Mirror symmetry in two steps: A-I-B

We suggest an interpretation of mirror symmetry for toric varieties via an equivalence of two conformal field theories. The first theory is the twisted sigma model of a toric variety in the infinite volume limit (the A-model). The second theory is an intermediate model, which we call the I-model. The equivalence between the A-model and the I-model is achieved by realizing the former as a deformation of a linear sigma model with a complex torus as the target and then applying to it a version of the T-duality. On the other hand, the I-model is closely related to the twisted Landau-Ginzburg model (the B-model) that is mirror dual to the A-model. Thus, the mirror symmetry is realized in two steps, via the I-model. In particular, we obtain a natural interpretation of the superpotential of the Landau-Ginzburg model as the sum of terms corresponding to the components of a divisor in the toric variety. We also relate the cohomology of the supercharges of the I-model to the chiral de Rham complex and the quantum cohomology of the underlying toric variety.Comment: 50 pages; revised versio

The Topological Cigar Observables

We study the topologically twisted cigar, namely the SL(2,R)/U(1) superconformal field theory at arbitrary level, and find the BRST cohomology of the topologically twisted N=2 theory. We find a one to one correspondence between the spectrum of the twisted coset and singular vectors in the Wakimoto modules constructed over the SL(2,R) current algebra. The topological cigar cohomology is the crucial ingredient in calculating the closed string spectrum of topological strings on non-compact Gepner models.Comment: 28 page

Earnings management using classification shifting of revenues

This paper examines a novel form of classification shifting as an earnings management tool using a sample of 12,804 UK listed firm-year observations for the 1995–2014 period. It proposes a new approach to classification shifting whereby firms have scope to misclassify revenues from non-operating activities as operating revenues. The results establish that firms engage in classification shifting of non-operating revenues to inflate operating revenues. They indicate that firms in the period following mandatory IFRS adoption are associated with an increase in this practice, consistent with IFRS offering greater scope for manipulation. Further tests reveal that classification shifting of revenues is more pervasive for firms that report operating losses or have low growth

Supersymmetric vertex algebras

We define and study the structure of SUSY Lie conformal and vertex algebras. This leads to effective rules for computations with superfields.Comment: 71 page

‘Pole Test’ Measurements in Critical Leg Ischaemia

AbstractBackgroundFor the quantification of critical limb ischaemia (CLI) most vascular surgery units use sphygmo-manometric and transcutaneous oxygen pressure (TcPO2) measurements. However, measurements obtained by cuff-manometry can be overestimated especially in diabetic patients because of medial calcification that makes leg arteries less compressible. TcPO2 measurements present a considerable overlap in the values obtained for patients with different degrees of ischaemia and its reproducibility has been questioned. Arterial wall stiffness has less influence on the pole test, based on hydrostatic pressure derived by leg elevation, and this test seems to provide a reliable index of CLI.ObjectiveThe objective of this study was to evaluate the pole pressure test for detection of critical lower limb ischaemia, correlating results with cuff-manometry and transcutaneous oxygen pressure.DesignUniversity hospital-prospective study.Materials and methodsSeventy-four patients (83 legs) with rest pain or gangrene were evaluated by four methods: pole test, cuff-manometry, TcPO2 and arteriography. CLI was present if the following criteria were met: (a) important arteriographic lesions+rest pain with an ankle systolic pressure (ASP) ≤40mmHg and/or a TcPO2 ≤30mmHg, or (b) important arteriographic lesions+tissue loss with an ASP ≤60mmHg and/or a TcPO2 ≤40mmHg. Fifty-seven lower limbs met the criteria for CLI.ResultsMeasurements obtained by cuff-manometry were significantly higher to those obtained by pole test (mean pressure difference: 40mmHg, p<0.001). The difference between the two methods remained statistically significant for both diabetics (50.73, p<0.001) and non-diabetics (31.46, p<0.001). Mean TcPO2 value was 15.51mmHg and there was no important difference between patients with and without diabetes. Overall, there was a correlation between sphygmomanometry and pole test (r=0.481). The correlation persisted for patients without diabetes (r=0.581), but was not evident in patients with diabetes. Correlation between pole test and TcPO2 was observed only for patients with diabetes (r=0.444). There was no correlation between cuff-manometry and TcPO2. The pole test offered an accuracy of 88% for the detection of CLI. The sensitivity of this test was 95% and the specificity 73%

Ways to control asynchronous motor with phase rotor of mining machines

The article describes various methods of controlling asynchronous motors with a phase rotor. To solve the problems of controlling speeds and moments in a modern electric drive, two main methods of frequency control are used: scalar and vector. Advantages and disadvantages of scalar and vector control, voltage dependence are given

Anterior minimally invasive extrapleural retroperitoneal approach to the thoraco-lumbar junction of the spine

SummaryBackgroundThe anterior approach to the thoraco-lumbar junction of the spine allows therapeutic interventions on post-traumatic, infectious, and neoplastic vertebral lesions from T11 to L2 combining spinal cord decompression, corporectomy, and vertebral body fusion. However, this approach also has a reputation for damaging the intervening anatomic structures (lungs, peritoneum, and diaphragm). The objective of this study was to show that both nervous structure decompression and anterior vertebral reconstruction can be achieved via an anterior minimally invasive extrapleural retroperitoneal (AMIER) approach.MaterialWe describe each of the steps of the AMIER approach to the thoraco-lumbar junction of the spine.ResultsThe AMIER approach ensures excellent exposure that allows full decompression and satisfactory anterior anatomic reconstruction. The main difficulties and complications relate to the lungs, and a painstaking and rigorous technique limits the complications compared to conventional thoraco-phreno-lumbotomy

Influence of high-dose ion implantation of NiTi equiatomic on shape memory and pseudoelastic

This work explains the method alloying process of the TiNi thin films in addition to the shape memory properties of the TiNi thin films made by alloying the TiNi multilayer thin films. The surface layer of an equiatomic TiNi alloy, which exhibits the shape memory effect in the martensitic slate, is modified with high-dose implantation ions N⁺, Ni⁺ -N⁺, and Mo⁺ -W⁺ ions at a dose of 10¹⁷ − 10¹⁸ cm⁻² and studied by Rutherford back scattering, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and by measuring the nanohardness and the elastic modulus. After double implantation ions, the hardness of the TiNi samples is 2.78 ± 0.95 GPa at a depth of 150 nm and 4.95 2.25 GPa at a depth of 50 nm; the elastic modulus is 59 GPa. The coating demonstratedthe increased corrosion resistance in acidic and alkaline media in comparison with that of the non-implanted surface. A correlation between the elemental composition, microstructure, shape memory effect, and mechanical properties of the near-surface layer in TiNi is found.В работе предложен метод модификации свойств тонких пленок TiNi с эффектом памяти формы путем легирования и формирования многослойных пленок. Поверхностный слой эквиатомного сплава TiNi, обладающего эффектом памяти формы в мартенситной фазе, изменялся путем высокодозной имплантации ионов N⁺, Ni⁺ -N⁺ и Mo⁺ -W⁺ с дозой 10¹⁷ − 10¹⁸ см⁻² и исследовался методами Резерфордовского обратного рассеяния, сканирующей электронной микроскопии, энергодисперсионной спектроскопия, дифракции рентгеновских лучей. Дополнительно измерялись нанотвердость и модуль упругости. Обнаружено, что при двойной имплантации ионов микротвердость образцов TiNi составляет 2.78 ± 0.95 ГПа на глубине 150 нм и 4.95 ± 2.25 ГПа на глубине 50 нм, а модуль упругости 59 ГПа. По сравнению с неимплантированной поверхностью покрытие обладает повышенной коррозионной стойкостью в кислых и щелочных средах. Обнаружена корреляция между элементным составом, микроструктурой и эффектом памяти формы и механическими свойствами приповерхностного слоя TiNi.У роботізапропоновано метод модифікації властивостей тонких плівок TiNi з ефектом пам’яті форми шляхом легування та формування багатошарових плівок. Поверхневий шар еквіатомного сплаву TiNi, що має ефект пам’яті форми в мартенситній фазі, змінювався шляхом високодозної імплантації іонів N⁺, Ni⁺ -N⁺ та Mo⁺ -W⁺ з дозою 10¹⁷ − 10¹⁸ см⁻² і досліджувався методами Резерфордівського оберненого розсіювання, скануючої електронноїмікроскопії, енергодисперсійної спектроскопії, дифракції рентгенівських променів. Додатково вимірювалися нанотвердость і модуль пружності. Виявлено, що при подвійний імплантації іонів мікротвердість зразків TiNi становить 2.78 ± 0.95 ГПа на глибині 150 нм та 4.95 ± 2.25 ГПа на глибині 50 нм, а модуль пружності становить 59 ГПа. У порівнянніз неімплантірованною поверхнею покриття має підвищену корозійну стійкість у кислих і лужних середовищах. Виявлено кореляцію міжелементним складом, мікроструктурою та ефектом пам’яті форми і механічними властивостями приповерхневого шару TiNi