleotide probes (TaqMan). Genotyping of the SARS-coronavirus isolates obtained from these patients were carried out by the allelic discrimination assays and confirmed by direct sequencing. RESULTS: Genotyping based on the allelic discrimination assays were fully concordant with direct sequencing. All of the 30 SARS-coronavirus genotypes studied were characteristic of genotypes previously documented to be associated with the latter part of the epidemic. Seven of the isolates contained a previously reported major deletion but in patients not epidemiologically related to the previously studied cohort. CONCLUSION: We have developed a simple and accurate method for the characterization and screening of SARS-coronavirus genotypes. It is a promising tool for the study of epidemiological relationships between documented cases during an outbreak

Integrated In Vitro and In Silico Modeling Delineates the Molecular Effects of a Synbiotic Regimen on Colorectal-Cancer-Derived Cells

By modulating the human gut microbiome, prebiotics and probiotics (combinations of which are called synbiotics) may be used to treat diseases such as colorectal cancer (CRC). Methodological limitations have prevented determining the potential combina- torial mechanisms of action of such regimens. We expanded our HuMiX gut-on-a-chip model to co-culture CRC-derived epithelial cells with a model probiotic under a simulated prebiotic regimen, and we integrated the multi-omic results with in silico metabolic modeling. In contrast to individual prebi- otic or probiotic treatments, the synbiotic regimen caused downregulation of genes involved in procarci- nogenic pathways and drug resistance, and reduced levels of the oncometabolite lactate. Distinct ratios of organic and short-chain fatty acids were produced during the simulated regimens. Treatment of primary CRC-derived cells with a molecular cocktail reflecting the synbiotic regimen attenuated self-renewal ca- pacity. Our integrated approach demonstrates the potential of modeling for rationally formulating synbi- otics-based treatments in the future