Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 504
Filtrar
Más filtros

Tipo del documento
Intervalo de año de publicación
1.
Nano Lett ; 16(9): 5605-11, 2016 09 14.
Artículo en Inglés | MEDLINE | ID: mdl-27529641

RESUMEN

We report the light-induced formation of conductive links across nanometer-wide insulating gaps. These are realized by incorporating spacers of molecules or 2D monolayers inside a gold plasmonic nanoparticle-on-mirror (NPoM) geometry. Laser irradiation of individual NPoMs controllably reshapes and tunes the plasmonic system, in some cases forming conductive bridges between particle and substrate, which shorts the nanometer-wide plasmonic gaps geometrically and electronically. Dark-field spectroscopy monitors the bridge formation in situ, revealing strong plasmonic mode mixing dominated by clear anticrossings. Finite difference time domain simulations confirm this spectral evolution, which gives insights into the metal filament formation. A simple analytic cavity model describes the observed plasmonic mode hybridization between tightly confined plasmonic cavity modes and a radiative antenna mode sustained in the NPoM. Our results show how optics can reveal the properties of electrical transport across well-defined metallic nanogaps to study and develop technologies such as resistive memory devices (memristors).

2.
Opt Express ; 24(23): 27009-27015, 2016 Nov 14.
Artículo en Inglés | MEDLINE | ID: mdl-27857428

RESUMEN

We demonstrate that Digital Holographic Microscopy can be used for accurate 3D tracking and sizing of a colloidal probe trapped in a diamond anvil cell (DAC). Polystyrene beads were optically trapped in water up to Gigapascal pressures while simultaneously recording in-line holograms at 1 KHz frame rate. Using Lorenz-Mie scattering theory to fit interference patterns, we detected a 10% shrinking in the bead's radius due to the high applied pressure. Accurate bead sizing is crucial for obtaining reliable viscosity measurements and provides a convenient optical tool for the determination of the bulk modulus of probe material. Our technique may provide a new method for pressure measurements inside a DAC.

3.
Intern Med J ; 46(2): 171-6, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26550806

RESUMEN

BACKGROUND: Lung cancer incidence, mortality and hospitalisation rates are higher for Indigenous Australians compared with non-Indigenous Australians and increase again when living in more remote areas. If Indigenous Australians are made more aware of lung cancer through better access to health services and programmes, lung cancer outcomes might improve. AIM: We aimed to survey the level of lung cancer awareness in rural and remote Aboriginal and Torres Strait Islander communities and discover perceived barriers to timely diagnosis and treatment of lung cancer. METHODS: Interviews were conducted in three discrete outer regional and remote Aboriginal communities and one urban setting in Queensland. Participants included Aboriginal and Torres Strait Islander peoples from three target population groups: patients referred for medical treatment with symptoms suspicious of lung cancer or confirmed lung cancer; Indigenous health workers; community members aged 18 years and over. Participants gave written, informed consent. RESULTS: Of 51 community members and 14 Indigenous health workers, 32 reflected they knew very little about lung cancer, 60 cited smoking as the cause of lung cancer and 54 recognised warning symptoms as a prompt to seek healthcare. Indigenous health workers were not able to describe a healthcare pathway that would apply to a patient with suspected lung cancer. CONCLUSION: The two main barriers identified as impacting on quality healthcare were communication and follow-up processes. These could be addressed by service improvement activities.


Asunto(s)
Detección Precoz del Cáncer/métodos , Neoplasias Pulmonares/etnología , Neoplasias Pulmonares/terapia , Nativos de Hawái y Otras Islas del Pacífico/etnología , Población Rural , Encuestas y Cuestionarios , Adulto , Femenino , Necesidades y Demandas de Servicios de Salud , Servicios de Salud del Indígena , Humanos , Neoplasias Pulmonares/diagnóstico , Masculino , Persona de Mediana Edad , Queensland/etnología , Características de la Residencia , Resultado del Tratamiento
4.
Opt Express ; 21(14): 16541-51, 2013 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-23938505

RESUMEN

Spatial Light Modulators (SLMs) can emulate the classic microscopy techniques, including differential interference (DIC) contrast and (spiral) phase contrast. Their programmability entails the benefit of flexibility or the option to multiplex images, for single-shot quantitative imaging or for simultaneous multi-plane imaging (depth-of-field multiplexing). We report the development of a microscope sharing many of the previously demonstrated capabilities, within a holographic implementation of a stereo microscope. Furthermore, we use the SLM to combine stereo microscopy with a refocusing filter and with a darkfield filter. The instrument is built around a custom inverted microscope and equipped with an SLM which gives various imaging modes laterally displaced on the same camera chip. In addition, there is a wide angle camera for visualisation of a larger region of the sample.


Asunto(s)
Holografía/instrumentación , Aumento de la Imagen/instrumentación , Imagenología Tridimensional/instrumentación , Iluminación/instrumentación , Microscopía/instrumentación , Diseño de Equipo , Análisis de Falla de Equipo
5.
Intern Med J ; 43(2): 174-82, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22471951

RESUMEN

BACKGROUND: Lung cancer is the leading cause of cancer-related mortality in Australia. Screening using low-dose computed tomography (LDCT) can reduce lung cancer mortality. The feasibility of screening in Australia is unknown. This paper describes the rationale, design and methods of the Queensland Lung Cancer Screening Study. AIMS: The aim of the study is to describe the methodology for a feasibility study of lung cancer screening by LDCT in Australia. METHODS: The Queensland Lung Cancer Screening Study is an ongoing, prospective observational study of screening by LDCT at a single tertiary institution. Healthy volunteers at high risk of lung cancer (age 60-74 years; smoking history ≥30 pack years, current or quit within 15 years; forced expiratory volume in 1s ≥50% predicted) are recruited from the general public through newspaper advertisement and press release. Participants receive a LDCT scan of the chest at baseline, year 1 and year 2 using a multidetector helical computed tomography scanner and are followed up for a total of 5 years. Feasibility of screening will be assessed by cancer detection rates, lung nodule prevalence, optimal management strategies for lung nodules, economic costs, healthcare utilisation and participant quality of life. CONCLUSIONS: Studying LDCT screening in the Australian setting will help us understand how differences in populations, background diseases and healthcare structures modulate screening effectiveness. This information, together with results from overseas randomised studies, will inform and facilitate local policymaking.


Asunto(s)
Detección Precoz del Cáncer/métodos , Neoplasias Pulmonares/diagnóstico por imagen , Neoplasias Pulmonares/epidemiología , Tomografía Computarizada por Rayos X/métodos , Anciano , Detección Precoz del Cáncer/normas , Estudios de Factibilidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Queensland/epidemiología , Factores de Riesgo , Tomografía Computarizada por Rayos X/normas
6.
Eye Contact Lens ; 39(3): 220-7, 2013 May.
Artículo en Inglés | MEDLINE | ID: mdl-23584043

RESUMEN

PURPOSE: To evaluate the effect of the double-K (DK) modification on third-generation formulas. METHODS: Thirty-eight previously myopic and 24 previously hyperopic eyes that underwent phacoemulsification with intraocular lens (IOL) insertion after Laser in situ keratomileusis (LASIK) were evaluated. Pre-LASIK refraction and keratometry, post-LASIK topography, axial length (AL), IOL type and power, and 1-month postphacoemulsification refraction were recorded spherical equivalent after phacoemulsification (SE(postphaco)). Measured corneal power was adjusted using published and validated methods for postmyopic and posthyperopic LASIK. For each eye, and using SE(postphaco), different DK-IOL formulas were used to calculate the corresponding IOL power, the outcome measure, which was compared with the implanted IOL. RESULTS: DK-Holladay 1 yielded the highest Pearson correlation coefficient (PCC), 0.955 for myopes and 0.943 for high myopes (AL>26 mm). Mean error (ME) and mean absolute error (MAE) for myopes for DK Sanders-Retzlaff-Kraff theoretical formula [DK-SRK/T] were 0.44±0.84 D and 0.75±0.61 D for DK-SRK/T compared with -0.04±0.67 D and 0.52±0.40 D for DK-Holladay 1 (P<0.001 and P=0.016, respectively), and 0.03±0.88 and 0.64±0.58 for DK-Hoffer Q. For high myopes, ME and MAE were 0.75±0.81 D and 0.84±0.69 D for DK-SRK/T, and -0.05±0.74 D (P<0.0001) and 0.57±0.45 D (P=0.019) for DK-Holladay 1. About 29% of DK-SRK/T eyes with large AL had MAE>1.5 D, compared with 0% for DK-Holladay 1 and 14% for DK-Hoffer-Q. Eyes with previous hyperopic LASIK faired similarly for all formulas, with similar PCCs, and only 8% in each category with MAE>1.5 D. CONCLUSIONS: DK-SRK/T overestimates IOL power in eyes with large AL, especially with concomitant steep pre-lasik keratometry. Among third-generation formulas, DK-Holladay 1 seems more accurate to use in postmyopic LASIK eyes.


Asunto(s)
Hiperopía/cirugía , Lentes Intraoculares , Miopía/cirugía , Refracción Ocular , Anciano , Longitud Axial del Ojo , Topografía de la Córnea , Femenino , Humanos , Hiperopía/fisiopatología , Queratomileusis por Láser In Situ , Implantación de Lentes Intraoculares , Masculino , Persona de Mediana Edad , Miopía/fisiopatología , Evaluación de Resultado en la Atención de Salud , Facoemulsificación/métodos , Estudios Retrospectivos
7.
BMJ Open Ophthalmol ; 8(Suppl 3): A3, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37798009

RESUMEN

Cerebral visual impairment (CVI) encompasses a heterogeneous group of disorders and a spectrum of types of visual impairments. Research is needed to characterise the different forms of CVI and identify the specific needs of these groups to inform individualised patient care. Homonymous hemianopia (HH) is a definable visual field defect that affect some children with CVI. As part of a new research programme, we conducted a scoping review of the literature on HH in children and young people to map current knowledge and identify evidence gaps.We used the PRISMA extension for Scoping Reviews methodology. Multiple online databases were searched using terms associated with 'homonymous hemianopia' and 'children'. This yielded 1588 papers which were screened by two reviewers. Of these 1001 were excluded at abstract screen and a further 415 excluded after full text review, with full text unavailable for 15. Data were extracted and charted from 157 studies and additional grey literature.Interim analysis shows reported studies are predominantly from high income countries with a paucity of higher-level evidence, and a preponderance of case reports. Most papers reported causative pathology and diagnosis of HH. There was minimal attention to or evidence relating to intervention. Child-specific grey literature on HH was limited.This review collates the current evidence-base for HH in children. It demonstrates the important evidence-gap relating to intervention in these cases that would help inform more individualised care. Similar scoping reviews may be prove useful in assessing the evidence relating to other definable groups within the CVI umbrella.


Asunto(s)
Encefalopatías , Hemianopsia , Humanos , Adolescente , Hemianopsia/diagnóstico , Pruebas del Campo Visual/efectos adversos , Encefalopatías/complicaciones
8.
Eye (Lond) ; 37(6): 1178-1183, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-35562551

RESUMEN

BACKGROUND/AIMS: Optic pathway gliomas (OPGs) may cause progressive visual loss despite chemotherapy. Newer, less toxic treatments might be given earlier, depending on visual prognosis. We aimed to investigate the prognostic value of visual evoked potentials (VEP) and optical coherence tomography (OCT). METHODS: A retrospective study of OPG patients (treated 2003-2017) was conducted. Primary outcome was PEDIG category visual acuity in better and worse eyes (good < = 0.2, moderate 0.3-0.6 and poor > = 0.7 logMAR). Binary logistic regression analysis was used to identify predictors of these outcomes. RESULTS: 60 patients (32 Neurofibromatosis type 1 [NF1] and 28 sporadic) had median presentation age 49 months (range 17-183) (NF1) and 27 months (range 4-92) (sporadic). Median follow up was 82 months (range 12-189 months). At follow up 24/32 (75%) of NF1 children and 14/28 (50%) of sporadic children had good better eye visual acuity and 11/32 (34%) of NF1 children and 15/28 (54%) of sporadics had poor worse eye acuity. Mean peripapillary retinal nerve fibre layer (RNFL) thickness predicted good better eye final acuity (OR 0.799, 95%CI 0.646-0.987, p = 0.038). Presenting with visual symptoms (OR 0.22 95% CI 0.001-0.508, p = 0.017) and poorer VEP scores (OR 2.35 95% CI 1.1-5.03, p = 0.027) predicted poor worse eye final acuity. 16 children had homonymous hemianopias at follow up, predicted by poor presenting binocular VEP score (OR 1.449 95%CI 1.052-1.995, p = 0.02). CONCLUSIONS: We found that both RNFL thickness on OCT and VEP were useful in predicting future visual acuity and vision and potentially in planning treatment. We had a high prevalence of homonymous hemianopia.


Asunto(s)
Neurofibromatosis 1 , Glioma del Nervio Óptico , Niño , Humanos , Estudios Retrospectivos , Potenciales Evocados Visuales , Glioma del Nervio Óptico/diagnóstico , Neurofibromatosis 1/diagnóstico , Retina , Tomografía de Coherencia Óptica/métodos , Hemianopsia
9.
Opt Express ; 20(28): 29679-93, 2012 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-23388796

RESUMEN

We demonstrate the use of an extended, optically trapped probe that is capable of imaging surface topography with nanometre precision, whilst applying ultra-low, femto-Newton sized forces. This degree of precision and sensitivity is acquired through three distinct strategies. First, the probe itself is shaped in such a way as to soften the trap along the sensing axis and stiffen it in transverse directions. Next, these characteristics are enhanced by selectively position clamping independent motions of the probe. Finally, force clamping is used to refine the surface contact response. Detailed analyses are presented for each of these mechanisms. To test our sensor, we scan it laterally over a calibration sample consisting of a series of graduated steps, and demonstrate a height resolution of ∼ 11 nm. Using equipartition theory, we estimate that an average force of only ∼ 140 fN is exerted on the sample during the scan, making this technique ideal for the investigation of delicate biological samples.


Asunto(s)
Óptica y Fotónica/instrumentación , Rotación , Propiedades de Superficie , Temperatura
10.
Stress ; 15(5): 524-32, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22168672

RESUMEN

Stress, depending on intensity and duration, elicits adaptive or maladaptive physiological effects. Increasing evidence shows those patterns of advantageous versus deleterious physiologic stress effects also exist for some brain functions, including learning and memory. For example, short stress enhances, while chronic stress impairs, performance on numerous cognitive tasks in male rats. In contrast, performance of female rats is enhanced, or not altered, following both short-term and long-term stress exposure on the same behavioral tasks. The current study was designed to better characterize the behavioral effects of sustained chronic restraint stress in female rats. Female Sprague Dawley rats were assigned to a stress (restraint, 6 h/day, 35 days) or control (no stress) condition, weighed weekly, and then tested on open field (OF), object recognition (OR) and object placement (OP) tasks. Stressed females gained less weight during stress than controls. On the OF, there were no group differences in locomotor activity, but stressed females made fewer inner visits than controls, indicating increased anxiety. Both groups successfully performed the OP and OR tasks across all inter-trial delays, indicating intact non-spatial and spatial memory in both control and stress females. The current results provide preliminary evidence that the commonly used chronic restraint stress model may not be an efficient stressor to female rats.


Asunto(s)
Ansiedad/psicología , Aprendizaje/fisiología , Memoria/fisiología , Estrés Psicológico , Animales , Conducta Animal , Modelos Animales de Enfermedad , Femenino , Actividad Motora/fisiología , Ratas , Ratas Sprague-Dawley , Restricción Física , Caracteres Sexuales , Percepción Espacial/fisiología , Estrés Fisiológico/fisiología
11.
Eur Respir J ; 38(4): 903-10, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21349912

RESUMEN

The clinical applicability of screening surgically resected nonsmall cell lung cancer (NSCLC) tumour tissue and serum for activating epidermal growth factor receptor (EGFR) mutation is unknown. Furthermore, the comparative accuracy of inexpensive EGFR mutation tests, mutant-enriched (ME)-PCR and high-resolution melt (HRM) has not been determined. Lung tumour DNA from 522 surgically resected stage I-IV NSCLC and matched serum DNA from a subset of 64 subjects was analysed for EGFR mutations in exons 19 and 21 using ME-PCR and HRM. Additionally, 97 subjects had previous EGFR DNA sequencing data available for comparison. ME-PCR and HRM detected EGFR mutations in 5% (27 out of 522) of tumour samples. Compared to DNA sequencing, ME-PCR had a sensitivity of 100% and specificity of 99%, while HRM had 100% sensitivity and specificity. Six subjects with EGFR mutation tumours had matched serum, where ME-PCR detected mutations in three samples and HRM in two samples. In the cohort of never-smoker subjects, those with EGFR mutated tumours had worse survival compared with wild-type tumours (30 versus 49 months; p=0.017). ME-PCR and HRM have similar accuracy in detecting EGFR mutations but the prognostic implications of the mutations in resected NSCLC warrants further study.


Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/genética , Análisis Mutacional de ADN/métodos , Análisis Mutacional de ADN/normas , Receptores ErbB/genética , Pruebas Genéticas/métodos , Pruebas Genéticas/normas , Neoplasias Pulmonares/genética , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma de Pulmón de Células no Pequeñas/patología , Carcinoma de Pulmón de Células no Pequeñas/cirugía , Exones/genética , Femenino , Secciones por Congelación , Humanos , Neoplasias Pulmonares/patología , Neoplasias Pulmonares/cirugía , Masculino , Persona de Mediana Edad , Mutación/genética , Pronóstico , Reproducibilidad de los Resultados , Estudios Retrospectivos , Sensibilidad y Especificidad , Temperatura de Transición
12.
Opt Express ; 19(21): 20622-7, 2011 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-21997071

RESUMEN

We investigate the degree of control that can be exercised over an optically trapped microscopic non-spherical force probe. By position clamping translational and rotational modes in different ways, we are able to dramatically improve the position resolution of our probe with no reduction in sensitivity. We also demonstrate control over rotational-translational coupling, and exhibit a mechanism whereby the average centre of rotation of the probe can be displaced away from its centre.


Asunto(s)
Pinzas Ópticas , Óptica y Fotónica , Algoritmos , Diseño de Equipo , Rayos Láser , Micromanipulación/métodos , Modelos Estadísticos , Estrés Mecánico , Grabación en Video
13.
Nanotechnology ; 22(28): 285503, 2011 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-21646693

RESUMEN

We present an imaging technique using an optically trapped cigar-shaped probe controlled using holographic optical tweezers. The probe is raster scanned over a surface, allowing an image to be taken in a manner analogous to scanning probe microscopy (SPM), with automatic closed loop feedback control provided by analysis of the probe position recorded using a high speed CMOS camera. The probe is held using two optical traps centred at least 10 µm from the ends, minimizing laser illumination of the tip, so reducing the chance of optical damage to delicate samples. The technique imparts less force on samples than contact SPM techniques, and allows highly curved and strongly scattering samples to be imaged, which present difficulties for imaging using photonic force microscopy. To calibrate our technique, we first image a known sample--the interface between two 8 µm polystyrene beads. We then demonstrate the advantages of this technique by imaging the surface of the soft alga Pseudopediastrum. The scattering force of our laser applied directly onto this sample is enough to remove it from the surface, but we can use our technique to image the algal surface with minimal disruption while it is alive, not adhered and in physiological conditions. The resolution is currently equivalent to confocal microscopy, but as our technique is not diffraction limited, there is scope for significant improvement by reducing the tip diameter and limiting the thermal motion of the probe.

14.
Eur Respir J ; 35(1): 152-9, 2010 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19608585

RESUMEN

Lung cancer remains a leading cause of disease globally, with smoking being the largest single cause. Phase I enzymes, including cytochrome P(450), family 1, subfamily A, polypeptide 1 (CYP1A1), are involved in the activation of carcinogens, such as polycyclic aromatic hydrocarbons, to reactive intermediates that are capable of binding covalently to DNA to form DNA adducts, potentially initiating the carcinogenic process. The aim of the present study was to investigate the association of CYP1A1 gene polymorphisms and haplotypes with lung cancer risk. A case-control study was carried out on 1,040 nonsmall cell lung cancer (NSCLC) cases and 784 controls to investigate three CYP1A1 variants, CYP1A1*2A (rs4646903; thymidine to cytosine substitution at nucleotide 3801 (3801T>C)), CYP1A1*2C (rs1048943; 2455A>G; substitution of isoleucine 462 with valine (exon 7)) and CYP1A1*4 (rs1799814; 2453C>A; substitution of threonine 461 with asparagine (exon 7)) using PCR restriction fragment length polymorphism methods. The CYP1A1*2A and CYP1A1*2C variants were significantly over-represented in NSCLC cases compared with controls, whereas the CYP1A1*4 variant was under-represented. CYP1A1 haplotypes (in allele order CYP1A1*4, CYP1A1*2C, CYP1A1*2A) CGC and CGT were associated with an increased risk of lung cancer, whereas AAT was associated with decreased lung cancer risk in this population. The present study has identified risk haplotypes for CYP1A1 in NSCLC and confirmed that CYP1A1 polymorphisms are a minor risk factor for NSCLC.


Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/genética , Citocromo P-450 CYP1A1/genética , Estudios de Asociación Genética , Haplotipos/genética , Neoplasias Pulmonares/genética , Polimorfismo Genético , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Adulto Joven
15.
Ophthalmology ; 117(5): 878-884.e6, 2010 May.
Artículo en Inglés | MEDLINE | ID: mdl-20346512

RESUMEN

PURPOSE: To compare the corneal higher-order aberration (HOA) after Descemet's stripping automated endothelial keratoplasty (DSAEK) and penetrating keratoplasty (PKP), and in age-matched controls. DESIGN: Cross-sectional, non-comparative interventional case series. PARTICIPANTS: Thirty-one eyes of 28 patients who underwent DSAEK, 20 eyes of 16 patients who underwent PKP, and 31 eyes of 31 control patients. INTERVENTION: The corneal topography and HOAs of the central 4- and 6-mm zones from anterior and posterior corneal surfaces were evaluated postoperatively with the Scheimpflug rotating imaging system (Oculus Gmbh, Wetzlar, Germany). MAIN OUTCOME MEASURES: Anterior and posterior corneal HOAs. RESULTS: The mean anterior corneal total HOAs of the central 4 and 6 mm were 0.599+/-0.288 microm and 1.215+/-0.496 microm, respectively, in eyes that underwent DSAEK; 1.730+/-0.826 microm and 3.349+/-1.490 microm, respectively, in eyes that underwent PKP; and 0.439+/-0.163 microm and 0.921+/-0.300 microm, respectively, in controls. Although the mean anterior corneal total HOAs of the central 4 and 6 mm were significantly higher in eyes that underwent PKP than in eyes that underwent DSAEK and in controls (P<0.01), there was no significant difference in anterior corneal total HOAs of the central 4 and 6 mm between eyes that underwent DSAEK and controls. The mean posterior corneal total HOAs of the central 4 and 6 mm were 3.680+/-1.586 microm and 7.142+/-3.011 microm, respectively, in eyes that underwent DSAEK; 2.957+/-1.238 microm and 5.314+/-2.095 microm, respectively, in eyes that underwent PKP; and 0.818+/-0.193 microm and 1.609+/-0.344 microm, respectively, in controls. Although there was no significant difference in posterior corneal total HOAs of the central 4 mm between the DSAEK group and the PKP group, the posterior corneal HOAs of the central 6 mm were significantly higher in the DSAEK group than in the PKP group (P<0.01). CONCLUSIONS: Although posterior corneal HOAs are significantly higher in eyes that underwent DSAEK, anterior corneal HOAs are not significantly different in eyes that underwent DSAEK than those of age-matched controls.


Asunto(s)
Aberración de Frente de Onda Corneal/etiología , Queratoplastia Endotelial de la Lámina Limitante Posterior , Queratoplastia Penetrante , Complicaciones Posoperatorias , Adulto , Anciano , Anciano de 80 o más Años , Enfermedades de la Córnea/cirugía , Topografía de la Córnea , Estudios Transversales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Refracción Ocular/fisiología , Agudeza Visual/fisiología
16.
Opt Express ; 18(25): 26084-91, 2010 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-21164957

RESUMEN

We present tailoring of three dimensional light fields which act as light moulds for elaborate particle micro structures of variable shapes. Stereo microscopy is used for visualization of the 3D particle assemblies. The powerful method is demonstrated for the class of propagation invariant beams, where we introduce the use of Mathieu beams as light moulds with non-rotationally-symmetric structure. They offer multifarious field distributions and facilitate the creation of versatile particle structures. This general technique may find its application in micro fluidics, chemistry, biology, and medicine, to create highly efficient mixing tools, for hierarchical supramolecular organization or in 3D tissue engineering.


Asunto(s)
Rayos Láser , Iluminación/métodos , Pinzas Ópticas , Luz , Tamaño de la Partícula , Dispersión de Radiación
17.
Nanotechnology ; 21(17): 175501, 2010 Apr 30.
Artículo en Inglés | MEDLINE | ID: mdl-20368683

RESUMEN

Holographically trapped nanotools can be used in a novel form of force microscopy. By measuring the displacement of the tool in the optical traps, the contact force experienced by the probe can be inferred. In the following paper we experimentally demonstrate the calibration of such a device and show that its behaviour is independent of small changes in the relative position of the optical traps. Furthermore, we explore more general aspects of the thermal motion of the tool.

18.
Intern Med J ; 40(11): 777-83, 2010 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-19811554

RESUMEN

AIMS: To determine whether in-hospital deaths of patients admitted through emergency departments with acute exacerbations of chronic obstructive pulmonary disease (COPD), acute myocardial infarction, intracerebral haemorrhage and acute hip fracture are increased by weekend versus weekday admission (the 'weekend effect'). METHODS: We performed a retrospective analysis of statewide administrative data from public hospitals in Queensland, Australia, during the 2002/2003-2006/2007 financial years. The primary outcome was 30-day in-hospital mortality. The secondary outcome of 2-day in-hospital mortality helped determine whether increased mortality of weekend admissions was closely linked to weekend medical care. RESULTS: During the study period, there were 30 522 COPD, 17 910 acute myocardial infarction, 4183 acute hip fracture and 1781 intracerebral haemorrhage admissions. There was no significant weekend effect on 30-day in-hospital mortality for COPD (adjusted risk ratio = 0.92, 95% CI: 0.81-1.04, P= 0.222), intracerebral haemorrhage (adjusted risk ratio = 1.01, 95% CI: 0.86-1.16, P= 0.935) or acute hip fracture (adjusted risk ratio = 0.78, 95% CI: 0.54-1.03, P= 0.13). There was a significant weekend effect for acute myocardial infarction (adjusted risk ratio = 1.15, 95% CI: 1.03-1.26, P= 0.007). Two-day in-hospital mortality showed similar results. CONCLUSION: This is the first Australian study on the 'weekend effect' (in a cohort other than neonates), and the first study worldwide to assess specifically the weekend effect among COPD patients. Observed patterns were consistent with overseas research. There was a significant weekend effect for myocardial infarction. Further research is needed to determine whether location (e.g. rural), clinical (e.g. disease severity) and service provision factors (e.g. access to invasive procedures) influence the weekend effect for acute medical conditions in Australia.


Asunto(s)
Mortalidad Hospitalaria/tendencias , Hospitales Públicos/normas , Hospitales Públicos/tendencias , Admisión del Paciente/normas , Admisión del Paciente/tendencias , Anciano , Anciano de 80 o más Años , Estudios de Cohortes , Bases de Datos Factuales/tendencias , Femenino , Hospitales Públicos/métodos , Humanos , Masculino , Queensland/epidemiología , Estudios Retrospectivos , Factores de Tiempo
19.
Eye Contact Lens ; 36(4): 223-7, 2010 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-20539235

RESUMEN

PURPOSE: To identify the incidence of and risk factors for intraocular pressure (IOP) elevation after Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: Retrospective review was conducted of 68 consecutive DSAEK procedures alone, or in combination with phacoemulsification with intraocular lens implantation or exchange, performed by two surgeons at the University of Texas Southwestern Medical Center between 2005 and 2009. Eyes that developed IOP elevation above 21 mm Hg after DSAEK and requiring initiation or escalation of glaucoma therapy were evaluated. RESULTS: Thirty-seven (54%) eyes showed IOP elevation responsive to medical treatment by a mean follow-up of 11.38 +/- 7.81 months. Six (8.8%) eyes required glaucoma surgery. In the eyes, which developed elevated IOP, gonioscopy did not reveal any new peripheral anterior synechiae formation. Prolonged topical steroid usage, rebubbling, combined DSAEK/cataract surgery, or repeat DSAEK were not significant factors (P>0.05) for development of elevated IOP, but history of previous glaucoma or ocular hypertension (OHTN) was significant (P=0.007). CONCLUSIONS: Intraocular pressure elevation is not uncommon in eyes after DSAEK, but most cases can be controlled with conservative management. Intraocular pressure elevation post-DSAEK occurred by mechanisms other than peripheral anterior synechial angle closure. The only significant risk factor for development of elevated IOP in our series was a previous history of glaucoma or OHTN.


Asunto(s)
Enfermedades de la Córnea/cirugía , Trasplante de Córnea/efectos adversos , Lámina Limitante Posterior/cirugía , Endotelio Corneal/trasplante , Presión Intraocular , Hipertensión Ocular/etiología , Adulto , Anciano , Anciano de 80 o más Años , Enfermedades de la Córnea/fisiopatología , Trasplante de Córnea/métodos , Lámina Limitante Posterior/patología , Endotelio Corneal/patología , Femenino , Estudios de Seguimiento , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Hipertensión Ocular/epidemiología , Hipertensión Ocular/fisiopatología , Complicaciones Posoperatorias , Estudios Retrospectivos , Factores de Riesgo , Texas/epidemiología , Tomografía de Coherencia Óptica
20.
Ophthalmology ; 116(3): 393-400.e1, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19264214

RESUMEN

PURPOSE: To identify key independent variables in estimating corneal refractive power (KBC) after hyperopic LASIK. DESIGN: Retrospective study. PARTICIPANTS: We included 24 eyes of 16 hyperopic patients who underwent LASIK with subsequent phacoemulsification and posterior chamber intraocular lens (IOL) implantation in the same eye. METHODS: Pre-LASIK and post-LASIK spherical equivalent (SE) refractions and topographies, axial length, implant type and power, and 3-month postphacoemulsification SE were recorded. Using the double-K Hoffer Q formula, corneal power was backcalculated for every eye (KBC), regression-based formulas derived, and corresponding IOL powers calculated and compared with published methods. MAIN OUTCOME MEASURES: The Pearson correlation coefficient (PCC) and arithmetic and absolute corneal and IOL power errors. RESULTS: Adjusting either the average central corneal power (ACCP(3mm)) or SimK based on the laser-induced spherical equivalent change (DeltaSE) resulted in an estimated corneal power (ACCP(adj) and SimK(adj)) with highest correlation with KBC (PCC=0.940 and 0.956, respectively) and lowest absolute corneal estimation error (0.37+/-0.45 and 0.38+/-0.39 diopter [D], respectively). The ACCP(adj) closely mirrored published DeltaSE-based adjustments of central corneal power on different topographers, whereas DeltaSE-based SimK adjustments varied across platforms. Using ACCP(adj) or SimK(adj) in the double-K Hoffer Q, using ACCP(3mm) or SimK in single-K Hoffer Q and adjusting the resultant IOL power based on DeltaSE, or applying Masket's formula all yielded accurate and similar IOL powers. The Latkany method consistently underestimated IOL power. The Feiz-Mannis and clinical history methods yielded poor IOL correlations and large IOL errors. CONCLUSION: After hyperopic LASIK, adjusting either corneal power or IOL power based on DeltaSE accurately estimates the appropriate IOL power.


Asunto(s)
Córnea/fisiopatología , Hiperopía/cirugía , Queratomileusis por Láser In Situ , Láseres de Excímeros/uso terapéutico , Lentes Intraoculares , Refracción Ocular/fisiología , Topografía de la Córnea , Humanos , Hiperopía/fisiopatología , Interferometría , Implantación de Lentes Intraoculares , Persona de Mediana Edad , Facoemulsificación , Estudios Retrospectivos
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA