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This research utilizes a descriptive research design to investigate the use of vocabulary learning strategies among English majors and identify the potential reasons for their difficulties in learning vocabulary. The study aims to describe the relationship between these reasons and second language vocabulary acquisition. A questionnaire, consisting of 62 items selected from the Vocabulary Learning Questionnaire (VLQ) 6.4 published by Gu and Johnson (1996), was administered to 115 sophomores majoring in English. The questionnaire was used to determine the types of vocabulary learning strategies employed by the participants, as well as the most and least frequently used strategies. The results indicate that English majors surveyed were moderate users of vocabulary learning strategies. Inferencing strategies were found to be the most commonly used, while Encoding strategies were the least used. After analyzing the participants' vocabulary learning strategies, the study proposes to improve their mother tongue competence to enhance their thinking ability, which is an essential factor in learning English vocabulary. Furthermore, the study suggests that the lack of mother tongue competence courses in higher education and the absence of effective vocabulary learning strategy guidance in the learning process are potential reasons for the difficulties experienced by English majors in vocabulary learning.

Free trial strategy, which allows a user to use service/product freely for a limited time, is widely applied in online service. With time-based pricing, we first consider that the service provider launches its initial version and offers a fixed length of free trial. We observe that the optimal length of free trial cannot be more than 1/3 of the initial version's lifespan. Then, we analyze the two-stage setting where a strategic or myopic service provider (SP) upgrades its initial version in the second stage with another fixed length of free trial. The findings show that the optimal length of free trial becomes shorter if a strategic SP sets the same price in two stages. When the paying users in the first stage pay the same for both the initial and the upgraded versions, the upgraded version has a shorter length of free trial and a lower price, which is counter-intuitive. For a myopic SP, the upgraded version has a longer length of free trial and a higher price. The above findings are insightful for the operation of online service.

Streptozotocin (STZ) is a pancreatic β cell-specific toxicant that is widely used to generate models of diabetes in rodents as well as in the treatment of tumors derived from pancreatic β cells. DNA alkylation, oxidative stress and mitochondrial toxicity have been recognized as the mechanisms for STZ-induced pancreatic β cell damage. Here, we found that pancreatic β cell-specific deficiency of nuclear factor erythroid-derived factor 2-related factor 1 (NFE2L1), a master regulator of the cellular adaptive response to a variety of stresses, in mice led to a dramatic resistance to STZ-induced hyperglycemia. Indeed, fifteen days subsequent to last dosage of STZ, the pancreatic β cell specific Nfe2l1 knockout [Nfe2l1(β)-KO] mice showed reduced hyperglycemia, improved glucose tolerance, higher plasma insulin and more intact islets surrounded by exocrine acini compared to the Nfe2l1-Flox control mice with the same treatment. Immunohistochemistry staining revealed a greater amount of insulin-positive cells in the pancreas of Nfe2l1(β)-KO mice than those in Nfe2l1-Flox mice 15 days after the last STZ injection. In line with this observation, both isolated Nfe2l1(β)-KO islets and Nfe2l1-deficient MIN6 (Nfe2l1-KD) cells were resistant to STZ-induced toxicity and apoptosis. Furthermore, pretreatment of the MIN6 cells with glycolysis inhibitor 2-Deoxyglucose sensitized Nfe2l1-KD cells to STZ-induced toxicity. These findings demonstrated that loss of Nfe2l1 attenuates pancreatic β cells damage and dysfunction caused by STZ exposure, partially due to Nfe2l1 deficiency-induced metabolic switch to enhanced glycolysis.

As more and more spacecraft launched into the space, the probability of radiofrequency (RF) interference raises and the burden of RF spectrum management increases as well. The monitoring of global RF beam information and identifying of spot beam emitters location can effectively obtain space data resources, which will do great help for mitigating global RF interference and optimising space spectrum resources. This study proposes a novel location awareness method for spot beam emitters based on the nanosatellite platform. The proposed method identifies the position of spot beam emitters on a global scale by flying a low earth orbit CubeSat constellation through the coverage of the spot beams. The properties such as geometry, the target motion equation, the measurement process, and the Particle Filter equations are all addressed with respect to the location methods. The authors illustrate a realistic scenario simulated within the Systems Tool Kit, in which CubeSats receive signals from the spot beam emitters. The scenario shows that their location awareness method proposed in this study is available and efficient.

One-lung ventilation (OLV) is essential in numerous clinical procedures, in which the left-sided double-lumen tube (LDLT) is the most commonly used device. The application of bronchial blockers, including the Uniblocker or Arndt blocker, has increased in OLV. The present study aimed to compare the efficacy and adverse effects of the Uniblocker and LDLT for OLV under the guidance of chest CT. A total of 60 adult patients undergoing elective left-side thoracic surgery requiring OLV were included in the study. The patients were randomly assigned to the Uniblocker group (U group, n=30) or the LDLT group (D group, n=30). The time for initial tube placement, the number of optimal positions of the tube upon blind insertion, the number of attempts to adjust the tube to the optimal position, incidence of airway device displacement, injury to the bronchi and carina, the duration until lung collapse and the occurrence of sore throat and hoarseness over 24 h following surgery were recorded. The time for successful placement of the LDLT was 83.9±19.4 sec and that for the Uniblocker was 84.3±17.1 sec (P>0.05). The degree of lung collapse 1 min following opening of the pleura was greater in the D group than that in the U group (P

We consider a periodic review, joint inventory and pricing control problem for a firm that faces general random price‐dependent demands. Any unsatisfied demand can be either backordered or lost immediately. The objective is to maximize the expected profit over a finite selling horizon by coordinating the inventory and pricing decisions in each period. For both the backorder model and the lost sales model, we derive some quite general sufficient conditions to ensure the optimality of a base‐stock list price (BSLP) policy based on the strict monotonicity of demand functions in the realizations of random noises. We are among the first to utilize the strict monotonicity of demand functions in the realizations of random noises for deriving the sufficient conditions. We derive the sufficient conditions in both the backorder model and the lost‐sales model by utilizing the new concept of upper‐set and lower‐set decreasing properties (USDP/LSDP), which is a generalized version of the first‐order stochastic dominance. This study reveals that the optimality of a BSLP policy is robust to more general business environments than what we previously thought. Finally, we also apply the USDP/LSDP in other inventory management problems.

In this paper, we study a dynamic inventory rationing problem of a single item with multiple demand classes and backorder. Demand classes are differentiated by their unit backlogging costs. The corresponding dynamic programming problem is multidimensional and computationally challenging. With a novel state transformation, we find that the optimal policy can be described by a nested base stock policy. In particular, we can decompose the value function as the sum of single-variable convex functions. This property breaks the curse of dimensionality and significantly reduces computational effort in computing optimal policies. Our approach allows us to extend the results to systems with ordering, exogenous supply, priority upgrading.

Direct value identification refers to the consumer-perceived value for a product itself. In the era of We-Media, consumers may also have indirect value identification for a product which stems from their fondness and emotional identification for some key opinion leaders (KOLs). To investigate the possible impacts of indirect value identification on product-selling strategy, and further explore the potential power of KOLs in green-product marketing, this paper analyzes the optimal product-selling strategy under direct and indirect value identification for firms producing and selling regular or green products. Results show that the optimal product-selling strategy is affected by the two kinds of value identification in a relatively independent way. Specifically, the fraction of followers in the whole consumer population and the relative marketing cost of KOLs affect the selling strategy while the marginal green production cost decides the product strategy.

Ground state properties and level statistics of the Dicke model for a finite number of atoms are investigated based on a progressive diagonalization scheme (PDS). Particle number statistics, the entanglement measure and the Shannon information entropy at the resonance point in cases with a finite number of atoms as functions of the coupling parameter are calculated. It is shown that the entanglement measure defined in terms of the normalized von Neumann entropy of the reduced density matrix of the atoms reaches its maximum value at the critical point of the quantum phase transition where the system is most chaotic. Noticeable change in the Shannon information entropy near or at the critical point of the quantum phase transition is also observed. In addition, the quantum phase transition may be observed not only in the ground state mean photon number and the ground state atomic inversion as shown previously, but also in fluctuations of these two quantities in the ground state, especially in the atomic inversion fluctuation.

Background: The use of bronchial blockers has been increased for one-lung ventilation; however, the placement of bronchial blockers is time consuming. The objective of this study was to compare the novel extraluminal technique of Uniblocker placement supported by trachea length measurement on computerized tomography images with conventional intraluminal Uniblocker placement method. Methods: Seventy adult patients undergoing left side thoracic surgery were included in the study. All the patients were randomly assigned to one of two groups: conventional intraluminal intubation group (CV-IN group, n = 35) or extraluminal CT guided group (CT-EX group, n = 35). The primary endpoints were the optimal positions of Uniblocker and the injuries of bronchi and carina. The secondary outcomes included the time of Uniblocker placement, the adequacy of lung collapse, the incidences of Uniblocker displacement, sore throat, and hoarseness postoperative. Results: In the CV-IN group, 19 of 35 Uniblockers went to the left main-stem bronchus on the initial blind insertion and 15 of 35 Uniblockers were considered as in optimal depth, whereas in the CT-EX group, 32 of 35 Uniblockers went to the left main-stem bronchus on the initial blind insertion and 31 of 35 Uniblockers were considered as in optimal depth (P .05). Conclusion: The novel extraluminal technique of Uniblocker placement supported by trachea length measurement on computerized tomography images was proved to be more rapid, more accurate and less complications than conventional intraluminal Uniblocker placement method.

Quantum phase transitions in nuclei have attracted a lot of attention from both experimental and theoretical perspectives [1‐25], since they provide new insights into understanding the evolution of nuclear properties. The quantum phase transition is not of the usual thermodynamic type, but relat ed to the equilibrium shape changes in the ground state of nuclei at zero temperature. It is thus also referred to as the shape phase transition or ground state phase transition, though t he concept can also be applied to excited states. Evidences of the shape phase transition in nuclei are signaled experimentally through a sudden change in the properties of the ground state. An excellent example is provided by a set of even Sm isotopes, of which the evolution of its properties can be identified as t he first-order shape phase phase transition experimentally [2 2]. On the other hand, odd-A nuclei can be approximately considered as systems with an even-even core coupled to a single valence nucleon. It is thus expected that the properties of odd-A nuclei should be definitely affected by the shape phase transition emerging along the related odd isotope or isotone chains. Currently, analyses of the phase transitions in nuclei are mostly focused on even-even systems and have been carried out in the frame of phenomenological geometrical models of nuclear potential [1, 2], or algebraic models of nuclear str ucture [25] since the phase transitions in the intermediate an d heavy mass region, such as the mass number A ∼ 150 region, are often out of reach of the microscopic shell models. In addition, phase transitions in odd-A nuclei may be more difficult to describe due to much more complicate dynamical situations [26] in contrast to the adjacent even-even speci es. However, if one only wants to emphasize some special aspects of nuclear phase transitions, the shell model (under some approximations) is still applicable to give a microscopic ana lysis of the phase transition in the A ∼ 150 region. The purpose of this work is to give a microscopic analysis of the shape phase transition in the odd Sm nuclei in terms of the effective order parameters and odd-even effects.

A recursive method for the construction of symmetric irreducible representations of $ O(2l+1)$ in the $ O(2l+1)\supset O(3)$ basis for identical boson systems is proposed. The formalism is realized based on the group chain $ U(2l+1)\supset U(2l-1)\otimes U(2)$ , of which the symmetric irreducible representations are simply reducible. The basis vectors for symmetric irreducible representations of the $ O(2l+1)\supset O(2l-1)\otimes U(1)$ can easily be constructed from those of U(2l + 1) $ \supset$ U(2l - 1) ⊗ U(2) $ \supset$ O(2l - 1) ⊗ U(1) with no l -boson pairs, namely with the total boson number exactly equal to the seniority number in the system, from which one can construct symmetric irreducible representations of $ O(2l+1)$ in the $ O(2l-1)\otimes U(1)$ basis when all symmetric irreducible representations of O(2l - 1) are known. As a starting point, basis vectors of symmetric irreducible representations of O(5) are constructed in the $ O_{1}(3)\otimes U(1)$ basis, where $ O_{1}(3)\equiv O(2l-1)$ , when l = 2 , which is generated not by the angular momentum operators of the d -boson system, but by the operators constructed from d -boson creation (annihilation) operators $ d^{\dagger}_{\mu}$ ( $ d_{\mu}$ with $ \mu=1$ , 0, -1 . Matrix representations of $ O(5)\supset O_{1}(3)\otimes U(1)$ , together with the elementary Wigner coefficients, are presented. After the angular momentum projection, a three-term relation in determining the expansion coefficients of the $ O(5)\supset O(3)$ basis vectors, where the O(3) group is generated by the angular momentum operators of the d -boson system, in terms of those of $ O_{1}(3)\otimes U(1)$ is derived. The eigenvectors of the projection matrix with zero eigenvalues constructed according to the three-term relation completely determine the basis vectors of $ O(5)\supset O(3)$ . Formulae for evaluating the elementary Wigner coefficients of $ O(5)\supset O(3)$ are derived explicitly. Analytical expressions of some elementary Wigner coefficients of $ O(5)\supset O(3)$ for the coupling $ (\tau 0)\otimes(1 0)$ with resultant angular momentum quantum number L = 2 $ \tau$ + 2 - k for $ k=0,2,3,\ldots,6$ with a multiplicity 2 case for k = 6 are presented.

Spectral clustering has aroused extensive attention in recent years. It performs well for the data with arbitrary shape and can converge to global optimum. But traditional spectral clustering algorithms set the importance of all attributes to 1 as default, when measuring the similarity of data points. In fact, each attribute contains different information and their contributions to the clustering are also different. In order to make full use of the information contained in each attribute and weaken the interference of noise data or redundant attributes, this paper proposes a feature weighted spectral clustering algorithm based on knowledge entropy (FWKE-SC). This algorithm uses the concept of knowledge entropy in rough set to evaluate the importance of each attribute, which can be used as the attribute weights, and then applies spectral clustering method to cluster the data points. Experiments show that FWKE-SC algorithm deals with high-dimensional data very well and has better robustness and generalization ability.

For high dimensional data, the redundant attributes of samplers will not only increase the complexity of the calculation, but also affect the accuracy of final result. The existing attribute reduction methods are encountering bottleneck problem of timeliness and spatiality. In order to looking for a relatively coarse attributes granularity of problem solving, this paper proposes an efficient attribute granulation method to remove redundancy attribute. The method calculates the similarity of attributes according attribute discernibility first, and then clusters attributes into several group through affinity propagation clustering algorithm. At last, representative attributes are produced through some algorithms to form a coarser attribute granularity. Experimental results show that the attribute granulation method based on affinity propagation clustering algorithm(AGAP) method is a more efficient algorithm than traditional attribute reduction algorithm(AR).

A new approach for solving the Bethe ansatz (Gaudin-Richardson) equations of the standard pairing problem is established based on the Heine-Stieltjes correspondence. For $k$ pairs of valence nucleons on $n$ different single-particle levels, it is found that solutions of the Bethe ansatz equations can be obtained from one (k+1)x(k+1) and one (n-1)x(k+1) matrices, which are associated with the extended Heine-Stieltjes and Van Vleck polynomials, respectively. Since the coefficients in these polynomials are free from divergence with variations in contrast to the original Bethe ansatz equations, the approach thus provides with a new efficient and systematic way to solve the problem, which, by extension, can also be used to solve a large class of Gaudin-type quantum many-body problems and to establish a new efficient angular momentum projection method for multi-particle systems., Comment: ReVTeX, 4 pages, no figure

New polynomials associated with a special Lipkin-Meshkov-Glick (LMG) model corresponding to the standard two-site Bose-Hubbard model are derived based on the Stieltjes correspondence. It is shown that there is a one-to-one correspondence between zeros of this new polynomial and solutions of the Bethe ansatz equations for the LMG model.A one-dimensional classical electrostatic analogue corresponding to the special LMG model is established according to Stieltjes early work. It shows that any possible configuration of equilibrium positions of the charges in the electrostatic problem corresponds uniquely to one set of roots of the Bethe ansatz equations for the LMG model, and the number of possible configurations of equilibrium positions of the charges equals exactly to the number of energy levels in the LMG model. Some relations of sums of powers and inverse powers of zeros of the new polynomials related to the eigenenergies of the LMG model are derived., 11 pages, LaTeX