Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 37
Filtrar
1.
Urban Transform ; 5(1): 1, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36694624

RESUMO

City governments and urban universities are well-positioned to play critical roles in advancing urban sustainability transformations. However, in partnering, cities and universities often focus efforts on discrete sustainability-related projects, neglecting the development of long-term relationships and deep, inter-organizational ties that can allow for collaboration on lasting and transformational change. Yet, at both cities and universities there are often individuals who are deeply interested in developing better partnerships that contribute to the sustainability and livability of their communities. This research develops and tests an evidence-based and facilitated process to guide sustainability researchers and municipal practitioners in the development of transformational City-university partnerships for sustainability. The Audacious Partnerships Process was tested by four City-university partnerships including Arizona State University and the City of Tempe, Dublin City University and the City of Dublin, King's College London and the City of Westminster and the National Autonomous University of Mexico and Mexico City. The Audacious Partnerships Process as well as results from post-surveys and interviews following implementation are elaborated. We conclude with key lessons for modifying and implementing the process to contribute to transformative partnership development. Supplementary Information: The online version contains supplementary material available at 10.1186/s42854-022-00045-5.

2.
Front Public Health ; 9: 690067, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34778164

RESUMO

Blue Shield of California's Community Health Advocate Program was created to support whole person-health needs by helping individuals of all socio-economic statuses navigate and access community resources, social services, and medical systems. Blue Shield's Health Reimagined team is partnering with medical providers, community resources centers, and community partners to provide intensive person-centered and technology-enabled care to patients, ensuring social needs are met while promoting health equity. A key aspect of the Health Reimagined initiative embeds Community Health Advocates (CHAs) within physician practices serving patients using a payor-agnostic approach, by which Blue Shield aims to increase access to social services and community resources, improve health outcomes, reduce medical costs, and improve overall patient experience. The purpose of this case study is to understand the provider's perspective of embedding a CHA into the care team and the resulting impact on the practice and patients. Blue Shield also sought to identify best practices and barriers of a CHA program within primary and specialty care practices. As part of an ongoing two-year mixed-methods impact evaluation (2019-2021), 10 semi-structured interviews were conducted with a total of 18 providers and office staff at five primary care and specialty practices where CHAs have been embedded. We also conducted two focus groups with the same five CHAs at different points in time. Several themes emerged from the provider, office staff, and CHA interviews. Provider practices found great value in adding a CHA to their care team as the CHA brings flexibility and continuity to patient care. They also found that having access to a CHA with shared life experiences of the communities they served is a key component to the program's success. Providers and staff reported a new understanding of the social determinants of health that impacts a patient's wellbeing with the embedding of a CHA in the care team. Overall, practitioners expressed high satisfaction with the CHA program. During the COVID-19 pandemic, CHAs have been critically important in care, as social needs have increased, and resources have shifted. The CHA program is constantly adapting to address challenges faced by all stakeholders and applying new knowledge to ensure best practices are implemented within the CHA program.


Assuntos
COVID-19 , Agentes Comunitários de Saúde , Humanos , Pandemias , Atenção Primária à Saúde , SARS-CoV-2
3.
Invest Ophthalmol Vis Sci ; 61(10): 54, 2020 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-32866268

RESUMO

Purpose: The spatial distribution of collagen fibril dispersion has a significant impact on both corneal biomechanical and optical behaviors. The goal of this study was to demonstrate a novel method to characterize collagen fibril dispersion using intraocular pressure (IOP)-induced changes in corneal optical aberrations for individualized finite-element (FE) modeling. Methods: The method was tested through both numerical simulations and ex vivo experiments. Inflation tests were simulated in FE models with three assumed patterns of collagen fibril dispersion and experimentally on three rhesus monkey corneas. Geometry, matrix stiffness, and the IOP-induced changes in wavefront aberrations were measured, and the collagen fibril dispersion was characterized. An individualized corneal model with customized collagen fibril dispersion was developed, and the estimated optical aberrations were compared with the measured data. Results: For the theoretical investigations, three assumed distributions of fibril dispersion were all successfully characterized. The estimated optical aberrations closely matched the measured data, with average root-mean-square (RMS) differences of 0.29, 0.24, and 0.10 µm for the three patterns, respectively. The overall features of the IOP-induced changes in optical aberrations were estimated for two ex vivo monkey corneas, with average RMS differences of 0.57 and 0.43 µm. Characterization of the fibril dispersion in the third cornea might have been affected by corneal hydration, resulting in an increased RMS difference, 0.8 µm. Conclusions: A more advanced corneal model with individualized distribution of collagen fibril dispersion can be developed and used to improve our ability to understand both biomechanical and optical behaviors of the cornea.


Assuntos
Colágeno/fisiologia , Córnea/fisiologia , Animais , Fenômenos Biomecânicos , Córnea/patologia , Análise de Elementos Finitos , Pressão Intraocular , Macaca mulatta , Masculino , Modems , Transtornos da Visão/etiologia , Transtornos da Visão/patologia
4.
Ann Biomed Eng ; 48(3): 905-912, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32026231

RESUMO

This paper provides a synopsis of discussions related to biomedical engineering core curricula that occurred at the Fourth BME Education Summit held at Case Western Reserve University in Cleveland, Ohio in May 2019. This summit was organized by the Council of Chairs of Bioengineering and Biomedical Engineering, and participants included over 300 faculty members from 100+ accredited undergraduate programs. This discussion focused on six key questions: QI: Is there a core curriculum, and if so, what are its components? QII: How does our purported core curriculum prepare students for careers, particularly in industry? QIII: How does design distinguish BME/BIOE graduates from other engineers? QIV: What is the state of engineering analysis and systems-level modeling in BME/BIOE curricula? QV: What is the role of data science in BME/BIOE undergraduate education? QVI: What core experimental skills are required for BME/BIOE undergrads? s. Indeed, BME/BIOI core curricula exists and has matured to emphasize interdisciplinary topics such as physiology, instrumentation, mechanics, computer programming, and mathematical modeling. Departments demonstrate their own identities by highlighting discipline-specific sub-specialties. In addition to technical competence, Industry partners most highly value our students' capacity for problem solving and communication. As such, BME/BIOE curricula includes open-ended projects that address unmet patient and clinician needs as primary methods to prepare graduates for careers in industry. Culminating senior design experiences distinguish BME/BIOE graduates through their development of client-centered engineering solutions to healthcare problems. Finally, the overall BME/BIOE curriculum is not stagnant-it is clear that data science will become an ever-important element of our students' training and that new methods to enhance student engagement will be of pedagogical importance as we embark on the next decade.


Assuntos
Engenharia Biomédica/educação , Currículo , Ciência de Dados , Humanos , Estudantes , Universidades
5.
Ambio ; 48(5): 529-538, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30448997

RESUMO

Cities worldwide are rising to the challenge of sustainable development, calling for large-scale and fast-paced transformations towards sustainability. Urban sustainability challenges are now being reframed as a lack of capacity of individuals and organizations to carry out such socio-technical transformations. This article expands on transformative capacity literature by elucidating the concept of actor-centric transformative capacity. It focuses on the unique role city-university partnerships (CUPs) can play in catalyzing and supporting effective urban sustainability transformations. Two case studies on CUPs in Portland, Oregon and Tempe, Arizona are used to identify determinants of actor-centric transformative capacity, their role in the transformative capacity of urban systems, and how they are built through CUPs. The article concludes with strategies for building effective CUPs capable of building actor-centric transformative capacity among university actors and city administrators.


Assuntos
Universidades , Arizona , Cidades , Humanos , Oregon
6.
Comput Methods Biomech Biomed Engin ; 21(3): 287-296, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29602301

RESUMO

The optical performance of the human cornea under intraocular pressure (IOP) is the result of complex material properties and their interactions. The measurement of the numerous material parameters that define this material behavior may be key in the refinement of patient-specific models. The goal of this study was to investigate the relative contribution of these parameters to the biomechanical and optical responses of human cornea predicted by a widely accepted anisotropic hyperelastic finite element model, with regional variations in the alignment of fibers. Design of experiments methods were used to quantify the relative importance of material properties including matrix stiffness, fiber stiffness, fiber nonlinearity and fiber dispersion under physiological IOP. Our sensitivity results showed that corneal apical displacement was influenced nearly evenly by matrix stiffness, fiber stiffness and nonlinearity. However, the variations in corneal optical aberrations (refractive power and spherical aberration) were primarily dependent on the value of the matrix stiffness. The optical aberrations predicted by variations in this material parameter were sufficiently large to predict clinically important changes in retinal image quality. Therefore, well-characterized individual variations in matrix stiffness could be critical in cornea modeling in order to reliably predict optical behavior under different IOPs or after corneal surgery.


Assuntos
Córnea/fisiologia , Fenômenos Ópticos , Anisotropia , Fenômenos Biomecânicos , Análise de Elementos Finitos , Humanos , Pressão Intraocular , Modelos Biológicos , Reprodutibilidade dos Testes , Estresse Mecânico , Tonometria Ocular
8.
Environ Manage ; 60(2): 176-184, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28624912

RESUMO

A growing population with increasing consumption of milk and dairy require more agricultural output in the coming years, which potentially competes with forests and other natural habitats. This issue is particularly salient in the tropics, where deforestation has traditionally generated cattle pastures and other commodity crops such as corn and soy. The purpose of this article is to review the concepts and discussion associated with reconciling food production and conservation, and in particular with regards to cattle production, including the concepts of land-sparing and land-sharing. We then present these concepts in the specific context of Colombia, where there are efforts to increase both cattle production and protect tropical forests, in order to discuss the potential for landscape planning for sustainable cattle production. We outline a national planning approach, which includes disaggregating the diverse cattle sector and production types, identifying biophysical, and economic opportunities and barriers for sustainable intensification in cattle ranching, and analyzing areas suitable for habitat restoration and conservation, in order to plan for both land-sparing and land-sharing strategies. This approach can be used in other contexts across the world where there is a need to incorporate cattle production into national goals for carbon sequestration and habitat restoration and conservation.


Assuntos
Criação de Animais Domésticos/métodos , Conservação dos Recursos Naturais/métodos , Florestas , Gado/crescimento & desenvolvimento , Criação de Animais Domésticos/economia , Animais , Sequestro de Carbono , Bovinos , Colômbia , Conservação dos Recursos Naturais/economia , Produtos Agrícolas/crescimento & desenvolvimento , Humanos , Clima Tropical , Zea mays/crescimento & desenvolvimento
9.
Asian-Australas J Anim Sci ; 30(7): 1054-1060, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28335096

RESUMO

OBJECTIVE: This study was aimed at evaluating effects of cattle breed resources and alternative mixed-feeding practices on meat productivity and emission intensities from household farming systems (HFS) in Daklak Province, Vietnam. METHODS: Records from Local Yellow×Red Sindhi (Bos indicus; Lai Sind) and 1/2 Limousin, 1/2 Drought Master, and 1/2 Red Angus cattle during the growth (0 to 21 months) and fattening (22 to 25 months) periods were used to better understand variations on meat productivity and enteric methane emissions. Parameters were determined by the ruminant model. Four scenarios were developed: (HFS1) grazing from birth to slaughter on native grasses for approximately 10 h plus 1.5 kg dry matter/d (0.8% live weight [LW]) of a mixture of guinea grass (19%), cassava (43%) powder, cotton (23%) seed, and rice (15%) straw; (HFS2) growth period fed with elephant grass (1% of LW) plus supplementation (1.5% of LW) of rice bran (36%), maize (33%), and cassava (31%) meals; and HFS3 and HFS4 computed elephant grass, but concentrate supplementation reaching 2% and 1% of LW, respectively. RESULTS: Results show that compared to HFS1, emissions (72.3±0.96 kg CH4/animal/life; least squares means± standard error of the mean) were 15%, 6%, and 23% lower (p<0.01) for the HFS2, HFS3, and HFS4, respectively. The predicted methane efficiencies (CO2eq) per kg of LW at slaughter (4.3±0.15), carcass weight (8.8±0.25 kg) and kg of edible protein (44.1±1.29) were also lower (p<0.05) in the HFS4. In particular, irrespective of the HSF, feed supply and ratio changes had a more positive impact on emission intensities when crossbred 1/2 Red Angus cattle were fed than in their crossbred counterparts. CONCLUSION: Modest improvements on feeding practices and integrated modelling frameworks may offer potential trade-offs to respond to climate change in Vietnam.

10.
J Orthop Res ; 35(10): 2233-2242, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28059475

RESUMO

Little is known about knee-specific factors that influence contact mechanics. Finite Element (FE) models offer a powerful tool to study contact mechanics, but there often exists ambiguity in the exact values of the inputs (e.g., tissue properties), which can result in a range of output values. Our objective was to quantify the reduction in the range of output values (defined herein as "uncertainty") from FE models of the human knee joint when known pre-defined values are used for clinically measurable inputs. To achieve this goal, we applied a statistically augmented FE approach to three human cadaveric knees for which full geometric and kinematic data were available. Two sets of conditions were simulated: All model inputs, clinically measurable or not, were varied to represent a "normal" patient population (Condition 1); subsets of clinically measurable variable inputs were fixed at specific values (called "patient derived inputs," or PDIs) while the other variables were varied over "normal" values (Condition 2). We found that by fixing body mass index and the anterior-posterior position of the meniscal-bony insertion points, model output uncertainty was reduced by one- to three-fifths. The magnitude of uncertainty reduction was strongly influenced by the individual knee. It was observed that knees with great anterior-posterior translation during gait had greater reductions in uncertainty when PDIs were used. This study represents the first step in developing FE models of the human knee joint based on inputs that can be derived from patients in a clinical setting. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2233-2242, 2017.


Assuntos
Análise de Elementos Finitos , Articulação do Joelho/fisiologia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Incerteza
12.
Arthroscopy ; 32(8): 1671-5, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27177437

RESUMO

PURPOSE: To study the degree of surface congruency between the talar dome and humeral head, to determine the size of graft harvestable from the talar dome, and to determine if there are surrogate markers that correspond to a higher degree of surface congruency. METHODS: Computer models of 7 nonmatched humeral heads and 7 talar domes were generated by digital segmentation of magnetic resonance (MR) images. Modeled defect regions of each humeral head were then aligned with medial and lateral surfaces of each talar dome using software to maximally limit surface mismatch. Modeled defect sizes ranging from 24 × 10 mm to 30 × 10 mm were tested. Congruence match of <1 mm separation was then measured. RESULTS: The average surface match between randomly selected talar domes to humeral head surfaces was 87.2% when 1 mm was selected as the maximal acceptable congruence difference. Congruence match was not affected by graft size or laterality of talar dome as source of graft. Matching radius of curvature of talar dome to humeral head and height of donor to recipient correlated with improved congruence match. Under best match conditions, a maximal congruence match of 95.2% was achieved. CONCLUSIONS: The present study indicates that the talar dome can be a potential source of osteochondral allograft for Hill-Sachs lesions with a maximal defect size of 30 × 10 mm for a single graft. Larger graft sizes resulted in decreased success of actual graft harvest as a result of dimensional constraints of the talar dome. Additional studies are required to determine the biomechanical compatibility of this graft. CLINICAL RELEVANCE: The talar dome has a high degree of surface congruency in comparison with the humeral head though the maximal graft size harvestable limits its clinical applicability.


Assuntos
Transplante Ósseo/métodos , Cabeça do Úmero/cirurgia , Modelos Anatômicos , Tálus/transplante , Adolescente , Adulto , Lesões de Bankart/cirurgia , Simulação por Computador , Humanos , Cabeça do Úmero/anatomia & histologia , Cabeça do Úmero/diagnóstico por imagem , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Software , Tálus/anatomia & histologia , Tálus/diagnóstico por imagem , Coleta de Tecidos e Órgãos/métodos , Adulto Jovem
13.
Knee ; 22(5): 405-410, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26213361

RESUMO

BACKGROUND: Several factors are believed to contribute to patellofemoral joint function throughout knee flexion including patellofemoral (PF) kinematics, contact, and bone morphology. However, data evaluating the PF joint in this highly flexed state have been limited. Therefore, the purpose of this study was to evaluate patellofemoral contact and alignment in low (0°), moderate (60°), and deep (140°) knee flexion, and then correlate these parameters to each other, as well as to femoral morphology. METHODS: Sagittal magnetic resonance images were acquired on 14 healthy female adult knees (RSRB approved) using a 1.5 T scanner with the knee in full extension, mid-flexion, and deep flexion. The patellofemoral cartilage contact area, lateral contact displacement (LCD), cartilage thickness, and lateral patellar displacement (LPD) throughout flexion were defined. Intra- and inter-rater repeatability measures were determined. Correlations between patellofemoral contact parameters, alignment, and sulcus morphology were calculated. RESULTS: Measurement repeatability ICCs ranged from 0.94 to 0.99. Patellofemoral cartilage contact area and thickness, LCD, and LPD were statistically different throughout all levels of flexion (p<0.001). The cartilage contact area was correlated to LPD, cartilage thickness, sulcus angle, and epicondylar width (r=0.47-0.72, p<0.05). DISCUSSION: This study provides a comprehensive analysis of the patellofemoral joint throughout its range of motion. CONCLUSIONS: This study agrees with past studies that investigated patellofemoral measures at a single flexion angle, and provides new insights into the relationship between patellofemoral contact and alignment at multiple flexion angles. CLINICAL RELEVANCE: The study provides a detailed analysis of the patellofemoral joint in vivo, and demonstrates the feasibility of using standard clinical magnetic resonance imaging scanners to image the knee joint in deep flexion.


Assuntos
Cartilagem Articular/anatomia & histologia , Imageamento por Ressonância Magnética , Movimento/fisiologia , Articulação Patelofemoral/anatomia & histologia , Adulto , Cartilagem Articular/fisiologia , Feminino , Voluntários Saudáveis , Humanos , Articulação Patelofemoral/fisiologia , Reprodutibilidade dos Testes
14.
Ambio ; 44(7): 685-93, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26121947

RESUMO

The increased use of grain-based feed for livestock during the last two decades has contributed, along with other factors, to a rise in grain prices that has reduced human food security. This circumstance argues for feeding more forages to livestock, particularly in the tropics where many livestock are reared on small farms. Efforts to accomplish this end, referred to as the 'LivestockPlus' approach, intensify in sustainable ways the management of grasses, shrubs, trees, and animals. By decoupling the human food and livestock feed systems, these efforts would increase the resilience of the global food system. Effective LivestockPlus approaches take one of two forms: (1) simple improvements such as new forage varieties and animal management practices that spread from farmer to farmer by word of mouth, or (2) complex sets of new practices that integrate forage production more closely into farms' other agricultural activities and agro-ecologies.


Assuntos
Agricultura/métodos , Grão Comestível , Abastecimento de Alimentos/métodos , Gado/fisiologia , Melhoramento Vegetal , Criação de Animais Domésticos , Animais , Grão Comestível/crescimento & desenvolvimento , Humanos
15.
J Biomech ; 48(8): 1444-53, 2015 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-25757666

RESUMO

Meniscal implants have been developed in an attempt to provide pain relief and prevent pathological degeneration of articular cartilage. However, as yet there has been no systematic and comprehensive analysis of the effects of the meniscal design variables on meniscal function across a wide patient population, and there are no clear design criteria to ensure the functional performance of candidate meniscal implants. Our aim was to develop a statistically-augmented, experimentally-validated, computational platform to assess the effect of meniscal properties and patient variables on knee joint contact mechanics during the activity of walking. Our analysis used Finite Element Models (FEMs) that represented the geometry, kinematics as based on simulated gait and contact mechanics of three laboratory tested human cadaveric knees. The FEMs were subsequently programmed to represent prescribed meniscal variables (circumferential and radial/axial moduli-Ecm, Erm, stiffness of the meniscal attachments-Slpma, Slamp) and patient variables (varus/valgus alignment-VVA, and articular cartilage modulus-Ec). The contact mechanics data generated from the FEM runs were used as training data to a statistical interpolator which estimated joint contact data for untested configurations of input variables. Our data suggested that while Ecm and Erm of a meniscus are critical in determining knee joint mechanics in early and late stance (peak 1 and peak 3 of the gait cycle), for some knees that have greater laxity in the mid-stance phase of gait, the stiffness of the articular cartilage, Ec, can influence force distribution across the tibial plateau. We found that the medial meniscus plays a dominant load-carrying role in the early stance phase and less so in late stance, while the lateral meniscus distributes load throughout gait. Joint contact mechanics in the medial compartment are more sensitive to Ecm than those in the lateral compartment. Finally, throughout stance, varus-valgus alignment can overwhelm these relationships while the stiffness of meniscal attachments in the range studied have minimal effects on the knee joint mechanics. In summary, our statistically-augmented, computational platform allowed us to study how meniscal implant design variables (which can be controlled at the time of manufacture or implantation) interact with patient variables (which can be set in FEMs but cannot be controlled in patient studies) to affect joint contact mechanics during the activity of simulated walking.


Assuntos
Simulação por Computador , Meniscos Tibiais/fisiopatologia , Modelos Biológicos , Fenômenos Biomecânicos , Cartilagem Articular/fisiopatologia , Análise de Elementos Finitos , Marcha , Humanos , Joelho/fisiopatologia , Caminhada
16.
Child Psychiatry Hum Dev ; 43(4): 544-59, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22331442

RESUMO

The high prevalence and early onset of anxiety disorders have inspired innovative prevention efforts targeting young at-risk children. With parent-child prevention models showing success for older children and adolescents, the goal of this study was to evaluate a parent-child indicated preventive intervention for preschoolers with mild to moderate anxiety symptoms. Sixteen children (ages 3-5) and at least one of their parents participated in Strengthening Early Emotional Development (SEED), a new 10-week intervention with concurrent groups for parents and children. Outcome measures included clinician-rated and parent-rated assessments of anxiety symptoms, as well as measures of emotion knowledge, parent anxiety, and parental attitudes about children's anxiety. Participation in SEED was associated with reduced child anxiety symptoms and improved emotion understanding skills. Parents reported decreases in their own anxiety, along with attitudes reflecting enhanced confidence in their children's ability to cope with anxiety. Reductions in child and parent anxiety were maintained at 3-month follow-up. Findings suggest that a parent-child cognitive-behavioral preventive intervention may hold promise for young children with mild to moderate anxiety. Improvements in parent anxiety and parental attitudes may support the utility of intervening with parents. Fostering increased willingness to encourage their children to engage in new and anxiety-provoking situations may help promote continued mastery of new skills and successful coping with anxiety.


Assuntos
Adaptação Psicológica , Transtornos de Ansiedade/prevenção & controle , Ansiedade/prevenção & controle , Relações Pais-Filho , Pais/psicologia , Pré-Escolar , Emoções , Feminino , Humanos , Masculino , Ajustamento Social , Resultado do Tratamento
17.
Geogr J ; 177(4): 311-20, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22180921

RESUMO

The global food system is coming under increasing strain in the face of urban population growth. The recent spike in global food prices (2007­08) provoked consumer protests, and raised questions about food sovereignty and how and where food will be produced. Concurrently, for the first time in history the majority of the global population is urban, with the bulk of urban growth occurring in smaller-tiered cities and urban peripheries, or 'peri-urban' areas of the developing world. This paper discusses the new emerging spaces that incorporate a mosaic of urban and rural worlds, and reviews the implications of these spaces for livelihoods and food security. We propose a modified livelihoods framework to evaluate the contexts in which food production persists within broader processes of landscape and livelihood transformation in peri-urban locations. Where and how food production persists are central questions for the future of food security in an urbanising world. Our proposed framework provides directions for future research and highlights the role of policy and planning in reconciling food production with urban growth.


Assuntos
Agricultura , Países em Desenvolvimento , Indústria Alimentícia , Abastecimento de Alimentos , Dinâmica Populacional , Fatores Socioeconômicos , Agricultura/economia , Agricultura/educação , Agricultura/história , Características Culturais/história , Países em Desenvolvimento/economia , Países em Desenvolvimento/história , Indústria Alimentícia/economia , Indústria Alimentícia/educação , Indústria Alimentícia/história , Abastecimento de Alimentos/economia , Abastecimento de Alimentos/história , História do Século XXI , Dinâmica Populacional/história , Política Pública/economia , Política Pública/história , População Rural/história , Fatores Socioeconômicos/história , População Urbana/história
18.
J Biomech ; 44(13): 2446-52, 2011 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-21803359

RESUMO

Patellofemoral (PF)-related pathologies, including joint laxity, patellar maltracking, cartilage degradation and anterior knee pain, affect nearly 25% of the population. Researchers have investigated the influence of articular geometry on kinematics and contact mechanics in order to gain insight into the etiology of these conditions. The purpose of the current study was to create a three-dimensional statistical shape model of the PF joint and to characterize relationships between PF shape and function (kinematics and contact mechanics). A statistical shape model of the patellar and femoral articular surfaces and their relative alignment was developed from magnetic resonance images. Using 15 shape parameters, the model characterized 97% of the variation in the training set. The first three shape modes primarily described variation in size, patella alta-baja and depth of the sulcus groove. A previously verified finite element model was used to predict kinematics and contact mechanics for each subject. Combining the shape and joint mechanics data, a statistical shape-function model was developed that established quantitative relations of how changes in the shape of the PF joint influence mechanics. The predictive capability of the shape-function model was evaluated by comparing statistical model and finite element predictions, resulting in kinematic root mean square errors of less than 3° and 2.5 mm. The key results of the study are dually in the implementation of a novel approach linking statistical shape and finite element models and the relationships elucidated between PF articular geometry and mechanics.


Assuntos
Modelos Anatômicos , Modelos Estatísticos , Articulação Patelofemoral/fisiologia , Fenômenos Biomecânicos , Análise de Elementos Finitos , Humanos , Instabilidade Articular , Imageamento por Ressonância Magnética , Articulação Patelofemoral/patologia
19.
IEEE Trans Biomed Eng ; 58(6): 1820-6, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21356612

RESUMO

Whole knee joint MR image datasets were used to compare the performance of geometric trabecular bone features and advanced machine learning techniques in predicting biomechanical strength properties measured on the corresponding ex vivo specimens. Changes of trabecular bone structure throughout the proximal tibia are indicative of several musculoskeletal disorders involving changes in the bone quality and the surrounding soft tissue. Recent studies have shown that MR imaging also allows non-invasive 3-D characterization of bone microstructure. Sophisticated features like the scaling index method (SIM) can estimate local structural and geometric properties of the trabecular bone and may improve the ability of MR imaging to determine local bone quality in vivo. A set of 67 bone cubes was extracted from knee specimens and their biomechanical strength estimated by the yield stress (YS) [in MPa] was determined through mechanical testing. The regional apparent bone volume fraction (BVF) and SIM derived features were calculated for each bone cube. A linear multiregression analysis (MultiReg) and a optimized support vector regression (SVR) algorithm were used to predict the YS from the image features. The prediction accuracy was measured by the root mean square error (RMSE) for each image feature on independent test sets. The best prediction result with the lowest prediction error of RMSE = 1.021 MPa was obtained with a combination of BVF and SIM features and by using SVR. The prediction accuracy with only SIM features and SVR (RMSE = 1.023 MPa) was still significantly better than BVF alone and MultiReg (RMSE = 1.073 MPa). The current study demonstrates that the combination of sophisticated bone structure features and supervised learning techniques can improve MR-based determination of trabecular bone quality.


Assuntos
Imageamento por Ressonância Magnética , Modelos Biológicos , Tíbia/fisiologia , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Inteligência Artificial , Fenômenos Biomecânicos/fisiologia , Bases de Dados Factuais , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Articulação do Joelho/fisiologia , Masculino , Análise de Regressão , Resistência ao Cisalhamento/fisiologia , Tíbia/anatomia & histologia
20.
Bone ; 48(3): 562-70, 2011 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-20950720

RESUMO

Despite the remarkable healing potential of long bone fractures, traumatic injuries that result in critical defects require challenging reconstructive limb sparing surgery. While devitalized allografts are the gold standard for these procedures, they are prone to failure due to their limited osseointegration with the host. Thus, the quest for adjuvants to enhance allograft healing remains a priority for this unmet clinical need. To address this, we investigated the effects of daily systemic injections of 40 µg/kg teriparatide (recombinant human parathyroid hormone) on the healing of devitalized allografts used to reconstruct critical femoral defects (4mm) in C57Bl/6 mice. The femurs were evaluated at 4 and 6 weeks using micro CT, histology, and torsion testing. Our findings demonstrated that teriparatide induced prolonged cartilage formation at the graft-host junction at 4 weeks, which led to enhanced trabeculated bone callus formation and remarkable graft-host integration at 6-weeks. Moreover, we observed a significant 2-fold increase in normalized callus volume (1.04 ± 0.3 vs. 0.54 ± 0.14 mm³/mm; p < 0.005), and Union Ratio (0.28 ± 0.07 vs. 0.13 ± 0.09; p < 0.005), compared to saline treated controls at 6-weeks. Teriparatide treatment significantly increased the torsional rigidity (1175 ± 311 versus 585 ± 408 N.mm²) and yield torque (10.5 ± 4.2 versus 6.8 ± 5.5 N.mm) compared to controls. Interestingly, the Union Ratio correlated significantly with the yield torque and torsional rigidity (R²=0.59 and R²=0.77, p < 0.001, respectively). These results illustrate the remarkable potential of teriparatide as an adjuvant therapy for allograft repair in a mouse model of massive femoral defect reconstruction, and warrant further investigation in a larger animal model at longer time intervals to justify future clinical trials for PTH therapy in limb sparing reconstructive procedures.


Assuntos
Fêmur/efeitos dos fármacos , Fêmur/transplante , Osseointegração/efeitos dos fármacos , Teriparatida/farmacologia , Animais , Fenômenos Biomecânicos/efeitos dos fármacos , Fêmur/diagnóstico por imagem , Fêmur/fisiologia , Modelos Lineares , Camundongos , Camundongos Endogâmicos C57BL , Modelos Animais , Osteogênese/efeitos dos fármacos , Teriparatida/administração & dosagem , Torção Mecânica , Transplante Homólogo , Cicatrização/efeitos dos fármacos , Microtomografia por Raio-X
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...