Over 90% of the organs transplanted in China before 2010 were procured from prisoners. Although Chinese officials announced in December 2014 that the country would completely cease using organs harvested from prisoners, no regulatory adjustments or changes in China’s organ donation laws followed. As a result, the use of prisoner organs remains legal in China if consent is obtained. We have collected and analysed available evidence on human rights violations in the organ procurement practice in China. We demonstrate that the (...) practice not only violates international ethics standards, it is also associated with a large scale neglect of fundamental human rights. This includes organ procurement without consent from prisoners or their families as well as procurement of organs from incompletely executed, still-living prisoners. The human rights critique of these practices will also address the specific situatedness of prisoners, often conditioned and traumatized by a cascade of human rights abuses in judicial structures. To end the unethical practice and the abuse associated with it, we suggest to inextricably bind the use of human organs procured in the Chinese transplant system to enacting Chinese legislation prohibiting the use of organs from executed prisoners and making explicit rules for law enforcement. Other than that, the international community must cease to abet the continuation of the present system by demanding an authoritative ban on the use of organs from executed Chinese prisoners. (shrink)
Since the outbreak of COVID-19, reaction quarantine, social distancing, and economic crises have posed a greater risk to physical and psychological health. Such derogatory mental health stigma is associated with adverse outcomes in the student population. The purpose of the current study is to provide a timely evaluation of the COVID-19 pandemic and its adverse effects on students’ psychological well-being to sustain economic sustainability. A thorough review of the literature and current studies, significant emphasis of socio-demographic indicators, interpretation of physical (...) symptoms, home quarantine activities, and COVID-19 unique stressors were extracted. Data were collected through electronic surveys from 640 university students at local and foreign universities. The findings revealed substantial adverse effects resulting in varying levels of stress, symptoms of depression, and specific discomfort in the case. Among COVID-19 stressors, financial instability, unpredictability toward future/career, and media exposure have been described as common factors that cause poor psychological well-being and weaken economic sustainability. COVID-19, quarantine, self-isolation, and onerous interventions primarily weaken university students’ mental health. The emphasis on this vulnerable category, however, is substantially absent from the literature. This research addresses the urgent need to develop possible solutions and preventive measures to promote economic sustainability by ensuring students’ psychological well-being. (shrink)
On the basis of the Conservation of Resource theory and using the Job Demands-Resources model, this study examines the relationships among job demands and job resources of online teaching, perceived instructional efficacy of OT, mindfulness in teaching, and emotional exhaustion to understand the psychological stress experienced by teachers engaged in OT and how mindfulness has moderating effects on relieving anxiety and preventing burnout. A total of 476 teachers with OT experience completed online a self-report survey with items adapted from related (...) scales. The hypotheses were validated using structural equation modeling. Causal relationships were assessed using path analysis, and multi-group analysis was performed to examine the moderating effect of MiT. JD-OT has significant and negative impact on PIE-OT, JR-OT has significant and positive impact on PIE-OT, and PIE-OT has significant and negative impact on EE. Moreover, PIE-OT mediates the positive relationship of JD-OT with EE and the negative relationship of JR-OT with EE. The moderating role of MiT in the relationship of JD-OT and JR-OT with PIE-OT was also validated. In OT work environments, teachers have great need and desire for JR, which can have a positive impact on PIE. Mindfulness training contributes to improving OT efficacy and reducing EE. Enhancing teachers’ MiT enables them to deal with demands from work and their superiors and motivates them to respond with ease to the stressful external environment. (shrink)
As one of the foundations of existential positive psychology, self-transcendence can bring positive intrapersonal and interpersonal outcomes, especially in the COVID-19 era in which people are suffering huge mental stress. Based on Schwartz's theory of human basic values, the current study combines variable-centered and person-centered approaches to examine the relationships between adolescents' values and mental health across two regions in China. The results generally showed that both self-enhancement and conservation values were positively correlated with depression and loneliness, while both self-transcendence (...) and openness to change values negatively correlated with depression and loneliness. The results also showed that there were four value clusters, and, compared to adolescents in the self-focus and undifferentiated values cluster, all adolescents in the anxiety-free values cluster reported lower depression and loneliness, while all adolescents in the other-focus values cluster reported higher depression and loneliness. The differences between the two regional groups only emerged in depression. Specifically, adolescents in Shanghai have higher levels of depression than adolescents in Qingdao. This study provides some evidence for the new science of self-transcendence among adolescents and also sheds light on how we may improve the level of mental health during the COVID-19 era. (shrink)
To deal with coordination problem of a supply chain consisting of two competitive suppliers and a dominant retailer, considering these factors such as cooperation effort degrees and competition on the supply chain members, we establish a two-stage model considering cooperation effort degrees and competition of the suppliers from the perspectives of decentralized decision and centralized decision and exploit it to discuss the optional decisions and explore the impact of cooperation effort degrees on the profits of supply chain members. Then, we (...) use a group negotiation model to establish a coordination mechanism. The results reveal that the decision variables and overall profit of the supply chain of suppliers and retailers under centralized decisions are better than those under the decentralized decisions. Besides, the degree of competition and price sensitivity have positive and negative effects on the efforts of suppliers and retailers, respectively. Meanwhile, the degree of cooperation between suppliers and retailers affects the profits of supply chain members and the whole supply chain in different degrees. Finally, the proposed value-added profit distribution mechanism can effectively deal with conflict problem and guarantee supply chain members and supply chain to maximize their profits and adopt the centralized decision. (shrink)
Retailers offer BOPS service to improve consumers shopping experience. However, this greatly increases the decision complexity for retailers and consumers. For consumers, whether to purchase online or from a store with the BOPS service is a complex decision. This is especially true when the product has fit uncertainty. That is, consumers are uncertain about product fitness before using it. Also, their store visit cost can be heterogeneous and follows some distribution function. For a retailer, it needs to jointly optimize multiple (...) decisions including the convenience degree of BOPS. To help the retailer develop the jointly optimal decisions, we first build a mathematical model where the retailer sells the product through online and store channel and analyzes the possible effects of BOPS. We find that the retailer should offer BOPS when the channel cost ratio is large enough. Through numerical studies, we show that the ratio of profit offering BOPS divided by the benchmark increases with the probability of product fit, shipment fee, and the convenience degree of BOPS. We then consider the case where the convenience degree of BOPS is also a decision itself. We find the optimal convenience degree of BOPS increases along with the average store visit cost and the probability of product fit. When the cost factor of offering the convenience for BOPS is larger than a threshold, the retailer should never offer BOPS. (shrink)
BackgroundIn December 2014, China announced that only voluntarily donated organs from citizens would be used for transplantation after January 1, 2015. Many medical professionals worldwide believe that China has stopped using organs from death-row prisoners.DiscussionIn the present article, we briefly review the historical development of organ procurement from death-row prisoners in China and comprehensively analyze the social-political background and the legal basis of the announcement. The announcement was not accompanied by any change in organ sourcing legislations or regulations. As a (...) fact, the use of prisoner organs remains legal in China. Even after January 2015, key Chinese transplant officials have repeatedly stated that death-row prisoners have the same right as regular citizens to “voluntarily donate” organs. This perpetuates an unethical organ procurement system in ongoing violation of international standards.ConclusionsOrgan sourcing from death-row prisoners has not stopped in China. The 2014 announcement refers to the intention to stop the use of organs illegally harvested without the consent of the prisoners. Prisoner organs procured with “consent” are now simply labelled as “voluntarily donations from citizens”. The semantic switch may whitewash sourcing from both death-row prisoners and prisoners of conscience. China can gain credibility only by enacting new legislation prohibiting use of prisoner organs and by making its organ sourcing system open to international inspections. Until international ethical standards are transparently met, sanctions should remain. (shrink)
In this paper, a dynamic two-stage Cournot duopoly game with R&D efforts is built. Then, the local stability of the equilibrium points are discussed, and the stability condition of the Nash equilibrium point is also deduced through Jury criterion. The complex dynamical behaviors of the built model are investigated by numerical simulations. We found that the unique route to chaos is flip bifurcation, and the increase of adjusting speed will cause the system to lose stability and produce more complex dynamic (...) behavior. In addition, we also found the phenomenon of multistability in the given model. Several kinds of coexistence of attractors are shown. In particular, we found that boundary attractors can coexist with internal attractors, which also aggravates the complexity of the system. At last, the chaotic state in the built system has been successfully controlled. (shrink)
The continuous increase of carbon emissions is a serious challenge all over the world, and many countries are striving to solve this problem. Since 2020, a widespread lockdown in the country to prevent the spread of COVID-19 escalated, severely restricting the movement of people and unnecessary economic activities, which unexpectedly reduced carbon emissions. This paper aims to analyze the carbon emissions data of 30 provinces in the 2020 and provide references for reducing emissions with epidemic lockdown measures. Based on the (...) method of time series visualization, we transform the time series data into complex networks to find out the hidden information in these data. We found that the lockdown would bring about a short-term decrease in carbon emissions, and most provinces have a short time point of impact, which is closely related to the level of economic development and industrial structure. The current results provide some insights into the evolution of carbon emissions under COVID-19 blockade measures and valuable insights into energy conservation and response to the energy crisis in the post-epidemic era. (shrink)
Conceptions of the ‘good citizen’ have implications for defining the goals of civic education and formulating civic education programs. In Mainland China, the concept of ‘good citizen’ is clearly defined by the authorities in the official curriculum guidelines. Teachers’ perceptions of a ‘good citizen’, however, may differ from any official definition and will influence their approaches to the implementation of civic education in schools. The research reported here used qualitative methods to explore some Chinese junior high school teachers’ perceptions of (...) a ‘good citizen’, drawing on Westheimer and Kahne’s identification of three ‘visions of citizenship’ used in the US as a baseline. We argue that an effective civic education curriculum must consider teachers’ actual perceptions of a ‘good citizen’ in practice and that Chinese teachers’ awareness and understanding of citizenship needs to improve. (shrink)
The eukaryotic helicase is an 11-subunit machine containing an Mcm2-7 motor ring that encircles DNA, Cdc45 and the GINS tetramer, referred to as CMG. CMG is “built” on DNA at origins in two steps. First, two Mcm2-7 rings are assembled around duplex DNA at origins in G1 phase, forming the Mcm2-7 “double hexamer.” In a second step, in S phase Cdc45 and GINS are assembled onto each Mcm2-7 ring, hence producing two CMGs that ultimately form two replication forks that travel (...) in opposite directions. Here, we review recent findings about CMG structure and function. The CMG unwinds the parental duplex and is also the organizing center of the replisome: it binds DNA polymerases and other factors. EM studies reveal a 20-subunit core replisome with the leading Pol ϵ and lagging Pol α-primase on opposite faces of CMG, forming a fundamentally asymmetric architecture. Structural studies of CMG at a replication fork reveal unexpected details of how CMG engages the DNA fork. The structures of CMG and the Mcm2-7 double hexamer on DNA suggest a completely unanticipated process for formation of bidirectional replication forks at origins. Here, we review the structure and function of CMG, the 11 subunit helicase for eukaryotic DNA replication. Two CMGs are assembled at origins starting from two Mcm2-7 hexamers oriented N-to-N. The orientation of CMG at a forked DNA implies that the two CMGs at an origin pass one another. (shrink)
Our current work examined the interface between thinking style and emotional experience at both the behavioral and neuropsychological levels. Thirty-nine Chinese participants completed the triad task, and we calculated the rate of individually selected relationship pairings to overall selections to represent their holistic thinking tendencies. In addition, participants in the top one-third of the ratio score were classified into the high holistic thinking group, while those in the bottom one-third of the ratio score were classified into the low holistic thinking (...) group. We used the sensitivity to punishment and sensitivity to reward questionnaire to examine how people elicit positive and negative affective behaviors. Additionally, we examined the volume of the amygdala and nucleus accumbens and their functional connectivity in the resting-state. We found that high holistic thinkers were much less sensitive to rewards than low holistic thinkers. In other words, individuals with high holistic thinking are less likely to pursue behaviors that have positive emotional outcomes. Furthermore, their bilateral nucleus accumbens and right amygdala volumes were smaller than those of low holistic thinkers. Hierarchical regression analysis showed that holistic thinking tendency can negatively predict the volume of the left nucleus accumbens and right amygdala. Finally, resting-state functional connectivity results showed increased functional connectivity FC between left nucleus accumbens and bilateral amygdala in high holistic thinkers. These findings provide emotion-related manifestations of thinking styles at the behavioral and neural levels. (shrink)
We report an eye movement experiment that investigates the effects of collocation strength and contextual predictability on the reading of collocative phrases by L2 English readers. Thirty-eight Chinese English as foreign language learners read 40 sentences, each including a specific two-word phrase that was either a strong or weak adjective-noun collocation and was either highly predictable or unpredictable from the previous sentence context. Eye movement measures showed that L2 reading times for the collocative phrases were sensitive to both collocation strength (...) and contextual predictability. However, an interaction effect between these factors, which appeared relatively late in the eye movement record, additionally revealed that contextual predictability more strongly influenced time spent reading weak compared with strong collocations. This was most likely because the greater familiarity of strong collocations facilitated their integration, even in the absence of strong contextual constraint. We discuss the findings in terms of the value of collocations in second language learning. (shrink)
Existing methods for evaluating manufacturing process chain complexity consider the number of machines, state of machines, number of parts, operation time, and processing sequence of parts. However, such evaluation methods ignore human factors. To consider human factors, human cognitive decision-making process factors are considered in the complexity evaluation of production processes. Accordingly, a new objective evaluation method of the human factor complexity is proposed. In the proposed method, sewing operations are taken as an example, and the human factor complexity is (...) classified into perceived and cognitive complexity. Information entropy is used to measure cognitive complexity according to the type and quantity of sewing workers’ cognitive activities. The results show that various methods have significant differences in the evaluation of the complexity level of the production process chain. Specifically, the calculation results of the proposed evaluation method are much greater than those of other methods. This indicates that human cognitive and perceived complexities account for a large proportion. Therefore, human factor complexity cannot be omitted. (shrink)
The South-to-North Water Diversion Project consists of long-distance water delivery channels and a complicated geological environment along the way. To deal with the operation safety of the water conveyance channels in the middle route of the South-to-North Water Diversion Project, this study analyzes six failure modes: structural cracks, poor water delivery during ice periods, instability of canal slopes, material aging, abnormal leakage, and foundation defects. Based on FMEA, a multigranularity language evaluation method that can be converted into interval intuitionistic fuzzy (...) numbers is used to evaluate the severity, occurrence, and detection difficulty of the six failure modes. Interval intuitionistic fuzzy entropy is used to calculate the weights of the risk factors. Finally, a ranking model of each failure mode is built based on the TODIM method. The final ranking results show that the risk of abnormal leakage is the largest, and the risk of poor water delivery during ice periods is the smallest. The feasibility and validity of the calculation results are verified by comparing them with the ranking results of the traditional RPN and TOPSIS methods. The TODIM-FMEA risk assessment model offers a new solution to the problem of risk assessment for water transfer projects. (shrink)
Due to the complexity and randomness of environmental change, the knowledge-sharing behavior of members in the PPP supply chain will be affected by random disturbance factors. Traditional evolutionary game models cannot describe this effect. In this study, Gaussian white noise is introduced into the stochastic evolutionary game model of PPP supply chain knowledge sharing. The numerical simulation of the model is carried out to analyze the influence of parameter changes on the strategy selection of enterprise groups. The result shows that (...) the strong knowledge power enterprise group is more sensitive with the variation of parameters than that of the weak knowledge power enterprise group. However, the weak enterprise group has a more vital willingness to share knowledge. Incentive measures can increase the knowledge-sharing benefits and promote the strong knowledge powerful enterprise group toward the sharing strategy. Increasing the mutual trust coefficient, reducing the sharing cost, and improving the enterprise’s transformation ability will help both sides to evolve into the sharing strategy more quickly. This study would have significance for PPP project performance and industry innovation. (shrink)
In this study, we focus on the problem of information expiration when using the traditional collaborative filtering algorithm and propose a new collaborative filtering algorithm by integrating the time factor. This algorithm considers information influence attenuation over time, introduces an information retention period based on the information half-value period, and proposes a time-weighted function, which is applied to the nearest neighbor selection and score prediction to assign different time weights to the scores. In addition, to further improve the quality of (...) the nearest neighbor selection and alleviate the problem of data sparsity, a method of calculating users’ sentiment tendency by analysis of user review features is proposed to mine users’ attitudes about the reviewed items, which expands the score matrix. The time factor and sentiment tendency are then integrated into the K-means clustering algorithm to select the nearest neighbor. A hybrid collaborative filtering model based on the improved K-means clustering algorithm is then proposed, by combining item-based and user-based collaborative filtering. Finally, the experimental results show that the proposed algorithm can address the time effect and sentiment analysis in recommendations and improve the predictive performance of the model. (shrink)
Narcissism is a deep-rooted personality trait that is particularly common in corporate leaders, and narcissistic leaders have a noticeable influence on the R&D investment behavior of enterprises. This paper empirically examines the effect of CEO narcissism on R&D investment and the moderating effects of financing constraints, and the nature of corporate ownership based on the Upper Echelons Theory, using the CEO signature size as a measure of CEO narcissism for the 2007–2020 Chinese A-share listed companies. The results show that CEO (...) narcissism has a significant negative effect on R&D investment; corporate financing constraints play a negative moderating role between CEO narcissism and R&D investment, and the negative effect of CEO narcissism on corporate R&D investment is more significant in non-state-owned firms than in state-owned firms. The study’s findings enrich and expand the theory related to CEO narcissism and have important practical implications for R&D investment decisions and the choice of corporate executives in China. (shrink)
Pathological Internet use will have a serious impact on normal individual study and work and has become one of the most important factors hindering the growth and development of contemporary college students. The purpose of this study was to examine the mechanisms of loneliness and depression in the relationship between the Big Five personality traits and pathological Internet use. A total of 1,179 college students were studied using the Chinese version of the Big Five Personality Scale, Loneliness Scale, Depression Scale, (...) and Pathological Internet Use Scale. The results showed that loneliness partially mediated the relationship between extraversion and PIU and completely mediated the relationship between agreeableness and PIU and neuroticism and PIU. Depression completely mediated the relationship between agreeableness and PIU, neuroticism completely mediated the relationship with PIU, and sense of responsibility partially mediated the relationship with PIU. This study revealed the relationship between different personality traits and PIU and the mediating role of loneliness and depression, suggesting that we should carry out targeted interventions on PIU for college students with different personality traits. (shrink)
Source-to-sink system analysis, a cutting-edge topic in the field of earth science, encompasses the whole system, from erosion and transportation to sediment accumulation on the earth’s surface, and involves multidisciplinary collaboration. This current analysis, based on high-precision 3D seismic data, well logs, and other drilling data, using quantitative characterization of the source-to-sink elements, documents that Archean-Proterozoic migmatitic granite, Cambrian-Ordovician carbonate and clastic rocks, and Mesozoic volcaniclastic rocks are developed in the Shaleitian uplift from south to north across large relief differences. (...) The relief and size of the catchment in the source area were calculated by denudation recovery, time-depth conversion and high-resolution interpretation on seismic data. Three types of sediment-transporting channel system and 20 catchment areas were documented around the edges of the uplift: paleovalley channels, fault-controlled channels, and fault-transfer channels. The Paleogene sink is dominated by near-source coarse-grained depositional systems, with the lithofacies characteristics of low lake level, lake transgressive, and uplift period. Three types of boundary conditions developed in the region of the Shaleitian uplift: fault-related steep-slopes, fault ramps, and slope patterns. The bedrock composition, catchment area, channel systems, and fault-border patterns in the Shaleitian uplift jointly controlled the types and scales of sedimentary sandbodies. The south Shaleitian tectonic zone functioned as a high-efficiency coupling system in which reservoir sandbodies were developed. The coupling system for the southwest and west Shaleitian tectonic zones is subordinate. The coupling system of the northeast Shaleitian tectonic zone is lowest in efficiency. (shrink)
The S-transform is one of the most widely used methods of time-frequency analysis. It combines the respective advantages of the short-time Fourier transform and wavelet transforms with scale-dependent resolution using Gaussian windows, scaled inversely with frequency. One of the problems with the traditional symmetric Gaussian window is the degradation of time resolution in the time-frequency spectrum due to the long front taper. We have studied the performance of an improved S-transform with an asymmetric bi-Gaussian window. The asymmetric bi-Gaussian window can (...) obtain an increased time resolution in the front direction. The increased time resolution can make event picking high resolution, which will facilitate an improved time-frequency characterization for oil and gas trap prediction. We have applied the slightly modified bi-Gaussian S-transform to a synthetic trace, a 2D seismic section, and a 3D seismic cube to indicate the superior performance of the bi-Gaussian S-transform in analyzing nonstationary signal components, hydrocarbon reservoir predictions, and paleochannels delineations with an obviously higher resolution. (shrink)
Online social network services have brought a kind of new lifestyle to the world that is parallel to people’s daily offline activities. Social network analysis provides a useful perspective on a range of social computing applications. Social interaction on the Web includes both positive and negative relationships, which is certainly important to social networks. The authors of this article found that the accuracy of the signs of links in the underlying social networks can be predicted. The trust that other users (...) impart on a node is an important attribute of networks. In this article, the authors present a model to compute the prestige of nodes in a trust-based network. The model is based on the idea that trustworthy nodes weigh more. To fulfill this task, the authors first attempt to infer the attitude of one user toward another by predicting signed edges in networks. Then, the authors propose an algorithm to compute the prestige and trustworthiness where the edge weight denotes the trust score. To prove the algorithm’s effectiveness, the authors conducted experiments on the public dataset. Theoretical analysis and experimental results show that this method is efficient and effective. (shrink)
The COVID-19 is creating panic among people around the world and is causing a huge public mental health crisis. Large numbers of observational studies focused on the prevalence of psychological problems during the COVID-19 pandemic were published. It is essential to conduct a meta-analysis of the prevalence of different psychological statuses to insight the psychological reactions of general population during the COVID-19 epidemic in China. Sixty six observational studies about the psychological statuses of people during the COVID-19 were included, searching (...) up to 1 December 2020. Strengthening the Reporting of Observational Studies in Epidemiology was used to evaluate the quality of the included studies. OpenMeta[Analyst] was used for the data analysis. High prevalence of acute stress and fear symptoms were observed in the early period of the epidemic. Additionally, anxiety and depression symptoms continued at a high prevalence rate during the epidemic. It should alert the lasting mental health problems and the risk of post-traumatic stress disorder and other mental disorders.Systematic Review Registration: PROSPERO CRD 42020171485. (shrink)
ObjectiveVirtual reality grasping exercise training helps patients participate actively in their recovery and is a critical approach to the rehabilitation of hand dysfunction. This study aimed to explore the effects of active participation and VR grasping on brain function combined with the kinematic information obtained during VR exercises.MethodsThe cerebral oxygenation signals of the prefrontal cortex, the motor cortex, and the occipital cortex were measured by functional near-infrared spectroscopy in 18 young people during the resting state, grasping movements, and VR grasping (...) movements. The EPPlus plug-in was used to collect the hand motion data during simulated interactive grasping. The wavelet amplitude of each cerebral cortex and the wavelet phase coherence of each pair of channels were calculated by wavelet analysis. The total difference in acceleration difference of the hand in the VR grasping movements was calculated to acquire kinematic characteristics. The cortical activation and brain functional connectivity of each brain region were compared and analyzed, and a significant correlation was found between VR grasping movements and brain region activation.ResultsCompared with the resting state, the WA values of LPFC, RPFC, LMC, RMC, and ROC increased during the grasping movements and the VR grasping movements, these changes were significant in LPFC and LMC. The WA values of LMC in the VR grasping movements were significantly higher than those in the grasping movements. The WPCO of the cerebral cortex increased during grasping exercise compared with the resting state. Nevertheless, the number of significant functional connections during VR grasping decreased significantly, and only the WPCO strength between the LPFC and LMC was enhanced. The increased WA of the LPFC, RPFC, LMC, and RMC during VR grasping movements compared with the resting state showed a significant negative correlation with KCs.ConclusionThe VR grasping movements can improve the activation and FC intensity of the ipsilateral brain region, inhibit the FC of the contralateral brain region, and reduce the quantity of brain resources allocated to the task. Thus, ordered grasping exercises can enhance active participation in rehabilitation and help to improve brain function. (shrink)
This paper addresses the synchronization issue for the drive-response fractional-order memristor‐based neural networks via state feedback control. To achieve the synchronization for considered drive-response FOMNNs, two feedback controllers are introduced. Then, by adopting nonsmooth analysis, fractional Lyapunov’s direct method, Young inequality, and fractional-order differential inclusions, several algebraic sufficient criteria are obtained for guaranteeing the synchronization of the drive-response FOMNNs. Lastly, for illustrating the effectiveness of the obtained theoretical results, an example is given.
The deformation and fracture of anisotropic shale rocks are of great interest to geoengineers concerned with assessing the stability of boreholes and underground excavations. However, some mechanic properties associated with anisotropic rock fracture remain ambiguous. We have purposely reported triaxial failure tests on two sets of transversely isotropic shale plugs cutting parallel and perpendicular to the bedding planes. The experimental results suggest that the bedding planes give rise to considerable differences in the elastic properties, failure strength, and failure modes in (...) the bedding-normal and bedding-parallel directions. In general, the static Young’s modulus is higher parallel to bedding than normal to bedding, whereas the static Poisson’s ratios measured from the vertical and horizontal shale plugs do not exhibit a certain relationship. The ratio between the bedding-parallel and bedding-normal failure strength is approximately 1.9 for Marcellus shales, whereas it is approximately 1.3 for Eagle Ford shales. At the failure point, the axial strains are appreciably larger than the radial strains. In contrast, the two orthogonal radial strains exhibit different characteristics in the bedding-normal and bedding-parallel directions, giving rise to complex failure modes. The extended cracks in the vertical plugs lead to fracturing in a shearing manner, with a single shear plane in the Eagle Ford shale and two conjugate shear planes in the Marcellus shale. In the horizontal plugs, the Eagle Ford shale exhibits shear banding in the bedding-normal direction and a combination of shear and extension in the bedding-normal direction. In contrast, the Marcellus shale exhibits three conjugated shear planes. (shrink)
By PFM, we mean a finitely generated module over a principal ideal domain; a linear sentence is a sentence that contains no disjunctive and negative symbols. In this paper, we present an algorithm which decides the truth for linear sentences on a given PFM, and we discuss its time complexity. In particular, when the principal ideal domain is the ring of integers or a univariate polynomial ring over the field of rationals, the algorithm is polynomial-time. Finally, we consider some applications (...) to Abelian groups. (shrink)
By inferences from fossil records and circumstantial evidences, it is now generally postulated that angiosperms have a much longer history than hitherto believed and that they have already existed probably in Jurassic time. Studies in vascular tissues and reproductive, structures have negated the possibility of originating angiosperms from various gymnosperm groups. Chronologically, this derivation will be also an impossibility.From a consideration of various aspects in the life history of angiosperms, a hypothesis is here presented postulating that protangiosperms originated in an (...) aquatic or subaquatic environment from an algal ancestry. The enclosure of ovules in the ovary is interpretated as a means of protection necessitated for the transmigration from an aquatic to an aerial habitat for the developing reproductive parts in the bud underwater. Trimery is suggested as a primitive condition, one that affords maximum efficiency in carrying out the purpose under the conditions.In the life history of angiosperms, the endosperm is of great significance in phylogeny. From morphological, physiological, cytological as well as genetical considerations, the endosperm should be regarded as of equal status with the gametophytic and sporophytic generations. There is no comparable structure in the gymnosperm groups and the ferns and “fern-allies”, while more or less similar conditions are present in the thallophytes. In the long life histories of many red algae, however, there is an especially notable resemblance to angiosperms, with certain details approaching the unique and characteristic features of the endosperms.Land plants are presumably all evolved from aquatic ancestors but instead of the usual concept of a monophyletic origin and lineal development of all vascular plants, a more plausible suggestion is the multiple and recurrent derivation of such plants from various algal ancestral groups. The angiosperms probably represent one of such major lines that originated more or less directly from a thallophytic ancestry. (shrink)