Ghost Factors of Laboratory Carbonate Chemistry Are Haunting Our Experiments.

AbstractFor many historical and contemporary experimental studies in marine biology, seawater carbonate chemistry remains a ghost factor, an uncontrolled, unmeasured, and often dynamic variable affecting experimental organisms or the treatments to which investigators subject them. We highlight how environmental variability, such as seasonal upwelling and biological respiration, drive variation in seawater carbonate chemistry that can influence laboratory experiments in unintended ways and introduce a signal consistent with ocean acidification. As the impacts of carbonate chemistry on biochemical pathways that underlie growth, development, reproduction, and behavior become better understood, the hidden effects of this previously overlooked variable need to be acknowledged. Here we bring this emerging challenge to the attention of the wider community of experimental biologists who rely on access to organisms and water from marine and estuarine laboratories and who may benefit from explicit considerations of a growing literature on the pervasive effects of aquatic carbonate chemistry changes.

First Observation of a Stable Highly Dissipative Divertor Plasma Regime on the Wendelstein 7-X Stellarator.

For the first time, the optimized stellarator Wendelstein 7-X has operated with an island divertor. An operation regime in hydrogen was found in which the total plasma radiation approached the absorbed heating power without noticeable loss of stored energy. The divertor thermography recorded simultaneously a strong reduction of the heat load on all divertor targets, indicating almost complete power detachment. This operation regime was stably sustained over several energy confinement times until the preprogrammed end of the discharge. The plasma radiation is mainly due to oxygen and is located at the plasma edge. This plasma scenario is reproducible and robust at various heating powers, plasma densities, and gas fueling locations. These experimental results show that the island divertor concept actually works and displays good power dissipation potential, producing a promising exhaust concept for the stellarator reactor line.

Tracer-Encapsulated Solid Pellet (TESPEL) injection system for Wendelstein 7-X.

Impurity confinement in fusion plasmas is mainly determined by transport mechanisms in the core region. For the Wendelstein 7-X stellarator, its island divertor is expected to screen effectively external impurity sources in the scrape-off layer at higher densities. However, the unique feature of Tracer-Encapsulated Solid Pellet (TESPEL) injection, releasing impurities at a well-localized radial position directly in the core plasma, enables investigating such transport mechanisms. This paper reports on the detailed design of a completely new TESPEL injection system, which has been designed by the National Institute for Fusion Science, Toki, Japan, and is currently being installed at Max-Planck-Institut für Plasmaphysik, Greifswald, Germany, for the Wendelstein 7-X. This injector consists of a storage and injection unit, attached to a system of guiding tubes which run through 3 successive differential pumping stages. A light-gate system and an optical observation system are used to determine the location of the deposited tracers. Laboratory tests carried out by shooting TESPELs onto a sample foil showed good performance after careful realignment of the guiding tubes.

Phased array Doppler reflectometry at Wendelstein 7-X.

A passive phased array Doppler reflectometry system has recently been installed in the Wendelstein-7X stellarator. In contrast to conventional Doppler reflectometry systems, the microwave beam can be steered on short time scales in the measurement plane perpendicular to the magnetic field in the range of ±25° without mechanical steering components. This paper characterizes the design and properties of the phased array antenna system and presents the first measurement results from the latest OP1.2a campaign.

Exposure history determines pteropod vulnerability to ocean acidification along the US West Coast.

The pteropod Limacina helicina frequently experiences seasonal exposure to corrosive conditions (Ωar < 1) along the US West Coast and is recognized as one of the species most susceptible to ocean acidification (OA). Yet, little is known about their capacity to acclimatize to such conditions. We collected pteropods in the California Current Ecosystem (CCE) that differed in the severity of exposure to Ωar conditions in the natural environment. Combining field observations, high-CO2 perturbation experiment results, and retrospective ocean transport simulations, we investigated biological responses based on histories of magnitude and duration of exposure to Ωar < 1. Our results suggest that both exposure magnitude and duration affect pteropod responses in the natural environment. However, observed declines in calcification performance and survival probability under high CO2 experimental conditions do not show acclimatization capacity or physiological tolerance related to history of exposure to corrosive conditions. Pteropods from the coastal CCE appear to be at or near the limit of their physiological capacity, and consequently, are already at extinction risk under projected acceleration of OA over the next 30 years. Our results demonstrate that Ωar exposure history largely determines pteropod response to experimental conditions and is essential to the interpretation of biological observations and experimental results.

Overview of diagnostic performance and results for the first operation phase in Wendelstein 7-X (invited).

Wendelstein 7-X, a superconducting optimized stellarator built in Greifswald/Germany, started its first plasmas with the last closed flux surface (LCFS) defined by 5 uncooled graphite limiters in December 2015. At the end of the 10 weeks long experimental campaign (OP1.1) more than 20 independent diagnostic systems were in operation, allowing detailed studies of many interesting plasma phenomena. For example, fast neutral gas manometers supported by video cameras (including one fast-frame camera with frame rates of tens of kHz) as well as visible cameras with different interference filters, with field of views covering all ten half-modules of the stellarator, discovered a MARFE-like radiation zone on the inboard side of machine module 4. This structure is presumably triggered by an inadvertent plasma-wall interaction in module 4 resulting in a high impurity influx that terminates some discharges by radiation cooling. The main plasma parameters achieved in OP1.1 exceeded predicted values in discharges of a length reaching 6 s. Although OP1.1 is characterized by short pulses, many of the diagnostics are already designed for quasi-steady state operation of 30 min discharges heated at 10 MW of ECRH. An overview of diagnostic performance for OP1.1 is given, including some highlights from the physics campaigns.

Confirmation of the topology of the Wendelstein 7-X magnetic field to better than 1:100,000.

Fusion energy research has in the past 40 years focused primarily on the tokamak concept, but recent advances in plasma theory and computational power have led to renewed interest in stellarators. The largest and most sophisticated stellarator in the world, Wendelstein 7-X (W7-X), has just started operation, with the aim to show that the earlier weaknesses of this concept have been addressed successfully, and that the intrinsic advantages of the concept persist, also at plasma parameters approaching those of a future fusion power plant. Here we show the first physics results, obtained before plasma operation: that the carefully tailored topology of nested magnetic surfaces needed for good confinement is realized, and that the measured deviations are smaller than one part in 100,000. This is a significant step forward in stellarator research, since it shows that the complicated and delicate magnetic topology can be created and verified with the required accuracy.

VINETA II: a linear magnetic reconnection experiment.

A linear experiment dedicated to the study of driven magnetic reconnection is presented. The new device (VINETA II) is suitable for investigating both collisional and near collisionless reconnection. Reconnection is achieved by externally driving magnetic field lines towards an X-point, inducing a current in the background plasma which consequently modifies the magnetic field topology. Owing to the open field line configuration of the experiment, the current is limited by the axial sheath boundary conditions. A plasma gun is used as an additional electron source in order to counterbalance the charge separation effects and supply the required current. Two drive methods are used in the device. First, an oscillating current through two parallel conductors drive the reconnection. Second, a stationary X-point topology is formed by the parallel conductors, and the drive is achieved by an oscillating current through a third conductor. In the first setup, the magnetic field of the axial plasma current dominates the field topology near the X-point throughout most of the drive. The second setup allows for the amplitude of the plasma current as well as the motion of the flux to be set independently of the X-point topology of the parallel conductors.

Oxygen pulse is not predictive of stroke volume in heart failure.

AIM: Stroke volume (SV) is the major cardiovascular discriminator between those that are exercise trained versus untrained individuals and healthy individuals versus those with pathologic left ventricular dysfunction. Furthermore, since the increase in oxygen pulse (O(2)P) (O(2)P=VO(2)/HR?oxygen uptake/heart rate) that occurs with exercise is a function of SV and the arterial-venous oxygen difference (a-vO(2)), O(2)P has been demonstrated a reliable indicator of SV for healthy individuals. Although commonly used as a physiological and clinical marker of SV, the validity of O(2)P as an indicator of SV in patients with heart failure has not been investigated. METHODS: Thirty-one (23 men, 8 women) patients (age: 64+/-7.9; ejection fraction: 24+/-7.8) with chronic heart failure had cardiac output measured during steady-state workloads (25 watts and 75% VO(2peak)) upon entry and again at completion of 12 weeks of exercise training. Four patients were excluded due to clinical complications and 3 because of non-compliance; therefore, 24 patients completed the study. RESULTS: The relationships between SV and O2P are: 1) baseline: SV=11.1+4(O2P), SEE=11.8; r(2)=0.39 and 2) study completion: SV=25.1+2.3(O2P), SEE=12.7; r(2)=0.21. While SV did not increase after 25 watts, O2P continued to increase by 17%, respectively. In addition, there were no training effects on SV or O(2)P. As SV increased, O(2)P underpredicted measured SV. CONCLUSIONS: In patients with heart failure and poor left ventricular function, O(2)P is not recommended as a marker of the SV during exercise.

Laser-induced fluorescence measurement of the ion-energy-distribution function in a collisionless reconnection experiment.

Observations in space and laboratory plasmas suggest magnetic reconnection as a mechanism for ion heating and formation of non-Maxwellian ion velocity distribution functions (IVDF). Laser-induced fluorescence measurements of the IVDF parallel to the X line of a periodically driven reconnection experiment are presented. A time-resolved analysis yields the evolution of the IVDF within a reconnection cycle. It is shown that reconnection causes a strong increase of the ion temperature, where the strongest increase is found at the maximum reconnection rate. Monte Carlo simulations demonstrate that ion heating is a consequence of the in-plane electric field that forms around the X line in response to reconnection.

Repopulation of moderately well-differentiated and keratinizing GL human squamous cell carcinomas growing in nude mice.

PURPOSE: It has been suggested that, reminiscent of the regulated proliferative response of normal squamous epithelium, squamous cell carcinomas that have preserved characteristics of differentiation have a greater repopulation capacity during fractionated irradiation than undifferentiated tumors. The aim of the present study was to investigate repopulation in moderately well-differentiated and keratinizing GL human squamous cell carcinomas in nude mice. METHODS AND MATERIALS: GL human squamous cell carcinomas were transplanted s.c. into the right hind leg of NMRI nu/nu mice. Irradiation was performed with 5.4 Gy fractions under clamp hypoxia or with 2 Gy fractions under ambient conditions. Six, 12, or 18 fractions were given daily, every second day, or every third day. Graded top-up doses were applied under clamp hypoxia to determine the tumor control dose 50% (TCD(50)). A total of 20 TCD(50) assays were performed and analyzed using maximum-likelihood techniques. RESULTS: With an increasing number of daily 5.4 Gy fractions under clamp hypoxia, the top-up TCD(50) values decreased significantly from 50.9 Gy (95% CI: 47, 54) after single doses to 0 Gy after 18 fractions. For the same number of fractions, the top-up TCD(50) increased with increasing overall treatment time. The results are consistent with a constant repopulation rate with a clonogenic doubling time (T(clon)) of 12.7 days (8.6, 16.8). Under ambient blood flow, the top-up TCD(50)s for daily 2 Gy fractions decreased significantly, but were less pronounced than for 5.4 Gy fractions under clamp hypoxia. For a given number of fractions under ambient conditions, the top-up TCD(50)s did not increase significantly with overall treatment time, except for irradiation with 12 fractions in 36 days compared to 12 and 24 days. The T(clon) value from these data was 24.0 days (11.6, 36.4). CONCLUSION: Our data demonstrate a slow but significant rate of repopulation of clonogenic tumor cells during fractionated irradiation of GL human squamous cell carcinomas under clamp hypoxia without indication of a change of the repopulation rate during treatment. Less pronounced repopulation was observed for irradiation under ambient conditions, which might be explained by preferential survival of hypoxic and therefore nonproliferating cells. Taken together with our previous studies on poorly differentiated FaDu tumors (Petersen et al., IJROBP 2001;51:483-493), the results support important heterogeneity of kinetics and mechanisms of repopulation, in particular of the influence of the oxygenation status of surviving clonogenic cells on the repopulation rate during fractionated irradiation, in different experimental squamous cell carcinoma.

Measuring energy expenditure in cardiac patients using the Body Media Armband versus indirect calorimetry. A validation study.

AIM: The purpose of this study was to compare differences in energy expenditure using the newly developed SenseWear Armband body monitor to indirect calorimetry in cardiac rehabilitation patients. METHODS: Twenty-four (62+/-8.1 years) patients completed steady state exercise for 8 minutes on 4 modes of exercise (arm ergometry, treadmill walking, recumbent stepping and rowing ergometry). Total cumulative kilojoules were recorded simultaneously by indirect calorimetry and the SenseWear Armband. Statistical analyses assessed the degree of agreement between the 2 measurement methods and 3 different versions of the SenseWear software. RESULTS: The correlations between indirect calorimetry and version 2.2 of the SenseWear armband for arm and rowing ergometry, the treadmill and recumbent stepper were r=0.90, r=0.67, r=0 .80 and r=0.74, respectively. There were no between method differences during arm ergometry (p<1.000) and the recumbent stepper (p<0.102). Bland and Altman plots revealed the greatest spread of scores for the rower and the treadmill. Between method differences were minimal when using the preliminary cardiac software. The correlations for arm and rowing ergometry, the treadmill and recumbent stepper were r=0.90, r=0.84, r=0.78 and r=0.82, respectively. CONCLUSIONS: The accuracy of the BodyMedia SenseWear Armband appears to be exercise modality dependent in those with heart disease when using software developed for the general population. Therefore, the information should be interpreted cautiously, particularly during treadmill walking and rowing. Initial experiments with cardiac-focused software are promising, but preliminary.

Treatment with donepezil in Alzheimer patients with and without cerebrovascular disease.

Donepezil, a selective acetylcholinesterase inhibitor, is approved for the symptomatic treatment of mild to moderate Alzheimer's disease (AD). In a post-marketing surveillance (PMS) study in Germany, patients under routine treatment conditions were observed while treatment was switched from other antidementia drugs (i.e., nootropics) to donepezil. A total of 913 patients were enrolled (60.1% female, mean+/-S.D. age 73.4+/-8.6 years, mean Mini-Mental Status Examination [MMSE] 18.0+/-5.3), and were treated with donepezil (5 or 10 mg/day according to recommended dosing). 709/913 (77.1%) of patients had been pretreated with other antidementive drugs (piracetam, memantine, ginkgo, and others). In 29.6% of patients, investigators documented concomitant cerebrovascular disease (CVD+) according to their clinical judgment. Observation period was 3 months for the individual patient. Efficacy parameters were changes in MMSE, global clinical (investigators) judgment of efficacy, and a clinical judgment about the patients' quality of life (QoL). Adverse events were also analyzed. The objective of the present investigation was to compare-in a "real-life" setting-the differential efficacy and tolerability of donepezil in AD patients with and without concomitant cerebrovascular disease. After 3 months, patients had improved by a mean MMSE change from baseline of 2.2 points (CVD+: 2.4 pts, CVD-: 2.1 pts). QoL was judged "improved" in 70.0% of patients (CVD+: 72.5%, CVD-: 69.6%). Adverse events were reported in 85/913 (9.3%) of patients (CVD+: 11.2%, CVD-: 7.9%). Reported adverse events were substantially less than reported previously in controlled clinical trials. This suggests that donepezil therapy is effective and well tolerated in AD patients, both with and without concomitant cerebrovascular disease.

New advanced operational regime on the W7-AS stellarator.

A promising new plasma operational regime on the Wendelstein stellarator W7-AS has been discovered. It is extant above a threshold density and characterized by flat density profiles, high energy and low impurity confinement times, and edge-localized radiation. Impurity accumulation is avoided. Quasistationary discharges with line-averaged densities n(e) to 4 x 10(20) m(-3), radiation levels to 90%, and partial plasma detachment at the divertor target plates can be simultaneously realized. Energy confinement is up to twice that of a standard scaling. At B(t) = 0.9 T, an average beta value of 3.1% is achieved. The high n(e) values allow demonstration of electron Bernstein wave heating using linear mode conversion.

Synchronization of drift waves.

Based on a thorough experimental study of the equilibrium plasma state and the description of coherent drift modes in the framework of a linear, nonlocal model, the response of drift modes to different external driver signal is reported. Purely temporal perturbations as well as corotating and counter-rotating electric fields of various mode numbers are applied to the system. Drift mode synchronization and periodic pulling, typical for driven nonlinear oscillator systems, are investigated in detail. The full spatio-temporal behavior of periodic pulling is observed with multiprobe arrays.

Mode selective control of drift wave turbulence.

Experiments on spatiotemporal open-loop synchronization of drift wave turbulence in a magnetized cylindrical plasma are reported. The synchronization effect is modeled by a rotating current profile with prescribed mode structure. Numerical simulations of an extended Hasegawa-Wakatani model show good agreement with experimental results.

Cardiac rehabilitation without exercise tests for post-myocardial infarction and post-bypass surgery patients.

PURPOSE: To compare the progress of patients who were exercise tested before or during cardiac rehabilitation versus those patients who were not tested. METHODS: Eighty-eight (88) post-myocardial infarction patients and 141 post-bypass surgery patients had a symptom-limited exercise test before or during 12 weeks of cardiac rehabilitation. Another 125 post-myocardial infarction and 146 post-surgery patients were not tested. RESULTS: Caloric expenditure during class increased for the entire group (P < 0.001) from week 1 to week 12. Body weight decreased for the entire group as a result of cardiac rehabilitation (P < 0.001). Tricep skinfolds decreased for the entire group (P < 0.001) while subscapular skinfolds did not change (P = 0.28). The percent change from week 1 to week 12 for both groups was similar for all variables. No problems occurred during cardiac rehabilitation that required emergency medical management. CONCLUSIONS: Patients completing a 12-week cardiac rehabilitation program can be safely progressed in terms of their exercise capacity without an entry exercise test. This is desirable in a managed-care setting for reducing costs while maintaining effective patient care. Such factors as staff training and experience, institutional philosophy, patient referral patterns, and facility location must be considered before adopting a no-test policy.