Dynamics of Hyporheic Flow and Heat Transport Across a Bed-to-Bank Continuum in a Large Regulated River

The lower Colorado River (LCR) near Austin, Texas is heavily regulated for hydropower generation. Daily water releases from a dam located 23 km upstream of our study site in the LCR caused the stage to fluctuate by more than 1.5 m about a mean depth of 1.3 m. As a result, the river switches from gaining to losing over a dam storage-release cycle, driving exchange between river water and groundwater. We assessed the hydrologic impacts of this by simultaneous temperature and head monitoring across a bed-to-bank transect. River-groundwater exchange flux is largest close to the bank and decreases away from the bank. Correspondingly, both the depth of the hyporheic zone and the exchange time are largest close to the bank. Adjacent to the bank, the streambed head response is hysteretic, with the hysteresis disappearing with distance from the bank, indicating that transient bank storage affects the magnitude and direction of vertical exchange close to the bank. Pronounced changes in streambed temperature are observed down to a meter. When the river stage is high, which coincides with when the river is coldest, downward advection of heat from a previous cycles\u27 warm-water pulse warms the streambed. When the river is at its lowest stage but warmest temperature, upwelling groundwater cools the streambed. Future research should consider and focus on a more thorough understanding of the impacts of dam regulation on the hydrologic, thermal, biogeochemical, and ecologic dynamics of rivers and their hyporheic and riparian zones

Is tension band wiring technique the "gold standard" for the treatment of olecranon fractures? A long term functional outcome study

<p>Abstract</p> <p>Background</p> <p>Tension band wiring (TBW) remains the most common operative technique for the internal fixation of olecranon fractures despite the potential occurrence of subjective complaints due to subcutaneous position of the hardware. Aim of this long term retrospective study was to evaluate the elbow function and the patient-rated outcome after TBW fixation of olecranon fractures.</p> <p>Methods</p> <p>We reviewed 62 patients (33 men and 29 women) with an average age of 48.6 years (range, 18–85 years) who underwent TBW osteosynthesis for isolated olecranon fractures. All patients were assessed both clinically with measurement of flexion-extension and pronation-supination arcs and radiologically with elbow X-Rays. Functional outcome was estimated using the Mayo Elbow Performance Score (MEPS), Visual Analogue Scale (VAS) subjective pain score and VAS patient satisfaction score. Follow up: 6–13 years (average 8.2 years).</p> <p>Results</p> <p>There was a higher prevalence of fractures among men until the 5th decade of life and among women in elderly (p = 0.032). Slip or simple fall onto the arm was the main mechanism of injury for 38 fractures (61.3%) while high energy trauma, such as fall from a height (> 2 m) or road accident, was reported in 24 fractures (38.7%). Hardware removal performed in 51 patients (82.3%) but 34 of them (66.6% of removals) were still complaining for mild pain during daily activities. The incidence of pin migration and loosening was not statistically decreased when penetration of the anterior ulnar cortex was accomplished (p = 0.304). Supination was more often affected than pronation (p = 0.027). According to MEPS, 53 patients (85.5%) had a good to excellent result, 6 (9.7%) fair and 3 (4.8%) poor result. The average satisfaction rating was 9.3 out of 10 (range, 6–10) with 31 patients (50%) to remain completely satisfied from the final result. Degenerative changes recorded in 30 elbows (48.4%). However, no correlation could be found between radiographic findings and MEPS (p = 0.073).</p> <p>Conclusion</p> <p>Tension band wiring fixation remains the "gold standard" for the treatment of displaced and minimally comminuted olecranon fractures. In long term, low levels of pain may be evident regardless of whether the metalware is removed and degenerative changes have been developed.</p

Self-reported concussion history: impact of providing a definition of concussion.

BackgroundIn recent years, the understanding of concussion has evolved in the research and medical communities to include more subtle and transient symptoms. The accepted definition of concussion in these communities has reflected this change. However, it is unclear whether this shift is also reflected in the understanding of the athletic community.What is known about the subjectSelf-reported concussion history is an inaccurate assessment of someone's lifetime exposure to concussive brain trauma. However, unfortunately, in many cases it is the only available tool.Hypothesis/purposeWe hypothesize that athletes' self-reported concussion histories will be significantly greater after reading them the current definition of concussion, relative to the reporting when no definition was provided. An increase from baseline to post-definition response will suggest that athletes are unaware of the currently accepted medical definition.Study designCross-sectional study of 472 current and former athletes.MethodsInvestigators conducted structured telephone interviews with current and former athletes between January 2010 and January 2013, asking participants to report how many concussions they had received in their lives. Interviewers then read participants a current definition of concussion, and asked them to re-estimate based on that definition.ResultsTHE TWO ESTIMATES WERE SIGNIFICANTLY DIFFERENT (WILCOXON SIGNED RANK TEST: z=15.636, P&lt;0.001). Comparison of the baseline and post-definition medians (7 and 15, respectively) indicated that the post-definition estimate was approximately twice the baseline. Follow-up analyses indicated that this effect was consistent across all levels of competition examined and across type of sport (contact versus non-contact).ConclusionOur results indicate that athletes' current understandings of concussions are not consistent with a currently accepted medical definition. We strongly recommend that clinicians and researchers preface requests for self-reported concussion history with a definition. In addition, it is extremely important that researchers report the definition they used in published manuscripts of their work.What this study adds to existing knowledgeOur study shows that unprompted reporting of concussion history produces results that are significantly different from those provided after a definition has been given, suggesting one possible mechanism to improve the reliability of self-reported concussion history across multiple individuals

Paediatric endoscopic endonasal dacryocystorhinostomy in congenital nasolacrimal duct obstruction

The original publication can be found at www.springerlink.comObjectives The objectives of this study were to report a series of paediatric patients who underwent endoscopic endonasal dacryocystorhinostomy (DCR) for primary congenital nasolacrimal duct obstruction (NLDO). Methods This is a retrospective, noncomparative review of all consecutive cases in two lacrimal clinics between January 1999 and October 2004. The main outcome measures were patients’ demographics, previous treatments, clinical presentation, operative and postoperative complications, postoperative follow-up and resolution of epiphora. Results Twenty-one patients (15 males) with a mean age of 6±3.5 years (range, 2–14 years) underwent 26 endoscopic DCR operations for congenital NLDO. Sixteen cases were unilateral, and five were bilateral. In 13 cases (50.0%), there was a history of epiphora and chronic dacryocystitis with or without a mucocele. Two cases (7.7%) presented with acute dacryocystitis, and 11 (42.3%) had only a history of epiphora. Previous procedures included probing and irrigation in 25 cases (96.2%) and insertion of Crawford tubes in 19 cases 973.1%). During a mean postoperative follow-up period of 18±8 months, the anatomical success rate (free flow of fluorescein sodium and patency of ostium on nasal endoscopy) was 100%, and the clinical success rate (resolution of epiphora) was 92.3%. Conclusion Endoscopic endonasal DCR is an effective treatment modality for congenital NLDO that compares favourably with the reported success rates of external DCR.Igal Leibovitch, Dinesh Selva, Angelo Tsirbas, Edward Greenrod, John Pater and Peter J. Wormal

Leveraging football accelerometer data to quantify associations between repetitive head impacts and chronic traumatic encephalopathy in males

Abstract Chronic traumatic encephalopathy (CTE) is a neurodegenerative tauopathy associated with repetitive head impacts (RHI), but the components of RHI exposure underlying this relationship are unclear. We create a position exposure matrix (PEM), composed of American football helmet sensor data, summarized from literature review by player position and level of play. Using this PEM, we estimate measures of lifetime RHI exposure for a separate cohort of 631 football playing brain donors. Separate models examine the relationship between CTE pathology and players’ concussion count, athletic positions, years of football, and PEM-derived measures, including estimated cumulative head impacts, linear accelerations, and rotational accelerations. Only duration of play and PEM-derived measures are significantly associated with CTE pathology. Models incorporating cumulative linear or rotational acceleration have better model fit and are better predictors of CTE pathology than duration of play or cumulative head impacts alone. These findings implicate cumulative head impact intensity in CTE pathogenesis