157 research outputs found
A Fuzzy Inference System for Closed-Loop Deep Brain Stimulation in Parkinsonâs Disease
Parkinsons disease is a complex neurodegenerative disorder for which patients present many symptoms, tremor being the main one. In advanced stages of the disease, Deep Brain Stimulation is a generalized therapy which can significantly improve the motor symptoms. However despite its beneficial effects on treating the symptomatology, the technique can be improved. One of its main limitations is that the parameters are fixed, and the stimulation is provided uninterruptedly, not taking into account any fluctuation in the patients state. A closed-loop system which provides stimulation by demand would adjust the stimulation to the variations in the state of the patient, stimulating only when it is necessary. It would not only perform a more intelligent stimulation, capable of adapting to the changes in real time, but also extending the devices battery life, thereby avoiding surgical interventions. In this work we design a tool that learns to recognize the principal symptom of Parkinsons disease and particularly the tremor. The goal of the designed system is to detect the moments the patient is suffering from a tremor episode and consequently to decide whether stimulation is needed or not. For that, local field potentials were recorded in the subthalamic nucleus of ten Parkinsonian patients, who were diagnosed with tremor-dominant Parkinsons disease and who underwent surgery for the implantation of a neurostimulator. Electromyographic activity in the forearm was simultaneously recorded, and the relation between both signals was evaluated using two different synchronization measures. The results of evaluating the synchronization indexes on each moment represent the inputs to the designed system. Finally, a fuzzy inference system was applied with the goal of identifying tremor episodes. Results are favourable, reaching accuracies of higher 98.7 % in 70 % of the patients.Centro de InvestigaciĂłn BiomĂ©dica en RedDepto. de PsicologĂa Experimental, Procesos Cognitivos y LogopediaDepto. de RadiologĂa, RehabilitaciĂłn y FisioterapiaFac. de PsicologĂaFac. de MedicinaTRUEpu
Areas of natural occurrence of melipona scutellaris Latreille, 1811(Hymenoptera: Apidae) in the state of Bahia, Brazil.
The bee Melipona scutellaris is considered the reared meliponine species with the largest distribution in the North and Northeast regions of Brazil, with records from the state of Rio Grande do Norte down to the state of Bahia. Considering the importance of this species in the generation of income for family agriculture and in the preservation of areas with natural vegetation, this study aimed at providing knowledge on the distribution of natural colonies of M. scutellaris in the state of Bahia. Literature information, interviews with stinglessbee beekeepers, and expeditions were conducted to confirm the natural occurrence of the species. A total of 102 municipalities showed records for M. scutellaris, whose occurrence was observed in areas ranging from sea level up to 1,200-meter height. The occurrence of this species in the state of Bahia is considered to be restricted to municipalities on the coastal area and the Chapada Diamantina with its rainforests. Geographic coordinates, elevation, climate and vegetation data were obtained, which allowed a map to be prepared for the area of occurrence in order to support conservation and management policies for the species
The Importance of Tree Size and Fecundity for Wind Dispersal of Big-Leaf Mahogany
Seed dispersal by wind is a critical yet poorly understood process in tropical forest trees. How tree size and fecundity affect this process at the population level remains largely unknown because of insufficient replication across adults. We measured seed dispersal by the endangered neotropical timber species big-leaf mahogany (Swietenia macrophylla King, Meliaceae) in the Brazilian Amazon at 25 relatively isolated trees using multiple 1-m wide belt transects extended 100 m downwind. Tree diameter and fecundity correlated positively with increased seed shadow extent; but in combination large, high fecundity trees contributed disproportionately to longer-distance dispersal events (>60 m). Among three empirical models fitted to seed density vs. distance in one dimension, the Student-t (2Dt) generally fit best (compared to the negative exponential and inverse power). When seedfall downwind was modelled in two dimensions using a normalised sample, it peaked furthest downwind (c. 25 m) for large, high-fecundity trees; with the inverse Gaussian and Weibull functions providing comparable fits that were slightly better than the lognormal. Although most seeds fell within 30 m of parent trees, relatively few juveniles were found within this distance, resulting in juvenile-to-seed ratios peaking at c. 35â45 m. Using the 2Dt model fits to predict seed densities downwind, coupled with known fecundity data for 2000â2009, we evaluated potential Swietenia regeneration near adults (â€30 m dispersal) and beyond 30 m. Mean seed arrival into canopy gaps >30 m downwind was more than 3Ă greater for large, high fecundity trees than small, high-fecundity trees. Tree seed production did not necessarily scale up proportionately with diameter, and was not consistent across years, and this resulting intraspecific variation can have important consequences for local patterns of dispersal in forests. Our results have important implications for management and conservation of big-leaf mahogany populations, and may apply to other threatened wind-dispersed Meliaceae trees
Revisiting perioperative chemotherapy: the critical importance of targeting residual cancer prior to wound healing
<p>Abstract</p> <p>Background</p> <p>Scientists and physicians have long noted similarities between the general behavior of a cancerous tumor and the physiological process of wound healing. But it may be during metastasis that the parallels between cancer and wound healing are most pronounced. And more particularly and for the reasons detailed in this paper, any cancer remaining after the removal of a solid tumor, whether found in micrometastatic deposits in the stroma or within the circulation, may be heavily dependent on wound healing pathways for its further survival and proliferation.</p> <p>Discussion</p> <p>If cancer cells can hijack the wound healing process to facilitate their metastatic spread and survival, then the period immediately after surgery may be a particularly vulnerable period of time for the host, as wound healing pathways are activated and amplified after the primary tumor is removed. Given that we often wait 30 days or more after surgical removal of the primary tumor before initiating adjuvant chemotherapy to allow time for the wound to heal, this paper challenges the wisdom of that clinical paradigm, providing a theoretical rationale for administering therapy during the perioperative period.</p> <p>Summary</p> <p>Waiting for wound healing to occur before initiating adjuvant therapies may be seriously compromising their effectiveness, and patients subsequently rendered incurable as a result of this wait. Clinical trials to establish the safety and effectiveness of administering adjuvant therapies perioperatively are needed. These therapies should target not only the residual cancer cells, but also the wound healing pathway utilized by these cells to proliferate and metastasize.</p
Significant heterogeneity in terms of diagnosis and treatment of renal cell carcinoma at a private and public hospital in Brazil
A megaxion at 750 GeV as a first hint of low scale string theory
Journal of High Energy Physics 2016.7 (2016): 021 reproduced by permission of Scuola Internazionale Superiore di Studi Avanzati (SISSA)Low scale string models naturally have axion-like pseudoscalars which couple directly to gluons and photons (but not Wâs) at tree level. We show how they typically get tree level masses in the presence of closed string fluxes, consistent with the axion discrete gauge symmetry, in a way akin of the axion monodromy of string inflation and relaxion models. We discuss the possibility that the hints for a resonance at 750 GeV recently reported at ATLAS and CMS could correspond to such a heavy axion state (megaxion). Adjusting the production rate and branching ratios suggest the string scale to be of order Ms â 7â104 TeV, depending on the compactification geometry. If this interpretation was correct, one extra Zâ gauge boson could be produced before reaching the string threshold at LHC and future collidersThis work is partially supported by the grants FPA2012-32828 and FPA2015-65929-P from the MINECO, the ERC Advanced Grant SPLE under contract ERC-2012-ADG-20120216-320421, the Consolider-Ingenio 2010 programme under grant MULTIDARK CSD2009-00064 and the grant SEV-2012-0249 of the âCentro de Excelencia Severo Ochoaâ Programm
Freeze-drying: An alternative method for the analysis of volatile organic compounds in the headspace of urine samples using solid phase micro-extraction coupled to gas chromatography - mass spectrometry
© 2016 Aggio et al. Background: Volatile organic compounds (VOCs) can be intermediates of metabolic pathways and their levels in biological samples may provide a better understanding about diseases in addition to potential methods for diagnosis. Headspace analysis of VOCs in urine samples using solid phase micro extraction (SPME) coupled to gas chromatography - mass spectrometry (GC-MS) is one of the most used techniques. However, it generally produces a limited profile of VOCs if applied to fresh urine. Sample preparation methods, such as addition of salt, base or acid, have been developed to improve the headspace-SPME-GC-MS analysis of VOCs in urine samples. These methods result in a richer profile of VOCs, however, they may also add potential contaminants to the urine samples, result in increased variability introduced by manually processing the samples and promote degradation of metabolites due to extreme pH levels. Here, we evaluated if freeze-drying can be considered an alternative sample preparation method for headspace-SPME-GC-MS analysis of urine samples. Results: We collected urine from three volunteers and compared the performances of freeze-drying, addition of acid (HCl), addition of base (NaOH), addition of salt (NaCl), fresh urine and frozen urine when identifying and quantifying metabolites in 4 ml samples. Freeze-drying and addition of acid produced a significantly higher number of VOCs identified than any other method, with freeze-drying covering a slightly higher number of chemical classes, showing an improved repeatability and reducing siloxane impurities. Conclusion: In this work we compared the performance of sample preparation methods for the SPME-GC-MS analysis of urine samples. To the best of our knowledge, this is the first study evaluating the potential of freeze-dry as an alternative sample preparation method. Our results indicate that freeze-drying has potential to be used as an alternative method for the SPME-GC-MS analysis of urine samples. Additional studies using internal standard, synthetic urine and calibration curves will allow a more precise quantification of metabolites and additional comparisons between methods
The influence of maternal psychosocial circumstances and physical environment on the risk of severe wasting in rural Gambian infants: a mixed methods approach
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