Primary production during nutrient-induced blooms at elevated CO2 concentrations

Mesocosms experiments (PeECE II and PeECE III) were carried out in 9 transparent mesocosms. Prior to the experimental period, the seawater carbonate system was manipulated to achieve three different levels of CO2. At the onset of the experimental period, nutrients were added to all mesocosms in order to initiate phytoplankton blooms. Rates of primary production were measured by in-situ incubations using 14C-incorporation and oxygen production/consumption. Particulate primary production by 14C was also size fractionated and compared with phytoplankton species composition. Nutrient supply increased the primary production rates, and a net autotrophic phase with 14C-fixation rates up to 4 times higher than initial was observed midway through the 24 days experiment before net community production returned to near-zero and 14C-fixation rates relaxed back to lower than initial. We found a trend in the 14C-based measurements towards higher cumulative primary production at higher pCO2, consistent with recently published results for DIC removal (Riebesell et al., 2007). There where found differences to the size fractionated primary production response to CO2 treatments. The plankton composition changes throughout the bloom, however, resulted in no significant response until the final phase of the experiment where phytoplankton growth became nutrient limited, and phytoplankton community changed from diatom to flagellate dominance. This opens for the two alternative hypotheses that such an effect is associated with mineral nutrient limited growth, and/or with phytoplankton species composition. The lack of a clear net heterotrophic phase in the last part of the experiment supports the idea that a substantial part of production in the upper layer was not degraded locally, but either accumulated there or was exported vertically

Comparison of Radiation Exposure During Thoracolumbar Fusion Using Fluoroscopic Guidance versus Anatomic Placement of Pedicle Screws

Introduction: There are multiple accepted surgical techniques for placing thoracolumbar pedicle screws. Some surgeons use fluoroscopy to aid in placement of instrumentation, while others use fluoroscopy as confirmation of positioning after anatomic placement of screws. The purpose of this study is to evaluate the difference in radiation exposure imparted to the patient using a fluoroscopic-guided technique versus anatomic placement of screws. Methods: A retrospective study evaluated 185 adult patients with non-percutaneous, posterior instrumented fusions over a four-year time period. For each patient, the fluoroscopy report was reviewed and the method of fluoroscopy utilization was ascertained from the patient’s operative report. Average seconds per screw inserted for each method was compared using a student’s t-test. Results: 82 patients underwent thoracolumbar fusion by an anatomic technique, with an average of 5.72 screws (range 2-26) placed. The mean fluoroscopy time was 11.85 seconds (median 6 sec.) and the average time for placement of a single screw was 2.65 seconds. 103 patients underwent fluoroscopic-guided surgery. An average of 5.1 screws (range 2-12) were placed and the mean fluoroscopy time was 83.26 seconds per operation. The average time for placement of a single screw was 17.08 seconds. Conclusion: Patients undergoing thoracolumbar fusion using the fluoroscopic-guided technique have increased radiation exposure, reaching 6.5 times the amount imparted using an anatomic technique, which is statistically significant (p\u3c0.01). Surgeons performing a large number of fluoroscopic-guided operations may have the potential to exceed annual radiation dose limits

Hemihepatectomy and Replacement of The Afferent Hepatic Blood Supply in The Dog

Hemihepatectomy along with portal vein or hepatic artery replacement in dogs was well tolerated, but combined with replacement of both vessels it was lethal because of outflow block and shock. Total liver blood flow should be kept as high as possible during such procedures in man

Predictors of Improved Pain, Quality of Life, and Physical Function after Surgical Treatment of Lumbar Spinal Stenosis

Introduction: Degenerative lumbar stenosis is common in adults and is frequently managed by surgical intervention after non-operative measures fail to relieve pain. Limited evidence-based information regarding optimal selection of patients for surgery exists. Current reform in healthcare policy has sparked significant interest in comparative effectiveness research with the goal of optimizing treatment strategies for common conditions such as degenerative lumbar stenosis. The purpose of this study is to quantify the effectiveness of surgical treatment of lumbar stenosis and to identify patient predictors of greatest improvement using patient reported measures of pain, physical function and quality of life. Methods: A retrospective study evaluated 229 adult patients who underwent decompression with or without posterior lumbar fusion for treatment of lumbar stenosis over a two year time period. Patient reported outcomes were measured using the SF36 health survey. 146 patients had 6 month follow-up and 106 patients had one year follow-up. Variations in scores of the SF36 pain, mental component summary (MCS), and physical component summary (PCS) subscales were analyzed by multivariate linear regression analysis. Results: At 6-12 months post-surgery, patients reported an improvement of 8 points in average pain (32.3 to 40.4), physical function (28.6 to 36.9), and PCS (29.0 to 36.9) subscales of the SF36. There was a 6 point average improvement in MCS scores (41.8 to 48.10). Greater post-operative pain was significantly associated with smoking (p In regards to improvements in quality of life, older age (p Conclusion: In general, surgical treatment for lumbar stenosis improves patient pain, quality of life, and physical function as indicated by substantial improvement in all subscales of the SF36 health survey. Predictive factors associated with poor pain relief after surgery include smoking, diabetes, the presence of instrumentation, and re-operation within a 12 month time period. Higher MCS scores are seen in older patients and those with an increase in physical function post-operatively. Predictive factors for poor MCS scores include revision surgery and mental health diagnosis. No specific predictors of PCS score were identified, most likely due to the complicated nature of the patient population with lumbar spinal stenosis. Further work is necessary to determine the ideal surgical candidate

Build-up and decline of organic matter during PeECE III

Increasing atmospheric carbon dioxide (CO2) concentrations due to anthropogenic fossil fuel combustion are currently changing the ocean's chemistry. Increasing oceanic [CO2] and consequently decreasing seawater pH have the potential to significantly impact marine life. Here we describe and analyze the build-up and decline of a natural phytoplankton bloom initiated during the 2005 mesocosm Pelagic Ecosystem CO2 Enrichment study (PeECE III). The draw-down of inorganic nutrients in the upper surface layer of the mesocosms was reflected by a concomitant increase of organic matter until day t11, the peak of the bloom. From then on, biomass standing stocks steadily decreased as more and more particulate organic matter was lost into the deeper layer of the mesocosms. We show that organic carbon export to the deeper layer was significantly enhanced at elevated CO2. This phenomenon might have impacted organic matter remineralization leading to decreased oxygen concentrations in the deeper layer of the high CO2 mesocosms as indicated by deep water ammonium concentrations. This would have important implications for our understanding of pelagic ecosystem functioning and future carbon cycling

Necrotising fasciitis of the shoulder in association with rheumatoid arthritis treated with etanercept: a case report

<p>Abstract</p> <p>Introduction</p> <p>Necrotising fasciitis is a severe infection characterised by the fulminant destruction of tissue with associated systemic signs of sepsis and toxicity. Etanercept is a fully human fusion protein that inhibits tumor necrosis factor and the inflammatory cascade. It is effective in the treatment of many disorders but concerns regarding severe life threatening infections have been raised in multiple reports.</p> <p>Case presentation</p> <p>We present the case of a 39-year-old Caucasian man, who presented with sudden onset of severe and progressive neck and left shoulder pain, with a two-year history of seronegative rheumatoid arthritis treated with azathoprine and etanercept. On examination the left side of his neck and his left shoulder were oedematous, tender with an erythematous rash and his active range of movement was limited. Magnetic resonance imaging of his shoulder showed extensive oedema of the subcutaneous and intramuscular fat of the left lower neck consistent with fasciitis. He was treated medically and made a good recovery.</p> <p>Conclusion</p> <p>Our patient, while having a pre-existing increased mortality risk, had a serious infection which responded well to optimum medical treatment without the need for surgery. As anti tumor necrosis factor agents are frequently associated with infection, including tuberculous infection, this case highlights the need for a high index of suspicion for other severe bacterial infections in patients on immunosuppressants.</p

High export of dissolved silica from the Greenland Ice Sheet

Silica is an essential element for marine life and plays a key role in the biogeochemistry of the ocean. Glacial activity stimulates rock weathering, generating dissolved silica that is exported to coastal areas along with meltwater. The magnitude of the dissolved silica export from large glacial areas such as the Greenland Ice Sheet is presently poorly quantified and not accounted for in global budgets. Here we present data from two fjord systems adjacent to the Greenland Ice Sheet which reveal a large export of dissolved silica by glacial meltwater relative to other macronutrients. Upscaled to the entire Greenland Ice Sheet, the export of dissolved silica equals 22 ± 10 Gmol Si yr−1. When the silicate-rich meltwater mixes with upwelled deep water, either inside or outside Greenland's fjords, primary production takes place at increased silicate to nitrate ratios. This likely stimulates the growth of diatoms relative to other phytoplankton groups

Blood volume measurement with indocyanine green pulse spectrophotometry: dose and site of dye administration

(1) To determine the optimal administration site and dose of indocyanine green (ICG) for blood volume measurement using pulse spectrophotometry, (2) to assess the variation in repeated blood volume measurements for patients after subarachnoid hemorrhage and (3) to evaluate the safety and efficacy of this technique in patients who were treated for an intracranial aneurysm. Four repeated measurements of blood volume (BV) were performed in random order of bolus dose (10 mg or 25 mg ICG) and venous administration site (peripheral or central) in eight patients admitted for treatment of an intracranial aneurysm. Another five patients with subarachnoid hemorrhage underwent three repeated BV measurements with 25 mg ICG at the same administration site to assess the coefficient of variation. The mean +/- SD in BV was 4.38 +/- 0.88 l (n = 25) and 4.69 +/- 1.11 l (n = 26) for 10 mg and 25 mg ICG, respectively. The mean +/- SD in BV was 4.59 +/- 1.15 l (n = 26) and 4.48 +/- 0.86 l (n = 25) for central and peripheral administration, respectively. No significant difference was found. The coefficient of variance of BV measurement with 25 mg of ICG was 7.5% (95% CI: 3-12%). There is no significant difference between intravenous administration of either 10 or 25 mg ICG, and this can be injected through either a peripheral or central venous catheter. The 7.5% coefficient of variation in BV measurements determines the detectable differences using ICG pulse spectrophotometr

Simulating MADMAX in 3D: Requirements for dielectric axion haloscopes

We present 3D calculations for dielectric haloscopes such as the currently envisioned MADMAX experiment. For ideal systems with perfectly flat, parallel and isotropic dielectric disks of finite diameter, we find that a geometrical form factor reduces the emitted power by up to 30 % compared to earlier 1D calculations. We derive the emitted beam shape, which is important for antenna design. We show that realistic dark matter axion velocities of 10-3 c and inhomogeneities of the external magnetic field at the scale of 10 % have negligible impact on the sensitivity of MADMAX. We investigate design requirements for which the emitted power changes by less than 20 % for a benchmark boost factor with a bandwidth of 50 MHz at 22 GHz, corresponding to an axion mass of 90 µ eV. We find that the maximum allowed disk tilt is 100 µ m divided by the disk diameter, the required disk planarity is 20 µ m (min-to-max) or better, and the maximum allowed surface roughness is 100 µ m (min-to-max). We show how using tiled dielectric disks glued together from multiple smaller patches can affect the beam shape and antenna coupling. © 2021 The Author(s)