238 research outputs found
Mapping the visual brain areas susceptible to phosphene induction through brain stimulation.
Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique whose effects on neural activity can be uncertain. Within the visual cortex, phosphenes are a useful marker of TMS: They indicate the induction of neural activation that propagates and creates a conscious percept. However, we currently do not know how susceptible different areas of the visual cortex are to TMS-induced phosphenes. In this study, we systematically map out locations in the visual cortex where stimulation triggered phosphenes. We relate this to the retinotopic organization and the location of object- and motion-selective areas, identified by functional magnetic resonance imaging (fMRI) measurements. Our results show that TMS can reliably induce phosphenes in early (V1, V2d, and V2v) and dorsal (V3d and V3a) visual areas close to the interhemispheric cleft. However, phosphenes are less likely in more lateral locations (hMT+/V5 and LOC). This suggests that early and dorsal visual areas are particularly amenable to TMS and that TMS can be used to probe the functional role of these areas.This study was funded by the European Community’s Seventh Framework Programme (FP7/2007-2013) under agreement PITN-GA-2011-290011 and the Welcome Trust (095183/Z/10/Z).This is the final version of the article. It first appeared from Springer via https://doi.org/10.1007/s00221-016-4784-
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The mixed-polarity benefit of stereopsis arises in early visual cortex.
Depth perception is better when observers view stimuli containing a mixture of bright and dark visual features. It is currently unclear where in the visual system sensory processing benefits from the availability of different contrast polarity. To address this question, we applied transcranial magnetic stimulation to the visual cortex to modulate normal neural activity during processing of single- or mixed-polarity random-dot stereograms. In line with previous work, participants gave significantly better depth judgments for mixed-polarity stimuli. Stimulation of early visual cortex (V1/V2) significantly increased this benefit for mixed-polarity stimuli, and it did not affect performance for single-polarity stimuli. Stimulation of disparity responsive areas V3a and LO had no effect on perception. Our findings show that disparity processing in early visual cortex gives rise to the mixed-polarity benefit. This is consistent with computational models of stereopsis at the level of V1 that produce a mixed polarity benefit
New primary renal diagnosis codes for the ERA-EDTA
The European Renal Association-European Dialysis and Transplant Association (ERA-EDTA) Registry has produced a new set of primary renal diagnosis (PRD) codes that are intended for use by affiliated registries. It is designed specifically for use in renal centres and registries but is aligned with international coding standards supported by the WHO (International Classification of Diseases) and the International Health Terminology Standards Development Organization (SNOMED Clinical Terms). It is available as supplementary material to this paper and free on the internet for non-commercial, clinical, quality improvement and research use, and by agreement with the ERA-EDTA Registry for use by commercial organizations. Conversion between the old and the new PRD codes is possible. The new codes are very flexible and will be actively managed to keep them up-to-date and to ensure that renal medicine can remain at the forefront of the electronic revolution in medicine, epidemiology research and the use of decision support systems to improve the care of patients
Optimal Placement of Active Bars for Buckling Control in Truss Structures under Bar Failures
Buckling of slender bars subject to axial compressive loads represents a critical design constraint for light-weight truss structures. Active buckling control by actuators provides a possibility to increase the maximum bearable axial load of individual bars and, thus, to stabilize the truss structure.For reasons of cost, it is in general not economically viable to use such actuators in each bar of the truss structure. Hence, it is an important practical question where to place these active bars. Optimized structures, especially when coupled with active elements to further decrease the number of necessary bars, however, lead to designs, which, while cost-efficient, are especially prone to bardamages, caused, e.g., by material failures. Therefore, this paper presents a mathematical optimization approach to optimally place active bars for buckling control in a way that secures both buckling and general stability constraints even after failure of any combination of a certain number of bars. This allows us to increase the resilience of the system and guarantee stable behavior even in case of failures
Cystatin C standardization decreases assay variation and improves assessment of glomerular filtration rate
Inflammation and erythropoiesis-stimulating agent response in hemodialysis patients : a self-matched longitudinal study of anemia management in the Dialysis Outcomes and Practice Patterns Study (DOPPS)
Rationale & objective: Previous studies of inflammation and anemia management in hemodialysis (HD) patients may be biased due to patient differences. We used a self-matched longitudinal design to test whether new inflammation, defined as an acute increase in C-reactive protein (CRP) level, reduces hemoglobin response to erythropoiesis-stimulating agent (ESA) treatment.
Study design: Self-matched longitudinal design.
Setting & participants: 3,568 new inflammation events, defined as CRP level > 10 mg/L following a 3-month period with CRP level ≤ 5 mg/L, were identified from 12,389 HD patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS) phases 4 to 6 (2009-2018) in 10 countries in which CRP is routinely measured.
Predictor: "After" (vs "before") observing a high CRP level.
Outcomes: Within-patient changes in hemoglobin level, ESA dose, and ESA hyporesponsiveness (hemoglobin 6,000 [Japan] or >8,000 [Europe] U/wk).
Analytical approach: Linear mixed models and modified Poisson regression.
Results: Comparing before with after periods, mean hemoglobin level decreased from 11.2 to 10.9 g/dL (adjusted mean change, -0.26 g/dL), while mean ESA dose increased from 6,320 to 6,960 U/wk (adjusted relative change, 8.4%). The prevalence of ESA hyporesponsiveness increased from 7.6% to 12.3%. Both the unadjusted and adjusted prevalence ratios of ESA hyporesponsiveness were 1.68 (95% CI, 1.48-1.91). These associations were consistent in sensitivity analyses varying CRP thresholds and were stronger when the CRP level increase was sustained over the 3-month after period.
Limitations: Residual confounding by unmeasured time-varying risk factors for ESA hyporesponsiveness.
Conclusions: In the 3 months after HD patients experienced an increase in CRP levels, hemoglobin levels declined quickly, ESA doses increased, and the prevalence of ESA hyporesponsiveness increased appreciably. Routine CRP measurement could identify inflammation as a cause of worsened anemia. In turn, these findings speak to a potentially important role for anemia therapies that are less susceptible to the effects of inflammation
First array of enriched ZnSe bolometers to search for double beta decay
The R&D activity performed during the last years proved the potential of ZnSe
scintillating bolometers to the search for neutrino-less double beta decay,
motivating the realization of the first large-mass experiment based on this
technology: CUPID-0. The isotopic enrichment in Se, the ZnSe
crystals growth, as well as the light detectors production have been
accomplished, and the experiment is now in construction at Laboratori Nazionali
del Gran Sasso (Italy). In this paper we present the results obtained testing
the first three ZnSe crystals operated as scintillating bolometers, and
we prove that their performance in terms of energy resolution, background
rejection capability and intrinsic radio-purity complies with the requirements
of CUPID-0
a global network of chronic kidney disease cohorts
Background Chronic kidney disease (CKD) is a global health burden, yet it is
still underrepresented within public health agendas in many countries. Studies
focusing on the natural history of CKD are challenging to design and conduct,
because of the long time-course of disease progression, a wide variation in
etiologies, and a large amount of clinical variability among individuals with
CKD. With the difference in health-related behaviors, healthcare delivery,
genetics, and environmental exposures, this variability is greater across
countries than within one locale and may not be captured effectively in a
single study. Methods Studies were invited to join the network. Prerequisites
for membership included: 1) observational designs with a priori hypotheses and
defined study objectives, patient-level information, prospective data
acquisition and collection of bio-samples, all focused on predialysis CKD
patients; 2) target sample sizes of 1,000 patients for adult cohorts and 300
for pediatric cohorts; and 3) minimum follow-up of three years. Participating
studies were surveyed regarding design, data, and biosample resources. Results
Twelve prospective cohort studies and two registries covering 21 countries
were included. Participants age ranges from >2 to >70 years at inclusion, CKD
severity ranges from stage 2 to stage 5. Patient data and biosamples (not
available in the registry studies) are measured yearly or biennially. Many
studies included multiple ethnicities; cohort size ranges from 400 to more
than 13,000 participants. Studies’ areas of emphasis all include but are not
limited to renal outcomes, such as progression to ESRD and death. Conclusions
iNET-CKD (International Network of CKD cohort studies) was established, to
promote collaborative research, foster exchange of expertise, and create
opportunities for research training. Participating studies have many
commonalities that will facilitate comparative research; however, we also
observed substantial differences. The diversity we observed across studies
within this network will be able to be leveraged to identify genetic,
behavioral, and health services factors associated with the course of CKD.
With an emerging infrastructure to facilitate interactions among the
investigators of iNET-CKD and a broadly defined research agenda, we are
confident that there will be great opportunity for productive collaborative
investigations involving cohorts of individuals with CKD
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