scholarly journals Comparative studies of the deformation techniques for the singular-drift problem in the complex Langevin method

2018 ◽  
Vol 175 ◽  
pp. 07019 ◽  
Author(s):  
Yuta Ito ◽  
Jun Nishimura
Keyword(s):  
Low Temperature ◽  
Dirac Operator ◽  
Matrix Model ◽  
Comparative Studies ◽  
Deformation Parameter ◽  
High Density ◽  
Large N ◽  
Singular Drift ◽  
Different Types ◽  
Data Points

In application of the complex Langevin method to QCD at high density and low temperature, the singular-drift problem occurs due to the appearance of near-zero eigenvalues of the Dirac operator. In order to avoid this problem, we proposed to de-form the Dirac operator in such a way that the near-zero eigenvalues do not appear and to extrapolate the deformation parameter to zero from the available data points. Here we test three different types of deformation in a simple large-N matrix model, which under-goes an SSB due to the phase of the fermion determinant, and compare them to see the consistency with one another.

scholarly journals Complex Langevin simulation of QCD at finite density and low temperature using the deformation technique

2018 ◽  
Vol 175 ◽  
pp. 07017 ◽  
Author(s):  
Keitro Nagata ◽  
Jun Nishimura ◽  
Shinji Shimasaki
Keyword(s):  
Low Temperature ◽  
Deformation Parameter ◽  
Original System ◽  
Baryon Number ◽  
Finite Density ◽  
Clear Sign ◽  
Sign Problem ◽  
Singular Drift ◽  
Langevin Simulation ◽  
Severe Sign

We study QCD at finite density and low temperature by using the complex Langevin method. We employ the gauge cooling to control the unitarity norm and intro-duce a deformation parameter in the Dirac operator to avoid the singular-drift problem. The reliability of the obtained results are judged by the probability distribution of the magnitude of the drift term. By making extrapolations with respect to the deformation parameter using only the reliable results, we obtain results for the original system. We perform simulations on a 43 × 8 lattice and show that our method works well even in the region where the reweighing method fails due to the severe sign problem. As a result we observe a delayed onset of the baryon number density as compared with the phase-quenched model, which is a clear sign of the Silver Blaze phenomenon.

scholarly journals GERMINATION AND VIGOUR IN SEEDS OF THE COWPEA IN RESPONSE TO SALT AND HEAT STRESS

2019 ◽  
Vol 32 (1) ◽  
pp. 143-151 ◽  
Author(s):  
Luma Rayane de Lima Nunes ◽  
Paloma Rayane Pinheiro ◽  
Charles Lobo Pinheiro ◽  
Kelly Andressa Peres Lima ◽  
Alek Sandro Dutra
Keyword(s):  
Salt Stress ◽  
Heat Stress ◽  
High Temperature ◽  
Low Temperature ◽  
Vigna Unguiculata ◽  
Salt Concentration ◽  
Dry Weight ◽  
Germination Percentage ◽  
Different Types ◽  
Different Temperatures

ABSTRACT Salinity is prejudicial to plant development, causing different types of damage to species, or even between genotypes of the same species, with the effects being aggravated when combined with other types of stress, such as heat stress. The aim of this study was to evaluate the tolerance of cowpea genotypes (Vigna unguiculata L. Walp.) to salt stress at different temperatures. Seeds of the Pujante, Epace 10 and Marataoã genotypes were placed on paper rolls (Germitest®) moistened with different salt concentrations of 0.0 (control), 1.5, 3.0, 4.5 and 6.0 dS m-1, and placed in a germination chamber (BOD) at temperatures of 20, 25, 30 and 35°C. The experiment was conducted in a completely randomised design, in a 3 × 4 × 5 scheme of subdivided plots, with four replications per treatment. The variables under analysis were germination percentage, first germination count, shoot and root length, and total seedling dry weight. At temperatures of 30 and 35°C, increases in the salt concentration were more damaging to germination in the Epace 10 and Pujante genotypes, while for the Marataoã genotype, damage occurred at the temperature of 20°C. At 25°C, germination and vigour in the genotypes were higher, with the Pujante genotype proving to be more tolerant to salt stress, whereas Epace 10 and Marataoã were more tolerant to high temperatures. Germination in the cowpea genotypes was more sensitive to salt stress when subjected to heat stress caused by the low temperature of 20°C or high temperature of 35°C.

scholarly journals Structures and impact strength variation of chemically crosslinked high-density polyethylene: effect of crosslinking density

RSC Advances ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 6791-6797
Author(s):  
Yueqing Ren ◽  
Xiaojie Sun ◽  
Lanlan Chen ◽  
Yafei Li ◽  
Miaomiao Sun ◽  
...  
Keyword(s):  
Low Temperature ◽  
Impact Strength ◽  
High Density Polyethylene ◽  
Crosslinking Density ◽  
High Density ◽  
Strength Variation

Crosslinking significantly improves the toughness and impact strength of HDPE and extends its application, especially at low temperature.

Cu to Cu direct bonding at low temperature with high density defect in electrodeposited Cu

2021 ◽  
Vol 550 ◽  
pp. 149337
Author(s):  
Haneul Han ◽  
Chaerin Lee ◽  
Youjung Kim ◽  
Jinhyun Lee ◽  
Rosa Kim ◽  
...  
Keyword(s):  
Low Temperature ◽  
High Density

scholarly journals Low-Temperature Mechanical Properties of High-Density and Low-Density Polyethylene and Their Blends

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1821
Author(s):  
Ildar I. Salakhov ◽  
Nadim M. Shaidullin ◽  
Anatoly E. Chalykh ◽  
Mikhail A. Matsko ◽  
Alexey V. Shapagin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Impact Strength ◽  
Relative Elongation ◽  
High Density ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Elongation At Break ◽  
Subzero Temperatures ◽  
Izod Impact

Low-temperature properties of high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and their blends were studied. The analyzed low-temperature mechanical properties involve the deformation resistance and impact strength characteristics. HDPE is a bimodal ethylene/1-hexene copolymer; LDPE is a branched ethylene homopolymer containing short-chain branches of different length; LLDPE is a binary ethylene/1-butene copolymer and an ethylene/1-butene/1-hexene terpolymer. The samples of copolymers and their blends were studied by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), 13С NMR spectroscopy, and dynamic mechanical analysis (DMA) using testing machines equipped with a cryochamber. It is proposed that such parameters as “relative elongation at break at −45 °C” and “Izod impact strength at −40 °C” are used instead of the ductile-to-brittle transition temperature to assess frost resistance properties because these parameters are more sensitive to deformation and impact at subzero temperatures for HDPE. LLDPE is shown to exhibit higher relative elongation at break at −45 °C and Izod impact strength at −20 ÷ 60 °C compared to those of LDPE. LLDPE terpolymer added to HDPE (at a content ≥ 25 wt.%) simultaneously increases flow properties and improves tensile properties of the blend at −45 °C. Changes in low-temperature properties as a function of molecular weight, MWD, crystallinity, and branch content were determined for HDPE, LLDPE, and their blends. The DMA data prove the resulting dependences. The reported findings allow one to understand and predict mechanical properties in the HDPE–LLDPE systems at subzero temperatures.

PHASE DIAGRAM AND ORTHOGONAL POLYNOMIALS IN MULTIPLE-WELL MATRIX MODELS

1991 ◽  
Vol 06 (25) ◽  
pp. 4491-4515 ◽  
Author(s):  
OLAF LECHTENFELD ◽  
RASHMI RAY ◽  
ARUP RAY
Keyword(s):  
Phase Diagram ◽  
Orthogonal Polynomials ◽  
Matrix Models ◽  
Matrix Model ◽  
Phase Structure ◽  
Saddle Points ◽  
Tree Level ◽  
Potential Wells ◽  
Large N

We investigate a zero-dimensional Hermitian one-matrix model in a triple-well potential. Its tree-level phase structure is analyzed semiclassically as well as in the framework of orthogonal polynomials. Some multiple-arc eigenvalue distributions in the first method correspond to quasiperiodic large-N behavior of recursion coefficients for the second. We further establish this connection between the two approaches by finding three-arc saddle points from orthogonal polynomials. The latter require a modification for nondegenerate potential minima; we propose weighing the average over potential wells.

scholarly journals Effective Action and Measure in Matrix Model of IIB Superstrings

1997 ◽  
Vol 12 (31) ◽  
pp. 2331-2340 ◽  
Author(s):  
L. Chekhov ◽  
K. Zarembo
Keyword(s):  
Matrix Model ◽  
Effective Action ◽  
Continuum Limit ◽  
Auxiliary Field ◽  
Large N ◽  
The Matrix ◽  
Reparametrization Invariance ◽  
The Continuum ◽  
Induced Measure

We calculate an effective action and measure induced by the integration over the auxiliary field in the matrix model recently proposed to describe IIB superstrings. It is shown that the measure of integration over the auxiliary matrix is uniquely determined by locality and reparametrization invariance of the resulting effective action. The large-N limit of the induced measure for string coordinates is discussed in detail. It is found to be ultralocal and, thus, is possibly irrelevant in the continuum limit. The model of the GKM type is considered in relation to the effective action problem.

Do Development and Democracy Positively Affect Gender Equality in Cabinets?

2015 ◽  
Vol 16 (3) ◽  
pp. 332-356 ◽  
Author(s):  
JOHN HÖGSTRÖM
Keyword(s):  
Economic Development ◽  
Gender Equality ◽  
Empirical Evidence ◽  
Comparative Studies ◽  
Developed Countries ◽  
Political Regimes ◽  
The World ◽  
Different Types ◽  
Negative Effect ◽  
Positive Effect

AbstractIt has been argued that economic development and democracy create new opportunities and resources for women to access political power, which should increase gender equality in politics. However, empirical evidence from previous research that supports this argument is mixed. The contribution of this study is to expand the research on gender equality in politics through an in-depth examination of the effect of development and democracy on gender equality in cabinets. This has been completed through separate analyses that include most of the countries in the world across three levels of development (least-developed, developing, and developed) and across different types of political regimes (democracies, royal dictatorships, military dictatorships, and civilian dictatorships). The results demonstrate that economic development and democracy only affect gender equality in cabinets positively in a few environments. Accordingly, the context is important and there seem to be thresholds before development and democracy have any effect. Development has a positive effect in developed countries and in democracies, but it has a negative effect in dictatorships, and the negative effect is strongest in military dictatorships. The level of democracy has a positive effect mainly in dictatorships, and the strongest effect is in civilian dictatorships. The article demonstrates the importance of dividing samples into subsets to increase understanding of what affects women's representation in cabinets in different environments, and I ask scholars to subset samples and run separate analyses more often in comparative studies.

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