159 research outputs found

    Space Charge Limited Transport and Time of Flight Measurements in Tetracene Single Crystals: a Comparative Study

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    We report on a systematic study of electronic transport in tetracene single crystals by means of space charge limited current spectroscopy and time of flight measurements. Both II-VV and time of flight measurements show that the room-temperature effective hole-mobility reaches values close to μ1\mu \simeq 1 cm2^2/Vs and show that, within a range of temperatures, the mobility increases with decreasing temperature. The experimental results further allow the characterization of different aspects of the tetracene crystals. In particular, the effects of both deep and shallow traps are clearly visible and can be used to estimate their densities and characteristic energies. The results presented in this paper show that the combination of II-VV measurements and time of flight spectroscopy is very effective in characterizing several different aspects of electronic transport through organic crystals.Comment: Accepted by J. Appl. Phys.; tentatively scheduled for publication in the January 15, 2004 issue; minor revisions compared to previous cond-mat versio

    A protocol for the development of Core Outcome Sets for effectiveness trials and clinical audits in Renal Cell Cancer (R-COS)

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    The data collection for the interview study is funded by NHS Grampian Endowments, and the costs of the interview transcriptions and eDelphi licences will be paid by the Arcobaleno Cancer Trust. Neither funder had any role in the design of the study. All other parts of the study are currently unfunded. The research team is not personally reimbursed for their time and efforts apart from research input by SD, which is financed by Swedish government funding of clinical research (ALF).Peer reviewedPublisher PD

    Management of Sporadic Renal Angiomyolipomas: A Systematic Review of Available Evidence to Guide Recommendations from the European Association of Urology Renal Cell Carcinoma Guidelines Panel

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    CONTEXT: Little is known about the natural history of sporadic angiomyolipomas (AMLs); there is uncertainty regarding the indications of treatment and treatment options. OBJECTIVE: To evaluate the indications, effectiveness, harms, and follow-up of different management modalities for sporadic AML to provide guidance for clinical practice. EVIDENCE ACQUISITION: A systematic review of the literature was undertaken, incorporating Medline, Embase, and the Cochrane Library (from 1 January 1990 to 30 June 2017), in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. No restriction on study design was imposed. Patients with sporadic AML were included. The main interventions included active surveillance, surgery (nephron-sparing surgery and radical nephrectomy), selective arterial embolisation, and percutaneous or laparoscopic thermal ablations (radiofrequency, microwaves, or cryoablation). The outcomes included indications for active treatment, AML growth rate, AML recurrence rate, risk of bleeding, post-treatment renal function, adverse events of treatments, and modalities of follow-up. Risk of bias assessment was performed using standard Cochrane methods. EVIDENCE SYNTHESIS: Among 2704 articles identified, 43 were eligible for inclusion (zero randomised controlled trials, nine nonrandomised comparative retrospective studies, and 34 single-arm case series). Most studies were retrospective and uncontrolled, and had a moderate to high risk of bias. CONCLUSIONS: In active surveillance series, spontaneous bleeding was reported in 2% of patients and active treatment was undertaken in 5%. Active surveillance is the most chosen option in 48% of the cases, followed by surgery in 31% and selective arterial embolisation in 17% of the cases. Selective arterial embolisation appeared to reduce AML volume but required secondary treatment in 30% of the cases. Surgery (particularly nephron-sparing surgery) was the most effective treatment in terms of recurrence and need for secondary procedures. Thermal ablation was an infrequent option. The association between AML size and the risk of bleeding remained unclear; as such the traditional 4-cm cut-off should not per se trigger active treatment. In spite of the limitations and uncertainties relating to the evidence base, the findings may be used to guide and inform clinical practice, until more robust data emerge. PATIENT SUMMARY: Sporadic angiomyolipoma (AML) is a benign tumour of the kidney consisting of a mixture of blood vessels, fat, and muscle. Large tumours may have a risk of spontaneous bleeding. However, the size beyond which these tumours need to be treated remains unclear. Most small AMLs can be monitored without any active treatment. For those who need treatment, options include surgical removal of the tumour or stopping its blood supply (selective embolisation). Surgery has a lower recurrence rate and lower need for a repeat surgical procedure

    Echocardiography practice, training and accreditation in the intensive care: document for the World Interactive Network Focused on Critical Ultrasound (WINFOCUS)

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    Echocardiography is increasingly used in the management of the critically ill patient as a non-invasive diagnostic and monitoring tool. Whilst in few countries specialized national training schemes for intensive care unit (ICU) echocardiography have been developed, specific guidelines for ICU physicians wishing to incorporate echocardiography into their clinical practice are lacking. Further, existing echocardiography accreditation does not reflect the requirements of the ICU practitioner. The WINFOCUS (World Interactive Network Focused On Critical UltraSound) ECHO-ICU Group drew up a document aimed at providing guidance to individual physicians, trainers and the relevant societies of the requirements for the development of skills in echocardiography in the ICU setting. The document is based on recommendations published by the Royal College of Radiologists, British Society of Echocardiography, European Association of Echocardiography and American Society of Echocardiography, together with international input from established practitioners of ICU echocardiography. The recommendations contained in this document are concerned with theoretical basis of ultrasonography, the practical aspects of building an ICU-based echocardiography service as well as the key components of standard adult TTE and TEE studies to be performed on the ICU. Specific issues regarding echocardiography in different ICU clinical scenarios are then described
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