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1.
J Fish Biol ; 104(1): 265-283, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37843923

RESUMO

The freshwater phase of the first seaward migration of juvenile Atlantic salmon (Salmo salar) is relatively well understood when compared with our understanding of the marine phase of their migration. In 2021, 1008 wild and 60 ranched Atlantic salmon smolts were tagged with acoustic transmitters in 12 rivers in England, Scotland, Northern Ireland and Ireland. Large marine receiver arrays were deployed in the Irish Sea at two locations: at the transition of the Irish Sea into the North Atlantic between Ireland and Scotland, and between southern Scotland and Northern Ireland, to examine the early phase of the marine migration of Atlantic salmon smolts. After leaving their natal rivers' post-smolt migration through the Irish Sea was rapid with minimum speeds ranging from 14.03 to 38.56 km.day-1 for Atlantic salmon smolts that entered the Irish Sea directly from their natal river, to 9.69-39.94 km.day-1 for Atlantic salmon smolts that entered the Irish Sea directly from their natal estuary. Population minimum migration success through the study area was strongly correlated with the distance of travel, populations further away from the point of entry to the open North Atlantic exhibited lower migration success. Post-smolts from different populations experienced different water temperatures on entering the North Atlantic. This was largely driven by the timing of their migration and may have significant consequences for feeding and ultimately survivorship. The influence of water currents on post-smolt movement was investigated using data from previously constructed numerical hydrodynamic models. Modeled water current data in the northern Irish Sea showed that post-smolts had a strong preference for migrating when the current direction was at around 283° (west-north-west) but did not migrate when exposed to strong currents in other directions. This is the most favorable direction for onward passage from the Irish Sea to the continental shelf edge current, a known accumulation point for migrating post-smolts. These results strongly indicate that post-smolts migrating through the coastal marine environment are: (1) not simply migrating by current following (2) engage in active directional swimming (3) have an intrinsic sense of their migration direction and (4) can use cues other than water current direction to orientate during this part of their migration.


Assuntos
Rios , Salmo salar , Animais , Sinais (Psicologia) , Migração Animal , Água
2.
Am J Obstet Gynecol ; 226(2S): S1145-S1156.e1, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34461078

RESUMO

BACKGROUND: Patients at high risk of severe preeclampsia and fetal growth restriction have low circulating levels of placental growth factor and features of maternal vascular malperfusion placental pathology at delivery. Multimodal screening and commencement of aspirin prophylaxis at 11 to 13 weeks' gestation markedly reduces the risk of preterm delivery with preeclampsia. However, the additional role of low-molecular-weight heparin and mechanisms of action remain uncertain. Because low-molecular-weight heparin augments the production and release of placental growth factor in vitro by both placental villi and vascular endothelium, it may be effective to suppress the risk of severe preeclampsia in a niche group of high-risk patients with low circulating placental growth factor in the early second trimester. OBJECTIVE: This study aimed to define a gestational age-specific reference range for placental growth factor and to test the hypothesis that prophylactic low-molecular-weight heparin administered in the early second trimester may restore deficient circulating placental growth factor levels and thereby prolong pregnancy. STUDY DESIGN: Centile curves for circulating placental growth factor levels from 12 to 36 weeks' gestation were derived using quantile regression of combined data from a published cohort of 4207 unselected nulliparous patients in Cambridge, United Kingdom, at 4 sampling time points (12, 20, 28, and 36 weeks' gestation) and the White majority (n=531) of a healthy nulliparous cohort in Toronto, Canada, at 16 weeks' gestation using the same test platform. Within a specialty high-risk clinic in Toronto, a niche group of 7 patients with a circulating placental growth factor at the <10th centile in the early second trimester received daily prophylactic low-molecular-weight heparin (enoxaparin; 40 mg subcutaneously) and were followed up until delivery (group 1). Their baseline characteristics, delivery details, and placental pathologies were compared with 5 similar patients who did not receive low-molecular-weight heparin during the observation period (group 2) and further with 21 patients who delivered with severe preeclampsia (group 3) in the same institution. RESULTS: A gestational age-specific reference range for placental growth factor levels at weekly intervals between 12 and 36 weeks was established for White women with singleton pregnancies. Within group 1, 5 of 7 patients demonstrated a sustained increase in circulating placental growth factor levels, whereas placental growth factor levels did not increase in group 2 or group 3 patients who did not receive low-molecular-weight heparin. Group 1 patients receiving low-molecular-weight heparin therapy exhibited a later gestation at delivery, relative to groups 2 and 3 (36 weeks [33-37] vs 23 weeks [22-26] and 28 weeks [27-31], respectively), and consequently had higher birthweights (1.93 kg [1.1-2.7] vs 0.32 kg [0.19-0.39] and 0.73 kg [0.52-1.03], respectively). The incidence of stillbirth was lowest in group 1 (14% [1 of 7]), relative to groups 2 and 3 (80% [4 of 5] and 29% [6 of 21], respectively). Maternal vascular malperfusion was the most common placental pathology found in association with abnormal uterine artery Doppler. CONCLUSION: In patients at high risk of a serious adverse pregnancy outcome owing to placental disease, the addition of low-molecular-weight heparin to aspirin prophylaxis in the early second trimester may restore deficient circulating placental growth factor to mediate an improved perinatal outcome. These data support the implementation of a multicenter pilot randomized control trial where patients are recruited primarily based on the assessment of placental function in the early second trimester.


Assuntos
Anticoagulantes/uso terapêutico , Heparina de Baixo Peso Molecular/uso terapêutico , Fator de Crescimento Placentário/sangue , Pré-Eclâmpsia/prevenção & controle , Adulto , Biomarcadores/sangue , Peso ao Nascer , Estudos de Coortes , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Projetos Piloto , Gravidez , Gravidez de Alto Risco , Nascimento Prematuro/epidemiologia
3.
BMJ Evid Based Med ; 27(6): 373-377, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-34933930

RESUMO

The disproportionate focus on statistical significance in reporting and interpreting clinical research studies contributes to publication bias and encourages selective reporting. This highlights a need for alternative approaches that clearly communicate the uncertainty in the data, enabling researchers to provide a more nuanced interpretation of clinical research findings.Our purpose in this article is to introduce the density strip method as one potential approach that might act as a bridge between data visualisation for descriptive purposes and formal statistical inference. We build on existing theory, translating it to the applied research context to illustrate its utility to clinical researchers.We achieve this by considering an exemplar clinical trial, Multiple Sclerosis-Secondary Progressive Multi-Arm Randomisation Trial (MS-SMART). MS-SMART was a multiarm randomised placebo-controlled trial of three potentially neuroprotective drugs in secondary progressive MS. We illustrate through MS-SMART the potential of the density strip as an effective visualisation of the distribution of clinical trial outcomes and as a complementary approach to aid the interpretation of formal, inferential, statistical analysis.We conclude by summarising the advantages and disadvantages of the density strip methodology and provide suggestions for its potential extensions and possible further uses.


Assuntos
Projetos de Pesquisa , Humanos , Incerteza , Viés de Publicação
4.
J R Stat Soc Ser C Appl Stat ; 70(3): 691-713, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34690375

RESUMO

The advent of high-resolution imaging has made data on surface shape widespread. Methods for the analysis of shape based on landmarks are well established but high-resolution data require a functional approach. The starting point is a systematic and consistent description of each surface shape and a method for creating this is described. Three innovative forms of analysis are then introduced. The first uses surface integration to address issues of registration, principal component analysis and the measurement of asymmetry, all in functional form. Computational issues are handled through discrete approximations to integrals, based in this case on appropriate surface area weighted sums. The second innovation is to focus on sub-spaces where interesting behaviour such as group differences are exhibited, rather than on individual principal components. The third innovation concerns the comparison of individual shapes with a relevant control set, where the concept of a normal range is extended to the highly multivariate setting of surface shape. This has particularly strong applications to medical contexts where the assessment of individual patients is very important. All of these ideas are developed and illustrated in the important context of human facial shape, with a strong emphasis on the effective visual communication of effects of interest.

5.
Psychiatry Res ; 291: 113243, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32593068

RESUMO

As understanding of the genetics of bipolar disorder increases, controversy endures regarding whether the origins of this illness include early maldevelopment. Clarification would be facilitated by a 'hard' biological index of fetal developmental abnormality, among which craniofacial dysmorphology bears the closest embryological relationship to brain dysmorphogenesis. Therefore, 3D laser surface imaging was used to capture the facial surface of 21 patients with bipolar disorder and 45 control subjects; 21 patients with schizophrenia were also studied. Surface images were subjected to geometric morphometric analysis in non-affine space for more incisive resolution of subtle, localised dysmorphologies that might distinguish patients from controls. Complex and more biologically informative, non-linear changes distinguished bipolar patients from control subjects. On a background of minor dysmorphology of the upper face, maxilla, midface and periorbital regions, bipolar disorder was characterised primarily by the following dysmorphologies: (a) retrusion and shortening of the premaxilla, nose, philtrum, lips and mouth (the frontonasal prominences), with (b) some protrusion and widening of the mandible-chin. The topography of facial dysmorphology in bipolar disorder indicates disruption to early development in the frontonasal process and, on embryological grounds, cerebral dysmorphogenesis in the forebrain, most likely between the 10th and 15th week of fetal life.


Assuntos
Transtorno Bipolar/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Anormalidades Craniofaciais/diagnóstico por imagem , Face/diagnóstico por imagem , Adulto , Transtorno Bipolar/complicações , Anormalidades Craniofaciais/complicações , Feminino , Humanos , Imageamento Tridimensional/métodos , Masculino , Análise de Componente Principal , Esquizofrenia/diagnóstico por imagem , Adulto Jovem
6.
Ann Appl Stat ; 13(4): 2539-2563, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-33479569

RESUMO

One of the data structures generated by medical imaging technology is high resolution point clouds representing anatomical surfaces. Stereophotogrammetry and laser scanning are two widely available sources of this kind of data. A standardised surface representation is required to provide a meaningful correspondence across different images as a basis for statistical analysis. Point locations with anatomical definitions, referred to as landmarks, have been the traditional approach. Landmarks can also be taken as the starting point for more general surface representations, often using templates which are warped on to an observed surface by matching landmark positions and subsequent local adjustment of the surface. The aim of the present paper is to provide a new approach which places anatomical curves at the heart of the surface representation and its analysis. Curves provide intermediate structures which capture the principal features of the manifold (surface) of interest through its ridges and valleys. As landmarks are often available these are used as anchoring points, but surface curvature information is the principal guide in estimating the curve locations. The surface patches between these curves are relatively flat and can be represented in a standardised manner by appropriate surface transects to give a complete surface model. This new approach does not require the use of a template, reference sample or any external information to guide the method and, when compared with a surface based approach, the estimation of curves is shown to have improved performance. In addition, examples involving applications to mussel shells and human faces show that the analysis of curve information can deliver more targeted and effective insight than the use of full surface information.

7.
Curr Behav Neurosci Rep ; 4(4): 322-330, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29201594

RESUMO

PURPOSE OF REVIEW: In the context of human developmental conditions, we review the conceptualisation of schizophrenia as a neurodevelopmental disorder, the status of craniofacial dysmorphology as a clinically accessible index of brain dysmorphogenesis, the ability of genetically modified mouse models of craniofacial dysmorphology to inform on the underlying dysmorphogenic process and how geometric morphometric techniques in mutant mice can extend quantitative analysis. RECENT FINDINGS: Mutant mice with disruption of neuregulin-1, a gene associated meta-analytically with risk for schizophrenia, constitute proof-of-concept studies of murine facial dysmorphology in a manner analogous to clinical studies in schizophrenia. Geometric morphometric techniques informed on the topography of facial dysmorphology and identified asymmetry therein. SUMMARY: Targeted disruption in mice of genes involved in individual components of developmental processes and analysis of resultant facial dysmorphology using geometric morphometrics can inform on mechanisms of dysmorphogenesis at levels of incisiveness not possible in human subjects.

8.
J Anat ; 228(3): 355-65, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26659272

RESUMO

The analysis of shape is a key part of anatomical research and in the large majority of cases landmarks provide a standard starting point. However, while the technology of image capture has developed rapidly and in particular three-dimensional imaging is widely available, the definitions of anatomical landmarks remain rooted in their two-dimensional origins. In the important case of the human face, standard definitions often require careful orientation of the subject. This paper considers the definitions of facial landmarks from an interdisciplinary perspective, including biological and clinical motivations, issues associated with imaging and subsequent analysis, and the mathematical definition of surface shape using differential geometry. This last perspective provides a route to definitions of landmarks based on surface curvature, often making use of ridge and valley curves, which is genuinely three-dimensional and is independent of orientation. Specific definitions based on curvature are proposed. These are evaluated, along with traditional definitions, in a study that uses a hierarchical (random effects) model to estimate the error variation that is present at several different levels within the image capture process. The estimates of variation at these different levels are of interest in their own right but, in addition, evidence is provided that variation is reduced at the observer level when the new landmark definitions are used.


Assuntos
Face/anatomia & histologia , Imageamento Tridimensional/métodos , Pontos de Referência Anatômicos , Cefalometria/métodos , Humanos , Processamento de Imagem Assistida por Computador
9.
Ecol Evol ; 5(21): 4875-84, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26640667

RESUMO

Ocean acidification threatens organisms that produce calcium carbonate shells by potentially generating an under-saturated carbonate environment. Resultant reduced calcification and growth, and subsequent dissolution of exoskeletons, would raise concerns over the ability of the shell to provide protection for the marine organism under ocean acidification and increased temperatures. We examined the impact of combined ocean acidification and temperature increase on shell formation of the economically important edible mussel Mytilus edulis. Shell growth and thickness along with a shell thickness index and shape analysis were determined. The ability of M. edulis to produce a functional protective shell after 9 months of experimental culture under ocean acidification and increasing temperatures (380, 550, 750, 1000 µatm pCO 2, and 750, 1000 µatm pCO 2 + 2°C) was assessed. Mussel shells grown under ocean acidification conditions displayed significant reductions in shell aragonite thickness, shell thickness index, and changes to shell shape (750, 1000 µatm pCO 2) compared to those shells grown under ambient conditions (380 µatm pCO 2). Ocean acidification resulted in rounder, flatter mussel shells with thinner aragonite layers likely to be more vulnerable to fracture under changing environments and predation. The changes in shape presented here could present a compensatory mechanism to enhance protection against predators and changing environments under ocean acidification when mussels are unable to grow thicker shells. Here, we present the first assessment of mussel shell shape to determine implications for functional protection under ocean acidification.

10.
Comput Stat Data Anal ; 86: 52-64, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26041943

RESUMO

Methods for capturing images in three dimensions are now widely available, with stereo-photogrammetry and laser scanning being two common approaches. In anatomical studies, a number of landmarks are usually identified manually from each of these images and these form the basis of subsequent statistical analysis. However, landmarks express only a very small proportion of the information available from the images. Anatomically defined curves have the advantage of providing a much richer expression of shape. This is explored in the context of identifying the boundary of breasts from an image of the female torso and the boundary of the lips from a facial image. The curves of interest are characterised by ridges or valleys. Key issues in estimation are the ability to navigate across the anatomical surface in three-dimensions, the ability to recognise the relevant boundary and the need to assess the evidence for the presence of the surface feature of interest. The first issue is addressed by the use of principal curves, as an extension of principal components, the second by suitable assessment of curvature and the third by change-point detection. P-spline smoothing is used as an integral part of the methods but adaptations are made to the specific anatomical features of interest. After estimation of the boundary curves, the intermediate surfaces of the anatomical feature of interest can be characterised by surface interpolation. This allows shape variation to be explored using standard methods such as principal components. These tools are applied to a collection of images of women where one breast has been reconstructed after mastectomy and where interest lies in shape differences between the reconstructed and unreconstructed breasts. They are also applied to a collection of lip images where possible differences in shape between males and females are of interest.

11.
Am J Med Genet A ; 167A(3): 529-36, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25691406

RESUMO

Persons with 22q11.2 deletion syndrome (22q11.2DS) are characterized inter alia by facial dysmorphology and greatly increased risk for psychotic illness. Recent studies indicate facial dysmorphology in adults with schizophrenia. This study evaluates the extent to which the facial dysmorphology of 22q11.2DS is similar to or different from that evident in schizophrenia. Twenty-one 22q11.2DS-sibling control pairs were assessed using 3D laser surface imaging. Geometric morphometrics was applied to 30 anatomical landmarks, 480 geometrically homologous semi-landmarks on curves and 1720 semi-landmarks interpolated on each 3D facial surface. Principal component (PC) analysis of overall shape space indicated PC2 to strongly distinguish 22q11.2DS from controls. Visualization of PC2 indicated 22q11.2DS and schizophrenia to be similar in terms of overall widening of the upper face, lateral displacement of the eyes/orbits, prominence of the cheeks, narrowing of the lower face, narrowing of nasal prominences and posterior displacement of the chin; they differed in terms of facial length (increased in 22q11.2DS, decreased in schizophrenia), mid-face and nasal prominences (displaced upwards and outwards in 22q11.2DS, less prominent in schizophrenia); lips (more prominent in 22q11.2DS; less prominent in schizophrenia) and mouth (open mouth posture in 22q11.2DS; closed mouth posture in schizophrenia). These findings directly implicate dysmorphogenesis in a cerebral-craniofacial domain that is common to 22q11.2DS and schizophrenia and which may repay further clinical and genetic interrogation in relation to the developmental origins of psychotic illness.


Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 22 , Anormalidades Craniofaciais/diagnóstico , Anormalidades Craniofaciais/genética , Imageamento Tridimensional , Fenótipo , Adolescente , Criança , Pré-Escolar , Síndrome de DiGeorge/diagnóstico , Síndrome de DiGeorge/genética , Feminino , Humanos , Imageamento Tridimensional/métodos , Masculino , Transtornos Psicóticos/diagnóstico , Transtornos Psicóticos/etiologia , Adulto Jovem
12.
Cleft Palate Craniofac J ; 51(4): 462-71, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23369016

RESUMO

BACKGROUND AND OBJECTIVE: Objective assessment of postsurgical facial asymmetry can be difficult, but three-dimensional (3D) imaging techniques have made this possible. The objective of this study was to assess residual asymmetry in surgically repaired unilateral cleft lip (UCL) and unilateral cleft lip and palate (UCLP) patients and to compare this with noncleft controls. DESIGN: Retrospective multicohort comparative study. PATIENTS AND METHODS: Fifty-one 10-year-old children with surgically managed UCLP and 44 children with UCL were compared with a control group of 68 ten-year-olds. The 3D facial models at rest and with maximum smile were created using a 3D imaging system. Asymmetry scores were produced using both anatomical landmarks and a novel method of facial curve analysis. RESULTS: Asymmetry for the whole face was significantly higher in both cleft groups compared with controls (P < .001). UCLP asymmetry was higher than UCL (P < .001). In cleft patients, the upper lip and nasal rim were the most asymmetric (P < .001 to .05). Control subjects also displayed a degree of facial asymmetry. Maximum smile did not significantly affect the symmetry of the whole face, but it increased asymmetry of the vermillion border and nasal rim in all three groups (P < .001). CONCLUSIONS: Despite surgical intervention at an early age, asymmetry remains significant in cleft patients at 10 years of age. Three-dimensional imaging is a noninvasive objective assessment tool that identifies specific areas of the face responsible for asymmetry. Facial curve analysis describes the face more comprehensively and characterizes soft tissue contours.


Assuntos
Fenda Labial/cirurgia , Fissura Palatina/cirurgia , Assimetria Facial/diagnóstico por imagem , Imageamento Tridimensional , Pontos de Referência Anatômicos , Criança , Feminino , Humanos , Masculino , Fotografação , Reprodutibilidade dos Testes , Estudos Retrospectivos , Escócia
13.
Paediatr Anaesth ; 24(2): 201-7, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24330482

RESUMO

BACKGROUND: Postoperative cognitive dysfunction (POCD) is well established in adults but has been underinvestigated in children. As day-case procedures are increasingly common, it is important to establish whether children suffer significant POCD. Pediatric POCD has been associated with several intravenous and inhalation anesthetics, but isoflurane has not been studied. As evidence indicates superior recovery after propofol, the study compared POCD after propofol or isoflurane anesthesia. OBJECTIVES: To compare the effects of propofol versus isoflurane upon children's POCD. METHODS: Fifty-eight children aged 5-14 years were randomized to propofol (total intravenous anesthesia) or isoflurane for day-case dental procedures. Reaction time (RT), verbal and visual memory, psychomotor coordination, and attention were assessed preoperatively, prior to discharge and at 24 h. RESULTS: Reaction time and psychomotor control were impaired postoperatively in both groups but recovered at 24 h. Delayed verbal recall was significantly impaired only after propofol. Both groups had significant impairment of visual memory postoperatively and at 24 h, and of recognition memory postoperatively only. CONCLUSIONS: Propofol and isoflurane exert similar adverse effects on RT, psychomotor coordination, and visual memory. Selective impairment of verbal recall by propofol is consistent with adult evidence of the drug's effect on retrieval. The enduring postoperative impairment of memory has implications for instructions to parents and caregivers for the safety and well-being of children in the 24 h after day-case anesthesia with propofol and isoflurane.


Assuntos
Procedimentos Cirúrgicos Ambulatórios , Anestesia Dentária , Anestesia Geral , Anestésicos Inalatórios/efeitos adversos , Anestésicos Intravenosos/efeitos adversos , Transtornos Cognitivos/induzido quimicamente , Transtornos Cognitivos/psicologia , Cognição/fisiologia , Isoflurano/efeitos adversos , Complicações Pós-Operatórias/induzido quimicamente , Complicações Pós-Operatórias/psicologia , Propofol/efeitos adversos , Anestesia por Inalação , Anestesia Intravenosa , Atenção/fisiologia , Criança , Restauração Dentária Permanente/métodos , Feminino , Seguimentos , Humanos , Masculino , Memória/fisiologia , Rememoração Mental/fisiologia , Complicações Pós-Operatórias/epidemiologia , Desempenho Psicomotor/efeitos dos fármacos , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Recuperação de Função Fisiológica , Extração Dentária/métodos , Resultado do Tratamento
14.
J R Stat Soc Ser C Appl Stat ; 63(1): 47-63, 2014 01.
Artigo em Inglês | MEDLINE | ID: mdl-25653460

RESUMO

Many statistical models are available for spatial data but the vast majority of these assume that spatial separation can be measured by Euclidean distance. Data which are collected over river networks constitute a notable and commonly occurring exception, where distance must be measured along complex paths and, in addition, account must be taken of the relative flows of water into and out of confluences. Suitable models for this type of data have been constructed based on covariance functions. The aim of the paper is to place the focus on underlying spatial trends by adopting a regression formulation and using methods which allow smooth but flexible patterns. Specifically, kernel methods and penalized splines are investigated, with the latter proving more suitable from both computational and modelling perspectives. In addition to their use in a purely spatial setting, penalized splines also offer a convenient route to the construction of spatiotemporal models, where data are available over time as well as over space. Models which include main effects and spatiotemporal interactions, as well as seasonal terms and interactions, are constructed for data on nitrate pollution in the River Tweed. The results give valuable insight into the changes in water quality in both space and time.

15.
Stat Modelling ; 14(5): 417-437, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30899199

RESUMO

Magneto-encephalography (MEG) is an imaging technique which measures neuronal activity in the brain. Even when a subject is in a resting state, MEG data show characteristic spatial and temporal patterns, resulting from electrical current at specific locations in the brain. The key pattern of interest is a 'dipole', consisting of two adjacent regions of high and low activation which oscillate over time in an out-of-phase manner. Standard approaches are based on averages over large numbers of trials in order to reduce noise. In contrast, this article addresses the issue of dipole modelling for single trial data, as this is of interest in application areas. There is also clear evidence that the frequency of this oscillation in single trials generally changes over time and so exhibits quasi-periodic rather than periodic behaviour. A framework for the modelling of dipoles is proposed through estimation of a spatiotemporal smooth function constructed as a parametric function of space and a smooth function of time. Quasi-periodic behaviour is expressed in phase functions which are allowed to evolve smoothly over time. The model is fitted in two stages. First, the spatial location of the dipole is identified and the smooth signals characterizing the amplitude functions for each separate pole are estimated. Second, the phase and frequency of the amplitude signals are estimated as smooth functions. The model is applied to data from a real MEG experiment focusing on motor and visual brain processes. In contrast to existing standard approaches, the model allows the variability across trials and subjects to be identified. The nature of this variability is informative about the resting state of the brain.

16.
J Plast Reconstr Aesthet Surg ; 66(5): 634-9, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23402935

RESUMO

BACKGROUND: To date breast assessment has been conducted mainly subjectively. However lately validated objective three-dimensional (3D) imaging was developed. The study aimed to assess breast reconstruction subjectively and objectively and conduct a comparison. METHODS: In forty-four patients after immediate unilateral breast reconstruction with solely the extended latissimus dorsi flap the breast was captured by validated 3D imaging method and standardized 2D photography. Breast symmetry was subjectively evaluated by six experts who applied the Harris score giving a mark of 1-4 for a poor to excellent result. An error study was conducted by examination of the intra and inter-observer agreement and agreement on controls. By Procrustes analysis an objective asymmetry score was obtained and compared to the subjective assessment. RESULTS: The subjective assessment showed that the inter-observer agreement was good or substantial (p-value: <0.0001). There was moderate agreement on the controls (p-value: <0.0001) and fair (p-values: 0.159, 0.134, 0.099) to substantial (p-value: 0.005) intra-observer agreement. The objective assessment revealed that the reconstructed breast showed a significantly smaller volume compared to the opposite side and that the average asymmetry score was 0.052, ranging from 0.019 to 0.136. When comparing the subjective and objective method the relationship between the two scores was highly significant. CONCLUSION: Subjective breast assessment lacked accuracy and reproducibility. This was the first error study of subjective breast assessment versus an objective validated 3D imaging method based on true 3D parameters. The substantial agreement between established subjective breast assessment and new validated objective method supported the value of the later and we expect its future role to expand.


Assuntos
Mama/cirurgia , Imageamento Tridimensional/instrumentação , Mamoplastia/métodos , Fotografação/instrumentação , Retalhos Cirúrgicos , Desenho de Equipamento , Feminino , Humanos , Reprodutibilidade dos Testes
17.
Biometrics ; 69(2): 537-44, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23409735

RESUMO

The distributed lag model (DLM), used most prominently in air pollution studies, finds application wherever the effect of a covariate is delayed and distributed through time. We specify modified formulations of DLMs to provide computationally attractive, flexible varying-coefficient models that are applicable in any setting in which lagged covariates are regressed on a time-dependent response. We investigate the application of such models to rainfall and river flow and in particular their role in understanding the impact of hidden variables at work in river systems. We apply two models to data from a Scottish mountain river, and we fit to some simulated data to check the efficacy of our model approach. During heavy rainfall conditions, changes in the influence of rainfall on flow arise through a complex interaction between antecedent ground wetness and a time-delay in rainfall. The models identify subtle changes in responsiveness to rainfall, particularly in the location of peak influence in the lag structure.


Assuntos
Biometria/métodos , Hidrologia/estatística & dados numéricos , Modelos Estatísticos , Interpretação Estatística de Dados , Chuva , Rios , Escócia , Fatores de Tempo
18.
Cleft Palate Craniofac J ; 50(2): 150-7, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21846256

RESUMO

Objective : Objective measure of scarring and three-dimensional (3D) facial asymmetry after surgical correction of unilateral cleft lip (UCL) and unilateral cleft lip (UCLP). It was hypothesized that the degree of scarring or asymmetry would be correlated with poorer psychological function. Design : In a cross-sectional design, children underwent 3D imaging of the face and completed standardized assessments of self-esteem, depression, and state and trait anxiety. Parents rated children's adjustment with a standard scale. Setting : Glasgow Dental School, School of Medicine, College of Medical, Veterinary and Life Sciences. Patients : Fifty-one children aged 10 years with UCLP and 43 with UCL were recruited from the cohort treated with the surgical protocol of the CLEFTSIS managed clinical network in Scotland. Methods : Objective assessment to determine the luminance and redness of the scar and facial asymmetry. Depression, anxiety, and a self-esteem assessment battery were used for the psychological analysis. Results : Cleft cases showed superior psychological adjustment when compared with normative data. Prevalence of depression matched the population norm. The visibility of the scar (luminance ratio) was significantly correlated with lower self-esteem and higher trait anxiety in UCLP children (P  =  .004). Similar but nonsignificant trends were seen in the UCL group. Parental ratings of poorer adjustment also correlated with greater luminance of the scar. Conclusions : The objectively defined degree of postoperative cleft scarring was associated with subclinical symptoms of anxiety, depression, and low self-esteem.


Assuntos
Fenda Labial , Assimetria Facial , Estudos de Casos e Controles , Cefalometria , Cicatriz , Fenda Labial/cirurgia , Fissura Palatina/cirurgia , Estudos Transversais , Humanos , Nariz/cirurgia
19.
J Plast Reconstr Aesthet Surg ; 65(12): e332-7, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22766492

RESUMO

BACKGROUND: Errors derive from the variability seen in the repeat volume measurements for a particular individual. The aim of this study was to evaluate the variation and errors of a three-dimensional (3D) multiple stereo camera system for objective breast assessment. It was also investigated whether there was any correlation between these errors and the size of the breast. METHODS: A prototype eight camera multiple stereophotogrammetry system was utilized. The volumes of nine plaster breast models were determined by 3D imaging and the correlation between the size of the models and the variability of the measurements was investigated after ten repeats. The breasts of six live volunteers were examined following a specific protocol. The breasts were captured six times, three times each on two different occasions; from each breast capture a three-dimensional model was built and the breast volume was measured three times with breast analysis tool (BAT) software. This allowed for an assessment of the variability introduced at each stage of the measurement procedure. The correlation between the size of the breast and the variability of the measurements was investigated. Results of volume measurements by water displacement method, repeated ten times with the plaster models and six times with the live models, were used for comparison. RESULTS: The correlation between the size of the plaster models and the variability of the measurements revealed a significant correlation (p = 0.033), indicating that the larger the model, the more variable were the results. The correlation between the size of the breasts in the live models and the variability of the results revealed a non-significant correlation (p = 0.342), but there was a visible trend that the larger breasts showed more variable results. The average variation in the repeated measurements on each individual was found to be 32.95 cc across the two different poses, 19.43 cc across the various captures, and 28.32 across the different volume calculations with the BAT software. The error is less than what is clinically visible with the human eye, which is about 50 cc variation in volume by subjective assessment. As a proportion of the mean volume, namely 6.9%, 4.0% and 5.9% respectably, the values are small and indicate that the reproducibility of the system is good. CONCLUSION: The 3D imaging system using multiple stereo cameras revealed a positive correlation between the size of plaster models and the breasts of live models and the reproducibility of the measurements, indicating that the variation was higher for the larger sizes. The relationship was significant in the plaster models but not in the live models, although a trend was observed. The assessment of the variation and errors of the system was part of the necessary procedure that should be considered for the validation of any new measurement technology for breast assessment.


Assuntos
Mama/anatomia & histologia , Imageamento Tridimensional/instrumentação , Fotogrametria/instrumentação , Adulto , Erros de Diagnóstico , Feminino , Humanos , Modelos Lineares , Imagens de Fantasmas , Reprodutibilidade dos Testes
20.
J Plast Reconstr Aesthet Surg ; 65(9): 1209-15, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22525253

RESUMO

BACKGROUND: The latissimus dorsi muscle flap is a common method for the reconstruction of the breast following mastectomy. The study aimed to assess the quality of this reconstruction using a three-dimensional (3D) imaging method. The null hypothesis was that there was no difference in volume between the reconstructed breast and the opposite side. METHODS: This study was conducted in forty-four patients who had had immediate unilateral breast reconstruction by latissimus dorsi muscle flap. The breast was captured using the 3D imaging system. Ten landmarks were digitised on the 3D images. The volume of each breast was measured by the application of Breast Analysis Tool software. The symmetry of the breast was measured using Procrustes analysis. The impact of breast position, orientation, size and intrinsic shape on the overall breast asymmetry was investigated. RESULTS: The null hypothesis was rejected. The reconstructed breast showed a significantly smaller volume when compared to the opposite side, p < 0.0001, a mean difference of 176.8 cc and 95% CI (103.5, 250.0). The shape and the position of the reconstructed breast were the main contributing factors to the measured asymmetry score. CONCLUSIONS: 3D imaging was efficient in evaluating the outcome of breast surgery. The latissimus dorsi muscle flap on its own for breast reconstruction did not restore the volume and shape of the breast fully lost due to complete mastectomy. The modification of this method and the selection of other or additional surgical techniques for breast reconstruction should be considered. The asymmetry analysis through reflection and Procrustes matching was a useful method for the objective shape analysis of the female breast and presented a new approach for breast shape assessment. The intrinsic breast shape and the positioning of the breast were major components of postoperative breast asymmetry. The reconstructed breast was smaller overall than the un-operated breast at a significant level when assessing the breast volume using the surface area. 3D imaging by multiple stereophotogrammetry was a useful tool for volume measurements, shape analysis and the evaluation of symmetry.


Assuntos
Neoplasias da Mama/diagnóstico , Neoplasias da Mama/cirurgia , Imageamento Tridimensional , Mamoplastia/métodos , Retalhos Cirúrgicos , Adulto , Pontos de Referência Anatômicos , Estudos de Coortes , Feminino , Seguimentos , Rejeição de Enxerto , Sobrevivência de Enxerto , Humanos , Interpretação de Imagem Assistida por Computador , Mastectomia/métodos , Pessoa de Meia-Idade , Músculo Esquelético/transplante , Fotogrametria , Cuidados Pós-Operatórios/métodos , Estudos Retrospectivos , Resultado do Tratamento , Reino Unido
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