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1.
Environ Sci Technol ; 57(14): 5957-5966, 2023 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-36994990

RESUMO

Organic aerosol (OA) is a key component of fine particulate matter (PM2.5) and affects the human health and leads to climate change. With strict control measures for air pollutants during the last decade, the OA concentration in China declined slowly, while its sources remain unclear. In this study, we simulate the primary OA (POA) and secondary OA (SOA) concentrations from 2005 to 2019 with a state-of-the-art air quality model, Community Multiscale Air Quality (CMAQ, version 5.3.2) coupled with a Two-Dimensional Volatility Basis Set (2D-VBS) module, and a long-term emission inventory of full-volatility organic compounds in China and conduct source apportionment and sensitivity analysis. The simulation results show that, from 2005 to 2019, the OA concentration in China decreased from 24.0 to 12.8 µg/m3 with most of the reduction from POA. The OA pollution from residential biomass burning declined 75% from 2005 to 2019, while it is still the major OA source in China. OA pollution from VCP increased by more than 2-fold and became the largest SOA source in China. From 2014 to 2019, the NOx control in China slightly offset the decrease of SOA concentration due to elevated oxidation capacity.


Assuntos
Poluentes Atmosféricos , Monitoramento Ambiental , Humanos , Monitoramento Ambiental/métodos , Poluentes Atmosféricos/análise , Material Particulado/análise , China , Aerossóis/análise
2.
Oecologia ; 186(4): 953-963, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29480451

RESUMO

Juvenile growth strongly impacts life-history traits during adulthood. Yet, in juveniles with delayed maturity, elusiveness has hindered age-specific studies of growth, precluding any detailed research on its consequences later in life. Different complex growth patterns have been extracted from captive animals, suggesting species-specific trajectories occur in free-ranging animals. How pronounced are growth and body size variation (VBS) throughout a long-lived ectotherm's life? Is VBS constant among age classes prior to maturity, or do compensatory and/or cumulative effects driven by long-lived-animal-specific strategies create distinct VBS cohorts, to ensure survival? To tackle the issue, we modelled growth data from continuous and dense annual capture-mark-recapture sampling (5096 body measurements of 1134 free-ranging individuals) of both immature and mature, long-lived Hermann's tortoises. We analysed population, cohort, and individual-based growth and VBS. Growth ring inferred ages were cross validated with annual recaptures in 289 juveniles. Analyses unravelled an S-shaped growth curve and identified three age cohorts across which VBS increases in a step-wise manner. Neonate-specific constraints and compensatory effects seem to control VBS until 4 years of age, possibly promoting survival with size. Subsequently, a hardened carapace takes over and cumulative effects fuelled by faster growth progressively increase VBS. Whereas ungulates are in a hurry to attain adult size before growth ceases (minimizing VBS), indeterminately growing tortoises can shape individual asymptotic sizes even after growth decelerates. Tortoise size is clearly shaped by age-specific ecological constraints; interestingly, it is likely the carapace that conducts the strategy, rather than maturity per se.


Assuntos
Exoesqueleto , Tartarugas , Adulto , Animais , Tamanho Corporal , Pré-Escolar , Humanos , Recém-Nascido , Especificidade da Espécie
3.
Geophys Res Lett ; 44(5): 2562-2570, 2017 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-28503004

RESUMO

Secondary organic aerosols (SOA) forms a major fraction of organic aerosols in the atmosphere. Knowledge of SOA properties that affect their dynamics in the atmosphere is needed for improving climate models. By combining experimental and modeling techniques, we investigated the factors controlling SOA evaporation under different humidity conditions. Our experiments support the conclusion of particle phase diffusivity limiting the evaporation under dry conditions. Viscosity of particles at dry conditions was estimated to increase several orders of magnitude during evaporation, up to 109 Pa s. However, at atmospherically relevant relative humidity and time scales, our results show that diffusion limitations may have a minor effect on evaporation of the studied α-pinene SOA particles. Based on previous studies and our model simulations, we suggest that, in warm environments dominated by biogenic emissions, the major uncertainty in models describing the SOA particle evaporation is related to the volatility of SOA constituents.

4.
Neurosurg Focus ; 42(1): E17, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28041330

RESUMO

OBJECTIVE The performance of surgery for spinal metastases is rapidly increasing. Different surgical procedures, ranging from stabilization alone to stabilization combined with corpectomy, are thereby performed for various indications. Little is known about the impact of these different procedures on patient quality of life (QOL), but this factor is crucial when discussing the various therapeutic options with patients and their families. Thus, the authors of this study investigated the effect of various surgical procedures for spinal metastases on patient QOL. METHODS The authors prospectively followed a cohort of 113 patients with spinal metastases who were referred to their clinic for surgical evaluation between July 2012 and July 2014. Quality of life was assessed using the EQ-5D at intake and at 3, 6, 9, and 12 months after treatment. RESULTS Nineteen patients were treated conservatively, 41 underwent decompressive surgery with or without stabilization, 47 underwent a piecemeal corpectomy procedure with stabilization and expandable cage reconstruction, and 6 had a stabilization procedure without decompression. Among all surgical patients, the mean EQ-5D score was significantly increased from 0.44 pretreatment to 0.59 at 3 months after treatment (p < 0.001). Mean EQ-5D scores at 1 year after surgery further increased to 0.84 following decompression with stabilization, 0.74 after corpectomy with stabilization, and 0.94 after stabilization without decompression. Frankel scores also improved after surgery. There were no significant differences in improvements in EQ-5D scores and Frankel grades among the different surgical procedures. In addition, mortality and complication rates were similar. CONCLUSIONS Quality of life can improve significantly after various extensive and less extensive surgical procedures in patients with spinal metastases. The relatively invasive corpectomy procedure, as compared with alternative less invasive techniques, does not negatively affect outcome.


Assuntos
Descompressão Cirúrgica/métodos , Procedimentos de Cirurgia Plástica/métodos , Qualidade de Vida , Neoplasias da Coluna Vertebral , Resultado do Tratamento , Idoso , Análise de Variância , Estudos de Coortes , Feminino , Humanos , Avaliação de Estado de Karnofsky , Masculino , Pessoa de Meia-Idade , Neoplasias da Coluna Vertebral/mortalidade , Neoplasias da Coluna Vertebral/psicologia , Neoplasias da Coluna Vertebral/secundário , Neoplasias da Coluna Vertebral/cirurgia , Inquéritos e Questionários , Fatores de Tempo
5.
Sensors (Basel) ; 17(1)2017 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-28106763

RESUMO

In this work, a Global Navigation Satellite System (GNSS) buoy that utilizes a Virtual Base Station (VBS) combined with the Real-Time Kinematic (RTK) positioning technology was developed to monitor water surface elevations in estuaries and coastal areas. The GNSS buoy includes a buoy hull, a RTK GNSS receiver, data-transmission devices, a data logger, and General Purpose Radio Service (GPRS) modems for transmitting data to the desired land locations. Laboratory and field tests were conducted to test the capability of the buoy and verify the accuracy of the monitored water surface elevations. For the field tests, the GNSS buoy was deployed in the waters of Suao (northeastern part of Taiwan). Tide data obtained from the GNSS buoy were consistent with those obtained from the neighboring tide station. Significant wave heights, zero-crossing periods, and peak wave directions obtained from the GNSS buoy were generally consistent with those obtained from an accelerometer-tilt-compass (ATC) sensor. The field tests demonstrate that the developed GNSS buoy can be used to obtain accurate real-time tide and wave data in estuaries and coastal areas.

6.
Front Psychol ; 15: 1323784, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38384354

RESUMO

Corporal punishment is believed to precede various forms of violent behavior, yet prior research has yielded inconsistent findings, partly due to variations in violent types and other factors. This meta-analysis systematically reviewed 35 studies including 144 effect sizes (comprising a total sample size of 159,213) investigating the association between corporal punishment and a spectrum of violent behaviors called Violent Behavior Spectrum (VBS). Additionally, meta-regressions were conducted to explore the moderating impact of punishment severity, violence type and cultural context. Our findings indicated a significant positive relationship between corporal punishment and VBS (r = 0.238, 95%, CI [0.176, 0.300]). Notably, punishment severity was found to influence the strength of this association. Namely, The more severe the corporal punishment, the more likely it is to lead to VBS. These results enhance our understanding of the intricate connection between corporal punishment and various forms of violence, providing valuable insights for both parenting practices and policy development.

7.
Neuroimage ; 83: 58-65, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23820436

RESUMO

In this work a method is described to discern the perfusion territories in the cerebellum that are exclusively supplied by either or both vertebral arteries. In normal vascular anatomy the posterior inferior cerebellar artery (PICA) is supplied exclusively by its ipsilateral vertebral artery. The perfusion territories of the vertebral arteries were determined in 14 healthy subjects by means of a super-selective pseudo-continuous ASL sequence on a 3T MRI scanner. Data is presented to show the feasibility of determining the PICA perfusion territory. In 10 subjects it was possible to accurately determine both PICA perfusion territories. In two subjects it was possible to determine the perfusion territory of one PICA. Examples in which it was not possible to accurately determine the PICA territory are also given. Additionally, the high variability of the extent of the PICA territory is illustrated using a statistical map. The posterior surface of the cerebellum is entirely supplied by the PICA in six subjects. The most posterior part of the superior surface is supplied by the PICA in eight subjects, and the inferior half of the anterior surface in six subjects. The inferior part of the vermis is supplied by the PICA in all subjects. Two subjects were found with interhemispheric blood flow to both tonsils from one PICA without contribution from the contralateral PICA. With the method as presented, clinicians may in the future accurately classify cerebellar infarcts according to affected perfusion territories, which might be helpful in the decision whether a stenosis should be considered symptomatic.


Assuntos
Cerebelo/irrigação sanguínea , Cerebelo/fisiopatologia , Artérias Cerebrais/fisiologia , Circulação Cerebrovascular/fisiologia , Interpretação de Imagem Assistida por Computador/métodos , Angiografia por Ressonância Magnética/métodos , Artéria Vertebral/fisiologia , Velocidade do Fluxo Sanguíneo , Feminino , Humanos , Aumento da Imagem/métodos , Masculino , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Marcadores de Spin
8.
Surg Neurol Int ; 14: 156, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37151457

RESUMO

Background: Vertebral body stenting systems (VBSs) are superior to balloon kyphoplasty for performing vertebral augmentation and height restoration. However, VBS may likely result in more material-related complications that have been under-reported. Here, an 84-year-old female's vertebral stents "toppled over" before the filling cement was fully applied, thus necessitating an additional posterior fusion. Case Description: An 84-year-old female presented with low back pain after a fall. Dynamic standing and decubitus X-rays revealed a vertebral compression fracture at T12 resulting in an intravertebral vacuum cleft (i.e., the lowermost level of diffuse idiopathic skeletal hyperostosis). When the VBS was performed, the stents "toppled over" just after removing the balloon catheters; we successfully restored with the cement volume in one stent but not the other, thus warranting an additional posterior fusion to maintain stability. Conclusion: The proper injection of cement into a VBS requires dual correct stent positioning, and careful control of requisite stent expansion. In an 84-year-old female with a T12 vertebral body fracture and a remarkable vacuum cleft, the VBS procedure resulted in an inadvertent injection into one stent thus warranting a secondary posterior fusion.

9.
Curr Cardiol Rev ; 19(1): e170322202296, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-35301953

RESUMO

Patients with posterior circulation ischemia due to vertebral artery stenosis account for 20 to 25% of ischemic strokes and have an increased risk of recurrent stroke. In patients treated with medical therapy alone, the risk of recurrence is particularly increased in the first few weeks after symptoms occur, with an annual stroke rate of 10 to 15%. Additionally, obstructive disease of the vertebrobasilar system carries a worse prognosis, with a 30% mortality at 2-years if managed medically without additional surgical or endovascular intervention. Percutaneous transluminal angioplasty and stenting of symptomatic vertebral artery stenosis are promising options widely used in clinical practice with good technical results; however, the improved clinical outcome has been examined in various clinical trials without a sufficient sample size to conclusively determine whether stenting is better than medical therapy. Surgical revascularization is an alternative approach for the treatment of symptomatic vertebral artery stenosis that carries a 10-20% mortality rate. Despite the advances in medical therapy and endovascular and surgical options, symptomatic vertebral artery stenosis continues to impose a high risk of stroke recurrence with associated high morbidity and mortality. This review aims to provide a focused update on the percutaneous treatment of vertebral artery stenosis, its appropriate diagnostic approach, and advances in medical therapies.


Assuntos
Acidente Vascular Cerebral , Insuficiência Vertebrobasilar , Humanos , Artéria Vertebral/diagnóstico por imagem , Insuficiência Vertebrobasilar/diagnóstico , Insuficiência Vertebrobasilar/terapia , Insuficiência Vertebrobasilar/complicações , Angioplastia/efeitos adversos , Angioplastia/métodos , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/terapia , Resultado do Tratamento , Stents
10.
Radiol Case Rep ; 17(11): 4232-4238, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36120524

RESUMO

Pulmonary hamartomas are common benign lung tumors; however, endobronchial hamartomas are relatively rare. We report a case of asymptomatic endobronchial hamartoma in a 51-year-old man. Chest computed tomography revealed a 10-mm protrusion in the right main bronchus. Preoperative virtual bronchoscopy (VBS) was performed; subsequently, minimally invasive bronchoscopic resection was safely performed under local anesthesia. The use of VBS is a useful treatment strategy and follow-up modality.

11.
Sci Total Environ ; 661: 375-385, 2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-30677683

RESUMO

A direct and quantitative linkage of air pollution-related health effects to emissions from different sources is critically important for decision-making. While a number of studies have attributed the PM2.5-related health impacts to emission sources, they have seldom examined the complicated nonlinear relationships between them. Here we investigate the nonlinear relationships between PM2.5-related premature mortality in the Beijing-Tianjin-Hebei (BTH) region, one of the most polluted regions in the world, and emissions of different pollutants from multiple sectors and regions, through a combination of chemical transport model (CTM), extended response surface model (ERSM), and concentration-response functions (CRFs). The mortalities due to both long-term and short-term exposures to PM2.5 are most sensitive to the emission reductions of primary PM2.5, followed by NH3, nonmethane volatile organic compounds and intermediate volatility organic compounds (NMVOC+IVOC). The sensitivities of long-term mortality to emissions of primary organic aerosol (POA), NMVOC+IVOC and SO2 do not change much with reduction ratio, whereas the sensitivities to primary inorganic PM2.5 (defined as all chemical components of primary PM2.5 other than POA), NH3 and NOx increase significantly with the increase of reduction ratio. The emissions of primary PM2.5, especially those from the residential and commercial sectors, contribute a larger fraction of mortality in winter (57-70%) than in other seasons (28-42%). When emissions of multiple pollutants or those from both local and regional emissions are controlled simultaneously, the overall sensitivity of long-term mortality is much larger than the arithmetic sum of the sensitivities to emissions of individual pollutants or from individual regions. This implies that a multi-pollutant, multi-sector and regional joint control strategy should be implemented to maximize the marginal health benefits. For NOx emissions, we suggest a nationwide control strategy which significantly enhances the effectiveness for reducing mortality by avoiding possible side effects when only the emissions within the BTH region are reduced.


Assuntos
Poluentes Atmosféricos/efeitos adversos , Exposição Ambiental/efeitos adversos , Mortalidade Prematura , Material Particulado/efeitos adversos , China/epidemiologia , Humanos , Dinâmica não Linear , Tamanho da Partícula
12.
J Neurosurg Spine ; : 1-12, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31860813

RESUMO

OBJECTIVE: Severe lytic cancerous lesions of the spine are associated with significant morbidity and treatment challenges. Stabilization and restoration of the axial load capability of the vertebral body (VB) are important to prevent or arrest vertebral collapse. Percutaneous stent screw-assisted internal fixation (SAIF), which anchors a VB stent/cement complex with pedicular screws to the posterior vertebral elements, is a minimally invasive, image-guided, 360° internal fixation technique that can be utilized in this patient cohort. The purpose of this study was to assess the feasibility, safety, and stabilization efficacy of VB reconstruction via the SAIF technique in a cohort of patients with extensive lytic vertebral lesions, who were considered to have an unstable or potentially unstable spine according to the Spinal Instability Neoplastic Score (SINS). METHODS: This study was a retrospective assessment of a prospectively maintained database of a consecutive series of patients with neoplastic extensive extracompartmental osteolysis (Tomita type 4-6) of the VB treated with the SAIF technique. VB reconstruction was assessed on postprocedure plain radiographs and CT by two independent raters. Technical and clinical complications were recorded. Clinical and imaging follow-ups were assessed. RESULTS: Thirty-five patients with extensive osteolytic metastatic lesions of the VB underwent 36 SAIF procedures. SAIF was performed as a stand-alone procedure in 31/36 cases and was associated with posterior surgical fixation in 5/36 (4/5 with decompressive laminectomy). In 1 case an epidural cement leak required surgical decompression. VB reconstruction was categorized as satisfactory (excellent or good rating) by the two raters in 34/36 cases (94.5%) with an interrater reliability of 94.4% (Cohen's kappa of 0.8). Follow-up, ranging from 1 to 30 months, was available for 30/36 levels. Long-term follow-up (6-30 months, mean 11.5 months) was available for 16/36 levels. Stability during follow-up was noted in 29/30 cases. CONCLUSIONS: SAIF provides 360° nonfusion internal fixation that stabilizes the VB in patients with extensive lytic lesions that would otherwise be challenging to treat.

13.
Huan Jing Ke Xue ; 38(3): 867-875, 2017 Mar 08.
Artigo em Zh | MEDLINE | ID: mdl-29965555

RESUMO

This study chose two months (January and July) in 2012 which represent winter and summer respectively, to assess the effects of fine particle(PM2.5) pollution elimination due to emission control from different sectors in the Bejing-Tianjin-Hebei region by using CMAQ/2D-VBS modeling system. The results showed that, industrial emissions contributed most to PM2.5 pollution in the Beijing-Tianjin-Hebei region, followed by domestic emissions, while the contribution of per ton emission reduced for industrial sectors subject to domestic sectors. The total contribution and contribution of per ton emission reduced for transportation and power plant were both at low level. Among industrial sectors, the iron, steel and metallurgical industry was the greatest contributor, followed by cement industry, industrial boiler, coking industry, lime and bricks industry and chemical industry. It was found that the contribution of each emission source had significant association with its primary PM2.5 emission level. The control of NOx emissions would promote the formation of PM2.5, and atmospheric vertical diffusion effect was weak during wintertime in the Beijing-Tianjin-Hebei region. As a result, emission control of various sectors was universally more effective for PM2.5 pollution mitigation in summer than in winter. Emission control in summer was significantly more effective for transportation, powerplant, cement industry, industrial boiler and lime and bricks industry. Due to considerable emissions in heating season, domestic emissions showed more contribution in winter. Agricultural sources showed greater contribution per emission reduction in winter by the reason of substantial emissions from straw open burning during this time. With respect to a certain reduction ratio of emission, future control strategies should pay more attention to industrial emissions, especially to the primary PM2.5 emissions. In details, priorities should be given to NOx and SO2 emission control for iron, steel and metallurgical industry, NOx emission control for cement industry and SO2 and NMVOC emission control for coking industry. Besides, domestic emission control should also be taken into consideration, and it will be more effective in winter.

14.
J Neurosurg Spine ; 24(6): 922-7, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26895528

RESUMO

OBJECTIVE Vertebroplasty and balloon kyphoplasty are effective treatment options for osteoporotic vertebral compression fractures but are limited in correction of kyphotic deformity. Lordoplasty has been reported as an alternative, cost-effective, minimally invasive, percutaneous cement augmentation technique with good restoration of vertebral body height and alignment. The authors report on its clinical and radiological midterm results. METHODS A retrospective review was conducted of patients treated with lordoplasty from 2002 to 2014. Inclusion criteria were clinical and radiological follow-up evaluations longer than 24 months. Radiographs were accessed regarding initial correction and progressive loss of reduction. Complications and reoperations were recorded. Actual pain level, pain relief immediately after surgery, autonomy, and subjective impression of improvement of posture were assessed by questionnaire. RESULTS Sixty-five patients (46 women, 19 men, age range 38.9-86.2 years old) were treated with lordoplasty for 69 vertebral compression and insufficiency fractures. A significant correction of the vertebral kyphotic angle (mean 13°) and segmental kyphotic angle (mean 11°) over a mean follow-up of 33 months (range 24-108 months) was achieved (p < 0.001). On average, pain was relieved to 90% of the initial pain level. In 24% of the 65 patients a second spinal intervention was necessary: 16 distant (24.6%) and 7 adjacent (10.8%) new osteoporotic fractures, 4 instrumented stabilizations (6.2%), 1 new adjacent traumatic fracture (1.5%), and 1 distant microsurgical decompression (1.5%). Cement leakage occurred in 10.4% but was only symptomatic in 1 case. CONCLUSIONS Lordoplasty appeared safe and effective in midterm pain alleviation and restoration of kyphotic deformity in osteoporotic compression and insufficiency fractures. The outcomes of lordoplasty are consistent with other augmentation techniques.


Assuntos
Fraturas por Compressão/cirurgia , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Procedimentos Ortopédicos/métodos , Fraturas da Coluna Vertebral/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Fraturas por Compressão/diagnóstico por imagem , Fraturas por Compressão/epidemiologia , Fraturas por Compressão/fisiopatologia , Humanos , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/cirurgia , Masculino , Pessoa de Meia-Idade , Procedimentos Cirúrgicos Minimamente Invasivos/efeitos adversos , Procedimentos Ortopédicos/efeitos adversos , Dor/diagnóstico por imagem , Dor/epidemiologia , Dor/fisiopatologia , Dor/cirurgia , Reoperação , Estudos Retrospectivos , Fraturas da Coluna Vertebral/diagnóstico por imagem , Fraturas da Coluna Vertebral/epidemiologia , Fraturas da Coluna Vertebral/fisiopatologia , Vértebras Torácicas/diagnóstico por imagem , Vértebras Torácicas/cirurgia , Fatores de Tempo , Resultado do Tratamento
15.
Acta Pharm Sin B ; 5(4): 316-22, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26579461

RESUMO

Traditionally, determination of inhibitory potency of complement inhibitors is performed by the hemolytic assay. However, this assay is not applicable to the lectin pathway, thus impeding the understanding of complement inhibitors against the overall function of the complement system. The main objective of our study was to develop a specific enzyme-linked immunosorbent assay (ELISA) as an alternative method to assess the anti-complement activity, particularly against the lectin pathway. By using respective coating substrates against different activation pathways, followed by capturing the stable C3c fragments, our ELISA method can be used to screen complement inhibitors against the classical pathway and the lectin pathway. The inhibitory effect of suramin on the classical pathway, as measured by our hemolytic assay is consistent with previous reports. Further assessment of suramin and Bupleurum polysaccharides against the lectin pathway showed a good reproducibility of the method. Comparison of the lectin pathway IC50 between Bupleurum smithii var. parvifolium polysaccharides (1.055 mg/mL) and Bupleurum chinense polysaccharides (0.98 mg/mL) showed that, similar to the classical and alterative pathway, these two Bupleurum polysaccharides had comparable anti-complementary properties against the lectin pathway. The results demonstrate that the described ELISA assay can compensate for the shortcomings of the hemolytic assay in lectin pathway.

16.
Neuroscience ; 254: 285-300, 2013 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-24090964

RESUMO

Does skill with a difficult task, such as tightrope walking, lead to improved balance through altered movement strategies or through altered weighting of sensory inputs? We approached this question by comparing tandem stance (TS) data between seven tightrope walkers and 12 untrained control subjects collected under different sensory conditions. All subjects performed four TS tasks with eyes open or closed, on a normal firm or foam surface (EON, ECN, EOF, ECF); tightrope walkers were also tested on a tightrope (EOR). Head, upper trunk and pelvis angular velocities were measured with gyroscopes in pitch and roll. Power spectral densities (PSDs) ratios, and transfer function gains (TFG) between these body segments were calculated. Center of mass (CoM) excursions and its virtual time to contact a virtual base of support boundary (VTVBS) were also estimated. Gain nonlinearities, in the form of decreased trunk to head and trunk to pelvis PSD ratios and TFGs, were present with increasing sensory task difficulty for both groups. PSD ratios and TFGs were less in trained subjects, though, in absolute terms, trained subjects moved their head, trunk, pelvis and CoM faster than controls, and had decreased VTVBS. Head roll amplitudes were unchanged with task or training, except above 3Hz. CoM amplitude deviations were not less for trained subjects. For the trained subjects, EOR measures were similar to those of ECF. Training standing on a tightrope induces a velocity modification of the same TS movement strategy used by untrained controls. More time is spent exploring the limits of the base of support with an increased use of fast trunk movements to control balance. Our evidence indicates an increased reliance on neck and pelvis proprioceptive inputs. The similarity of TS on foam to that on the tightrope suggests that the foam tasks are useful for effective training of tightrope walking.


Assuntos
Atletas , Movimento/fisiologia , Equilíbrio Postural/fisiologia , Propriocepção/fisiologia , Desempenho Psicomotor/fisiologia , Caminhada/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
17.
Neuroimage Clin ; 1(1): 48-56, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-24179736

RESUMO

Autism is a neurodevelopmental disorder in which white matter (WM) maturation is affected. We assessed WM integrity in 16 adolescents and 14 adults with high-functioning autism spectrum disorder (ASD) and in matched neurotypical controls (NT) using diffusion weighted imaging and Tract-based Spatial Statistics. Decreased fractional anisotropy (FA) was observed in adolescents with ASD in tracts involved in emotional face processing, language, and executive functioning, including the inferior fronto-occipital fasciculus and the inferior and superior longitudinal fasciculi. Remarkably, no differences in FA were observed between ASD and NT adults. We evaluated the effect of age on WM development across the entire age range. Positive correlations between FA values and age were observed in the right inferior fronto-occipital fasciculus, the left superior longitudinal fasciculus, the corpus callosum, and the cortical spinal tract of ASD participants, but not in NT participants. Our data underscore the dynamic nature of brain development in ASD, showing the presence of an atypical process of WM maturation, that appears to normalize over time and could be at the basis of behavioral improvements often observed in high-functioning autism.

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