Slowing down as an early warning signal for abrupt climate change

In the Earth's history, periods of relatively stable climate have often been interrupted by sharp transitions to a contrasting state. One explanation for such events of abrupt change is that they happened when the earth system reached a critical tipping point. However, this remains hard to prove for events in the remote past, and it is even more difficult to predict if and when we might reach a tipping point for abrupt climate change in the future. Here, we analyze eight ancient abrupt climate shifts and show that they were all preceded by a characteristic slowing down of the fluctuations starting well before the actual shift. Such slowing down, measured as increased autocorrelation, can be mathematically shown to be a hallmark of tipping points. Therefore, our results imply independent empirical evidence for the idea that past abrupt shifts were associated with the passing of critical thresholds. Because the mechanism causing slowing down is fundamentally inherent to tipping points, it follows that our way to detect slowing down might be used as a universal early warning signal for upcoming catastrophic change. Because tipping points in ecosystems and other complex systems are notoriously hard to predict in other ways, this is a promising perspective.     

Intraductal papillary adenoma: Usefulness of magnetic resonance cholangiopancreatography in the diagnosis of cystic branch-duct dilatation of the pancreas

A 70-year-old woman with gastric cancer was referred to our hospital for further evaluation of a cystic mass in the head of the pancreas. Endoscopic ultrasonography (EUS) showed a mural nodule in the cystic mass. Endoscopic retrograde cholangio pancreatography (ERCP) revealed a cystic lesion with a filling defect caused by obstruction with mucus. Magnetic resonance cholangiopancreatography (MRCP) allowed visualization of the entire configuration of the cystic lesion despite the presence of mucus. Pancreatic juice was positive for K-ras point mutation. Pancreatoduodenectomy was performed, with a diagnosis of intraductal papillary adenoma or adenocarcinoma with gastric cancer. Pancreatography of the resected specimen showed a cystic lesion in the uncinate process, consistent with the MRCP findings. Histological examination revealed an intraductal papillary adenoma. MRCP is very useful for demonstrating the total configuration of cystic lesions and is not impeded by impacted mucin. Nevertheless, because of its lower spatial resolution, this noninvasive modality is of limited value in detecting mural nodules. At present, therefore, surgical indications for cystic lesion of the pancreas should be determined by comprehensively analyzing: size and sequential changes in size of the cyst; presence of mural nodules, cytologic examination for presence of malignant cells, and/or K-ras point mutation in pure pancreatic juice.     

不同参数督脉走罐对亚健康人体背部局部皮肤血流量影响的初步观察

[目的]通过观察不同参数督脉走罐对亚健康人体背部局部皮肤血流量影响及规律的变化,探讨走罐对机体阳气的影响。[方法]对20名亚健康成年人分别进行静息空白观察,以及罐压为-0.01~-0.02 MPa,走罐时间为5 min,罐压为-0.02~-0.03 MPa,走罐时间为5 min,罐压为-0.02~-0.03 MPa,走罐时间为3 min的督脉走罐,应用激光散斑血流监测视频系统监测上述不同干预方法对亚健康人体大椎穴、身柱穴及大椎与身柱连线的中点,在走罐后即刻、5、10、15、20、25、30 min穴区局部皮肤血流量的变化。[结果]走罐后皮肤局部血流量升高(P<0.05),随时间延长血流量逐渐降低。不同参数督脉走罐对局部血流量的影响差异无统计学意义(P>0.05),但压力较大或刺激时间较长时,血流量的变化反而较小。3个观察点在静息状态下血流量随时间变化差异无统计学意义(P>0.05),但相同压力刺激时大椎穴与身柱穴从走罐后15 min起,血流量存在区别,且走罐后大椎穴变化幅度大,身柱穴维持高峰时间长。[结论]1)不同的走罐方法对督脉阳气的调节是不同的。2)走罐后皮肤局部血流量增加,机体阳气功能增强。3)穴位具有特异性。     

中国针灸腧穴与尼泊尔传统医学生命点的对比研究

中国和尼泊尔的传统医学理论体系都有悠久的历史, 且两者的治疗手段都源自相同的哲学和理论基础。在使用自然疗法治疗疾病的过程中, 两种医疗体系均提出了人体的重要位置点的理论, 即中医的经络腧穴理论和尼泊尔传统医学中的生命点理论。初步将中国针灸腧穴以及尼泊尔传统医学中的生命点的进行对比研究, 为今后两者的结合应用提供依据。     

穴位注射、针刺结合康复训练对痉挛型小儿脑瘫的临床观察

目的：观察研究穴位注射、针刺结合康复训练对痉挛型小儿脑瘫的临床效果。方法选取2009年7月—2013年7月该院收治并确诊的84例痉挛性小儿脑瘫患儿作为研究对象,并随机分为观察组和对照组各42例。对照组患儿进行传统康复训练,观察组患儿在对照组基础上结合穴位注射、针刺治疗,6个月后比较临床疗效。结果观察组患儿总有效率为92.86%,明显高于对照组的57.14%的有效率,差异有统计学意义（P＜0.05）;观察组患儿治疗后的关节活动度、痉挛程度、以及步行能力相对于对照组均有显著疗效（P＜0.05）。结论穴位注射、针刺结合康复训练能有效改善痉挛型脑瘫患儿关节活动度、减少患儿痉挛发作,且增强患儿的步行能力,疗效显著。     

黄芪足三里穴位注射治疗急性胰腺炎并发肠麻痹的临床随机对照研究

目的 评价黄芪足三里穴位注射治疗急性胰腺炎并发肠麻痹的疗效.方法 204例符合纳入标准的急性胰腺炎患者按随机数字表分为A、B和C组.A组患者给予禁食、胃肠减压、抑制胰酶活性药物、抗感染、营养支持、中药汤剂管喂及灌肠等基础治疗.B组在基础治疗上加用生理盐水穴位注射;C组在基础治疗上加用黄芪注射液穴位注射.比较3组患者肠道功能恢复、治疗总有效率、住院时间、中转手术率和死亡率等情况.结果 C组肛门排气时间和排便时间以及肠鸣音恢复时间与A、B两组比较均缩短,组间差异有统计学意义(P＜0.05).C组总有效率高于A、B组,组间差异有统计学意义(P＜0.05).C组住院时间较A、B组短,组间差异有统计学意义(P＜0.05).C组的中转手术率、多器官衰竭发生率和死亡率均低于A、B组,但组间差异无统计学意义(P＞0.05).结论 黄芪足三里穴位注射治疗胰腺炎能缩短患者的肛门排气时间、肛门排便时间及肠鸣音恢复时间,促进肠道功能的恢复,改善肠麻痹;能提高胰腺炎治疗的总体有效率,缩短患者住院时间.     

艾灸神阙穴辅助宫缩药治疗宫缩乏力性产后出血的临床观察

目的：观察艾灸神阙穴辅助宫缩药治疗宫缩乏力性产后出血的临床疗效。方法将纳入研究的137例患者随机分为观察组（74例）和对照组（63例）,对照组给予西医常规宫缩药物,观察组在常规西医治疗的基础上给予隔盐灸神阙。1 d之后统计观察两组患者2 h和24 h出血量,以及分娩前后血细胞分析。结果两组孕妇治疗后,观察组24 h出血量少于对照组24 h,两组24 h出血量比较差异有显著性（P＜0．05）,且治疗后持续出血观察组少于对照组,比较差异有显著性意义（P＜0．05）;治疗后,观察组与对照组比较红细胞计数（RBC）、血红蛋白（Hb）、红细胞压积（HCT）差异均有显著性（P均＜0．05）。结论艾灸神阙穴辅助宫缩药治疗宫缩乏力性产后出血疗效确切,值得推广。     

Gas Exchange and Ventilatory Efficiency During Exercise in Pulmonary Vascular Diseases

Background and ObjectiveVentilatory inefficiency (high V′_E/V′CO₂) and resting hypocapnia are common in pulmonary vascular disease and are associated with poor prognosis. Low resting PaCO₂ suggests increased chemosensitivity or an altered PaCO₂ set-point. We aimed to determine the relationships between exercise gas exchange variables reflecting the PaCO₂ set-point, exercise capacity, hemodynamics and V′_E/V′CO₂.MethodsPulmonary arterial hypertension (n = 34), chronic thromboembolic pulmonary hypertension (CTEPH, n = 19) and pulmonary veno-occlusive disease (PVOD, n = 6) patients underwent rest and peak exercise arterial blood gas measurements during cardiopulmonary exercise testing. Patients were grouped according to resting PaCO₂: hypocapnic (PaCO₂ ≤34 mmHg) or normocapnic (PaCO₂ 35–45 mmHg). The PaCO₂ set-point was estimated by the maximal value of end-tidal PCO₂ (maximal P_ETCO₂) between the anaerobic threshold and respiratory compensation point.ResultsThe hypocapnic group (n = 39) had lower resting cardiac index (3.1 ±0.8 vs. 3.7 ±0.7 L/min/m², p < 0.01), lower peak V′O₂ (15.8 ± 3.5 vs. 20.7 ± 4.3 mL/kg/min, p < 0.01), and higher V′_E/V′CO₂ slope (60.6 ± 17.6 vs. 38.2 ± 8.0, p < 0.01). At peak exercise, hypocapic patients had lower PaO₂, higher V_D/V_T and higher P_(a-ET)CO₂. Maximal P_ETCO₂ (r = 0.59) and V_D/V_T (r = −0.59) were more related to cardiac index than PaO₂ or PaCO₂ at rest or peak exercise. Maximal P_ETCO₂ was the strongest correlate of V′_E/V′CO₂ slope (r = −0.86), peak V′O₂ (r = 0.64) and peak work rate (r = 0.49).ConclusionsResting hypocapnia is associated with worse cardiac function, more ventilatory inefficiency and reduced exercise capacity. This could be explained by elevated chemosensitivity and lower PaCO₂ set-point. Maximal P_ETCO₂ may be a useful non-invasive marker of PaCO₂ setpoint and disease severity even with submaximal effort.     

Foraging trade-offs,flagellar arrangements,and flow architecture of planktonic protists

Unicellular flagellated protists are a key element in aquatic microbial food webs. They all use flagella to swim and to generate feeding currents to encounter prey and enhance nutrient uptake. At the same time, the beating flagella create flow disturbances that attract flow-sensing predators. Protists have highly diverse flagellar arrangements in terms of number of flagella and their position, beat pattern, and kinematics, but it is unclear how the various arrangements optimize the fundamental trade-off between resource acquisition and predation risk. Here we describe the near-cell flow fields produced by 15 species and demonstrate consistent relationships between flagellar arrangement and swimming speed and between flagellar arrangement and flow architecture, and a trade-off between resource acquisition and predation risk. The flow fields fall in categories that are qualitatively described by simple point force models that include the drag force of the moving cell body and the propulsive forces of the flagella. The trade-off between resource acquisition and predation risk varies characteristically between flow architectures: Flagellates with multiple flagella have higher predation risk relative to their clearance rate compared to species with only one active flagellum, with the exception of the highly successful dinoflagellates that have simultaneously achieved high clearance rates and stealth behavior due to a unique flagellar arrangement. Microbial communities are shaped by trade-offs and environmental constraints, and a mechanistic explanation of foraging trade-offs is a vital part of understanding the eukaryotic communities that form the basis of pelagic food webs.

Unicellular flagellated protists play a key role in the biogeochemical cycles of the global ocean. Their photosynthetic activity and grazing on microbes are major processes in the microbial food web, and they may control the populations of bacteria and cyanobacteria (1). By being grazed, they transfer primary production to higher trophic levels (2–4). Thus, flagellates are both consumers and prey, but we do not understand how their resource acquisition trades off against predation mortality, or how this trade-off shapes their foraging behavior.In the low Reynolds number (Re) world of protists, viscosity impedes predator-prey contact. The physical mechanisms that nevertheless allow flagellates to daily clear a volume of water for prey that corresponds to approximately 10⁶ times their own cell volume (5, 6) are not well understood. Many marine flagellates are mixotrophic and can acquire resources both through photosynthesis and by eating other organisms (7). Their demand for inorganic mineral nutrients is also constrained by viscosity that retards the advective enhancement of diffusive uptake (8).To encounter prey and enhance advective transport of nutrients, protists may swim or create a feeding current through the beating of one or several flagella (9, 10). However, the beating of flagella produces fluid disturbances that exposes the flagellate to its rheotactic (flow-sensing) predators (11). Small flagellates are grazed by microzooplankton, many of which perceive their prey from the fluid disturbance that the prey generates (12, 13). Thus, there are fundamental foraging trade-offs. Such trade-offs are largely unexplored among the eukaryotic microbes that form the basis of aquatic food webs. This is crucial, because the diversity of microbial communities is determined by such trade-offs in concert with environmental constraints (14–17). Microbial diversity in turn governs the functionality and “services” of microbial communities, and hence also their role in ocean biogeochemistry (18, 19).Here we explore the trade-off between resource acquisition and predation risk in marine nanoflagellates and microflagellates by describing the flow fields produced by the action of their flagella. The quantification of near-cell feeding currents has been reported in only a few species of free-swimming protists (10, 20). The kinematics, wave patterns, and arrangement and number of flagella are highly diverse among flagellated protists (Fig. 1). Theoretical models suggest that the feeding currents and fluid signal generated by a swimming cell depends on the arrangement of the flagella (11, 13, 21, 22). We use microparticle image velocimetry (µPIV) to visualize and quantify the flow fields generated by free-swimming planktonic protists with diverse flagellar arrangements and beat patterns. We show how the different modes of swimming produce very different flow architectures and demonstrate a trade-off between resource acquisition and predation risk in flagellated protists.Open in a separate windowFig. 1.Schematic overview of the diverse flagellar arrangements and beat patterns represented in this study. Latin names below each taxonomic group indicate the species (or other taxonomic unit) examined. Flagellar hairs are drawn when feasible, but some flagellar morphologies (e.g., the dinoflagellates) are deliberately simplified (25, 63). Redrawn from several sources; not to scale.     

Accuracy and safety of dry needle placement in the piriformis muscle in cadavers

Objectives: The purpose of this anatomic investigation is to (1) establish accuracy of dry needle placement into the medial third of the piriformis muscle as it exits the pelvis from the greater sciatic notch in unembalmed cadaveric specimens, while avoiding puncture of the sciatic nerve, and (2) establish guidelines for dry needle length selection.

Methods: Dry needles were placed in nineteen unembalmed cadaveric posterior hips. Dissection of the posterior hip musculature was performed to confirm location of the needle. A binary decision (yes/no) was made to determine whether the needle reached the piriformis muscle, went through the piriformis muscle, and/or pierced the sciatic nerve. Additionally, mean adipose tissue thickness, gluteus maximus muscle thickness, and perpendicular distance from the needle to the exiting sciatic nerve were recorded.

Results: The needle reached the medial third of the piriformis in 16 out of 19 hips (84.2% accuracy) and never punctured the sciatic nerve. There was a fair (r = 0.493) and good (r = 0.759) correlation between the needle length and the mean fat thickness for the left and right hips, respectively.

Discussion: A physical therapist was able to use bony landmark palpation to locate the piriformis muscle and use estimated adipose tissue thickness to choose a sufficient needle length to reach the medial third of the piriformis muscle. While the needle placement technique was safe and no sciatic nerve puncture occurred, the proximity of the piriformis muscle to the sciatic nerve warrants caution during needle placement.

Level of Evidence: 2c