On the Σ classes in E6 Engel, P.
Acta crystallographica. Section A, Foundations and advances,
September 2020, 20200901, Letnik:
76, Številka:
5
Journal Article
Recenzirano
In E6, the cone of positive definite quadratic forms is subdivided into Σs subcones and its equivalence classes are determined for s = 0–3, and 18–21.
The cone of positive definite quadratic forms is ...subdivided. The equivalence classes are determined for several levels.
The cone of positive-definite quadratic forms is subdivided into aggregates of parallelohedra having certain properties. In E
, the Σ-subcones are investigated and, in particular, the Σ
-subcone will ...be described which first occurs in E
and which is governed by the group {\cal G}_{E_6^*}. Further the \Sigma_{d+1 \choose 2}\-subcone which is governed by the group {\cal G}_{A_d^*} will be discussed for d = 6.
The cone of positive‐definite quadratic forms is subdivided into aggregates of parallelohedra having certain properties. In E6, the Σ‐subcones are investigated and, in particular, the Σ0‐subcone will ...be described which first occurs in E6 and which is governed by the group . Further the ‐subcone which is governed by the group will be discussed for d = 6.
The structures of quasicrystals can be considered as sections of lattices of translations in higher dimensions, which has greatly stimulated the investigation of lattices in arbitrary dimensions. The structure of the cone of positive definite quadratic forms in Ed×d is investigated for d = 6. A partition of the cone in Φ and Σ domains is performed and its local symmetries are determined.
Aliment Pharmacol Ther 2011; 34: 1225–1234
Summary
Background Uncertainty remains on topography and persistence of histological subgroups of microscopic colitis (MC).
Aim To assess longitudinal ...clinical, endoscopic, histological, and therapeutic description of MC subgroups including patients with incomplete findings of MC (MCi).
Methods Retrospective review of a consecutive cohort with MC and histological reassessment of MCi.
Results Clinical characteristics of 168 patients with lymphocytic colitis (LC), 270 with collagenous colitis (CC) and 101 with MCi were similar. At colonoscopy 95% (95% CI: 91–98%) of CC and 98% (93–100%) of LC cases had diagnostic histopathology of MC in both left and right colon. Eight and three patients had characteristics of MC only in the left and right colon, respectively. Histology findings resembling coexistence of the other MC subtype was present in 48% (40–55%) with CC and 24% (18–31%) with LC. A first diagnosis of MC was made in 49 (30%) of 164 patients only at repeat endoscopy. Another 34 of 115 (30%) with MC in the first endoscopy did not fulfil the MC criteria at repeat endoscopy. Only seven cases had a primary endoscopy without histopathological abnormalities. Fifteen percentage of MCi were reclassified as MC. Ileal inflammation was present in 33 of 81 patients. Budesonide was efficacious in all MC subgroups irrespective of bile acid malabsorption.
Conclusions Clinical characteristics of microscopic colitis subgroups are indistinguishable. Biopsies from the left colon suffice to exclude microscopic colitis, and the histological diagnosis of microscopic colitis is inconsistent over time. Ileal inflammation is common. The term microscopic colitis should perhaps be considered one clinical entity and include lymphocytic colitis, collagenous colitis, and incomplete findings of microscopic colitis.
It is expected that in the near future the use of high-voltage dc (HVDC) transmission and medium-voltage dc (MVDC) distribution technology will expand. This development is driven by the growing share ...of electrical power generation by renewable energy sources that are located far from load centers and the increased use of distributed power generators in the distribution grid. Power converters that transfer the electric energy between voltage levels and control the power flow in dc grids will be key components in these systems. The recently presented modular multilevel dc converter (M2DC) and the three-phase dual-active bridge converter (DAB) are benchmarked for this task. Three scenarios are examined: a 15 MW converter for power conversion from an HVDC grid to an MVDC grid of a university campus, a gigawatt converter for feeding the energy from an MVDC collector grid of a wind farm into the HVDC grid, and a converter that acts as a power controller between two HVDC grids with the same nominal voltage level. The operation and degrees of freedom of the M2DC are investigated in detail aiming for an optimal design of this converter. The M2DC and the DAB converter are thoroughly compared for the given scenarios in terms of efficiency, amount of semiconductor devices, and expense on capacitive storage and magnetic components.
Colorectal cancer (CRC) patients with metastatic disease can become cured if neoadjuvant treatment can enable a resection. The search for predictive biomarkers is often performed on primary tumours ...tissue. In order to assess the effectiveness of tailored treatment in regard to the primary tumour the differences in the genomic profile needs to be clarified.
Fresh-frozen tissue from primary tumours, synchronous liver metastases and adjacent normal liver was collected from 21 patients and analysed by whole-exome sequencing on the Illumina HiSeq 2500 platform. Gene variants designated as 'damaging' or 'potentially damaging' by Ingenuity software were used for the subsequent comparative analysis. BAM files were used as the input for the analysis of CNAs using NEXUS software.
Shared mutations between the primary tumours and the synchronous liver metastases varied from 50 to 96%. Mutations in APC, KRAS, NRAS, TP53 or BRAF were concordant between the primary tumours and the metastases. Among the private mutations were well-known driver genes such as PIK3CA and SMAD4. The number of mutations was significantly higher in patients with right- compared to left-sided tumours (102 vs. 66, p = 0.004). Furthermore, right- compared to left-sided tumours had a significantly higher frequency of private mutations (p = 0.023). Similarly, CNAs differed between the primary tumours and the metastases. The difference was mostly comprised of numerical and segmental aberrations. However, novel CNAs were rarely observed in specific CRC-relevant genes.
The examined primary colorectal tumours and synchronous liver metastases had multiple private mutations, indicating a high degree of inter-tumour heterogeneity in the individual patient. Moreover, the acquirement of novel CNAs from primary tumours to metastases substantiates the need for genomic profiling of metastases in order to tailor metastatic CRC therapies. As for the mutational status of the KRAS, NRAS and BRAF genes, no discordance was observed between the primary tumours and the metastases.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The three-phase dual-active bridge (DAB) is a dc-dc converter, which provides galvanic isolation, inherent soft-switching capability, and small filter size. In this study, the dynamic behavior of ...three-phase DAB is analyzed and a dynamic control strategy is developed. Furthermore, a compensation technique is implemented to compensate unbalanced transformer phase currents. The latter is often caused by asymmetric leakage inductances. State space averaging and first harmonic approximation models, both for the steady state and transient analysis, are developed to describe the dynamic behavior of the three-phase DAB. The accuracy of the models is compared with a detailed circuit simulation and the benefits of each model are identified. When the transferred power of the DAB changes fast, the transformer currents can become unbalanced, leading to oscillations in the output current. A unique control method is presented, which allows settling of the transformer currents within one-third of the switching period. Additionally, the transformer currents stay symmetrical and oscillations are avoided. Based on this fast current control, an outer voltage controller is designed. The comparison of the control system using the fast current control and the conventional quasi-steady-state control demonstrates the potential advantages of the new approach under dynamic conditions. In practice, it is difficult to achieve completely symmetrical short-circuit impedances in a high-power medium-voltage transformer. Asymmetric leakage inductances, however, result in unbalanced phase currents and higher dc current ripple in a three-phase DAB. The new control scheme that is developed here can be extended to compensate any unbalances in the transformer. This approach enables effectively the balancing of the three-phase currents. The new control schemes are experimentally verified.
After a short introduction to the topic of Fedorov's parallelohedra, the fundamentals of this topic are reviewed in sections and . The cone of positive‐definite quadratic forms is described in ...section where also new results on its shape are given. In the following sections aggregates of parallelohedra having certain properties are investigated and their connected domains in the cone of quadratic forms are determined. Results on combinatorial types of parallelohedra and their refined classification into contraction and similarity types are summarized in section . New results on Σ‐ and Ω‐domains are discussed in sections and , respectively.
Tilings of the plane by quadrilatterals and hexagons are known since the antique. In order to explain the structure of crystalls, Fedorov at the end of the 19th century was the first to investigate systematically parallelohedra in 2‐ and 3‐dimensional space. The new class of quasicrystalls requires to extend the theory to higher dimensions where we find a rich field of new insight into the theory of positive‐definite quadratic forms.
Loss of E-cadherin is a key initial step in the transdifferentiation of epithelial cells to a mesenchymal phenotype, which occurs when tumor epithelial cells invade into surrounding tissues. ...Expression of the nuclear factor ZEB1 induces an epithelial-to-mesenchymal transition and confers a metastatic phenotype on carcinomas by repressing the E-cadherin gene at the transcriptional level. In this study, we show that ZEB1 interacts with the SWI/SNF chromatin-remodeling protein BRG1 to regulate E-cadherin independently of CtBP, its traditional co-repressor. Blocking the interaction between ZEB1 and BRG1 induces expression of E-cadherin and downregulation of the mesenchymal marker vimentin. ZEB1 and BRG1 colocalize in E-cadherin-negative cells from cancer lines and in the stroma of normal colon. Colocalization of ZEB1 and BRG1 in epithelial cells is only found in those de-differentiated cells characterized by nuclear beta-catenin staining at the invasive edge of the tumor. Our results identify ZEB1/BRG1 as a new transcriptional mechanism regulating E-cadherin expression and epithelial-to-mesenchymal transdifferentiation that may be involved during the initial stages of tumor invasion.
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