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This work was supported by the EPSRC (Grant No. EP/K503162/1). Significance : Optical microscopy is characterized by the ability to get high resolution, below 1 μm, high contrast, functional and quantitative images. The use of shaped illumination, such as with lightsheet microscopy, has led to greater three-dimensional isotropic resolution with low phototoxicity. However, in most complex samples and tissues, optical imaging is limited by scattering. Many solutions to this issue have been proposed, from using passive approaches such as Bessel beam illumination to active methods incorporating aberration correction, but making fair comparisons between different approaches has proven to be challenging. Aim : We present a phase-encoded Monte Carlo radiation transfer algorithm (φMC) capable of comparing the merits of different illumination strategies or predicting the performance of an individual approach. Approach : We show that φMC is capable of modeling interference phenomena such as Gaussian or Bessel beams and compare the model with experiment. Results : Using this verified model, we show that, for a sample with homogeneously distributed scatterers, there is no inherent advantage to illuminating a sample with a conical wave (Bessel beam) instead of a spherical wave (Gaussian beam), except for maintaining a greater depth of focus. Conclusion : φMC is adaptable to any illumination geometry, sample property, or beam type (such as fractal or layered scatterer distribution) and as such provides a powerful predictive tool for optical imaging in thick samples. Publisher PDF

INTRODUCTION AND OBJECTIVE:Use of freehand-guided transperineal prostate biopsy has allowed biopsies to be performed under local anesthesia (LA) or IV sedation (IVS) with less analgesia requirement...

Purpose To determine the impact on clinical management of patients with high-risk (HR) prostate cancer at diagnosis and patients with biochemical recurrence (BCR) using a new kit form of 68Ga-prostate-specific membrane antigen (PSMA), namely tris(hydroxypyridinone) (THP)-PSMA, with positron emission tomography-computed tomography (PET-CT). Methods One hundred eighteen consecutive patients (50 HR, 68 BCR) had management plans documented at a multidisciplinary meeting before 68Ga-THP-PSMA PET-CT. Patients underwent PET-CT scans 60-min post-injection of 68Ga-THP-PSMA (mean 159 ± 21.2 MBq). Post-scan management plans, Gleason score, prostate-specific antigen (PSA) and PSA doubling time (PSAdt) were recorded. Results HR group: 12/50 (24%) patients had management changed (9 inter-modality, 3 intra-modality). Patients with PSA < 20 μg/L had more frequent management changes (9/26, 34.6%) compared with PSA > 20 μg/L (3/24, 12.5%). Gleason scores > 8 were associated with detection of more nodal (4/16, 25% vs 5/31, 16.1%) and bone (2/16, 12.5% vs 2/31, 6.5%) metastases. BCR group: Clinical management changed in 23/68 (34%) patients (17 inter-modality, 6 intra-modality). Forty out of 68 (59%) scans were positive. Positivity rate increased with PSA level (PSA < 0.5 μg/L, 0%; PSA 0.5–1.0 μg/L, 35%; PSA 1.0–5.0 μg/L, 69%; PSA 5.0–10.0 μg/L, 91%), PSAdt of < 6 months (56% vs 45.7%) and Gleason score > 8 (78.9% vs 51.2%). Conclusions 68Ga-THP-PSMA PET-CT influences clinical management in significant numbers of patient with HR prostate cancer pre-radical treatment and is associated with PSA. Management change also occurs in patients with BCR and is associated with PSA and Gleason score, despite lower scan positivity rates at low PSA levels < 0.5 μg/L.

Purpose To evaluate the outcomes from a Urology Nurse Practitioner (UNP)-led service for the initial assessment and diagnostic decision making and for suspected prostate cancer referrals. Methods Using a modified Delphi analysis approach, a panel of Urological Prostate Cancer specialists were asked to review the UNP management plans of a convenience sample of 60 randomly selected patient cases – between June 2012 and June 2015. The panel was required to establish consensus or identify divergence of clinical practice, based on five key statements. In addition, cost analysis, waiting time and patient satisfaction evaluation were made regarding the nurse-led service. Results In 87% (52/60 cases), consensus was reached by the panel that the UNP management plan was entirely appropriate and in only two cases was there discordance, where the panel felt that the management plan by the UNP was inappropriate with errors potentially and significantly affecting the patient. Over the 3 years, a modest cost saving of £11,500.38 was realised, which due to increased referrals has now realised in 1 year (2017/18) a saving of £11,335.50. Compared to the previous physician-led service, waiting times for patient appointment fell by 52% over the 3-year period; 57/63 (90%) patients reported being satisfied with seeing a UNP instead of a doctor for their first appointment; 60/63 (95%) reported that, following the initial hospital visit with the UNP, they had a clear understanding of what the next steps were in their assessment. Overall, 54/63 (86%) were ‘very satisfied’ with the UNP-led service. Conclusion Our study demonstrates that a UNP approach to the assessment and management of suspected prostate cancer referrals provides an effective approach to care in an ever-demanding healthcare arena. Through a supported training programme, urology nurses can deliver a high standard of service.

Objectives To present our series of patients with penetrating renal trauma treated at two urban major trauma centres and to discuss the contemporary management of such injuries. Methods We reviewed prospective urological trauma databases for all patients presenting with penetrating renal trauma between January 2005 and October 2016. Patient demographics, clinical characteristics, imaging, management and follow-up data were analysed. Results Over the 11-year period, 63 patients presented with penetrating renal injuries. The vast majority of patients were male (n = 61; 96.8%), with a mean (range) age of 27.4 (14-71) years. Injuries were equally common on either side (31 left, 32 right). The most common mechanism of injury was stabbing (n = 55; 87.3%), followed by gunshot (n = 7; 11.1%) and crossbow injuries (n = 1; 1.6%). All patients underwent contrast-enhanced computed tomography. Using the American Association for the Surgery of Trauma renal injury grading system, 11 (17.5%) had grade II, 26 (41.3%) had grade III and 26 (41.3%) had grade IV injury. The most common associated injuries were thoracic (n = 23; 36.5%), liver (n = 11; 17.5%), splenic (n = 10; 15.9%), gastrointestinal tract (n = 8; 12.7%) and musculoskeletal (n = 6; 9.5%). At presentation, 16 patients (25.4%) were haemodynamically unstable. The majority of patients did not require blood transfusion (n = 56; 88.9%), while transfusion of >5 units was rare (n = 4; 6.3%). Fifty-two patients (82.5%) were managed by observation alone, while 10 (15.9%) underwent emergency angiography and embolization. Patients with grade IV injury were more likely to require embolization than those with grade III injury; however, the difference was not significant (26.9% vs 15.4%; P = 0.29). One patient (1.6%) underwent retroperitoneal exploration of their renal injury and was managed conservatively. Eight patients underwent laparotomy for other visceral injuries while their renal injury was managed conservatively. Renal artery pseudoaneurysm developed in five patients (7.9%) and one patient (1.6%) developed renal arteriovenous malformation. No patients underwent nephrectomy and no mortality was reported. Conclusions The vast majority of patients with penetrating renal injuries can be safely managed non-operatively in this setting. Selective renal artery embolization is an effective option for patients in an unstable condition, with excellent outcomes. Associated thoracic or visceral injuries requiring operative management are common in penetrating renal trauma, while urologists should limit or have a high threshold for surgical intervention.

In the last decade, active surveillance (AS) has emerged as an acceptable choice for low-risk prostate cancer (PC), however there is discordance amongst large AS cohort studies with respect to entry and monitoring protocols. We systematically reviewed worldwide AS practices in studies reporting ≥5 years follow-up. We searched PubMed and Medline 2000-now and identified 13 AS cohorts. Three key areas were identified: (I) patient selection; (II) monitoring protocols; (III) triggers for intervention—(I) all studies defined clinically localised PC diagnosis as T2b disease or less and most agreed on prostate-specific antigen (PSA) threshold (

To date, demonstrated ultrashort pulse seed sources for Ho3+-doped amplifiers, such as Ho:YAG and Ho:YLF, leave a lot to be desired in terms of complexity, cost, and efficiency. Sources like those used in [1] involve nonlinear energy transfer schemes, requiring numerous stages before a pulse covering a suitable spectral range (Ho:YAG, 2090 nm; Ho:YLF, 2050/2060 nm) is generated. The more direct approach of using a Ho:fiber laser, as reported in [2], benefits from a less complex setup. However, the requirement of multiple pump stages inevitably reduces the systems overall efficiency in addition to increasing the cost. A clear route for reducing the overall cost and complexity of such ultrashort pulse seed sources would be to employ a gain medium that could utilise direct diode pumping as well as being able to target the gain spectra of existing Ho3+-doped amplifiers. Here we report on our recent developments of diode-pumped ultrashort pulse Tm3+-doped Lu 2 O 3 and LuScO 3 lasers broadly tunable in the 2000–2100 nm spectral range.

Need: Dental enamel is an acellular and avascular mineralised tissue, containing more than 95% calcium phosphate mineral. Although, the underlying softer dentine is connected with the microvasculature via the soft tissue and, therefore, possesses intrinsic regenerative capacity for mineralisation, the superficial enamel lacks regenerative potential. Consequently, the oral acid induced erosive damage on enamel is irreversible, and leads to lesion formation, which if unattended, may lead to hypersensitivity and feeling of pain. Advanced stage of eroded enamel with symptoms of hypersensitivity might lead to tooth loss in adults. Traditional clinical strategies for the repair of acid-eroded enamel include the use of off-shelf toothpastes and BIS-GMA polymeric materials; the latter is structurally incompatible with natural enamel due to mismatched thermal expansion coefficient and mechanical properties. As a result this type of bonding leads to failure of restored enamel area in a challenging oral environment [1]. Modern toothpastes only provide temporary symptomatic relief from hypersensitivity. Till date, no long-term or permanent solution for treating early stages of acid erosion is on offer. Associated with acid erosion is also erosive wear which affects especially the ageing population and leads to lingual tooth thinning and weakening. Rebuilding the entire damaged tissue region remains a challenge.

We report on the development of a femtosecond Tm:Lu2O3 ceramic master oscillator power amplifier system at 2080 nm. A maximum average output power of 816 mW is achieved with the pulse duration of 313 fs.

In this paper we present on-chip mode-locked waveguide lasers fabricated in Yb-doped phosphate glass and Er, Ybdoped phosphate glass. At 1 micron wavelength, pulse repetition rates of up to 15 GHz with pulses ~800 fs were demonstrated and at 1.5 micron, picosecond pulses with a repetition rate up to 7 GHz were demonstrated. Dispersion was controlled in the cavity by varying the spacing between the waveguide and the SESAM, while the repetition rate could be controlled by varying the optical power. The average power can also be scaled using an integrated optical amplifier and on-chip gain of up to 10 dB was demonstrated. All these individual components can be integrated in a single platform to achieve a high-power on-chip multi-GHz optical frequency comb. Furthermore, we discuss an application of such laser sources in high-capacity telecommunications applications.

We report on the first demonstration, to the best of our knowledge, of a diode-pumped Tm:LuScO3 laser. Efficient and broadly tunable continuous wave operation in the 1973-2141 nm region and femtosecond mode-locking through the use of an ion-implanted InGaAsSb quantum-well-based semiconductor saturable absorber mirror are realized. When mode-locked, near-transform-limited pulses as short as 170 fs were generated at 2093 nm with an average output power of 113 mW and a pulse repetition frequency of 115.2 MHz. Tunable picosecond pulse generation was demonstrated in the 2074-2104 nm spectral range.

Funding: UK EPRSC PhD studentship number EP/N509759/1. Nonmelanoma and melanoma skin cancers are attributable to DNA damage caused by ultraviolet (UV) radiation exposure. One DNA photoproduct, the Cyclobutane Pyrimidine Dimer (CPD), is believed to lead to DNA mutations caused by UV radiation. Using radiative transfer simulations, we compare the number of CPDs directly induced by UV irradiation from artificial and natural UV sources (a standard sunbed and the midday summer Mediterranean sun) for skin types I and II on the Fitzpatrick scale. We use Monte Carlo Radiative Transfer (MCRT) modelling to track the progression of UV photons through a multilayered three dimensional (3D) grid that simulates the upper layers of the skin. By recording the energy deposited in the DNA-containing cells of the basal layer, the number of CPDs formed can be quantified. The aim of this work was to compare the number of CPDs formed in the basal layer of the skin, and by implication the risk of developing cancer, as a consequence of irradiation by artificial and natural sources. Our simulations show that the number of CPDs formed per second during sunbed irradiation is almost three times that formed during solar irradiation. Postprint

Ultrafast laser inscription (ULI) allows the fabrication of compact, highly-efficient and robust laser sources over a broad range of crystalline, ceramic and glass gain media. For instance, subsurface waveguides can be formed by the stress induced refractive index modification effect which takes place between two parallel modified regions referred to as “Type II” guiding [1]. Previously, a family of laser hosts known as sesquioxides, namely Lu 2 O 3 , Sc 2 O 3 and LuScO 3 , have been shown to demonstrate efficient, high-power and tunable laser operation around the 2 μm region in both continuous-wave and pulsed regimes when doped with Tm3+ [2, 3]. Combining the Tm3+-doped sesquioxide material properties with the ULI waveguide laser geometry provides a means to produce compact, low-threshold and efficient laser sources near 2 μm with the potential for high pulse repetition rate ultrafast operation. Here we report, to the best of our knowledge, the first demonstration of a ceramic Tm:Lu 2 O 3 waveguide laser source fabricated by ULI.

ML acknowledges support from the Engineering and Physical Sciences Research Council (EPSRC) through the Centre for Doctoral Training in Applied Photonics. We demonstrate a frequency comb-based time transfer technique on a 159 km long installed fiber link. Timing information is superimposed onto the optical pulse train of an ITU-channel-filtered mode-locked laser using an intensity modulation scheme. The environmentally induced optical path length fluctuations are compensated using a round-trip phase noise cancellation technique. When the fiber link is stabilized, a time deviation of 300 fs at 5 s and an accuracy at the 100 ps level are achieved. Postprint

C L Campbell acknowledges financial support from an UK EPSRC PhD studentship (EP/K503162/1) and the Alfred Stewart Trust. Most existing theoretical models of photodynamic therapy (PDT) assume a uniform initial distribution of the photosensitive molecule, Protoporphyrin IX (PpIX). This is an adequate assumption when the prodrug is systematically administered; however for topical PDT this is no longer a valid assumption. Topical application and subsequent diffusion of the prodrug results in an inhomogeneous distribution of PpIX, especially after short incubation times, prior to light illumination. In this work a theoretical simulation of PDT where the PpIX distribution depends on the incubation time and the treatment modality is described. Three steps of the PpIX production are considered. The first is the distribution of the topically applied prodrug, the second in the conversion from the prodrug to PpIX and the third is the light distribution which affects the PpIX distribution through photobleaching. The light distribution is modelled using a Monte Carlo radiation transfer model and indicates treatment depths of around 2 mm during daylight PDT and approximately 3 mm during conventional PDT. The results suggest that treatment depths are not only limited by the light penetration but also by the PpIX distribution Postprint

The authors acknowledge support from the sponsors of this work; the EPSRC LUMIN (EP/K020234/1) and EU-Marie-Curie-IAPP LUSTRE (324538) projects. Direct laser sintering on hard tissues is likely to open new pathways for personalised medicine. To minimise irradiation damage of the surrounding soft tissues, lasers operating at wavelengths that are ‘safe’ for the tissues and biomaterials with improved optical properties are required. In this work laser sintering is demonstrated with the use of an ultrafast, femtosecond (100 fs) pulsed laser operating at a wavelength of 1045 nm and two existing calcium phosphate minerals (brushite and hydroxyapatite) which have been improved after doping with iron (10 mol%). Femtosecond laser irradiation caused transformation of the Fe3+-doped brushite and Fe3+-doped HAp samples into β-calcium pyrophosphate and calcium-iron-phosphate, respectively, with simultaneous evidence for microstructural sintering and densification. After estimating the temperature profile at the surface of the samples we suggest that soft tissues over 500 μm from the irradiated zone would be safe from thermal damage. This novel laser processing provides a means to control the phase constitution and the morphology of the finished surfaces. The porous structure of β-pyrophosphate might be suitable for applications in bone regeneration by supporting osteogenic cell activity while, the densified Fe3+-rich calcium-iron-phosphate may be promising for applications like dental enamel restoration. Postprint

C L Campbell acknowledges financial support from an UK EPSRC PhD studentship (EP/K503162/1) and the Alfred Stewart Trust. We explore the effects of three dimensional (3D) tumour structures on depth dependent fluence rates, photodynamic doses (PDD) and fluorescence images through Monte Carlo radiation transfer modelling of photodynamic therapy. The aim with this work was to compare the commonly used uniform tumour densities with non-uniform densities to determine the importance of including 3D models in theoretical investigations. It was found that fractal 3D models resulted in deeper penetration on average of therapeutic radiation and higher PDD. An increase in effective treatment depth of 1 mm was observed for one of the investigated fractal structures, when comparing to the equivalent smooth model. Wide field fluorescence images were simulated, revealing information about the relationship between tumour structure and the appearance of the fluorescence intensity. Our models indicate that the 3D tumour structure strongly affects the spatial distribution of therapeutic light, the PDD and the wide field appearance of surface fluorescence images. Postprint

Optical interconnects have attracted significant research interest for use in short-reach board-level optical communication links in supercomputers and data centres. Multimode polymer waveguides in particular constitute an attractive technology for on-board optical interconnects as they provide high bandwidth, offer relaxed alignment tolerances, and can be cost-effectively integrated onto standard printed circuit boards (PCBs). However, the continuing improvements in bandwidth performance of optical sources make it important to investigate approaches to develop high bandwidth polymer waveguides. In this paper, we present dispersion studies on a graded-index (GI) waveguide in siloxane materials designed to deliver high bandwidth over a range of launch conditions. Bandwidth-length products of >70 GHzxm and ~65 GHzxm are observed using a 50/125 um multimode fibre (MMF) launch for input offsets of +/- 10 um without and with the use of a mode mixer respectively; and enhanced values of >100 GHzxm are found under a 10x microscope objective launch for input offsets of ~18 x 20 um^2. The large range of offsets is within the -1 dB alignment tolerances. A theoretical model is developed using the measured refractive index profile of the waveguide, and general agreement is found with experimental bandwidth measurements. The reported results clearly demonstrate the potential of this technology for use in high-speed board-level optical links, and indicate that data transmission of 100 Gb/s over a multimode polymer waveguide is feasible with appropriate refractive index engineering., 8 pages, 10 figures

The choice of light source is important for the efficacy of photodynamic therapy (PDT) of non-melanoma skin cancer. We simulated the photodynamic dose (PDD) delivered to a tumour during PDT using theoretical radiation transfer simulations performed via our 3D Monte Carlo radiation transfer (MCRT) model for a range of light sources with light doses up to 75 J cm(-2). The PDD delivered following superficial irradiation from (A) non-laser light sources, (B) monochromatic light, (C) alternate beam diameters and (D) re-positioning of the tumour within the tissue was computed. (A) The final PDD deposited to the tumour at a depth of 2 mm by the Paterson light source was 2.75, 2.50 and 1.04 times greater than the Waldmann 1200, Photocure and Aktilite, respectively. (B) Tumour necrosis occurred at a depth of 2.23 mm and increased to 3.81 mm for wavelengths 405 and 630 nm, respectively. (C) Increasing the beam diameter from 10 to 50 mm had very little effect on depth of necrosis. (D) As expected, necrosis depths were reduced when the tumour was re-positioned deeper into the tissue. These MCRT simulations show clearly the importance of choosing the correct light source to ensure optimal light delivery to achieve tumour necrosis.

Upper urinary tract fungal infections are rare, under-reported and potentially fatal. Infections often develop in patients with significant co-morbidity and are difficult to identify and treat. They can manifest as local (funguria) or systemic infection (fungaemia). The management is complex and mortality appears unchanged in the past 20 years. Unlike lower urinary tract funguria, which is classified as low risk, upper ureteric infections and fungaemia are classified as high risk. The incidence is increasing and may be associated with changing population demographics, advances in medical diagnostics, and new stent and catheter technologies with longer durations of insertion. We review the current literature and report on six cases.

We report on the performance around 1970 nm of a thulium-doped TZNG bulk glass laser pumped by a semiconductor disk laser (SDL) emitting at 1211 nm. A pump-limited maximum output power of 60 mW at 1946 nm was obtained with a measured slope efficiency of 22.4%. The tuning range of 115 nm extended from 1850 nm to 2040 nm. Comparison with a previously reported performance when pumped at 793 nm with Ti:sapphire laser is discussed highlighting the competitiveness of pumping at 1211 nm.

The authors present Raman cluster mapping of de-paraffinized normal cervical tissue and demonstrate the ability of this approach to differentiate between normal squamous epithelium and cervical intraepithelial neoplasia (CIN). Multivariate analysis was performed by hierarchical cluster analysis (HCA) of the Raman spectra associated with the different tissue types and Raman maps were generated using the resultant clusters. Using normal cervical tissue, squamous epithelium and the epithelial-stromal interface, a muscular artery and endocervical glands were successfully mapped. Analysis of a tissue section containing a cervical intraepithelial neoplasia (CIN) grade 2 lesion adjacent to normal squamous epithelium demonstrated that the CIN lesion clustered predominantly with the basal epithelial cells of normal epithelium and allowed visual discrimination of these areas using the Raman map. These findings suggest that Raman mapping has the potential to provide images that are useful for disease diagnosis. In particular, the discrimination between normal cervical squamous epithelium and CIN is of relevance to cervical screening pathology. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Optical micromanipulation of transparent microparticles such as cellular materials relies upon the application of optical forces that are crucially dependent on the refractive index contrast between the particle and the surrounding medium. We briefly review the application of optical forces for cell manipulation and sorting, highlighting some of the key experiments over the last twenty years. We then introduce a new technique for enhancing the dielectric contrast of mammalian cells, which is a result of cells naturally taking up microspheres from their environment. We explore how these intracellular dielectric tags can influence the scattering and gradient forces upon these cells from an externally applied optical field. We show that intracellular polymer microspheres can serve as highly directional optical scatterers and that scattering forces can enable sorting through axial guiding onto laminin-coated glass coverslips upon which the selected cells adhere. Such internal dielectric tagging presents a simple, inexpensive, sterile technique to enhance optical manipulation procedures for cellular material and may enable new sorting techniques within microfluidic systems.

Some key recent achievements in the development of novel saturable absorbers that are based on semiconductor quantum-dot (QD) structures for the passive mode locking of near-infrared lasers are outlined. These are group IV–VI semiconductor nanoparticles (quantum dots) in glass matrices and self-assembled semiconductor quantum dots (group III–V) grown on semiconductor mirrors (QD-SESAMs). The performance of solid-state (Yb3+, Nd3+ and Cr4+-based), Yb-doped fibre and monolithically integrated semiconductor lasers has been described within the context of ultrashort-pulse generation using these types of QD-based modulators. Particular attention has been paid to the nonlinear parameters of the QD-based saturable absorbers that determine the quality of the mode locking in such laser systems.

The growth, spectroscopy and lasing performance of a novel Tm, Ho:KY(WO4)2 crystal are reported. The peak emission cross-section of the Ho3+5I7→5I8 transition and lifetime of the 5I7 excited state were determined to be 4.8×10−20 cm2 and 1.8 ms, respectively, in a spectral range at around 2060 nm. Using a Ti:sapphire laser as a pump source at 802 nm, a maximum slope efficiency of up to 44% has been achieved with a corresponding output power of 460 mW at 2056 nm during continuous-wave operation of a Tm, Ho:KY(WO4)2 laser at room temperature. A tuning range of 1890–2080 nm has been demonstrated.

We show that it is possible to eliminate group delay dispersion over wide bandwidths in low-finesse, resonant saturable absorber mirrors, whilst maintaining a low saturation fluence and a high modulation depth. By modelling the mirror structure we demonstrate that these properties can be produced by capping a resonant device with a single dielectric layer of carefully selected refractive index. We show that a specially capped dispersionless structure minimises the temporal broadening of femtosecond pulses reflected from the mirror. We compare this device against uncapped-resonant and anti-resonant structures. The superior performance of the capped, dispersionless device was verified experimentally by comparing resonant, anti-resonant and dispersionless quantum-dot (QD) saturable absorber mirrors incorporated into a Cr4+:forsterite laser system. We found that a minimum pulse duration of 86 fs could be achieved for the dispersionless structure at 1290 nm with an output power of 55 mW compared to 122 fs in an anti-resonant structure and several-picosecond pulses for a resonant structure.

OBJECTIVE To review our long-term use of the thermo-expandable metallic ureteric stent, (model 051, PNN Medical, Denmark) for ureteric obstruction, and review current reports on its use. PATIENTS AND METHODS Data were collected prospectively on all patients who had a Memokath 051 ureteric stent inserted between November 1996 and November 2007. The standard stent, and wide and dual expansion versions were used. The stricture characteristics were recorded in a standard way. All stents were inserted by one surgeon in the UK and internationally, following a standard protocol. RESULTS In all, 74 stents were inserted into 55 patients in the study period (mean age 60 years, range 11–90). The indications for metallic stenting included primary stenting for malignancy, failed conventional open and endoscopic techniques, palliation, and where significant comorbidity limited repetitive stent changes. In 28 patients the obstruction was caused by malignancy, whereas in 27 it was caused by recurrent benign disease. The mean (range) hospital stay was 1.43 (0–7) days. Imaging after insertion showed normal or improved functional drainage in all but three patients, with immediate complications including urinary extravasation (one), poor thermo-expansion (one) and equipment failure (locking assembly) (one). Late complications included migration (13), encrustation (two) and fungal infections (three). In all, 14 patients needed reinsertion (mean of 7.1 months, range 1–14) after insertion for migration (eight), encrustation (two), stricture progression (three) and incorrect stent length (one). Overall, 29 patients have died with the stents in-situ. The mean (range) follow-up was 16 (4–98) months. CONCLUSIONS The thermo-expandable metallic Memokath 051 ureteric stent offers effective and durable long-term relief from ureteric obstruction, and is a safe alternative to conventional JJ stenting. In addition there is an emerging role in palliation and the primary management of ureteric strictures.

In this work we present a review and discussion on the enhancement of femtosecond (fs) lasers for use within biophotonics with a particular focus on their use in optical transfection techniques. We describe the broad range of source options now available for the generation of femtosecond pulses before briefly reviewing the application of fs laser in optical transfection studies. We show that major performance enhancements may be obtained by optimising the spatial and temporal performance of the laser source before considering possible future directions in this field. In relation to optical transfection we describe how such laser sources initiate a multiphoton process to permeate the cell membrane in a transient fashion. We look at aspects of this technique including the ability to combine transfection with optical trapping. For future implementation of such transfection we explore the role of new sources and “nondiffracting” light fields. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We report on precise two-photon ablation with 110 fs laser pulses at 1278 nm, emitted from a Cr:forsterite laser. Selective two-photon ablation of Muntjac deer chromosomes is demonstrated. The two-photon absorption at 639 nm was enhanced by using Methylene blue dye as a photosensitizer. This stain has a strong absorption in the region around 650 nm but 100% transmission around 1300 nm, allowing increased specificity: material that has absorbed the dye is ablated but undyed material is left unaffected. The low group velocity dispersion in glass at 1278 nm led to negligible pulse broadening in the focusing objective where the 100 fs pulses stretched to 110 fs. This contrasts to the 100 fs pulses at 780 nm that were measured to stretch to 300 fs under the same conditions.

We review the emergent techniques of microfluidic sorting of colloidal and cellular samples using optical forces. We distinguish between what we term as passive and active forms of particle sorting where we can sort either with the use of a fluorescent marker (active) or based on physical attributes alone (passive). We then examine cell sorting with optical potential landscapes such as a Bessel light beam and a multibeam interference pattern. For both forms of optical potential energy landscape, we further present the possibility of enhancing the optical sorting process by tagging dielectric microspheres onto the cells. The results suggest that the methodology of tagging can enhance the sorting of cells as they subsequently respond more strongly to an applied optical field or potential energy landscape. This technique presents a simple method to enhance the sorting process.

We report enhanced graded-index multimode polymer waveguides with >70GHz×m for MMF launch and >200GHz×m for restricted launch, indicating the capability of on-board waveguide transmission of >100 Gb/s. Simulations using the measured refractive index profile agree well with the experiments.

Dispersion studies are conducted on 1m long multimode polymer spiral waveguides with different refractive index profiles. Bandwidth-length products >40GHzxm are obtained from such waveguides under a 50/125 um MMF, indicating the potential of this technology., 3 pages, 2 figures, IEEE Optical Interconnects Conference (OIC), paper MD2, 2015

The treatment of super cial skin lesions via daylight activated photodynamic therapy (PDT) has been explored theoretically with three dimensional (3D) Monte Carlo radiation transfer (MCRT) simulations. For similar parameters and conditions, daylight activated PDT was compared to conventional PDT using a commercially available light source. Under reasonable assumptions for the optical properties of the tissue, protoporphyrin IX (PpIX) concentration, and a treatment dose of 75 J cm-2, it was found that during a clear summer day an effective treatment depth of over 2 mm can be achieved after 30 min of daylight illumination at a latitude of 56 degrees North. The same light dose would require 2.5 h of daylight illumination during an overcast summer day where a treatment depth of about 2 mm can be achieved. For conventional PDT the developed model suggests that 15 min of illumination is required to deliver a light dose of 75 J cm-2, which would result in an e effective treatment depth of about 3 mm. The model developed here allows for the determination of phototoxicity in skin tissue as a function of depth for different weather conditions as well as for conventional light sources. Our theoretical investigation supports clinical studies and shows that daylight activated PDT has the potential for treating superficial skin lesions during different weather conditions. Postprint

MJC is funded by an Australian Research Council grant FS110200057. CTAB acknowledges support for instrument development and shipping costs from the United Kingdom Engineering and Physical Sciences Research Council Grant EP/M000869/1 (Shaped Light at the Interface). The accurate observation of physiological changes on in vivo samples of important animal species such as Euphasia superba (Antarctic krill) is an important goal in helping to understand how environmental changes can affect animal development. Using a custom made ‘krill trap’, live un-anaesthetized krill were confined for seven hours, during which three hours of optical imaging were obtained and no subsequent ill effects observed. The trap enabled two imaging methods to be employed: Optical Coherence Tomography (OCT) and microscopy. OCT enabled internal structure and tissues to be imaged to a depth of approximately 2 mm and resolution of approximately 12 μm. Microscopy was used to observe heart rate. During our experiments, we imaged a range of internal structures in live animals including the heart and gastric areas. The trap design enables a new generation of mixed modality imaging of these animals in vivo. These techniques will enable detailed studies of the internal physiology of live krill to be undertaken under a wide range of environmental conditions and have the potential to highlight important variations in behaviour and animal development. Postprint

Bessel beams are propagation invariant light fields. It has very recently been shown that they may be created with temporally incoherent (white) light. Such fields may have applications in low coherence interferometric imaging for biomedicine and optical micromanipulation. White light Bessel beams may be deemed at first glance to generate a white focal line of light at the beam centre due to the absence of chromatic aberration. We investigate the spectral characteristics of the reformation or self-healing of this light field in the presence of a circular obstruction and reveal that the spectral characteristics of the beam generation and reformation results in a dispersive focal line at the beam centre which is 'white' only over a certain region.

Efficient generation of continuous-wave (CW) tunable light in the yellow region is reported. The method is based on sum-frequency mixing of a tunable Cr 4+ :forsterite laser with a Nd:YVO 4 laser. A periodically poled lithium niobate crystal was placed intra-cavity in a Nd:YVO 4 laser, and the Cr 4+ :forsterite laser was single-passed through the non-linear media. With this setup, it was possible to generate up to 3 mW of yellow light smoothly tunable from 573 to 587 nm. This is the highest output demonstrated to date for a tunable diode pumped solid-state CW laser in this wavelength region. The ways to improve the efficiency further are discussed.

This paper reports a novel optical-time-division-multiplexing (OTDM)/wavelength-division-multiplexing (WDM) source based on spectral slicing of a Kerr-lens mode-locked Cr/sup 4+/-YAG femtosecond laser. This mode-locked laser produces bandwidth-limited pulses having durations of 70 fs and corresponding spectral widths of 40 nm. This bandwidth is sufficiently large that an arrayed-waveguide grating (AWG) could be employed to spectrally slice the laser output into 32 different wavelength channels. A total capacity of 1.36 Tb/s (32 /spl times/ 40.64 Gb/s) with measured Q factors of 8 to 13 is achieved. The spectral efficiency is 0.4 b/s/Hz.

The use of PbS quantum-dot-doped glass as an intracavity saturable absorber for passive mode locking of a Cr4+:YAG laser was investigated. We obtained 10 ps pulses at a repetition rate of 235 MHz with an average output power of 35 mW. This mode-locked laser was tunable from 1460 to 1550 nm.

We report a compact self-starting passively mode-locked femtosecond Cr:YAG laser which incorporates a saturable Bragg reflector and uses a diode-pumped Yb-fiber laser as the pump source. Transform-limited 120-fs pulses are generated at an average power of 95 mW with a 22 nm spectral bandwidth centered at 1528 nm.