The Onset of the 1997-1998 El Nino and its Impact on the Phytoplankton Community of the Central Equatorial Pacific

Using physical and bio-optical data from moorings in the central equatorial Pacific, the perturbations to phytoplankton biomass and productivity associated with the onset of the 1997-98 El Nino event were investigated. The data presented depict the physical progression of El Nino onset, from reversal of the trade winds in the western equatorial Pacific, through eastward propagation of equatorially trapped Kelvin waves and advection of waters from the nutrient-poor western equatorial warm pool. The physical perturbations led to fluctuations in phytoplankton biomass, quantum yield of fluorescence and a 50% reduction in primary productivity

Frequency-dependent top-down modulation of temporal summation by anodal transcranial direct-current stimulation of the primary motor cortex in healthy adults

12 months embargo, now expired.Background Transcranial direct-current stimulation (tDCS) applied over the primary motor cortex has been shown to be effective in the treatment of a number of chronic pain conditions. However, there is a lack of understanding of the top-down analgesic mechanisms involved. Method In this study, we investigated the effects of tDCS on the facilitation of subjective sensory and pain scores using a transcutaneous electrically evoked measure of temporal summation. In this randomized, blinded, cross-over study healthy subjects received a single stimulus given at 0.9× pain threshold (pTh) over the L5 dermatome on the lateral aspect of the right leg, followed by a train of 5 stimuli given at 0.5, 1, 5 and 20 Hz before and after 20 min of sham or anodal tDCS (2 mA) applied over the primary motor cortex. Ratings of sensation and pain intensity were scored on a visual analogue scale (VAS). Results Temporal summation leading to pain only occurred at higher frequencies (5 and 20 Hz). Sham or real tDCS had no effect over temporal summation evoked at 5 Hz; however, there was a significant analgesic effect at 20 Hz. Sham or real tDCS had no effect over acute, single stimuli-evoked responses. Conclusion These results indicate that anodal tDCS applied to the primary motor cortex preferentially modulates temporal summation induced by high-frequency electrical stimulation-induced pain. The inhibitory effects of tDCS appear to be dynamic and dependent on the degree of spinal cord excitability and may explain the higher analgesic efficacy in patients with moderate to severe chronic pain symptoms. Significance The analgesic effects of tDCS are dependent on spinal cord excitability. This work provides insight into top-down modulation during acute pain and temporal summation. This knowledge may explain why tDCS has a higher analgesic efficacy in chronic pain patients

Why do older adults stand-up differently to young adults?: investigation of compensatory movement strategies in sit-to-walk

Functional motor redundancy enables humans to move with distinct muscle activation patterns while achieving a similar outcome. Since humans select similar strategies, there seems to be an optimal control. However, older adults move differently to young adults. The question is whether this is this due to an altered reinforcement scheme, altered sensory inputs, or due to alterations in the neuromusculoskeletal systems, so that it is no longer optimal or possible to execute the same movement strategies. The aim of this study was to analyse natural compensation strategies in the vital daily-life-task, sit-to-walk, in relation to neuromuscular capacity and movement objectives in younger (27.2 ± 4.6 years, N = 27, 14♀) and elderly (75.9 ± 6.3 years, N = 23, 12♀) adults. Aspects of the neuromuscular system that are prone to age-related decline and feasible to quantify were assessed (i.e. strength, nerve conductivity, fear of falling). Kinematics and muscle activity were recorded and joint kinetics were estimated using biomechanical models. Elderly men consistently used their arms when standing up. This strategy was not associated with a lack of or a reduction in strength, but with a reduction, but no lack of, ankle joint range of motion, and with increased fear of falling. The results show that humans preferentially maintain a minimum threshold of neuromuscular reserve to cope with uncertainties which results in compensation prior to coming up against physical limitations. Smaller base of support while standing up, a compensatory strategy with possibly greater risk of falls, was associated with muscular weakness, and longer nerve conduction latencies

Understanding the impact of lumbar disc degeneration and chronic low back pain: A cross-sectional electromyographic analysis of postural strategy during predicted and unpredicted postural perturbations

People with chronic low back pain (LBP) exhibit changes in postural control. Stereotypical muscle activations resulting from external perturbations include anticipatory (APAs) and compensatory (CPAs) postural adjustments. The aim and objective of this study was to determine differences in postural control strategies (peak amplitude, APAs and CPAs) between symptomatic and asymptomatic adults with and without Lumbar Disc Degeneration (LDD) using surface electromyography during forward postural perturbation. Ninety-seven subjects participated in the study (mean age 50 years (SD 12)). 3T MRI was used to acquire T2 weighted images (L1-S1). LDD was determined using Pfirrmann grading. A bespoke translational platform was designed to deliver horizontal perturbations in sagittal and frontal planes. Electromyographic activity was analysed bilaterally from 8 trunk and lower limb muscles during four established APA and CPA epochs. A Kruskal-Wallis H test with Bonferroni correction for multiple comparisons was conducted. Four groups were identified: no LDD no pain (n = 19), LDD no pain (n = 38), LDD pain (n = 35) and no LDD pain (n = 5). There were no significant differences in age or gender between groups. The most significant difference between groups was observed during forward perturbation. In the APA and CPA phases of predictable forward perturbation there were significant differences ankle strategy between groups (p = 0.007-0.008); lateral gastrocnemius and tibialis anterior activity was higher in the LDD pain than the LDD no pain group. There were no significant differences in the unpredictable condition (p>0.05). These findings were different from the remaining groups, where significant differences in hip strategy were observed during both perturbation conditions (p = 0.004-0.006). Symptomatic LDD patients exhibit different electromyographic strategies to asymptomatic LDD controls. Future LBP electromyographic research should benefit from considering assessment of both lower limbs in addition to the spine. This approach could prevent underestimation of postural control deficits and guide targeted rehabilitation

Impact of 13-valent pneumococcal conjugate vaccine (PCV13) in a pandemic similar to the 2009 H1N1 in the United States

Background: High rates of bacterial coinfection in autopsy data from the 2009 H1N1 influenza (“flu”) pandemic suggest synergies between flu and pneumococcal disease (PD) during pandemic conditions, and highlight the importance of interventions like the 13-valent pneumococcal conjugate vaccine (PCV13) that may mitigate the impact of a pandemic. Methods: We used a decision-analytic model, estimated from published sources, to assess the impact of pediatric vaccination with PCV13 versus the 7-valent vaccine (PCV7) on PD incidence and mortality in a normal flu season (10% flu incidence) and in a pandemic similar to 2009-2010 H1N1 (20% flu incidence, mild virulence, high impact in children). Both direct and indirect (herd) effects against PD were considered. Effectiveness of PCV13 was extrapolated from observed PCV7 data, using assumptions of serotype prevalence and PCV13 protection against the 6 serotypes not in PCV7. To simulate 2009–2010 H1N1, autopsy data were used to estimate the overall proportion of flu deaths with bacterial coinfections. By assuming that increased risk of death during the pandemic occurred among those with comorbidity (using obesity as proxy) and bacterial coinfections primarily due to S. pneumoniae or S. aureus, we estimated the proportion co-infected among all (fatal and non-fatal) flu cases (7.6% co-infected with any organism; 2.2% with S. pneumoniae). PD incidence, mortality, and total healthcare costs were evaluated over a 1-year horizon. Results: In a normal flu season, compared to PCV7, PCV13 is expected to prevent an additional 13,400 invasive PD (IPD) cases, 399,000 pneumonia cases, and 2,900 deaths, leading to cost savings of $472 M. In a pandemic similar to 2009–2010 H1N1, PCV13 would prevent 22,800 IPD cases, 872,000 pneumonia cases, and 3,700 deaths, resulting in cost savings of$1.0 B compared to PCV7. Conclusions: In a flu pandemic similar to the 2009–2010 H1N1, protection against the 6 additional serotypes in PCV13 would likely be effective in preventing pandemic-related PD cases, mortality, and associated costs

Mathematical modelling long-term effects of replacing Prevnar7 with Prevnar13 on invasive pneumococcal diseases in England and Wales

England and Wales recently replaced the 7-valent pneumococcal conjugate vaccine (PCV7) with its 13-valent equivalent (PCV13), partly based on projections from mathematical models of the long-term impact of such a switch compared to ceasing pneumococcal conjugate vaccination altogether. A compartmental deterministic model was used to estimate parameters governing transmission of infection and competition between different groups of pneumococcal serotypes prior to the introduction of PCV13. The best-fitting parameters were used in an individual based model to describe pneumococcal transmission dynamics and effects of various options for the vaccination programme change in England and Wales. A number of scenarios were conducted using (i) different assumptions about the number of invasive pneumococcal disease cases adjusted for the increasing trend in disease incidence prior to PCV7 introduction in England and Wales, and (ii) a range of values representing serotype replacement induced by vaccination of the additional six serotypes in PCV13. Most of the scenarios considered suggest that ceasing pneumococcal conjugate vaccine use would cause an increase in invasive pneumococcal disease incidence, while replacing PCV7 with PCV13 would cause an overall decrease. However, the size of this reduction largely depends on the level of competition induced by the additional serotypes in PCV13. The model estimates that over 20 years of PCV13 vaccination, around 5000–62000 IPD cases could be prevented compared to stopping pneumococcal conjugate vaccination altogether. Despite inevitable uncertainty around serotype replacement effects following introduction of PCV13, the model suggests a reduction in overall invasive pneumococcal disease incidence in all cases. Our results provide useful evidence on the benefits of PCV13 to countries replacing or considering replacing PCV7 with PCV13, as well as data that can be used to evaluate the cost-effectiveness of such a switch

The impact of hyperhidrosis on patients' daily life and quality of life : A qualitative investigation

Background: An understanding of the daily life impacts of hyperhidrosis and how patients deal with them, based on qualitative research, is lacking. This study investigated the impact of hyperhidrosis on the daily life of patients using a mix of qualitative research methods. Methods: Participants were recruited through hyperhidrosis patient support groups such as the Hyperhidrosis Support Group UK. Data were collected using focus groups, interviews and online surveys. A grounded theory approach was used in the analysis of data transcripts. Data were collected from 71 participants, out of an initial 100 individuals recruited. Results: Seventeen major themes capturing the impacts of hyperhidrosis were identified; these covered all areas of life including daily life, psychological well-being, social life, professional /school life, dealing with hyperhidrosis, unmet health care needs and physical impact. Conclusions: Psychosocial impacts are central to the overall impacts of hyperhidrosis, cutting across and underlying the limitations experienced in other areas of life.Peer reviewe

Modeling the impact of the 13-valent pneumococcal conjugate vaccine serotype catch-up program using United States claims data

Background: Analysis of US claims data from April 2010 to June 2011 estimated that 39% of the 13-valent pneumococcal conjugate vaccine (PCV13) catch-up eligible cohort would ever receive the catch-up vaccination; a previous analysis assumed 87%. Methods: This updated figure was applied to a previously published 10-year Markov model while holding all other inputs constant. Results: Our model estimated that the catch-up program as currently implemented is estimated to prevent an additional 1.7 million cases of disease in children aged ≤59 months over a 10-year period, compared with routine PCV13 vaccination with no catch-up program. Conclusions: Because 39% catch-up uptake is less than the level of completion of the 4-dose primary PCV13 series, vaccine-preventable cases of pneumococcal disease and related deaths could be decreased further with additional uptake of catch-up vaccination in the catch-up eligible cohort

The biogeochemical structure of Southern Ocean mesoscale eddies

Mesoscale eddies play a key role in modulating physical and biogeochemical properties across the global ocean. They also play a central role in cross‐frontal transport of heat, freshwater, and carbon, especially in the Southern Ocean. However, the role that eddies play in the biogeochemical cycles is not yet well constrained, partly due to a lack of observations below the surface. Here, we use hydrographic data from two voyages, conducted in the austral summer and autumn, to document the vertical biogeochemical structure of two mesoscale cyclonic eddies and quantify the role of these eddies in the meridional transport of nutrients across the Subantarctic Front. Our study demonstrates that the nutrient distribution is largely driven by eddy dynamics, yielding identical eddy structure below the mixed layer in both seasons. This result allowed us to relate nutrient content to dynamic height and estimate the average transport by eddies across the Subantarctic Front. We found that relative to Subantarctic Zone waters, long‐lived cold‐core eddies carry nitrate anomalies of 1.6±0.2×1010 moles and silicate anomalies of −5.5±0.7×1010 moles across the fronts each year. This cross‐frontal transport of nutrients has negligible impact on Subantarctic Zone productivity; however, it has potential to modify the nutrient content of mode waters that are exported from the Southern Ocean to lower latitudes