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We consider a parabolic nonlinear equation on the Heisenberg group. Applying the Gidas–Spruck type estimates, we prove that under suitable conditions, the equation does not have positive solutions. As an application of the nonexistence result, we provide optimal universal estimates for positive solutions.

Abstract Subway stations are important components of subway system planning and urban rail transit where passengers can board, alight, transfer, or wait. With an increase in urban passenger flow, subway stations must meet greater transfer‐space demands commensurate with growing station structure sizes. In this study, the field‐monitoring and analysis method was adopted to investigate the Huaxing Street Station of the Chengdu Metro Line 19 project and explore the temperature‐variation rule in the process of mass‐concrete pouring in the station floor. Based on an ABAQUS large‐finite‐element calculation programme and secondary development of damage and failure research methods, a mechanical model of mass‐concrete pouring in subway‐station floor construction was established. The pouring temperature effect, damage, and failure mechanism of mass‐concrete pouring in subway stations were comprehensively studied. The main results were as follows: (1) the maximum temperature difference between the upper and middle layers of the floor was dominant and reached a peak within 1–3 d after the completion of pouring, and the temperature difference gradually decreased with a decrease in the hydration‐heat reaction. (2) At 0–10 d, the damage ratio of the floor increased by 1.8%, predominantly in the form of longitudinal damage. Within 10–30 d, the damage and failure ratio of the floor increased by 1.86%, primarily in the form of transverse damage and failure. Within 30–40 d, the temperature of the floor stabilized and gradually approached the ambient temperature. The damage and failure ratio of the floor increased by 0.32% at this time. (3) The lower the ambient temperature, the greater was the damage sustained by the floor at different ages, and the ambient temperature had a significant influence on floor damage.

By applying the gluing method, we construct infinitely many axial symmetric singular positive solutions to the Lane-Emden equation: ΔHu+up=0,inHn\{0}{\Delta }_{{\mathbb{H}}}u+{u}^{p}=0\left,\hspace{1.0em}\hspace{0.1em}\text{in}\hspace{0.1em}\hspace{0.33em}{{\mathbb{H}}}^{n}\backslash \left\{0\right\} on the Heisenberg group Hn{{\mathbb{H}}}^{n}, where n>1,Q⁄(Q−4)

Abstract Since the ( $$\beta $$ β -deformed) Hurwitz Kontsevich model corresponds to the special case of affine Yangian of $${\mathfrak {gl}}(1)$$ gl ( 1 ) . In this paper, we construct two general cases of the $$\beta $$ β -deformed Hurwitz Kontsevich model. We find that the W-operators of these two models can be represented by the generators $$e_k,\ f_k,\psi _k$$ e k , f k , ψ k of the affine Yangian of $${\mathfrak {gl}}(1)$$ gl ( 1 ) , and the eigenstates (the symmetric functions $$Y_\lambda $$ Y λ and 3-Jack polynomials) can be obtained from the 3D Young diagram representation of affine Yangian of $${\mathfrak {gl}}(1)$$ gl ( 1 ) . Then we can see that the W-operators and eigenstates are symmetric about the permutations of coordinate axes.

As deep space exploration activities increase worldwide, the exploration environment becomes increasingly complex and the exploration tasks become increasingly difficult. Therefore, it is of great practical significance to research on deep space security issues. In this study, we first clarify the basic connotation of deep space security, briefly describe the significance and key issues of deep space security research, and summarize the research status and future development of four key deep space security issues: space radiation threat, planetary protection, space heritage protection, and space legislation. The study indicates that space radiation has the characteristics of multiple threat sources and high radiation intensity and should be researched from the perspectives of physical, biomedical, and chemical protection. Planetary protection mainly faces the challenges of pollution and impact of deep space spacecraft, and research should be conducted from the perspectives of deep space microbial detection and disinfection technologies as well as policy formulation. Space heritage protection is controversial in terms of evaluation and protection measures owing to political, cultural, and legal differences among countries, and it should be researched from the perspectives of international cooperation, deep space spacecraft, and reduction of human impact. Due to the complex international relations among countries, it is difficult for the effectiveness of current laws and regulations to become the consensus of the international community; therefore, research should be conducted from the aspects of international legislative organizations, domestic research institutions, and the improvement of domestic legal systems.

Objective To investigate the application and influence factors of revisional surgery after breast reconstruction in breast cancer patients in China. Methods It is a cross-section national study by distributing questionnaires to 110 hospitals with more than 200 annual breast cancer surgeries each. The questionnaire included questions concerning the application, operative programme, influence factors and complications of revisional surgery including nipple reconstruction, fat grafting and symmetric surgery. Results A total of 96 (87.3%) in 110 hospitals had breast reconstruction and 87 (79.1%) hospitals with revisonal surgery. There was nipple reconstruction in 55 (50.0%) hospitals, fat grafting in 41 (37.3%) hospitals and symmetric surgery in 64 (58.2%) hospitals. Two types of revisonal surgery were performed in 31 (28.2%) hospitals and three types in 21 (19.1%) hospitals. The application of revisonal surgery did not have relationship significantly with local economy. There were more cases with nipple reconstruction (P=0.01) and symmetric surgery (P

Abstract Background This study aimed to establish and validate a nomogram for predicting brain metastasis in patients with bladder cancer (BCa) and assess various treatment modalities using a primary cohort comprising 234 patients with clinicopathologically-confirmed BCa from 2004 to 2015 in the National Cancer Database. Methods Machine learning method and Cox model were used for nomogram construction. For BCa patients with brain metastasis, surgery of the primary site, chemotherapy, radiation therapy, palliative care, brain confinement of metastatic sites, and the Charlson/Deyo Score were predictive features identified for building the nomogram. Results For the original 169 patients considered in the model, the areas under the receiver operating characteristic curve (AUC) were 0.823 (95% CI 0.758–0.889, P

Stroke is an acute cerebrovascular disorder caused by sudden decrease or interruption of blood flow in brain arteries. Deficiency of timely and effective reperfusion of ischemic brain tissue can lead to irreversible brain injury and neurological dysfunction. Currently, recombinant tissue plasminogen activator (rt-PA) is the only appropriate thrombolytic agent which is approved by FDA for patients with acute ischemic stoke. However, due to the limitation of very narrow therapeutic time window and severe intracranial hemorrhagic complication, the outcome of stroke treatment mediated by rt-PA still remains unsatisfactory. Therefore, it is urgent to find new alternative drugs or develop novel drug delivery system to achieve better outcomes. In recent years, with the rapid development of nanotechonology, nanomaterials as a drug delivery system can provide new strategies and methods to carry t-PA specifically to the occlusion site and provide advanced treatment for stroke. In this review, we briefly introduced the physiopathologic mechanisms of thrombolysis and focused on the comparison of the t-PA mediated thrombolysis and t-PA conjugated nanomaterial mediated thrombolysis.

In this paper, we used the panel smooth transition model (PSTR) to study the nonlinear relationship between sulfur dioxide emissions and economic growth in the three regions of China’s eastern, middle and western regions, based on panel data from 31 provinces and autonomous regions in China from 2005 to 2017. And calculated the elasticity of the impact of total export-import volume and urbanization rate on emissions. The empirical results indicate that economic development and sulfur dioxide emissions are positively correlated in the three regions of East, Middle and West. In the eastern region, when the economic scale is lower than the threshold value, it has a negative impact on SO2 emissions; but when it is higher than the threshold value, it has a positive impact on SO2 emissions, and the smoothing rate between the two regime is slow. The per capita GDP in the middle and western regions is weakly positively correlated with SO2 emissions. When the economic scale reaches the threshold value, its positive impact on SO2 emissions will increase, and economic development will further increase emissions.

To study coordination in complex social systems such as financial markets, the authors introduce a new prediction market set-up that accounts for fundamental uncertainty. Nonetheless, the market is designed so that its total value is known, and thus its rationality can be evaluated. In two experiments, the authors observe that quick consensus emerges early yielding pronounced mispricing, which however does not show the standard “bubble-and-crash”. The set-up is implemented within the xYotta collaborative platform (https://xyotta.com). xYotta’s functionality offers a large number of extensions of various complexity such as running several parallel markets with the same or different users, as well as collaborative project development in which projects undergo the equivalent of an IPO (initial public offering) and whose subsequent trading matches the role of financial markets in determining value. xYotta is thus offered to researchers as an open source software for the broad investigation of complex systems with human participants.

Iron matrix cermet reinforced with TiC has been produced by vacuum carbothermal reduction of ilmenite followed by sintering processes. The influences of reduction temperature and carbon mass ratio were discussed in detail. X-Ray diffraction (XRD), electron probe micro-analyzer (EPMA) and scanning electron microscope (SEM) with energy dispersive spectrometer (EDS) were employed to characterize the phase composition and microstructures. After carbothermic reduction, most of Mg, Mn, Ca evaporated from the sample; Si and part of Al was dissolved in the iron matrix. The obtained powders were used as the raw materials to produce TiC-Fe cermet by vacuum sintering. Density, hardness and bending strength of the samples were examined. The optimal cermet products after heat treatment had a density of 5.38 g·cm-1, a hardness of 1125.5 HV and a bending strength of 667 MPa, which was obtained at the carbon/ilmenite mass ratio of 0.378:1 at 1773 K under the pressure of 10 Pa.

This study developed a teaching module that incorporated the Monty Hall problem to introduce conditional probability in a college introductory statistics course. This teaching module integrated a guess -- experiment -- discussion approach with game-based instruction. The researchers piloted this module and made modifications. The work of 20 non-mathematics major undergraduate students was examined for changes in their perceptions about conditional probability through a pre-and-post survey design. The Structure of the Observed Learning Outcome (SOLO) taxonomy was used for data analysis to show the quality of the student work. Findings suggest that most students' perceptions were at higher levels after the teaching module. [Note: The page range (93-109) shown on the PDF is incorrect. The correct page range is 93-108.]

A fixed-value mask algorithm for SMS4 was proposed in order to resist power analysis attack based SMS4.Firstly,an atomic mask algorithm of SMS4 was designed to resist against high-order power analysis attack based on the study of the structure of SMS4 algorithm,the intermediate variables were masked in the method.Secondly,pseudo-random fixed-value mask method（PFM） was proposed based on the above method,when its hardware implementation aiming at low power and less areas was considered about.Moreover,PFM has the ability to resist against high-order power analysis attacks when applied to the sensor node of special environment of communication.Finally,the experimental results show that the proposed algorithm has the ability to effectively resist second high-order differential power analysis attack without increasing much power and hardware resources.