Protocol for black student well-being study: a multi-site qualitative study on the mental health and well-being experiences of black UK university students.

Introduction: There is an increasing concern about the mental health and mental well-being of university students in the UK. Black university students who report a mental health condition are less likely to complete their course, achieve a first-class or upper second-class degree and progress to further education. This study will document black university students' accounts of their mental health experiences and perceptions of key turning points of biographical changes to their mental health as they move through the university life cycle.

Replies to critics.

I reply to my critics in this symposium on my book, (Oxford University Press, 2019).

Modelling multiple laser pulses for port wine stain treatment.

Many port wine stains (PWS) are still resistant to pulsed dye laser treatment. However, anecdotal information suggests that multiple-pulse laser irradiation improves patient outcome. Our aims in this note are to explain the underlying mechanism and estimate the possible thermal effects of multiple pulses in vascular structures typical of PWS.

Bioheat transfer analysis of cryogen spray cooling during laser treatment of port wine stains.

Background And Objective: The thermal response of port wine stain (PWS) skin to a combined treatment of pulsed laser irradiation and cryogen spray cooling (CSC) was analyzed through a series of simulations performed with a novel optical-thermal model that incorporates realistic tissue morphology.

Study Design/materials And Methods: The model consisted of (1) a three-dimensional reconstruction of a PWS biopsy, (2) a Monte Carlo optical model, (3) a finite difference heat transfer model, and (4) an Arrhenius thermal damage calculation. Simulations were performed for laser pulses of 0.

Modeling laser treatment of port wine stains with a computer-reconstructed biopsy.

Background And Objective: The efficacy of laser treatment of port wine stains (PWS) has been shown to be highly dependent on patient-specific vasculature. The effect of tissue structure on optical and thermal mechanisms was investigated for different pulse durations by using a novel theoretical model that incorporates tissue morphology reconstructed tomographically from a PWS biopsy.

Study Design/materials And Methods: An optical-thermal numerical model capable of simulating arbitrarily complex, three-dimensional tissue geometries was developed.

Accuracy and noise in optical Doppler tomography studied by Monte Carlo simulation.

A Monte Carlo model has been developed for optical Doppler tomography (ODT) within the framework of a model for optical coherence tomography (OCT). A phantom situation represented by blood flowing in a horizontal 100 microm diameter vessel placed at 250 microm axial depth in 2% intralipid solution was implemented for the Monte Carlo simulation, and a similar configuration used for experimental ODT measurements in the laboratory. Simulated depth profiles through the centre of the vessel of average Doppler frequency demonstrated an accuracy of 3-4% deviation in frequency values and position localization of flow borders, compared with true values.

Signal attenuation and localization in optical coherence tomography studied by Monte Carlo simulation.

A Monte Carlo model has been developed for optical coherence tomography (OCT). A geometrical optics implementation of the OCT probe with low-coherence interferometric detection was combined with three-dimensional stochastic Monte Carlo modelling of photon propagation in the homogeneous sample medium. Optical properties of the sample were selected to simulate intralipid and blood, representing moderately (g = 0.

Accuracy of subsurface temperature distributions computed from pulsed photothermal radiometry.

Pulsed photothermal radiometry (PPTR) is a non-contact method for determining the temperature increase in subsurface chromophore layers immediately following pulsed laser irradiation. In this paper the inherent limitations of PPTR are identified. A time record of infrared emission from a test material due to laser heating of a subsurface chromophore layer is calculated and used as input data for a non-negatively constrained conjugate gradient algorithm.

Infrared imaging of in vivo microvasculature following pulsed laser irradiation.

Infrared emission images of the chick chorioallantoic membrane (CAM) microvasculature following pulsed laser irradiation were recorded using a high speed infrared focal plane array camera. A three-dimensional tomographic reconstruction algorithm was applied to compute the initial space-dependent temperature increase in discrete CAM blood vessels caused by light absorption. The proposed method may provide consistent estimates of the physical dimensions of subsurface blood vessels and may be useful in understanding a variety of biomedical engineering problems involving laser-tissue interaction.

Optical Monte Carlo modeling of a true portwine stain anatomy.

A unique Monte Carlo program capable of accommodating an arbitrarily complex geometry was used to determine the energy deposition in a true port wine stain anatomy. Serial histologic sections taken from a biopsy of a dark red, laser therapy resistant stain were digitized and used to create the program input for simulation at wavelengths of 532 and 585 nm. At both wavelengths, the greatest energy deposition occurred in the superficial blood vessels, and subsequently decreased with depth as the laser beam was attenuated.

Three-dimensional reconstruction of port wine stain vascular anatomy from serial histological sections.

Port wine stains (PWSs) treated with a flashlamp-pumped pulsed dye laser show a variability in clinical response that is incompletely understood. To identify any vascular structure that might adversely affect treatment response, we obtained a three-dimensional reconstruction of the vascular anatomy of a non-responsive, light-purple superficial PWS on the forearm. The reconstructed PWS consisted of multiple clusters of small diameter (10-50 microns) blood vessels.

The blanching process due to copper vapour laser treatment of port-wine stains.

We describe the causes and speed of transient blanching during copper vapour laser treatment of port-wine stains. Five watts of yellow (578 nm) light from a copper vapour laser was scanned over the lesion using a computer controlled scanning system. The clinical response of the lesion to treatment is transient blanching, followed immediately by erythema.

Non-invasive determination of port wine stain anatomy and physiology for optimal laser treatment strategies.

The treatment of port wine stains (PWSs) using a flashlamp-pumped pulsed dye laser is often performed using virtually identical irradiation parameters. Although encouraging clinical results have been reported, we propose that lasers will only reach their full potential provided treatment parameters match individual PWS anatomy and physiology. The purpose of this paper is to review the progress made on the technical development and clinical implementation of (i) infrared tomography (IRT), optical reflectance spectroscopy (ORS) and optical low-coherence reflectometry (OLCR) to obtain in vivo diagnostic data on individual PWS anatomy and physiology and (ii) models of light and heat propagation, predicting irreversible vascular injury in human skin, to select optimal laser wavelength, pulse duration, spot size and radiant exposure for complete PWS blanching in the fewest possible treatment sessions.

Modelling light distributions of homogeneous versus discrete absorbers in light irradiated turbid media.

Laser treatment of port wine stains has often been modelled assuming that blood is distributed homogeneously over the dermal volume, instead of enclosed within discrete vessels. The purpose of this paper is to analyse the consequences of this assumption. Due to strong light absorption by blood, fluence rate near the centre of the vessel is much lower than at the periphery.

Wavelengths for port wine stain laser treatment: influence of vessel radius and skin anatomy.

Recent Monte Carlo computations in realistic port wine stain (PWS) models containing numerous uniformly distributed vessels suggest equal depth of vascular injury at wavelengths of 577 and 585 nm. This finding contradicts clinical experience and previous theory. From a skin model containing normal and PWS vessels in separate dermal layers, we estimate analytically the average volumetric heat production in the deepest targeted PWS vessel.

Depth determination of chromophores in human skin by pulsed photothermal radiometry.

We report on the application of pulsed photothermal radiometry (PPTR) to determine the depth of in-vitro and in-vivo subsurface chromophores in biological materials. Measurements provided by PPTR in combination with a nonnegative constrained conjugate-gradient algorithm are used to determine the initial temperature distribution in a biological material immediately following pulsed laser irradiation. Within the experimental error, chromophore depths (50-450 µm) in 55 in-vitro collagen phantoms determined by PPTR and optical low-coherence reflectometry are equivalent.

Modelling the distribution of laser light in port-wine stains with the Monte Carlo method.

Using the Monte Carlo method, we have calculated the distribution of absorbed light in skin during the laser treatment of port-wine stains. Our model includes the effect that the blood capillaries and epidermis have on the propagation of light through skin. It is more complete than those used by previous workers.

A computer controlled scanner for the laser treatment of vascular lesions and hyperpigmentation.

A computer controlled scanner has been used with a copper vapour laser for the treatment of vascular lesions and hyperpigmented lesions. The computer controls the position and speed of travel of the laser spot during treatment. The illumination time is adjustable with a minimum of 1 ms.