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AIM To establish and evaluate an experimental porcine model of fistula-in-ano. METHODS Twelve healthy pigs were randomly divided into two groups. Under general anesthesia, the experimental group underwent rubber band ligation surgery, and the control group underwent an artificial damage technique. Clinical magnetic resonance imaging (MRI) and histopathological evaluation were performed on the 38th d and 48th d after surgery in both groups, respectively. RESULTS There were no significant differences between the experimental group and the control group in general characteristics such as body weight, gender, and the number of fistula (P > 0.05). In the experimental group, 15 fistulas were confirmed clinically, 13 complex fistulas were confirmed by MRI, and 11 complex fistulas were confirmed by histopathology. The success rate in the porcine complex fistula model establishment was 83.33%. Among the 18 fistulas in the control group, 5 fistulas were confirmed clinically, 4 complex fistulas were confirmed by MRI, and 3 fistulas were confirmed by histopathology. The success rate in the porcine fistula model establishment was 27.78%. Thus, the success rate of the rubber band ligation group was significantly higher than the control group (P < 0.05). CONCLUSION Rubber band ligation is a stable and reliable method to establish complex fistula-in-ano models. Large animal models of complex anal fistulas can be used for the diagnosis and treatment of anal fistulas.

Aiming at the existing problems of the DFIG grid side converter, this paper studies its control technology and proposes a composite control strategy which includes a terminal sliding mode variable structure control of the current inner-loop and a PI controller of the voltage outer-loop in grid side converter. The simulation results show that the control strategy proposed in this paper can achieve better control of the inverter output voltage and input current. What's more important, this method can not only reduce the adverse effects on the grid side converter due to parameter variations and other factors, but also increases the robustness of the system. It has important actual significance and practical application value.

AIM To evaluate the diagnostic value of different sonographic methods in hemorrhoids. METHODS Forty-two healthy volunteers and sixty-two patients with grades I-IV hemorrhoids received two different sonographic examinations from January 2013 to January 2016 at the First and Second Hospitals of Xinjiang Medical University in a prospective way. We analyzed the ultrasonographic findings of these participants and evaluated the outcomes. Resected grades III and IV hemorrhoid tissues were pathologically examined. The concordance of ultrasonographic results with pathology results was assessed with the Cohen's kappa coefficient. RESULTS All healthy volunteers and all patients had no particular complications related to sonography. There were no statistically significant differences between the participants regarding age (P = 0.5919), gender (P = 0.4183), and persistent symptoms (P > 0.8692). All healthy control participants had no special findings. However, 30 patients with hemorrhoids showed blood signals around the dentate line on ultrasonography. When grades I and II hemorrhoids were analyzed, there were no significant differences between transrectal ultrasound (TRUS), transperianal ultrasound (TPUS), and transvaginal ultrasound (TVUS) (P > 0.05). Grades III and IV hemorrhoids revealed blood flow with different directions which could be observed as a "mosaic pattern". In patients with grades III and IV hemorrhoids, the number of patients with "mosaic pattern" as revealed by TRUS, TPUS and TVUS was 22, 12, and 4, respectively. Patients with grades III and IV disease presented with a pathologically abnormal cushion which usually appeared as a "mosaic pattern" in TPUS and an arteriovenous fistula in pathology. Subepithelial vessels of resected grades III and IV hemorrhoid tissues were manifested by obvious structural impairment and retrograde and ruptured changes of internal elastic lamina. Some parts of the Trietz's muscle showed hypertrophy and distortion. Arteriovenous fistulas and venous dilatation were obvious in the anal cushion of hemorhoidal tissues. After pathological results with arteriovenous fistulas were taken as the standard reference, we evaluated the compatibility between the two methods according to the Cohen's kappa co-efficiency calculation. The compatibility (Cohein kappa co-efficiency value) between "mosaic pattern" in the TPUS and arteriovenous fistula in pathology was very good (ĸ = 0.8939). When compared between different groups, TRUS presented the advantage that the mosaic pattern could be confirmed in more patients, especially for group A. There was a statistical difference when comparing group A with group B or C (P < 0.05 for both). There were obvious statistical differences between group A and group B with regard to the vessel diameter and blood flow velocity measured by TRUS (P < 0.05). CONCLUSION Patients with grades III and IV hemorrhoids present with a pathologically abnormal cushion which usually appears as a "mosaic pattern" in sonography, which is in accord with an arteriovenous fistula in pathology. There are clearly different hemorrhoid structures shown by sonography. "Mosaic pattern" may be a parameter for surgical indication of grades III and IV hemorrhoids.

The changes of the tip geometry due to the tip wear can completely alter the variation of the adhesion force dependence on the humidity. In this paper, we propose a simple method to calculate the width of tip wear using the adhesion force at inflection point of the experimental adhesion force versus humidity curves. Theoretical results show that the turning point of the adhesion versus humidity curve is closely correlated with the width of the worn tip, which can be precise calculated. The validity of the proposed method is proved by the agreement of our calculate results and the existing experimental data.

Acquiring information of the neural structures in the whole-brain level is vital for systematically exploring mechanisms and principles of brain function and dysfunction. Most methods for whole brain imaging, while capable of capturing the complete morphology of neurons, usually involve complex sample preparation and several days of image acquisition. The whole process including optical clearing or resin embedding is time consuming for a quick survey of the distribution of specific neural circuits in the whole brain. Here, we develop a high-throughput light-sheet tomography platform (HLTP), which requires minimum sample preparation. This method does not require optical clearing for block face light sheet imaging. After fixation using paraformaldehyde, an aligned 3 dimensional image dataset of a whole mouse brain can be obtained within 5 hours at a voxel size of 1.30 × 1.30 × 0.92 μm. HLTP could be a very efficient tool for quick exploration and visualization of brain-wide distribution of specific neurons or neural circuits.

In strained graphene, lattice deformation can create pseudo-magnetic fields and result in zero-field Landau level-like quantization. In the presence of an external magnetic field, valley-polarized Landau levels are predicted to be observed because the pseudo-magnetic fields are of opposite directions in the K and K' valleys of graphene. Here, we present experimental spectroscopic measurements by scanning tunneling microscopy of strained graphene on Rh foil. We direct observed valley splitting of the Landau level induced by the coexistence of the pseudo-magnetic fields and external magnetic fields. The observed result paves the way to exploit novel electronic properties in graphene through the combination of the pseudo-magnetic fields and the external magnetic fields., 3 Figures in main text and 3 figures in Supplementary Materials

Spatially varying strained graphene can acquire interesting electronic properties because of the strain-induced valley-dependent gauge (pseudomagnetic) fields1,2. Here we report the realization of strained graphene regions located close to the step edges of Cu(111), obtained by using thermal strain engineering3,4. We study these strained structures with sub-nanometre-resolved scanning tunnelling microscopy and spectroscopy and identify their spatially modulated Dirac points, demonstrating the effect of overlap of Cu and graphene wave functions on the charge transfer between them5. By applying a magnetic field of 8 Tesla, electron confinement, as revealed by regularly spaced sharp resonances6,7, is observed in the strained graphene. In some regions of the strained graphene, repetitive pairs of resonance peaks appear in the tunnelling spectra. This provides direct and compelling evidence for lifting of valley degeneracy due to the coexistence of both the magnetic field and the pseudomagnetic field., Comment: 4 Figures in main text

The cellular automaton model is suggested to describe the traffic-flow at the grade roundabout crossing. After the simulation with computer, the fundamental properties of this model have been revealed. Analysing this kind of road structure, this paper transforms the grade roundabout crossing with inner-roundabout-lane and outer-roundabout-lane into a configuration with many bottlenecks. Because of the self-organization, the traffic flow remains unblocked under a certain vehicle density. Some results of the simulation are close to the actual design parameter.

To resolve fine structures of biological systems like neurons, it is required to realize microscopic imaging with sufficient spatial resolution in three dimensional systems. With regular optical imaging systems, high lateral resolution is accessible while high axial resolution is hard to achieve in a large volume. We introduce an imaging system for high 3D resolution fluorescence imaging of large volume tissues. Selective plane illumination was adopted to provide high axial resolution. A scientific CMOS working in sub-array mode kept the imaging area in the sample surface, which restrained the adverse effect of aberrations caused by inclined illumination. Plastic embedding and precise mechanical sectioning extended the axial range and eliminated distortion during the whole imaging process. The combination of these techniques enabled 3D high resolution imaging of large tissues. Fluorescent bead imaging showed resolutions of 0.59 μm, 0.47μm, and 0.59 μm in the x, y, and z directions, respectively. Data acquired from the volume sample of brain tissue demonstrated the applicability of this imaging system. Imaging of different depths showed uniform performance where details could be recognized in either the near-soma area or terminal area, and fine structures of neurons could be seen in both the xy and xz sections.

The harmonic optical frequency chain is the only tool for measuring optical frequency till the advent of a femtosecond optical frequency comb (FOFC). However, its disadvantages are obvious, such as high cost, difficult construction, complex usage, and complicated maintenance. The emergence of femtosecond optical frequency combs (FOFCs) makes it possible to measure the absolute frequency of a laser, which greatly simplifies the quantity traceability of the absolute frequency value and comparison, and allows the length unit “m” to be directly traced back to the time unit “s”. The beat note (fb) between an FOFC and a test laser is one of the most important data in measuring absolute frequency of the test laser. In order to ensure the accuracy and reliability of the measurement, the signal-to-noise ratio (SNR) of fb should be above 30 dB at 300 kHz resolution bandwidth. Among the wavelength standards recommended to replicate “meter” (SI), iodine-stabilized 633 nm lasers and iodine-stabilized 532 nm lasers have been widely used. Compared with iodine-stabilized 633 nm lasers, iodine-stabilized 532 nm lasers have the advantages of high stability, high output power, no modulation and fiber coupled output. Therefore, it is of great importance to measure and monitor the absolute frequency of an iodine-stabilized 532 nm laser. Aiming at the specific requirements for absolute frequency measurement of an iodine-stabilized 532 nm laser, the absolute frequency measurement of its fundamental 1064 nm laser has been studied. In this paper, a high-repetition-rate Er-doped femtosecond fiber laser is adopted as an optical source in the system. The repetition rate of the fiber laser is 303 MHz, the output power in the continuous-wave state is 130 mW and the average output power in the mode-locking state is 80 mW. The highest SNR of fb between the comb light and a 1064 nm laser generated by an iodine-stabilized 532 nm laser is only 30 dB due to the low intensity at 1 μm wavelength in the supercontinuum, which just reaches the SNR threshold meeting the counter's working condition. In order to improve the accuracy and reliability of absolute frequency measurement, the technique of cascading an Yb-doped fiber amplifier after spectral broadening is adopted to enhance the spectral intensity at 1 μm wavelength. The experimental results indicate that the SNR of fb between a 1 μm laser after spectral enhancement and a 1064 nm laser is increased by 5 dB and kept at 35 dB for several days, meeting requirements for long-term continuous monitoring. This method can effectively reduce the intensity requirements at 1 μm wavelength when the spectrum is directly broadened in the Er-FOFC.

As a promising legume for forage in arid and semi-arid areas, Medicago ruthenica (L.) Trautv. is widely distributed in northern China. For this study, twenty four accessions from northern China were analyzed by allozyme and microsatellites markers to determine its genetic variation patterns, two assays were found different in the amounts of polymorphism. Higher amounts of polymorphism were detected by microsatellites. For allozymes and microsatellite markers, mean expected heterozygosity (He) of 24 populations ranged from 0.160 to 0.485 and 0.274 to 0.5316 respectively. Mean observed heterozygosity per locus (Ho) of 24 populations was 0.422 for allozymes and 0.4149 for simple sequence repeats (SSR) markers. For allozymes, average interpopulation genetic diversity (Hs) was 0.2733 and average intrapopulation genetic diversity (D ST ) was 0.0473, mean coefficient of gene differentiation for loci (G ST ) at the population level was estimated 0.1813. According to G ST , gene flow at population level was 1.4427 for allozymes and 1.2040 for SSR markers, which indicated there was definite gene flow between populations. Low differentiations among populations at allozymes (F ST = 0.1719) and SSR markers (F ST = 0.1816) means genetic variations is mainly lied in populations. The results showed there was high genetic diversity in M. ruthenica populations. Key words: Medicago ruthenica , genetic diversity, allozyme, micro-satellite, North China.

To compare biofeedback-guided pelvic floor exercise therapy (BFT) with the use of oral polyethylene glycol (PEG) for the treatment of obstructive defecation.A total of 88 subjects were assigned to treatment with either BFT (n = 44) or oral PEG (n = 44). Constipation symptoms (including difficult evacuation, hard stool, digitation necessity, incomplete emptying sensation, laxative dependence, perianal pain at defecation, and constipation satisfaction), Wexner Scores, and quality of life scores were assessed after 1, 3, and 6 mo.At the 6 mo follow-up, the symptoms of the BFT group patients showed significantly greater improvements compared with the PEG group regarding difficult evacuation, hard stools, digitation necessity, laxative dependence, perianal pain at defecation, constipation satisfaction, Wexner Constipation Score, and quality of life score (P0.05). The quality of life score of the BFT group at the final follow-up time (6 mo) was 80 ± 2.2. After a complete course of training, improvements in the clinical symptoms of the BFT group were markedly improved (P0.05), and the Wexner Constipation Scores were greatly decreased compared with the oral PEG group (P0.05).We concluded that manometric biofeedback-guided pelvic floor exercise training is superior to oral polyethylene glycol therapy for obstructive defecation.