网络中的数学问题

1．量短距离的连接如图1,把数字当作距离(千米),点当作城镇,找出煤气公司铺设连接所有城镇的煤气管道的最短长度．这个问题是要决定哪一段弧线可以不在网络内,但任何城镇并不被孤立在外,同时弧线的总长度是最短的．

Novel p-Channel Selected n-Channel Divided Bit-Line NOR Flash Memory Using Source Induced Band-to-Band Hot Electron Injection Programming

A novel p-channel selected n-channel divided bit-line NOR(PNOR) flash memory,which features low programming current,low power,high access current,and slight bit-line disturbance,is proposed.By using the source induced band-to-band hot electron injection (SIBE) to perform programming and dividing the bit-line to the sub-bit-lines,the programming current and power can be reduced to 3.5μA and 16.5μW with the sub-bit-line width equaling to 128,and a read current of 60μA is obtained.Furthermore,the bit-line disturbance is also significantly alleviated.

Dirac Particles' Tunneling Radiation from Dilaton Space-time with Squashed Horizons

The aim of this paper is to investigate Hawking radiation of Dirac particles from the Dilaton space-time with squashed horizons by improving the method of Kerner and Man’s tunneling analysis.We construct appropriate matrices for general covariant Dirac equation,and derive the tunneling probability and Hawking temperature.The results show that both Dirac particles and scalar particles radiate at the same Hawking temperature.

Dynamic leakage mechanism of gas drainage borehole and engineering application

Borehole leakage not only affects the gas drainage effect but also presents considerable risk to human security. For the research on the leakage mechanism of gas drainage borehole, the rheological and visco-elastic-plastic characteristics were considered to establish the mechanical model of coal mass around borehole, which is used to analyze the leakage mechanism and deduce the dynamic leakage model. On the basis of the real coal seam conditions, the variation rules of the stress, leakage ring, and air leakage amount were analyzed through numerical simulation, and the influence factors of air leakage amount were also investigated to provide the theoretical basis for the sealing technology. Results show that the air leakage amount of borehole is inversely proportional to the increase in supporting stress and sealing length, and directly correlated with the increase in borehole radius and softening modulus. Using theoretical analysis, we design a novel active supporting sealing technology that can use grouting material to seal the fractures to reduce the leakage channels and also provide supporting stress to prevent borehole deformation. The engineering test results indicate that the average gas concentration with the novel active supporting sealing technology is increased by 162.12% than that of traditional polyurethane sealing method. Therefore, this technology not only effectively resolves borehole leakage but also significantly improves the gas drainage effect.

The effect of digital health technologies on managing symptoms across pediatric cancer continuum:A systematic review

Objective:Pediatric cancer patients endure multiple symptoms during treatment and also in survivorship.Digital health technologies provide an innovative way to support their symptom management.This review aimed to examine the effect of digital health technologies on managing symptoms among across pediatric cancer continuum.Methods:A systematic literature search of six English and three Chinese electronic databases was combined with hand searching,to identify eligible research studies from database establishment to November 30,2019.Two reviewers carried out data selection,data extraction,and quality appraisal independently.A narrative approach was taken to summarize data.Results:Four randomized control trials,two quasi-experiments,and five one group pre-posttest designed studies,were included in the review with a total of 425 participants.The methodological quality of the studies was generally fair.Seven symptoms(anxiety,depression,pain,anger,fatigue,fear,distress)and seven digital health technologies(visual reality,website,humanoid robot,app,wearable devices,short messages and videoconference)were reported in the included studies.Conclusions:Current evidence supports the effect of digital health technologies is generally mixed and inconclusive.There is a trend of positive effects found in the interventions that feature digital health technologies’interactive function.This review highlights the need for further investigation with rigorous research designs and the consideration of influencing factors from the symptoms,participants,and context levels to inform a better digital health implementation.

A Multi-Domain Boundary Element Method to Analyze the Reflection and Transmission of Oblique Waves From Double Porous Thin Walls

In the present paper, we examine the performance of an efficient type of wave-absorbing porous marine structure under the attack of regular oblique waves by using a Multi-Domain Boundary Element Method(MDBEM). The structure consists of two perforated vertical thin barriers creating what can be called a wave absorbing chamber system. The barriers are surface piercing, thereby eliminating wave overtopping. The problem of the interaction of obliquely incident linear waves upon a pair of perforated barriers is first formulated in the context of linear diffraction theory. The resulting boundary integral equation, which is matched with far-field solutions presented in terms of analytical series with unknown coefficients, as well as the appropriate boundary conditions at the free surface, seabed, and barriers, is then solved numerically using MDBEM. Dissipation of the wave energy due to the presence of the perforated barriers is represented by a simple yet effective relation in terms of the porosity parameter appropriate for thin perforated walls. The results are presented in terms of reflection and transmission coefficients. The effects of the incident wave angles, relative water depths, porosities, depths of the walls, and other major parameters of interest are explored.

Capillary Rise between Parallel Perforated Plates in Microgravity

This paper presents the setup and performance of a drop tower experiment which investigates the behavior of liquid during self-driven capillary transport between two parallel perforated plates under microgravity. With the onset ofmicrogravity the liquid rises between the two parallel plates as a result of capillary pressure. Eight different sets of plates are tested in this study and the free surface height and the volume of transported liquid is subsequently analyzed. The plate sets differ in geometric properties of their perforations, distance, and width. In each set the perforations of both plates are identical and have a diameter of a few millimeters. The capillary rise velocity is influenced by the perforation diameter and the area porosity of the plates. As could be expected, the capillary transport capability increases with decreasing plate porosity.

Lower extremity injury in female basketball players is related to a large difference in peak eversion torque between barefoot and shod conditions

Background： The majority of injuries reported in female basketball players are ankle sprains and mechanisms leading to injury have been debated. Investigations into muscular imbalances in barefoot versus shod conditions and their relationship with injury severity have not been performed. The purpose of this study was to investigate the effects of wearing athletic shoes on muscular strength and its relationship to lower extremity injuries, specifically female basketball players due to the high incidence of ankle injuries in this population. Methods： During pre-season, 11 female collegiate basketball players underwent inversion and eversion muscle strength testing using an iso- kinetic dynamometer in both a barefoot and shod conditions. The difference between conditions was calculated for inversion and eversion peak torque, time to peak torque as well as eversion-to-inversion peak torque percent strength ratio for both conditions. Lower extremity injuries were documented and ranked in severity. The ranked difference between barefoot and shod conditions for peak torque and time to peak torque as well as percent strength ratio was correlated with injury ranking using a Spearman rho correlation （p） with an a level of 0.05. Results： The ranked differences in barefoot and shod for peak eversion and inversion torque at 120°/s were correlated with their injury ranking. Ranking of the athletes based on the severity of injuries that were sustained during the season was found to have a strong, positive relationship with the difference in peak eversion torque between barefoot and shod （p = 0.78; p = 0.02）. Conclusion： It is possible that a large discrepancy between strength in barefoot and shod conditions can predispose an athlete to injury. Nar- rowing the difference in peak eversion torque between barefoot and shod could decrease propensity to injury. Future work should investigate the effect of restoration of muscular strength during barefoot and shod exercise on injury rates.

Right iliac fossa abscess as first manifestation of perforated adenocarcinoma of sigmoid: a rare case report

Colorectal cancer usually present with known symptoms while there are less common manifestation including abscess formation which can be intra or extra peritoneal. A 60-year-old Caucasian male with a history of RLQ abdominal pain, nausea, vomiting and anorexia from 15 days ago referred to surgery ward. Ultrasound showed a hypoachoic lesion with diameters 50 mm x 70 mm in RLQ of abdomen and a round echogenic area in right lobe of liver with diameter 15 mm. The findings were revealed an abscess located in right lilac fossa then local drainage of abscess was performed. Four days later the patient was re-admitted because of severe abdominal distention and lack of bowel movement. Laparoscopy was performed before proceeding with further examinations, due to the poor general condition of the patient. The sigmoid was adherent into the abdominal wall and mild intestinal loop distention and apple-core view was observed during operation. Can- cer of sigmoid complicated by a right lilac fossa abscess was diagnosed and Hartman colestomy was undertaken. At the last follow-up examination 3 months after operation, the patient was in good health with no clinical evidence of recurrence.

Analysis of colonoscopic perforations at a local clinic and a tertiary hospital

AIM： To define the clinical characteristics, and to as- sess the management of colonoscopic complications at a local clinic. METHODS： A retrospective review of the medical re- cords was performed for the patients with iatrogenic colon perforations after endoscopy at a local clinic be- tween April 2006 and December 2010. Data obtained from a tertiary hospital in the same region were also analyzed. The underlying conditions, clinical presenta- tions, perforation locations, treatment types （operative or conservative） and outcome data for patients at the local clinic and the tertiary hospital were compared. RESULTS： A total of 10 826 colonoscopies, and 2625 therapeutic procedures were performed at a local clinic and 32 148 colonoscopies, and 7787 therapeutic proce-dures were performed at the tertiary hospital. The clinic had no perforations during diagnostic colonoscopy and 8 （0.3%） perforations were determined to be related to therapeutic procedures. The perforation rates in each therapeutic procedure were 0.06% （1/1609） in polyp- ectomy, 0.2% （2/885） in endoscopic mucosal resection （EMR）, and 3.8% （5/131） in endoscopic submucosal dis- section （ESD）. Perforation rates for ESD were significantly higher than those for polypectomy or EMR （P 〈 0.01）. All of these patients were treated conservatively. On the oth- er hand, three （0.01%） perforation cases were observed among the 24 361 diagnostic procedures performed, and these cases were treated with surgery in a tertiary hospi- tal. Six perforations occurred with therapeutic endoscopy （perforation rate, 0.08%; 1 per 1298 procedures）. Perfo- ration rates for specific procedure types were 0.02% （1 per 5500） for polypectomy, 0.17% （1 per 561） for EMR, 2.3% （1 per 43） for ESD in the tertiary hospital. There were no differences in the perforation rates for each therapeutic procedure between the clinic and the tertiary hospital. The incidence of iatrogenic perforation requiring surgical treatment was quite low in both the clinic and the tertiary hospital. No procedure-related mortalities occurred. Performing closure with endoscopic clipping reduced the C-reactive protein （CRP） titers. The mean maximum CRP titer was 2.9：1：1.6 mg/dL with clipping and 9.7 ＋ 6.2 mg/dL without clipping, respectively （P 〈 0.05）. An operation is indicated in the presence of a large perforation, and in the setting of generalized peritonitis or ongoing sepsis. Although we did not experience such case in the clinic, patients with large perforations should be immediately transferred to a tertiary hospital. Good relationships between local clinics and nearby tertiary hospitals should therefore be maintained. CONCLUSION： It was therefore found to be possible to perform endoscopic treatment at a local clinic when sufficient back up was available at a nearby tertiary hospital.

Multinanoparticle Translocations in Phospholipid Membranes:Translocation Modes and Dynamic Processes

Multinanoparticles interacting with the phospholipid membranes in solution were studied by dissipative particle dynamics simulation.The selected nanoparticles have spherical or cylindrical shapes,and they have various initial velocities in the dynamical processes.Several translocation modes are defined according to their characteristics in the dynamical processes,in which the phase diagrams are constructed based on the interaction strengths between the particles and membranes and the initial velocities of particles.Furthermore,several parameters,such as the system energy and radius of gyration,are investigated in the dynamical processes for the various translocation modes.Results elucidate the effects of multiparticles interacting with the membranes in the biological processes.

Path prediction of flexible needles based on Fokker-Planck equation and disjunctive Kriging model

Path prediction of flexible needles based on the Fokker-Planck equation and disjunctive Kriging model is proposed to improve accuracy and consider the nonlinearity and anisotropy of soft tissues.The stochastic differential equation is developed into the Fokker-Planck equation with Gaussian noise,and the position and orientation probability density function of flexible needles are then optimized by the stochastic differential equation.The probability density function obtains the mean and covariance of flexible needle movement and helps plan puncture paths by combining with the probabilistic path algorithm.The weight coefficients of the ordinary Kriging are extended to nonlinear functions to optimize the planned puncture path,and the Hermite expansion is used to calculate nonlinear parameter values of the disjunctive Kriging optimization model.Finally,simulation experiments are performed.Detailed comparison results under different path planning maps show that the kinematics model can plan optimal puncture paths under clinical requirements with an error far less than 2 mm.It can effectively optimize the path prediction model and help improve the target rate of soft tissue puncture with flexible needles through data analysis and processing of the mean value and covariance parameters derived by the probability density and disjunctive Kriging algorithms.

Tunneling Radiation of Massive Vector Bosons from Dilaton Black Holes

It is well known that Hawking radiation can be treated as a quantum tunneling process of particles from the event horizon of black hole. In this paper, we attempt to apply the massive vector bosons tunneling method to study the Hawking radiation from the non-rotating and rotating dilaton black holes. Starting with the Proca field equation that govern the dynamics of massive vector bosons, we derive the tunneling probabilities and radiation spectrums of the emitted vector bosons from the static spherical symmetric dilatonic black hole, the rotating Kaluza–Klein black hole,and the rotating Kerr–Sen black hole. Comparing the results with the blackbody spectrum, we satisfactorily reproduce the Hawking temperatures of these dilaton black holes, which are consistent with the previous results in the literature.

Non-microsurgical skin flaps for reconstruction of difficult wounds in distal leg and foot

Purpose： To express the versatility of a variety of non-microsurgical skin flaps used for coverage of difficult wounds in the lower third of the leg and the foot over 4 years period. Five kinds of flaps were used. Each flap was presented with detailed information regarding indication, blood supply, skin territory and technique. Methods： Altogether 26 patients underwent lower leg reconstruction were included in this study. The reconstructive procedures applied five flaps, respectively distally based posterior tibial artery perforator flap （n - 8）, distally based peroneal artery perforator flap （n = 4）, distally based sural flap （n - 6）, medial planter artery flap （n - 2） and cross leg flaps （n - 6）. Results： In all cases, there were no signs of osteomyelitis of underlying bones or discharge from the undersurface of the flaps. Fat necrosis occurred at the distal end of posterior tibial artery perforator flap in one female patient. The two cases of medial planter artery flap showed excellent healing with closure of donor site primarily. One cross leg flap had distal necrosis. Conclusion： Would at lower third of leg can be efficiently covered by posterior tibial, peroneal artery and sural flaps. Heel can be best covered by nearby tissues such as medial planter flap. In presence of vascular compromise of the affected limb or exposure of dorsum of foot, cross leg flap can be used.

instanton quantum tunneling Jacobi elliptic functions Lamé functions

Under condition of four potential fields, equations of motion and fluctuations in imaginary time are utilized to analytically derive the basic and fluctuating periodic instantons. It is shown that the basic instantons satisfy the elliptic or simple pendulum equations and their solutions are Jacobi elliptic functions, and fluctuating periodic instantons satisfy the Lam′e equation and their solutions are Lame functions. These results indicate that there exists the common solution family for different potential fields which are called the super-symmetry family.

Quantum tunnelling radiation from static and rotating black lenses in five dimensions

Black lenses with L(n,1) horizon topology in five dimensions have many unusual properties shared by neither Myers-Perry black holes with event-horizon topology S 3,nor 5-dimensional black rings with event-horizon topology S 2 × S 1.In this work,by constructing appropriate matrices γμ for the general covariant Dirac equation,we further extend the fermion tunnelling method to 5-dimensional static and rotating black lenses.As a result,it is interesting to find as in black hole cases,fermions tunnelling can also result in correct Hawking temperatures for the static and rotating black lenses.