One-dimensional Quantum Spin Dynamics of Bethe String States

Quantum dynamics of strongly correlated systems is a challenging problem. Although the low energy fractional excitations of one dimensional integrable models are often well-understood, exploring quantum dynamics in these systems remains challenging in the gapless regime, especially at intermediate and high energies. Based on the algebraic Bethe ansatz formalism, we study spin dynamics in a representative one dimensional strongly correlated model, {\it i.e. }, the antiferromagnetic spin-$\frac{1}{2}$ XXZ chain with the Ising anisotropy, via the form-factor formulae. Various excitations at different energy scales are identified crucial to the dynamic spin structure factors under the guidance of sum rules. At small magnetic polarizations, gapless excitations dominate the low energy spin dynamics arising from the magnetic-field-induced incommensurability. In contrast, spin dynamics at intermediate and high energies is characterized by the two- and three-string states, which are multi-particle excitations based on the commensurate N\'eel ordered background. Our work is helpful for experimental studies on spin dynamics in both condensed matter and cold atom systems beyond the low energy effective Luttinger liquid theory. Based on an intuitive physical picture, we speculate that the dynamic feature at high energies due to the multi-particle anti-bound state excitations can be generalized to non-integrable spin systems.Comment: 15 pages, to appear in Phys. Rev.

Standardizing catch per unit effort by machine learning techniques in longline fisheries: a case study of bigeye tuna in the Atlantic Ocean

Support vector machine (SVM) is shown to have better performance in catch per unit of effort (CPUE) standardization than other methods. The SVM performance highly relates to its parameters selection and has not been discussed in CPUE standardization. Analyzing the influence of parameter selection on SVM performance for CPUE standardization could improve model construction and performance, and thus provide useful information to stock assessment and management. We applied SVM to standardize longline catch per unit fishing effort of fishery data for bigeye tuna (Thunnus obesus) in the tropical fishing area of Atlantic Ocean and evaluated three parameters optimization methods: a Grid Search method, and two improved hybrid algorithms, namely SVMs in combination with the particle swarm optimization (PSO-SVM), and genetic algorithms (GA-SVM), in order to increase the strength of SVM. The mean absolute error (MAE), mean square error (MSE), three types of correlation coefficients and the normalized mean square error (NMSE) were computed to compare the algorithm performances. The PSO-SVM and GA-SVM algorithms had particularly high performances of indicative values in the training data and dataset, and the performances of PSO-SVM were marginally better than GA-SVM. The Grid search algorithm had best performances of indicative values in testing data. In general, PSO was appropriate to optimize the SVM parameters in CPUE standardization. The standardized CPUE was unstable and low from 2007 to 2011, increased during 2011- 2013, then decreased from 2015 to 2017. The abundance index was lower compared with before 2000 and showed a decreasing trend in recent years

Nonsymmorphic bosonization in one-dimensional generalized Kitaev spin-1/2 models

In this work, we perform a detailed study on the consequences of nonsymmorphic symmetries in the Luttinger phase of the one-dimensional spin-1/2 Kitaev-Heisenberg-Gamma model with an antiferromagnetic Kitaev interaction. Nonsymmorphic bosonization formulas for the spin operators are proposed, containing ten non-universal coefficients which are determined by our density matrix renormalization group simulations to a high degree of accuracy. Using the nonsymmorphic bosonization formulas, different Fourier components and decay powers in the correlation functions are disentangled, the response to weak magnetic fields is analyzed, and the zigzag magnetic order in two dimensions is recovered from a system of weakly coupled chains. We also find a line of critical points with an emergent SU(2)$_1$ conformal symmetry located on the boundary of the Luttinger liquid phase, where a nonabelian version of nonsymmorphic bosonization should be applied.Comment: 22 pages, 7 figure

Chemical synthesis and characterization of zinc borohydride

AbstractMetal borohydrides have received increasing research interests on account of their high hydrogen storage capacities. In this paper, zinc borohydride Zn(BH4)2 was synthesized using NaBH4 and ZnCl2 in THF under room temperature for 72h, and the crystallographic constitution of the synthesized products were analyzed by XRD. The results showed that the major phase of the products was NaCl, alternatively, NaBH4 or ZnCl2 disappeared. This concluded the formation of Zn(BH4)2. Moreover, both experiment phenomena and fired products further confirmed the synthesis of Zn(BH4)2, which a XRD pattern of Zinc borohydride was obtained

Bigeye tuna fishing ground in relation to thermocline in the Western and Central Pacific Ocean using Argo data

444-451The relationship beween thermocline and bigeye tuna (Thunnus obesus) fishing grounds in the Western and Central Pacific Ocean was evaluated by Argo data and monthly CPUE (catch per unit effort). The generalized additive model indicated evidence of nonlinear relationships between CPUE and six thermocline characteristics. The results suggested that the fishing grounds distributed where the upper boundary temperature was about 26 ºC and the upper boundary depth values between 70 and 100 m. The fishing grounds located between the two high value shapes of the lower boundary depth of thermocline, if the depth was >300 or <150 m, the CPUE tended to be low. The lower boundary temperature of the thermocline in the fishing grounds was lower than 13 ºC. Conversely, if the temperature was higher than 17 ºC, the hooking rates were very low. The strongest relationship between CPUE with thermocline thickness and thermocline strength was approximately at 60 m and 0.1 ºC/m. The optimum ranges for the upper boundary thermocline temperature and depth and the lower boundary thermocline temperature and depth, thermocline thickness and thermocline strength were between 26-29 ºC, 70-110 m, 11-13 ºC, 200-280 m, and 0.01-0.15 ºC/m, 60-80 m, respectively

From confined spinons to emergent fermions: Observation of elementary magnetic excitations in a transverse-field Ising chain

We report on spectroscopy study of elementary magnetic excitations in an Ising-like antiferromagnetic chain compound SrCo$_2$V$_2$O$_8$ as a function of temperature and applied transverse magnetic field up to 25 T. An optical as well as an acoustic branch of confined spinons, the elementary excitations at zero field, are identified in the antiferromagnetic phase below the N\'{e}el temperature of 5 K and described by a one-dimensional Schr\"{o}dinger equation. The confinement can be suppressed by an applied transverse field and a quantum disordered phase is induced at 7 T. In this disordered paramagnetic phase, we observe three emergent fermionic excitations with different transverse-field dependencies. The nature of these modes is clarified by studying spin dynamic structure factor of a 1D transverse-field Heisenberg-Ising (XXZ) model using the method of infinite time evolving block decimation. Our work reveals emergent quantum phenomena and provides a concrete system for testifying theoretical predications of one-dimension quantum spin models.Comment: 8 pages and 6 figure

PO-168 Reliability and validity of a new accelerometer-based device for detecting physical activities and energy expenditure

Objective Objective assessments of sedentary behavior, physical activity (PA) and the associated energy expenditure (EE) using accelerometer-based wearable devices are ever expanding, given their importance in the global context of health maintenance. However, among these numerous devices, the different underlying algorithms and available output parameters make it difficult to determine their accuracy. Furthermore, the function and accuracy of those devices may significantly differ between the different wearing locations (i.e., wrist-worn, waist-worn or thigh-based), where the center of the body (hip or thigh) is the optimal recommendation. Thus, a thigh-based device that has the possibility to differentiate between sedentary behavior, PAs, and EE is required to optimize research in PA. This study aimed to determine the reliability and validity of a new accelerometer-based analyzer (Fibion) with two-fold: First, to assess the reliability of the Fibion as compared to a designed repeated protocol and ActiGraph GT9X (one of the most widely used devices with favorable validity and reliability) in a laboratory re-test protocol; Second, to determine the validity of the Fibion in differentiating PAs and estimating EE throughout a simulated 12-hour free-living day. Methods Fibion (Fibion Inc, Jyväskylä, Finland) is a new 3-axial lightweight (20g, L•W•T = 30•32•10mm) accelerometer-based device, which was designed to follow the orientation and movement of the thigh. Thus, it can be worn either on the thigh (FT) or in the front pocket of the trousers (FP). According to information provided by the manufacturer, it is able to detect no-wear time and differentiates between different types (sitting, long sitting, standing, walking, and cycling) and intensities (LPA, MVPA, and VPA) of PA and the associated EE through the use of proprietary algorithms. The study consisted of two parts: a reliability (n=18) and validity (n=19) test, respectively. All 37 participants were young and healthy volunteers, who were normal weight (i.e., BMI &lt; 25 kg/m2) and recreationally physically active. Exclusion criteria included acute and chronic diseases, which would prevent participants from prolonged sitting and/or standing or would interfere with the basic metabolic rate. All participants were informed about the study procedures and provided written informed consent prior to commencing with testing. The study was carried out in accordance with the Declaration of Helsinki and the local Ethical Committee (ML16027). Reliability was assessed by a designed 15-min protocol by repeating sitting, standing, and walking (a total of 90 min = 15 min *3 types * 2 repeats) using both Fibion (FT) and ActiGraph. Validity was assessed by a prolonged 12-h protocol which was designed as simulated free-living conditions with two criteria. Criterion 1: Direct observation of the 12-h continuous sequence of tasks with measurement logs, to determine the duration of different types (sitting, standing, walking, and cycling) and intensities (light [LPA], moderate-to-vigorous [MVPA], and vigorous [VPA])) of PA. Indirect calorimetry served as the criterion 2 for EE estimation. Pulmonary gas exchange of the participants was continuously measured throughout the 12-h guided sequence of tasks by a portable breath-by-breath gas analyzer (Cosmed K4b2, Rome, Italy). During the entire 12-h protocol, two Fibion devices (worn both on the thigh (FT) and in the pocket (FP), respectively) and K4b2 were used simultaneously.&nbsp; Results Reliability. Fibion located on the thigh (FT) (ICCs: 0.687-0.806) provided similar reliability for EE estimation as the Actigraph (ICCs: 0.661-0.806). However, the measurement error for FT indicated an underestimation of activity times by 5.1 ± 1.2%, 3.8 ± 0.3% and 14.9 ± 2.6% during sitting, walking, and standing, respectively. Furthermore, low correlations were observed between subsequent measurements with both devices (ICCs 0.189-0.459), especially in low intensities (sitting). Validity. During the prolonged 12-h simulated real-life conditions, FT but not FP showed a moderate agreement with the direct observation in assessing the duration of sitting, long sitting, LPA, MVPA, and VPA (p&gt;0.05, ICCs: 0.071-0.537), but the low correlations between Fibion and the criteria (ICCs FT: 0.016-0.638; FP: -0.046 to 0.650) indicate that the measurement error is random. Similarly, FT but not FP showed a moderate agreement with the K4b2 for EE estimation of standing, LPA, MVPA, and VPA (p&gt;0.05, ICCs: 0.673-0.894).&nbsp; Conclusions In summary, the location of the accelerometer is essential for accurately assessing PA and EE. FT appeared to detect sitting and walking with a small measurement error, similar to that of the Actigraph. Considering the random error observed in our study, further studies with larger populations are needed to confirm the practical usability of Fibion (FT) for estimating different types and intensities of PA

Energy-driven mechanism of failure and instability of anchored surrounding rock in deep gob-side entry

Affected by the dynamic load induced by the fracture of lateral roof in the deep gob-side entry, the anchored surrounding rock is prone to produce large deformation, even failure and instability. Taking the tailgate of the 31120 working face in the Suncun Coal Mine as an engineering background, firstly, the development law of cracks in the anchored roof and the main failure mode of brittle tension crack were obtained by using the YTJ20 rock detection recorder. In addition, based on the similar material simulation test, the typical characteristics of three stages of lateral roof movement in the deep gob-side entry were obtained, and the fracture evolution and energy release law of anchored surrounding rock in different stages were analyzed. It is noted that the internal stress and deformation of anchored surrounding rock increase sharply, the cracks develop obviously and the energy is released significantly in the transitional movement stage, which has the greatest influence on the stability of anchored surrounding rock in the gob-side entry. Finally, the structural mechanical model of gob-side entry under lateral roof fracture movement was constructed, the quantitative calculation method of input and resistant energy of anchored surrounding rock were firstly provided, the energy-driven mechanism of failure and instability was revealed, and the instability energy criterion was defined, that is, when the energy applying on anchoring surrounding rock in gob-side entry is greater than the resistant energy of anchoring surrounding rock, the instability will occur. Accordingly, the instability risk classification method of anchoring surrounding rock and the corresponding strengthening control technology were put forward. The calculation results show that the instability risk level of anchored surrounding rock in the gob-side entry of the 31120 working face was medium risk. After strengthening the support, the deformation of roof and floor and the two sides of gob-side entry were reduced by 35.47% and 35.71%, respectively, the force of anchor cable was reduced by 23.43%, the deformation speed was obviously reduced, and the energy accumulation degree of anchoring surrounding rock was reduced

Process of Extraction Protein from Selenium-enriched Lyophyllum decastes Mycelia and Analysis of Its Amino Acid

The process of extracting seleno-protein from the selenium enriched Lyophyllum decastes mycelia cultured in a 20 L fermentor was optimized, and the effects of selenium enrichment on both types and contents of amino acids in Lyophyllum decastes mycelia were analyzed. Single factor tests and Box-Benhnken central combined response surface test were used to optimize process of extracting seleno-protein from Lyophyllum decastes mycelia. The content of protein was determined by 3,3'-diaminobenzidine spectrophotometry. The types and contents of amino acids in mycelia protein before and after selenium enrichment were compared by means of amino acid analyzer. The results showed that the optimal conditions of extracting seleno-protein from mycelia of Lyophyllum decastes were extraction temperature of 64 ℃, extraction time of 60 min, liquid-solid ratio of 200:1 g/mL, and extraction times of 2. The protein extraction rate was 75.13%, and the content of selenium in mycelia was 63.87 μg/g. The amino acid composition were analyzed by means amino acid score (AAS) and chemical score (CS), and the nutritional value of the protein in the selenium-enriched Lyophyllum decastes mycelia was evaluated. The varieties of amino acids in the selenium-enriched Lyophyllum decastes mycelia were abundant and the content of essential amino acids for human body was 17.20 g/100 g, 19.75% higher than that in the non-selenium-ecriched Lyophyllum decastes mycelia. The ratio of EAA/NEAA was 0.51, close to the recommended value proposed by WHO, and the values of both AAS and CS were close to the those in the model protein. In summary, the protein extraction rate could be improved by optimizing the extraction process, and there was selenium in the protein from selenium-enriched mycelia, which promoted the increase of amino acid content. The nutritional value of protein in selenium-enriched mycelia was higher than that in non-selenium-riched mycelia, and selenium-enrichec mycelia had potential edible and application value