铁道车祸危险因素与行车安全经济效益的探讨

作者以1380名机车乘务员为研究对象,测查其生理心理指标,探讨发生车祸的危险因素,分析34年车祸流行的规律,并对行车安全的社会经济效盖进行了估算。研究结果显示,社会安定是减少车祸、保证行车安全的重要因素。通过多因素分析,揭示车祸的危险因素是低文化程度、过度疲劳、睡眠不足、视运动反应迟钝和弱神经类型,其间存在交互作用。实践表明,推行安全行车千日活动,可获巨大社会经济效益(1∶7)。     

铁路警察和监狱警察应对方式比较

目的了解铁路警察和监狱警察应对方式的差异。方法采用应对方式问卷对87名广州铁路警察进行调查，并以87名监狱警察作为对照组。结果铁路警察的主要应对方式是解决问题，与监狱警察相类似，但铁路警察的退避、自责得分较高（P〈0．05）。女性和青年的应对方式无差异（P〉0．05），而男性和中年铁路警察的自责、退避得分较高（P〈0．05）。对铁路警察的应对方式进行回归分析发现他们的应对方式与其待遇评价、警龄、是否想转行和婚姻状况密切相关。结论铁路警察的应对方式是积极的，退避和自责可能是与铁路警察职业相适应的应对方式调整。     

4个铁路区段提速列车噪声影响调查

为探讨提速列车噪声对铁路两侧环境及居民健康影响,依据声源,环境噪声等固定标准,对４个铁路运行区段进行了调查。     

天津铁路辖区某车轮车间生产性噪声分析

目的通过对天津铁路辖区某车轮车间生产性噪声特点进行分析,确定该车轮车间噪声重点关注岗位,为该企业进行噪声治理、保护工人健康提供依据。方法采用职业卫生现场调查法于2018年9月识别该车轮车间噪声作业岗位,根据国家相关标准对上述作业岗位进行检测,根据噪声作业8 h等效声级测定结果,确定噪声危害作业级别。结果现场调查显示,某车轮车间噪声作业点超标率为9.8%,存在2个轻度危害作业点,1个中度危害作业点,1个重度危害作业点。结论某车轮车间的噪声状况应引起用人单位高度重视,针对存在噪声隐患的作业点应及时为生产工人配备相应噪声防护用品,保障作业人员听力安全。     

Subcutaneous tunneling technique to improve outcomes for patients undergoing chemotherapy with peripherally inserted central catheters: a randomized controlled trial

ObjectiveTo compare the value of the subcutaneous tunneling technique versus the normal technique in improving the outcomes of patients undergoing chemotherapy with peripherally inserted central catheters (PICCs).MethodsOne hundred thirty patients were randomly divided into an experimental group (subcutaneous tunneling technique) and control group (normal technique) according to the PICC placement technique, and clinical data were compared between the groups.ResultsIn total, 129 PICCs were successfully inserted. Compared with the control group, the experimental group had a lower occurrence of complications after placement (especially catheter dislodgement: 3.1% vs. 15.4%, venous thrombosis: 3.1% vs. 15.4%, and wound oozing: 14.1% vs. 27.7%), lower occurrence of unscheduled PICC removal (3.1% vs. 13.8%), greater comfort during placement (14.16 ± 2.21 vs. 15.09 ± 2.49 on a scale ranging from 6 to 30 points, with higher scores indicating lower degrees of comfort), and lower costs of PICC maintenance (median (interquartile range) per-day maintenance cost: 13.90 (10.99–32.83) vs. 15.69 (10.51–57.46) Yuan). The occurrence of complications and amount of bleeding during placement were not significantly different between the two groups.ConclusionsThe subcutaneous tunneling technique can improve PICC placement by reducing complications and costs of maintenance with better patient comfort during placement.     

Switchable hardening of a ferromagnet at fixed temperature

The intended use of a magnetic material, from information storage to power conversion, depends crucially on its domain structure, traditionally crafted during materials synthesis. By contrast, we show that an external magnetic field, applied transverse to the preferred magnetization of a model disordered uniaxial ferromagnet, is an isothermal regulator of domain pinning. At elevated temperatures, near the transition into the paramagnet, modest transverse fields increase the pinning, stabilize the domain structure, and harden the magnet, until a point where the field induces quantum tunneling of the domain walls and softens the magnet. At low temperatures, tunneling completely dominates the domain dynamics and provides an interpretation of the quantum phase transition in highly disordered magnets as a localization/delocalization transition for domain walls. While the energy scales of the rare earth ferromagnet studied here restrict the effects to cryogenic temperatures, the principles discovered are general and should be applicable to existing classes of highly anisotropic ferromagnets with ordering at room temperature or above.     

The Micropillar Structure on Silk Fibroin Film Influence Intercellular Connection Mediated by Nanotubular Structures

Tunneling nanotubes are important membrane channels for cell-to-cell communication. In this study, we investigated the effect of the microenvironment on nanotubular structures by preparing a three-dimensional silk fibroin micropillar structure. In previous reports, tunneling nanotubes were described as stretched membrane channels between interconnected cells at their nearest distance. They hover freely in the cell culture medium and do not contact with the substratum. Interestingly, the micropillars could provide supporting points for nanotubular connection on silk fibroin films, where nanotubular structure formed a stable anchor at contact points. Consequently, the extension direction of nanotubular structure was affected by the micropillar topography. This result suggests that the hovering tunneling nanotubes in the culture medium will come into contact with the raised roadblock on the substrates during long-distance extension. These findings imply that the surface microtopography of biomaterials have an important influence on cell communication mediated by tunneling nanotubes.     

车站客运人员健康素养现状调查及其影响因素分析

目的了解车站客运人员健康素养现状及其影响因素,为以后开展有针对性的卫生相关工作提供依据。方法采用《中国公民健康素养调查问卷》对车站客运人员进行调查。结果车站客运人员健康素养合格率为6.49%,其中基本知识和健康理念、健康生活方式与行为、健康技能具备率分别为40.54%、70.00%、89.19%。干部健康素养水平高于其它岗位职工(χ2=5.29,P0.05),大专学历以上职工健康素养水平高于大专以下职工(χ2=5.27,P0.05)。结论车站客运人员健康素养总体水平与各省市调查结果相当,健康素养水平受到性别、年龄、婚姻、文化程度等因素的影响,培训可以较快提高健康技能,但健康理念、健康生活方式与行为的改变可能需要较长时间。     

Moiréless correlations in ABCA graphene

Atomically thin van der Waals materials stacked with an interlayer twist have proven to be an excellent platform toward achieving gate-tunable correlated phenomena linked to the formation of flat electronic bands. In this work we demonstrate the formation of emergent correlated phases in multilayer rhombohedral graphene––a simple material that also exhibits a flat electronic band edge but without the need of having a moiré superlattice induced by twisted van der Waals layers. We show that two layers of bilayer graphene that are twisted by an arbitrary tiny angle host large (micrometer-scale) regions of uniform rhombohedral four-layer (ABCA) graphene that can be independently studied. Scanning tunneling spectroscopy reveals that ABCA graphene hosts an unprecedentedly sharp van Hove singularity of 3–5-meV half-width. We demonstrate that when this van Hove singularity straddles the Fermi level, a correlated many-body gap emerges with peak-to-peak value of 9.5 meV at charge neutrality. Mean-field theoretical calculations for model with short-ranged interactions indicate that two primary candidates for the appearance of this broken symmetry state are a charge-transfer excitonic insulator and a ferrimagnet. Finally, we show that ABCA graphene hosts surface topological helical edge states at natural interfaces with ABAB graphene which can be turned on and off with gate voltage, implying that small-angle twisted double-bilayer graphene is an ideal programmable topological quantum material.

Two-dimensional (2D) van der Waals heterostructures with an interlayer twist have provided a new avenue for observing emergent tunable many-body electron phenomena. Recent experimental realizations include twisted bilayer graphene (tBG) near the so-called “magic angle” of 1.1° (1–3), twisted double-bilayer graphene (tDBG) (4–6), ABC trilayer graphene on near-perfectly aligned hexagonal boron nitride (hBN) (ABC-tLG/hBN) (7, 8) and transition-metal dichalcogenide heterostructures (9–12) [with predictions on a variety of other systems (13, 14)]. All of these systems host an interplay of two phenomena––the presence of one or more van Hove singularities (which we colloquially refer to as “flat bands” henceforth) at low energy where the density of states is sharply peaked, and the existence of a moiré pattern that creates a unit cell that is about a hundred times larger than the carbon–carbon nearest-neighbor distance in graphene. The large number of electrons with quenched kinetic energy make the flat bands conducive to interaction-driven phases (15). The enlarged moiré unit cell is thought to reduce both the flat-band bandwidth and the interaction energy scales, and also introduces easily accessible integer fillings that create Mott-like insulating states (1–12), the relation of which to nearby superconductivity is debated. A natural question that arises from all of these works is whether the moiré pattern is a necessary condition for the observation of correlated many-body phases, or whether it is simply sufficient to further reduce the flat-band bandwidth and hence the kinetic energy in the heterostructure.In this regard, multilayer rhombohedral (ABC) graphene offers a different perspective toward achieving a flat-band edge without the use of a moiré potential (16). Indeed, in a seminal work (17), it was theoretically shown that the low-energy band structure of multilayer rhombohedral graphene has a sharply peaked density of state (DOS), with the band structure E(k)∝kN (where N is the number of layers) at low energy in the nearest-neighbor hopping approximation. This implies a peak in the DOS at charge neutrality in this material for N>2, with an appreciable fraction of the entire band within this peak (18). Indeed, this physics is already at play in ABC-tLG/hBN (7, 8), where some of the flatness of the bands comes from the intrinsic band structure of ABC graphene, which is then further flattened and isolated by the moiré pattern from the hBN alignment. A facile alternative to flatten the bandwidth without introducing a moiré potential is to simply increase the number of layers of the rhombohedral stacked graphene. Unfortunately, isolating rhombohedral stacked graphene of any thickness is extremely difficult as it is less energetically favorable than the multilayer counterpart, Bernal stacked graphene. Since the difference between rhombohedral and Bernal graphene is simply a lattice shift, and the interlayer van der Waals forces are weak, it is well known that rhombohedral graphene reverts to the Bernal form when samples are processed with heat, pressure, or while performing lithography (19). In this work, we show that twisting two sheets of tDBG by a tiny (<0.1°) angle is a simple and robust method to create large area (up to micrometer-scale) rhombohedral graphene of four-layer thickness (ABCA graphene). We present gate-tunable scanning tunneling microscopy and spectroscopy (STM/STS) measurements at 5.7 K on these regions. We show that correlated phases can be achieved without the need for a moiré pattern and that rhombohedral graphene has unique topological properties.     

Endoscopic resection of benign esophageal schwannoma: Three case reports and review of literature

BACKGROUNDEsophageal schwannomas are uncommon esophageal submucosal benign tumors and are usually treated with surgery. CASE SUMMARYHere, we report three cases of middle/lower thoracic esophageal schwannoma treated successfully with endoscopic resection. These lesions were misdiagnosed as leiomyoma on preoperative imaging. During the endoscopic resection of such tumors, there is a risk of esophageal perforation due to their deep location. If possible, submucosal tunneling endoscopic resection should be used. CONCLUSIONFor larger schwannomas, endoscopy combined with thoracoscopy can be considered for en bloc resection. We performed a mini literature review in order to present the current status of diagnosis and treatment for esophageal schwannoma.