校园足球教学与训练方法--基于国外足球Small-Sided Games的解读

教学与训练方法的落后已经成为我国校园足球高质量发展和高效率普及的瓶颈。基于丰富我国足球教学与训练方法,提高校园足球普及质量与效率的现实需要,对国外足球小场训练赛(SSGs)的概念、特点、理论基础、训练效果影响因素及实践操作过程等进行解读。以期增进广大中小学足球专项教师和教练对该方法的理解和掌握,同时,引导和提高他们对该方法的科学使用。

Meta-sided exchange环及其扩张

讨论了meta-sided exchange环的性质。证明了如果R是Abelian meta-sided exchange环,则对R的任意素理想P,都有R/P是局部环;如果R是Abelian环,(S,≤)是严格序幺半群且对任意s∈S,都有0≤s,则广义幂级数环[[RS,≤]]是meta-sided exchange环当且仅当R是meta-si-ded exchange环。

关于Meta-sided Exchange环的几点注记

给出了meta-sided exchange环的性质;讨论了Morita系统环的meta-sided exchange性质和具有零化条件的meta-sided exchange环;证明了满足一定条件的meta-sided exchange环是环.

Laparoscopic cholecystectomy for a left-sided gallbladder

Cholecystectomy is a common procedure.Abnormalities in the anatomy of the biliary system are common but an abnormal location of the gallbladder is much rarer.Despite frequent pre-operative imaging,the aberrant location of the gallbladder is commonly discovered at surgery.This article presents a case of a patient with the gallbladder located to the left of the falciform ligament in the absence of situs inversus totalis that presented with right upper quadrant pain.A laparoscopic cholecystectomy was performed and it was noted that the cystic duct originated from the right side.The presence of a left sided gall bladder is often associated with various biliary,portal venous and other anomalies that might lead to intra-operative injuries.The spectrum of unusual positions and anatomical gallbladder abnormalities is reviewed in order to facilitate elective and emergent cholecystectomy as well as other hepatobiliary procedures.With proper identification of the anatomy,minimally invasive approaches are still considered safe.

Numerical simulation of dynamic thermal process during doublesided asymmetrical TIG backing welding of large thick plates

The dynamic thermal process during double-sided asymmetrical TIG backing welding of large thick plates （ 1 000 mm×700 mm×50 mm） is numerically simulated using MSC. MARC. The effect of arc distance on the thermal cycle in weld zone during double-sided asymmetrical T1G backing welding is investigated. The results show that the workpiece experiences double-peak thermal cycle in double-sided asymmetrical TIG backing welding. On the one hand, the fore arc has the pre- heating effect on the rear pass, and the pre-heating temperature depends on the distance between the double arcs, the heat input of fore arc, and the initial temperature of workpiece. On the other hand, the rear arc has the post-heating effect on the fore pass. The mutual effects of two heat sources decrease with the increase of arc distance.

Left sided Amyand's hernia

The presence of the appendix in an inguinal hernia sac has been referred to as Amyand’s hernia.Vermiform appendix located in an external hernia sac is not an uncommon condition,and the incidence of these cases is approximately 1%.In Amyand’s hernias,appendices are frequently found in the hernia sac;but an incarceration particularly on the left side is a very unusual sight.In this report we present 32-year-old male with Amyand’s hernia on the left side.

Preparation of Large Area Double Sided YBCO Thin Films by DC Magneton Sputtering

Tc, Jc and Rs properties of large area double sided YBCO thin films deposited on LaAlO3 substrates by direct current sputtering were reported.Film thickness of the obtained thin films is over 300 nm, Tc > 90 K; Rs can be as low as less than 1.0 mΩ(77 K, 10 GHz).Homogenousity of the properties around the plane was studied.Under the measnous distributions.Influences of substrate temperature and Ar and O2 pressures on properties of the double-sided thin films were discussed.

THE ONE-SIDED HANDAMARD PRINCIPAL VALUE FOR SINGULAR-INTEGRALS OF HIGH ORDER AND ITS APPLICATIONS

0 IntroductionLet L = ab be a non-closed smooth arc oriented from a to b, t∈ L, t≠a,b, be the fixed point, andf(t) ∈H. (L) . The usual Hadamard principal value is defined asAbout properties and applications of singular integals of high order were investigated by many authors([1],[2],[3] etc. ) In 1987, the concepts of Hadamard principal value at one-side for singular integralsof high order and the rules of their differentiation are introduced [4]. In this paper we established the rulesof substitution of variable for one-sided Hadamard principal value of singular integrals of high order, andthen, we gave some applications in evaluation of real definite integrals.

Right-and left-sided colorectal cancers respond differently to traditional Chinese medicine

AIM To explore the differences in the responses of left-sided colorectal cancer(LSCRC) and right-sided colon cancer(RSCC) to traditional Chinese medicine(TCM).METHODS Patients with postoperative stage I-III colorectal cancer(CRC) were enrolled and divided into the LSCRC with or without TCM and RSCC with or without TCM groups depending on the primary tumor side and TCM administration. Patients in the TCM group were given TCM for at least 6 mo. Our research adopted diseasefree survival(DFS) as the primary endpoint. We applied a Cox proportional hazards regression model for the multivariate factor analysis using Stata 12.0 and SPSS 22.0 software for data analysis.RESULTS Of the 817 patients included in our study, 617 had LSCRC(TCM group, n = 404; Non-TCM group, n = 213), and 200 had RSCC(TCM group, n = 132; NonTCM group, n = 68). The 6-year DFS for patients with LSCRC was 56.95% in the TCM group and 41.50% in the Non-TCM group(P = 0.000). For patients with RSCC, the 6-year DFS was 52.92% in the TCM group and 37.19% in the Non-TCM group(P = 0.003). Differences between LSCRC and RSCC were not statistically significant regardless of TCM ingestion.CONCLUSION Patients with either LSCRC or RSCC and who took TCM experienced longer DFS; furthermore, patients with RSCC benefited more from TCM in DFS.

Left-sided gallbladder:A rare biliary tree anomaly

To the Editor:Hepatobiliary anatomical variations may increase the complexity of surgery with a relevant risk of iatrogenic lesions.Left-sided gallbladder(LSG)is a rare and little known condition whereby the viscus is located on the visceral surface of the left lobe of the liver and is often discovered unexpectedly during surgery.The position of the gallbladder over the liver pedicle and the simultaneous presence of variations in the liver vascularization are potentially associated to a challenging surgical dissection and consequently to an increased risk of morbidity.Despite open approach remains an option in more complex procedures,cholecystectomy is usually performed with a minimally invasive technique,which is generally safe even in the rare case of an LSG,as long as a high level of awereness of anatomical variations and a careful surgical dissection are pursued.

Applications of the CE/SE Scheme to Incompressible Viscous Flows in Two-Sided Lid-Driven Square Cavities

The spacetime conservation element-solution element(CE/SE)method is extended to two-dimensional incompressible viscous flow in a two-sided lid-driven square cavity.Based on the SIMPLE method concept,the preconditioned dual-time scheme is introduced for unsteady computations.The CE/SE-based code is validated by simulating one-sided lid-driven cavity flows.The two-sided lid-driven square cavity problem involves several interesting characteristics being successfully predicted,including development of a pair of off-corner vortices and a free shear layer in the case of parallel wall motion,as well as the appearance of corner vortices for lower Reynolds numbers in the case of anti-parallel motion of the walls.It is found that both the Reynolds number and the direction of the moving walls affect the fluid flow in the cavity.

Deformation behavior of TC1 titanium alloy sheet under double-sided pressure

In order to investigate the influence of normal stress through thickness on the formability of sheet metal,the viscous pressure bulge(VPB)tests of an annealed TC1 titanium alloy sheet were carried out under two different conditions:double-sided pressure bulging and conventional single-sided pressure bulging.The automated strain analysis,measurement environment(ASAME)and scanning electron microscope(SEM)were used to study the strain distributions and the fracture morphology of bulged specimens.It is found that thickness strain is increased for double-sided pressure bulging specimens,and the limiting dome height(LDH)of double-sided pressure bulging specimens is increased by 31.8% compared with conventional single-sided pressure bulging specimens.The dimples in fracture surface for double-sided pressure bulging specimens are larger and deeper than those for conventional single-sided pressure bulging specimens.The results indicate that normal stress through thickness is helpful in improving the formability of titanium alloy sheet metal.

Characterization of CIAE developed double-sided silicon strip detector for charged particles

A double-sided silicon strip detector(DSSD)with active area of 48 mm x 48 mm and thickness of300μm has been developed. Each side of DSSD consists of48 strips, each with width of 0.9 mm and inter-strip separation of 0.1 mm. Electrical properties and detection performances including full depletion bias voltage, reverse leakage current, rise time, energy resolution and cross talk have been studied. At a bias of 80 V, leakage current in each strip is less than 15 nA, and rise time for alpha particle at 5157 keV is approximately 15 ns on both sides.Good energy resolutions have been achieved with0.65-0.80% for the junction strips and 0.85-1.00% for the ohmic strips. The cross talk is found to be negligible on both sides. The overall good performance of DSSD indicates its readiness for various nuclear physics experiments.

Construction of n-sided polygonal spline element using area coordinates and B-net method

In general, triangular and quadrilateral elements are commonly applied in two-dimensional finite element methods. If they are used to compute polycrystalline materials, the cost of computation can be quite significant. Polygonal elements can do well in simulation of the materials behavior and provide greater flexibility for the meshing of complex geometries. Hence, the study on the polygonal element is a very useful and necessary part in the finite element method. In this paper, an n-sided polygonal element based on quadratic spline interpolant, denoted by PS2 element, is presented using the triangular area coordinates and the B-net method. The PS2 element is conforming and can exactly model the quadratic field. It is valid for both convex and non-convex polygonal element, and insensitive to mesh distortions. In addition, no mapping or coordinate transformation is required and thus no Jacobian matrix and its inverse are evaluated. Some appropriate examples are employed to evaluate the performance of the proposed element.

Primary colon resection or Hartmann's procedure in malignant left-sided large bowel obstruction? The use of stents as a bridge to surgery

There is still significant debate regarding the best surgical treatment for malignant left-sided large bowel obstruction.Primary resection and anastomosis offers the advantages of a definite procedure without need for further surgery.Its main disadvantages are related to the increased technical challenge and to the potential higher risk of anastomotic leakage that occurs in the emergency setting.Primary resection with end colostomy(Hartmann's procedure) is considered the safer option.Tan et al compared in a systematic review and meta-analysis the use of self-expanding metallic stents(SEMS) as a bridge to surgery vs emergency surgery in the management of acute malignant left-sided large bowel obstruction.The authors concluded that the technical and clinical success rates for stenting were lower than expected.SEMS was associated with a high incidence of clinical and silent perforation.Stenting instead of loop colostomy can be recommended only if the appropriate expertise is available in the hospital.The goal of stenting,a decrease of the stoma rate,may be advocated only if the complication rates of stenting are lower than those of stoma creation in the emergency situation.Until now,this was not demonstrated in a prospective randomized trial.

Nonlinear optical properties in double-sided nonlinear media with Z-scan technique based on the Huygens-Fresnel principle

We present a theoretical model to analyse the propagation of a Gaussian laser beam through double-sided nonlinear media. This model is based on the Huygens-Fresnel diffraction integral method. This theoretical model is not only consistent with the cascade structure model for a small nonlinear phase-shift but also can be used for a large nonlinear phase-shift. It has been verified that it is suitable to characterize the double-sided nonlinear media compared with the cascade structure model. A good agreement between the experimental data and the results from the theoretical model is obtained. It will be useful for the design of multi-sided nonlinear materials.

Left-sided appendicitis:Review of 95 published cases and a case report

AIM:To give an overview of the literature on left-sided acute appendicitis (LSAA) associated with situs inversus totalis (SIT) and midgut malrotation (MM).METHODS:We present a new case of LSAA with SIT and a literature review of studies published in the English language on LSAA,accessed via PubMed and Google Scholar databases.RESULTS:Ninety-five published cases of LSAA were evaluated and a 25-year-old female,who presented to our clinic with left lower abdominal pain caused by LSAA,is reported.In the reviewed literature,fiftyseven patients were male and 38 were female with an age range of 8 to 82 years and a median age of 29.1 ± 15.9 years.Sixty-six patients had SIT,23 had MM,three had cecal malrotation,and two had a previously unnoted congenital abnormality.Fifty-nine patients had presentedto the hospital with left lower,14 with right lower and seven with bilateral lower quadrant pain,and seven subjects complained of left upper quadrant pain.The diagnosis was established preoperatively in 49 patients,intraoperatively in 19,and during the postoperative period in five;14 patients were aware of having this anomaly.The data of eight patients were not unavailable.Eleven patients underwent laparoscopic appendectomy,which was combined with cholecystectomy in two cases.Histopathological examination of the appendix specimens revealed adenocarcinoma in only two of 95 patients.CONCLUSION:The diagnosis of left lower quadrant pain is based on well-established clinical symptoms,physical examination and physician's experience.

Double-sided gas tungsten arc welding process on TC4 titanium alloy

TC4 titanium alloy was welded by double-sided gas tungsten arc welding(GTAW) process in comparison with conventional GTAW process, the microstructure and mechanical performance of weld were also studied. The results indicate that double-sided GTAW is superior over regular single-sided GTAW on the aspects of increasing penetration, reducing welding deformation and improving welding efficiency. Good weld joint was obtained, which can reach 96.14% tensile strength and 70.85% elongation percentage of the base metal. The grains in heat-affected zone(HAZ) are thin and equiaxed and the degree of grain coarsening increases as one moves to the weld center line, and the interior of grains are α and α′ structures. The coarse columned and equiaxed grains, which interlace martensitic structures α′ and acicular α structures, are observed in weld zone. The fracture mode is ductile fracture.

En bloc pancreaticoduodenectomy and right hemicolectomy for locally advanced right-sided colon cancer

AIM To assess the usefulness of en bloc right hemicolectomy with pancreaticoduodenectomy(RHCPD) for locally advanced right-sided colon cancer(LARCC).METHODS We retrospectively reviewed the database of Saitama Medical Center, Jichi Medical University, between January 2009 and December 2016. During this time, 299 patients underwent radical right hemicolectomy for right-sided colon cancer. Among them, 5 underwent RHCPD for LARCC with tumor infiltration to adjacent organs. Preoperative computed tomography(CT) was routinely performed to evaluate local tumor infiltration into adjacent organs. During the operation, we evaluated the resectability and the amount of infiltration into the adjacent organs without dissecting the adherent organs from the cancer. When we confirmed that radical resection was feasible and could lead to R0 resection, we performed RHCPD. The clinical data were carefully reviewed, and the demographic variables, intraoperative data, and postoperative parameters were recorded.RESULTS The median age of the 5 patients who underwent RHCPD for LARCC was 70 years. The tumors were located in the ascending colon(three patients) and transverse colon(two patients). Preoperative CT revealed infiltration of the tumor into the duodenum in all patients, the pancreas in four patients, the superior mesenteric vein(SMV) in two patients, and tumor thrombosis in the SMV in one patient. We performed RHCPD plus SMV resection in three patients. Major postoperative complications occurred in 3 patients(60%) as pancreatic fistula(grade B and grade C, according to International Study Group on Pancreatic Fistula Definition) and delayed gastric empty. None of the patients died during their hospital stay. A histological examination confirmed malignant infiltration into the duodenum and/or pancreas in 4 patients(80%), and no patients showed any malignant infiltration into the SMV. Two patients were histologically confirmed to have tumor thrombosis in the SMV. All of the tumors had clear resection margins(R0). The median follow-up time was 77 mo. During this period, two patients with tumor thrombosis died from liver metastasis. The overall survival rates were 80% at 1 year and 60% at 5 years. All patients with node-negative status(n = 2) survived for more than seven years.CONCLUSION This study showed that the long-term survival is possible for patients with LARCC if RHCPD is performed successfully, particularly in those with node-negative status.

Numerical Simulation of Current Density Distribution in Keyhole Double-Sided Arc Welding

In the double-sided arc welding system (DSAW) composing of PAW+TIG arcs, the PAW arc is guided by the TIG arc so that the current mostly flows through the direction of the workpiece thickness and the penetration is greatly improved. To analyze the current density distribution in DSAW is beneficial to understanding of this process. Considering all kinds of dynamic factors acting on the weldpool, this paper discusses firstly the surface deformation of the weldpool and the keyhole formation in PAW+TIG DSAW process on the basis of the magnetohydrodynamic theory and variation principles. Hence, a model of the current density distribution is developed. Through numerical simulation, the current density distribution in PAW+TIG DSAW process is quantitatively analyzed. It shows that the minimal radius of keyhole formed in PAW+TIG DSAW process is 0.5 mm and 89.5 percent of current flows through the keyhole.