In this paper,by utilizing the Marcinkiewicz-Zygmund inequality and Rosenthal-type inequality of negatively superadditive dependent(NSD)random arrays and truncated method,we investigate the complete f-moment convergen...In this paper,by utilizing the Marcinkiewicz-Zygmund inequality and Rosenthal-type inequality of negatively superadditive dependent(NSD)random arrays and truncated method,we investigate the complete f-moment convergence of NSD random variables.We establish and improve a general result on the complete f-moment convergence for Sung’s type randomly weighted sums of NSD random variables under some general assumptions.As an application,we show the complete consistency for the randomly weighted estimator in a nonparametric regression model based on NSD errors.展开更多
Assume that{a_(i),−∞<i<∞}is an absolutely summable sequence of real numbers.We establish the complete q-order moment convergence for the partial sums of moving average processes{X_(n)=Σ_(i=−∞)^(∞)a_(i)Y_(i+...Assume that{a_(i),−∞<i<∞}is an absolutely summable sequence of real numbers.We establish the complete q-order moment convergence for the partial sums of moving average processes{X_(n)=Σ_(i=−∞)^(∞)a_(i)Y_(i+n),n≥1}under some proper conditions,where{Yi,-∞<i<∞}is a doubly infinite sequence of negatively dependent random variables under sub-linear expectations.These results extend and complement the relevant results in probability space.展开更多
With a three-dimensional semiclassical ensemble method, we theoretically investigated the nonsequential double ionization of Ar driven by the spatially inhomogeneous few-cycle negatively chirped laser pulses. Our resu...With a three-dimensional semiclassical ensemble method, we theoretically investigated the nonsequential double ionization of Ar driven by the spatially inhomogeneous few-cycle negatively chirped laser pulses. Our results show that the recollision time window can be precisely controlled within an isolated time interval of several hundred attoseconds, which is useful for understanding the subcycle correlated electron dynamics. More interestingly, the correlated electron momentum distribution (CEMD) exhibits a strong dependence on laser intensity. That is, at lower laser intensity, CEMD is located in the first quadrant. As the laser intensity increases,CEMD shifts almost completely to the second and fourth quadrants, and then gradually to the third quadrant.The underlying physics governing the CEMD's dependence on laser intensity is explained.展开更多
Objective: This study aims to investigate the drainage effect and clinical outcomes of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery, comparing the differences in postoperativ...Objective: This study aims to investigate the drainage effect and clinical outcomes of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery, comparing the differences in postoperative pain, hospital stay, and other factors between the negative pressure group and the control group. Methods: This study is a prospective controlled trial that selected patients undergoing two-port thoracoscopic valve surgery at a certain hospital from January 2019 to December 2024. Patients were randomly assigned to the control group and the negative pressure group using a random number table method. The control group consisted of 30 patients (20 males, 10 females, mean age 42.03 ± 12.89 years), and the negative pressure group consisted of 35 patients (26 males, 9 females, mean age 41.84 ± 11.83 years). The control group received traditional chest drainage, while the negative pressure group received negative pressure chest drainage. Postoperative pain scores, hospital stay, drainage time, number of tube blockages, and incidences of pneumothorax or subcutaneous emphysema were recorded and statistically analyzed. Results: The negative pressure group had a significantly shorter postoperative drainage time compared to the control group (49.09 ± 11.99 hours vs. 79.10 ± 7.32 hours, P < 0.001). The postoperative pain score was lower in the negative pressure group (4.49 ± 1.27 vs. 7.03 ± 0.85, P < 0.001), and the hospital stay was significantly shorter (9.83 ± 1.69 days vs. 14.73 ± 2.32 days, P < 0.001). The incidence of pneumothorax or subcutaneous emphysema was significantly lower in the negative pressure group than in the control group (14.29% vs. 56.67%, P = 0.0003). Conclusion: The application of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery can effectively reduce postoperative pain, shorten hospital stay, and lower the incidence of tube blockage and pneumothorax, demonstrating good clinical outcomes.展开更多
In recent decades, event-related potentials have been used for the clinical electrophysiological assessment of patients with disorders of consciousness （DOCs）. In this paper, an oddball paradigm with two types of fr...In recent decades, event-related potentials have been used for the clinical electrophysiological assessment of patients with disorders of consciousness （DOCs）. In this paper, an oddball paradigm with two types of frequencydeviant stimulus （standard stimuli were pure tones of 1000 Hz; small deviant stimuli were pure tones of 1050 Hz; large deviant stimuli were pure tones of 1200 Hz） was applied to elicit mismatch negativity （MMN） in 30 patients with DOCs diagnosed using the JFK Coma Recovery Scale- Revised （CRS-R）. The results showed that the peak amplitudes of MMN elicited by both large and small deviant stimuli were significantly different from baseline. In terms of the spatial properties of MMN, a significant interaction effect between conditions （small and large deviant stimuli） and electrode nodes was centered at the frontocentral area. Furthermore, correlation coefficients were calculated between MMN amplitudes and CRS-R scores for each electrode among all participants to generate topographic maps. Meanwhile, a significant negative correlation between the MMN amplitudes elicited by large deviant stimuli and the CRS-R scores was also found at the frontocentral area. In consequence, our results combine the above spatial properties of MMN in patients with DOCs, and provide a more precise location （frontocentral area） at which to evaluate the correlation between clinical electrophysiological assessment and the level of consciousness.展开更多
In this experiment, 97 patients with obstructive sleep apnea hypopnea syndrome were divided into three groups （mild, moderate, severe） according to minimum oxygen saturation, and 35 healthy subjects were examined as...In this experiment, 97 patients with obstructive sleep apnea hypopnea syndrome were divided into three groups （mild, moderate, severe） according to minimum oxygen saturation, and 35 healthy subjects were examined as controls. Cognitive function was determined using the mismatch negativity paradigm and the Montreal Cognitive Assessment. The results revealed that as the disease worsened, the mismatch negativity latency was gradually extended, and the amplitude gradually declined in patients with obstructive sleep apnea hypopnea syndrome. Importantly, mismatch negativity latency in severe patients with a persistent time of minimum oxygen saturation 〈 60 seconds was significantly shorter than that with a persistent time of minimum oxygen saturation 〉 60 seconds. Correlation analysis revealed a negative correlation between minimum oxygen saturation latency and Montreal Cognitive Assessment scores. These findings indicate that intermittent night-time hypoxemia affects mismatch negativity waveforms and Montrea Cognitive Assessment scores. As indicators for detecting the cognitive functional status of obstructive sleep apnea hypopnea syndrome patients, the sensitivity of mismatch negativity is 82.93%, the specificity is 73.33%, the accuracy rate is 81.52%, the positive predictive value is 85.00%, the negative predictive value is 70.21%, the positive likelihood ratio is 3, and the negative likelihood ratio is 0.23. These results indicate that mismatch negativity can be used as an effective tool for diagnosis of cognitive dysfunction in obstructive sleep apnea hypopnea syndrome patients.展开更多
We studied quantum correlation and quantum entanglement of a quantum system in which a coherent state light field interacts with two qubits that are initially prepared in a separable and mixed state.The influence of m...We studied quantum correlation and quantum entanglement of a quantum system in which a coherent state light field interacts with two qubits that are initially prepared in a separable and mixed state.The influence of mean photon number of the coherent field and distribution probability of the atom on the geometrical quantum discord and the negativity are discussed.Our results show that the mean photon number of light field and distribution function of the atom can regulate and control the quantum correlation and quantum entanglement.展开更多
This paper contains two main contents.In the first part,we provide two counterexamples of monogamy inequalities for the squared entanglement negativity:one three-qutrit pure state which violates of the He–Vidal monog...This paper contains two main contents.In the first part,we provide two counterexamples of monogamy inequalities for the squared entanglement negativity:one three-qutrit pure state which violates of the He–Vidal monogamy conjecture,and one four-qubit pure state which disproves the squared-negativity-based Regula–Martino–Lee–Adessoclass strong monogamy conjecture.In the second part,we investigate the sharing of the entanglement negativity in a composite cavity-reservoir system using the corresponding multipartite entanglement scores,and then we find that there is no simple dominating relation between multipartite entanglement scores and the entanglement negativity in composite cavity-reservoir systems.As a by-product,we further validate that the entanglement of two cavity photons is a decreasing function of the evolution time,and the entanglement will suddenly disappear interacting with independent reservoirs.展开更多
Rapid and accurate perception of threat information is a critical ability and a prerequisite to survive natural selection for humans.To investigate whether threatening stimuli,especially phylogenetic and ontogenetic t...Rapid and accurate perception of threat information is a critical ability and a prerequisite to survive natural selection for humans.To investigate whether threatening stimuli,especially phylogenetic and ontogenetic threats,are processed automatically,we analyzed the visual mismatch negativity(vMMN,an event-related potential component reflecting automatic processing)elicited by the threats with a cross-modal oddball paradigm,where participants were required to focus on the auditory stimuli and ignore the visual stimuli in each block.In this study,neutral(non-threatening)images served as standard stimuli(80%),and phylogenetic(10%)and ontogenetic(10%)threat stimuli served as deviant stimuli when testing a large sample(N=96)of healthy volunteers.Threat-related visual mismatch negativity(threat-vMMN)was obtained by subtracting the event-related potential(ERP)elicited by standard stimuli from that elicited by deviant stimuli.The results indicated that the vMMN can be elicited by threat information.More importantly,the phylogenetic threat information elicited larger threat-vMMN than ontogenetic threat information.These findings suggest that perception of threat information was automatic,providing an evidential basis for the attentional advantages of survival processing.That is,automatic perception of phylogenetic threats has a particular evolutionary origin.展开更多
We propose a scheme to characterize the non-Markovian dynamics and quantify the non-Markovianity via the non-classicality measured by the negativity of quantumness. By considering a qubit in contact with a critical Is...We propose a scheme to characterize the non-Markovian dynamics and quantify the non-Markovianity via the non-classicality measured by the negativity of quantumness. By considering a qubit in contact with a critical Ising spin bath and introducing an ancilla, we show that revivals of negativity of quantumness indicate the non-Markovian dynamics.Furthermore, a normalized measure of non-Markovianity based on the negativity of quantumness is introduced and the influences of bath criticality, bath temperature and bath size on the non-Markovianity are discussed. It is shown that,at the critical point, the decay of non-Markovianity versus the size of spin bath is the fastest and the non-Markovianity is exactly zero only in the thermodynamic limit. Besides, non-trivial behaviours of negativity of quantumness such as sudden change, double sudden changes and keeping constant are found for different relations between parameters of the initial state. Finally, how the non-classicality of the system is affected by a series of bang-bang pulses is also examined.展开更多
We detected the event-related potential mismatch negativity （MMN） of 30 depression patients and compared to 30 age,gender,and education-matched healthy controls.Results showed that amplitudes of frequency and durati...We detected the event-related potential mismatch negativity （MMN） of 30 depression patients and compared to 30 age,gender,and education-matched healthy controls.Results showed that amplitudes of frequency and duration MMN were lower in depression patients compared with control patients,indicating abnormality in auditory processing （i.e.,cognitive impairment）.Following escitalopram treatment for 8 weeks,the amplitudes of frequency and duration MMN were significantly increased and Hamilton Rating Scale for Depression scores were significantly decreased in depression patients.These data suggest that escitalopram can improve cognitive function of patients with depression.Further,MMN may be a useful tool for evaluating cognitive function and treatment effects.展开更多
Using Majorana representation of symmetric N-qubit pure states, we have examined the monogamous nature of the family of states with two-distinct spinors, the W class of states. We have evaluated the N-concurrence tang...Using Majorana representation of symmetric N-qubit pure states, we have examined the monogamous nature of the family of states with two-distinct spinors, the W class of states. We have evaluated the N-concurrence tangle and showed that all the states in this family have vanishing concurrence tangle. The negativity tangle for the W class of states is shown to be non-zero, illustrating the fact that the concurrence tangle is always lesser than or equal to the negativity tangle in a pure N-qubit state.展开更多
The realization of double negative electromagnetic wave media, sometimes called left-handed materials (LHMs) or metamaterials, have drawn considerable attention in the past few years. We will examine the possibility o...The realization of double negative electromagnetic wave media, sometimes called left-handed materials (LHMs) or metamaterials, have drawn considerable attention in the past few years. We will examine the possibility of extending the concept to acoustic waves. We will see that acoustic metamaterials require both the effective density and bulk modulus to be simultaneously negative in the sense of an effective medium. If we can find a double negative (negative density and bulk modulus) acoustic medium, it will be an acoustic analogue of Veselago’s medium in electromagnetism, and share many novel consequences such as negative refractive index and backward wave characteristics. We will give one example of such a medium.展开更多
We give a study result to analyze a rather different, semi-analytical numerical algorithms based on splitting-step methods with their applications to mathematical finance. As certain subsistent numerical schemes may f...We give a study result to analyze a rather different, semi-analytical numerical algorithms based on splitting-step methods with their applications to mathematical finance. As certain subsistent numerical schemes may fail due to producing negative values for financial variables which require non-negativity preserving. These algorithms which we are analyzing preserve not only the non-negativity, but also the character of boundaries (natural, reflecting, absorbing, etc.). The derivatives of the CIR process and the Heston model are being extensively studied. Beyond plain vanilla European options, we creatively apply our splitting-step methods to a path-dependent option valuation. We compare our algorithms to a class of numerical schemes based on Euler discretization which are prevalent currently. The comparisons are given with respect to both accuracy and computational time for the European call option under the CIR model whereas with respect to convergence rate for the path-dependent option under the CIR model and the European call option under the Heston model.展开更多
基金supported by the National Social Science Fundation(Grant No.21BTJ040)the Project of Outstanding Young People in University of Anhui Province(Grant Nos.2023AH020037,SLXY2024A001).
文摘In this paper,by utilizing the Marcinkiewicz-Zygmund inequality and Rosenthal-type inequality of negatively superadditive dependent(NSD)random arrays and truncated method,we investigate the complete f-moment convergence of NSD random variables.We establish and improve a general result on the complete f-moment convergence for Sung’s type randomly weighted sums of NSD random variables under some general assumptions.As an application,we show the complete consistency for the randomly weighted estimator in a nonparametric regression model based on NSD errors.
基金Supported by the Academic Achievement Re-cultivation Projects of Jingdezhen Ceramic University(Grant Nos.215/20506341215/20506277)the Doctoral Scientific Research Starting Foundation of Jingdezhen Ceramic University(Grant No.102/01003002031)。
文摘Assume that{a_(i),−∞<i<∞}is an absolutely summable sequence of real numbers.We establish the complete q-order moment convergence for the partial sums of moving average processes{X_(n)=Σ_(i=−∞)^(∞)a_(i)Y_(i+n),n≥1}under some proper conditions,where{Yi,-∞<i<∞}is a doubly infinite sequence of negatively dependent random variables under sub-linear expectations.These results extend and complement the relevant results in probability space.
基金supported by the National Natural Science Foundation of China (Grant No. 12074329)Nanhu Scholars Program for Young Scholars of Xinyang Normal University。
文摘With a three-dimensional semiclassical ensemble method, we theoretically investigated the nonsequential double ionization of Ar driven by the spatially inhomogeneous few-cycle negatively chirped laser pulses. Our results show that the recollision time window can be precisely controlled within an isolated time interval of several hundred attoseconds, which is useful for understanding the subcycle correlated electron dynamics. More interestingly, the correlated electron momentum distribution (CEMD) exhibits a strong dependence on laser intensity. That is, at lower laser intensity, CEMD is located in the first quadrant. As the laser intensity increases,CEMD shifts almost completely to the second and fourth quadrants, and then gradually to the third quadrant.The underlying physics governing the CEMD's dependence on laser intensity is explained.
文摘Objective: This study aims to investigate the drainage effect and clinical outcomes of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery, comparing the differences in postoperative pain, hospital stay, and other factors between the negative pressure group and the control group. Methods: This study is a prospective controlled trial that selected patients undergoing two-port thoracoscopic valve surgery at a certain hospital from January 2019 to December 2024. Patients were randomly assigned to the control group and the negative pressure group using a random number table method. The control group consisted of 30 patients (20 males, 10 females, mean age 42.03 ± 12.89 years), and the negative pressure group consisted of 35 patients (26 males, 9 females, mean age 41.84 ± 11.83 years). The control group received traditional chest drainage, while the negative pressure group received negative pressure chest drainage. Postoperative pain scores, hospital stay, drainage time, number of tube blockages, and incidences of pneumothorax or subcutaneous emphysema were recorded and statistically analyzed. Results: The negative pressure group had a significantly shorter postoperative drainage time compared to the control group (49.09 ± 11.99 hours vs. 79.10 ± 7.32 hours, P < 0.001). The postoperative pain score was lower in the negative pressure group (4.49 ± 1.27 vs. 7.03 ± 0.85, P < 0.001), and the hospital stay was significantly shorter (9.83 ± 1.69 days vs. 14.73 ± 2.32 days, P < 0.001). The incidence of pneumothorax or subcutaneous emphysema was significantly lower in the negative pressure group than in the control group (14.29% vs. 56.67%, P = 0.0003). Conclusion: The application of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery can effectively reduce postoperative pain, shorten hospital stay, and lower the incidence of tube blockage and pneumothorax, demonstrating good clinical outcomes.
基金supported by the National Natural Science Foundation of China (81471742, 91748105)Fundamental Research Funds for the Central Universities [DUT16JJ(G)03] in Dalian University of Technology, China
文摘In recent decades, event-related potentials have been used for the clinical electrophysiological assessment of patients with disorders of consciousness （DOCs）. In this paper, an oddball paradigm with two types of frequencydeviant stimulus （standard stimuli were pure tones of 1000 Hz; small deviant stimuli were pure tones of 1050 Hz; large deviant stimuli were pure tones of 1200 Hz） was applied to elicit mismatch negativity （MMN） in 30 patients with DOCs diagnosed using the JFK Coma Recovery Scale- Revised （CRS-R）. The results showed that the peak amplitudes of MMN elicited by both large and small deviant stimuli were significantly different from baseline. In terms of the spatial properties of MMN, a significant interaction effect between conditions （small and large deviant stimuli） and electrode nodes was centered at the frontocentral area. Furthermore, correlation coefficients were calculated between MMN amplitudes and CRS-R scores for each electrode among all participants to generate topographic maps. Meanwhile, a significant negative correlation between the MMN amplitudes elicited by large deviant stimuli and the CRS-R scores was also found at the frontocentral area. In consequence, our results combine the above spatial properties of MMN in patients with DOCs, and provide a more precise location （frontocentral area） at which to evaluate the correlation between clinical electrophysiological assessment and the level of consciousness.
基金supported by the National Natural Science Foundation of China,No. 30973309
文摘In this experiment, 97 patients with obstructive sleep apnea hypopnea syndrome were divided into three groups （mild, moderate, severe） according to minimum oxygen saturation, and 35 healthy subjects were examined as controls. Cognitive function was determined using the mismatch negativity paradigm and the Montreal Cognitive Assessment. The results revealed that as the disease worsened, the mismatch negativity latency was gradually extended, and the amplitude gradually declined in patients with obstructive sleep apnea hypopnea syndrome. Importantly, mismatch negativity latency in severe patients with a persistent time of minimum oxygen saturation 〈 60 seconds was significantly shorter than that with a persistent time of minimum oxygen saturation 〉 60 seconds. Correlation analysis revealed a negative correlation between minimum oxygen saturation latency and Montreal Cognitive Assessment scores. These findings indicate that intermittent night-time hypoxemia affects mismatch negativity waveforms and Montrea Cognitive Assessment scores. As indicators for detecting the cognitive functional status of obstructive sleep apnea hypopnea syndrome patients, the sensitivity of mismatch negativity is 82.93%, the specificity is 73.33%, the accuracy rate is 81.52%, the positive predictive value is 85.00%, the negative predictive value is 70.21%, the positive likelihood ratio is 3, and the negative likelihood ratio is 0.23. These results indicate that mismatch negativity can be used as an effective tool for diagnosis of cognitive dysfunction in obstructive sleep apnea hypopnea syndrome patients.
基金Project supported by the National Natural Science Foundation of China(Grant No.11604090)
文摘We studied quantum correlation and quantum entanglement of a quantum system in which a coherent state light field interacts with two qubits that are initially prepared in a separable and mixed state.The influence of mean photon number of the coherent field and distribution probability of the atom on the geometrical quantum discord and the negativity are discussed.Our results show that the mean photon number of light field and distribution function of the atom can regulate and control the quantum correlation and quantum entanglement.
基金Supported by the National Natural Science Foundation of China under Grant No.60973135Shandong Provincial Natural Science Foundation of China under Grant No.ZR2015FQ006
文摘This paper contains two main contents.In the first part,we provide two counterexamples of monogamy inequalities for the squared entanglement negativity:one three-qutrit pure state which violates of the He–Vidal monogamy conjecture,and one four-qubit pure state which disproves the squared-negativity-based Regula–Martino–Lee–Adessoclass strong monogamy conjecture.In the second part,we investigate the sharing of the entanglement negativity in a composite cavity-reservoir system using the corresponding multipartite entanglement scores,and then we find that there is no simple dominating relation between multipartite entanglement scores and the entanglement negativity in composite cavity-reservoir systems.As a by-product,we further validate that the entanglement of two cavity photons is a decreasing function of the evolution time,and the entanglement will suddenly disappear interacting with independent reservoirs.
文摘Rapid and accurate perception of threat information is a critical ability and a prerequisite to survive natural selection for humans.To investigate whether threatening stimuli,especially phylogenetic and ontogenetic threats,are processed automatically,we analyzed the visual mismatch negativity(vMMN,an event-related potential component reflecting automatic processing)elicited by the threats with a cross-modal oddball paradigm,where participants were required to focus on the auditory stimuli and ignore the visual stimuli in each block.In this study,neutral(non-threatening)images served as standard stimuli(80%),and phylogenetic(10%)and ontogenetic(10%)threat stimuli served as deviant stimuli when testing a large sample(N=96)of healthy volunteers.Threat-related visual mismatch negativity(threat-vMMN)was obtained by subtracting the event-related potential(ERP)elicited by standard stimuli from that elicited by deviant stimuli.The results indicated that the vMMN can be elicited by threat information.More importantly,the phylogenetic threat information elicited larger threat-vMMN than ontogenetic threat information.These findings suggest that perception of threat information was automatic,providing an evidential basis for the attentional advantages of survival processing.That is,automatic perception of phylogenetic threats has a particular evolutionary origin.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11247308 and 11274274the National Natural Science Foundation of Special Theoretical Physics under Grant No.11347196+1 种基金the Natural Science Foundation of Jiangsu Province of China under Grant No.BK20130162the Fundamental Research Funds for the Central Universities under Grant No.JUSRP11405
文摘We propose a scheme to characterize the non-Markovian dynamics and quantify the non-Markovianity via the non-classicality measured by the negativity of quantumness. By considering a qubit in contact with a critical Ising spin bath and introducing an ancilla, we show that revivals of negativity of quantumness indicate the non-Markovian dynamics.Furthermore, a normalized measure of non-Markovianity based on the negativity of quantumness is introduced and the influences of bath criticality, bath temperature and bath size on the non-Markovianity are discussed. It is shown that,at the critical point, the decay of non-Markovianity versus the size of spin bath is the fastest and the non-Markovianity is exactly zero only in the thermodynamic limit. Besides, non-trivial behaviours of negativity of quantumness such as sudden change, double sudden changes and keeping constant are found for different relations between parameters of the initial state. Finally, how the non-classicality of the system is affected by a series of bang-bang pulses is also examined.
基金the Medical Research Foundation of Jiangsu Provincial Department of Public Health,No.H201043
文摘We detected the event-related potential mismatch negativity （MMN） of 30 depression patients and compared to 30 age,gender,and education-matched healthy controls.Results showed that amplitudes of frequency and duration MMN were lower in depression patients compared with control patients,indicating abnormality in auditory processing （i.e.,cognitive impairment）.Following escitalopram treatment for 8 weeks,the amplitudes of frequency and duration MMN were significantly increased and Hamilton Rating Scale for Depression scores were significantly decreased in depression patients.These data suggest that escitalopram can improve cognitive function of patients with depression.Further,MMN may be a useful tool for evaluating cognitive function and treatment effects.
基金supported by Department of Science and Technology,Government of India through the award of INSPIRE fellowship
文摘Using Majorana representation of symmetric N-qubit pure states, we have examined the monogamous nature of the family of states with two-distinct spinors, the W class of states. We have evaluated the N-concurrence tangle and showed that all the states in this family have vanishing concurrence tangle. The negativity tangle for the W class of states is shown to be non-zero, illustrating the fact that the concurrence tangle is always lesser than or equal to the negativity tangle in a pure N-qubit state.
基金Project (No. CA02/03.SC01) supported by Research Grant Council(RGC) Hong Kong, China
文摘The realization of double negative electromagnetic wave media, sometimes called left-handed materials (LHMs) or metamaterials, have drawn considerable attention in the past few years. We will examine the possibility of extending the concept to acoustic waves. We will see that acoustic metamaterials require both the effective density and bulk modulus to be simultaneously negative in the sense of an effective medium. If we can find a double negative (negative density and bulk modulus) acoustic medium, it will be an acoustic analogue of Veselago’s medium in electromagnetism, and share many novel consequences such as negative refractive index and backward wave characteristics. We will give one example of such a medium.
文摘We give a study result to analyze a rather different, semi-analytical numerical algorithms based on splitting-step methods with their applications to mathematical finance. As certain subsistent numerical schemes may fail due to producing negative values for financial variables which require non-negativity preserving. These algorithms which we are analyzing preserve not only the non-negativity, but also the character of boundaries (natural, reflecting, absorbing, etc.). The derivatives of the CIR process and the Heston model are being extensively studied. Beyond plain vanilla European options, we creatively apply our splitting-step methods to a path-dependent option valuation. We compare our algorithms to a class of numerical schemes based on Euler discretization which are prevalent currently. The comparisons are given with respect to both accuracy and computational time for the European call option under the CIR model whereas with respect to convergence rate for the path-dependent option under the CIR model and the European call option under the Heston model.
