Author Correction: Carbon nanotubes as emerging quantum-light sources.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Publisher Correction: Carbon nanotubes as emerging quantum-light sources.

In the version of this Perspective originally published, the x-axis label of Fig. 1d was missing; it should have read 'Wavelength (nm)'. The units of the y axis of Fig. 3b were incorrect; they should have been meV. And the citation of Fig. 3c in the main text was incorrect; it should have been to Fig. 3b. These issues have now been corrected.

Carbon nanotubes as emerging quantum-light sources.

Progress in quantum computing and quantum cryptography requires efficient, electrically triggered, single-photon sources at room temperature in the telecom wavelengths. It has been long known that semiconducting single-wall carbon nanotubes (SWCNTs) display strong excitonic binding and emit light over a broad range of wavelengths, but their use has been hampered by a low quantum yield and a high sensitivity to spectral diffusion and blinking. In this Perspective, we discuss recent advances in the mastering of SWCNT optical properties by chemistry, electrical contacting and resonator coupling towards advancing their use as quantum light sources. We describe the latest results in terms of single-photon purity, generation efficiency and indistinguishability. Finally, we consider the main fundamental challenges stemming from the unique properties of SWCNTs and the most promising roads for SWCNT-based chip integrated quantum photonic sources.

Interplay of spectral diffusion and phonon-broadening in individual photo-emitters: the case of carbon nanotubes.

At cryogenic temperatures, the photoluminescence (PL) spectrum of nano-emitters may still be significantly broadened due to interactions with the environment. The interplay of spectral diffusion (SD) and phonon broadening in this context is still a debated issue. Singlewall carbon nanotubes (SWNTs) are a particularly relevant system to address this topic as they show intense spectral diffusion and undergo a high exciton-phonon coupling due to their one-dimensional geometry. Here, we investigate the correlations between the spectral diffusion of the main line and that of the wings in SWNTs quantitatively and demonstrate that the photoluminescence spectrum undergoes spectral jumps as a whole, without distortions. This behavior suggests that the spectral shape of SWNT PL is defined by exciton-phonon interactions and that spectral diffusion results in an additional flat broadening. The methodology developed here can be used to investigate a broad range of non-Lorentzian emitters undergoing spectral diffusion.

Exploiting One-Dimensional Exciton-Phonon Coupling for Tunable and Efficient Single-Photon Generation with a Carbon Nanotube.

Condensed-matter emitters offer enriched cavity quantum electrodynamical effects due to the coupling to external degrees of freedom. In the case of carbon nanotubes, a very peculiar coupling between localized excitons and the one-dimensional acoustic phonon modes can be achieved, which gives rise to pronounced phonon wings in the luminescence spectrum. By coupling an individual nanotube to a tunable optical microcavity, we show that this peculiar exciton-phonon coupling is a valuable resource to enlarge the tuning range of the single-photon source while keeping an excellent exciton-photon coupling efficiency and spectral purity. Using the unique flexibility of our scanning fiber cavity, we are able to measure the efficiency spectrum of the very same nanotube in the Purcell regime for several mode volumes. Whereas this efficiency spectrum looks very much like the free-space luminescence spectrum when the Purcell factor is small (large mode volume), we show that the deformation of this spectrum at lower mode volumes can be traced back to the strength of the exciton-photon coupling. It shows an enhanced efficiency on the red wing that arises from the asymmetry of the incoherent energy exchange processes between the exciton and the cavity. This allows us to obtain a tuning range up to several hundred times the spectral width of the source.

Widely Tunable Single-Photon Source from a Carbon Nanotube in the Purcell Regime.

The narrow emission of a single carbon nanotube at low temperature is coupled to the optical mode of a fiber microcavity using the built-in spatial and spectral matching brought by this flexible geometry. A thorough cw and time-resolved investigation of the very same emitter both in free space and in cavity shows an efficient funneling of the emission into the cavity mode together with a strong emission enhancement corresponding to a Purcell factor of up to 5. At the same time, the emitted photons retain a strong sub-Poissonian statistics. By exploiting the cavity feeding effect on the phonon wings, we locked the emission of the nanotube at the cavity resonance frequency, which allowed us to tune the frequency over a 4 THz band while keeping an almost perfect antibunching. By choosing the nanotube diameter appropriately, this study paves the way to the development of carbon-based tunable single-photon sources in the telecom bands.

Phenotypic and genotypic risk factors for cardiovascular events in an incident dialysis cohort.

Cardiovascular disease (CVD) remains the major cause of death in patients with end-stage renal disease (ESRD). Traditional risk factors do not explain the high prevalence of CVD in this population, and other non-traditional cardiovascular (CV) risk markers have now been described. Therefore, the potential relationship between CVD and phenotypic and genotypic risk markers was investigated prospectively in incident dialysis patients cohort. The 279 patients (244 on hemodialysis, 35 on peritoneal dialysis) within the Diamant Alpin Dialysis Cohort Study were investigated. Phenotypic and genotypic parameters were determined at dialysis initiation, patients monitored over a 2-year period, and CV events (morbidity and mortality) recorded. Globally, 82 CV events occurred and 26 patients (9.3%) died from CVD, whereas 28 (10%) died from non-CV causes. Previous CV events were strongly predictive of CV events occurrence, whatever patients had had one (hazard ratio (HR) 2, 95% confidence intervals (CI) 1.1-3.5) or more (HR 3.9, 95% CI 2.1-7.1) CV accidents before starting dialysis. Both lipoprotein(a) (HR 1.67, 95% CI 1-2.5) and total plasma homocysteine at cutoff 30 micromol/l (HR 1.7, 95% CI 1.1-2.8) were independent predictors of CV events outcome. In the subgroup of patients with homocysteine < 30 micromol/l, methylenetetrahydrofolate reductase (MTHFR) TT was the sole biological parameter predictive of CV event outcome (HR 2.5, 95% CI 1.1-10, P = 0.03). ESRD patients who enter chronic dialysis with a previous CV event, high total homocysteinemia levels, or MTHFR 677TT genotype must be considered at high risk of incident CV events.

CKD patients and erythropoietin: do we need evidence-based informed consent?

BACKGROUND: Consent to therapy is increasingly requested in the form of ''informed consent''. OBJECTIVE: To validate an evidence-based informed consent form for erythropoietin (EPO) therapy and to evaluate patient opinions about the informed consent approach. METHODS: An evidence-based informed consent form was developed as part of the Evidence-Based-Medicine course at the Medical School of Turin, Italy. It was validated by anonymous questionnaires (0-10 analogical scales and open answers) administered to patients at different stages of CKD (19 pre-ESRD, 26 hemodialysis, 12 transplant patients) attending an outpatient unit of the University of Turin, to 8 nurses, and to 26 medical students. RESULTS: All individuals filled in the questionnaire. Interest in a detailed explanation of the therapy was high (median 9), as was comprehension (median 9), with no differences between patients with regard to disease stage (pre-ESRD vs. RRT) or educational level. Prior knowledge of the therapy was affected by the educational level (p=0.013 for the advantages and p=0.004 for the side effects) and the professional role (patients vs caregivers: p=0.009 for the advantages and p<0.001 for side affects); patient knowledge of the advantages (median 6) tended to increase as the disease progressed (p=0.015). The most common response by patients was that informed consent was necessary for all drugs (35.1%); 73.1% of the caregivers considered it necessary only for severe side effects. The preferred modality of consent was discussion with the caregiver during the clinical controls (42% of all cases). CONCLUSIONS: Patient interest in and comprehension of an informed consent form with a detailed explanation of the therapy was high; the caregiver's opinion was still the most valued teaching tool.

Play-back theatre, theatre laboratory, and role-playing: new tools in investigating the patient-physician relationship in the context of continuing medical education courses.

AIM: The aim of this study was to report on the validation of a role-playing approach, using play-back and theatre laboratory in the context of a continuing medical education (CME) course on predialysis and transplantation, to discuss the patient-physician relationship. METHODS: The course was developed with the help of a theatre director. The role-playing 2-day course was designed to be highly interactive for a small group (15-20 participants), based on a core of case reports (dialysis, transplantation, and return to dialysis after graft failure). Two stages were included: play-back theatre in which experiences told by the participants were mimed by a group of actors, and theatre laboratory in which different aspects of voice and touch were explored. Opinions were gathered by an anonymous semistructured questionnaire completed by all participants. RESULTS: The course obtained a high score from The Ministry of Health (14 credits, 1 per teaching hour). The opinions of the 18 participants were highly positive; all liked the courses. Sixteen of 18 asked to repeat the experience. The strong emotional involvement was an advantage for 15 of 18, sharing emotional aspects of the profession for 10 of 18, and usefulness in clarifying opinions on "dark sides" of our profession for 10 of 18. CONCLUSION: The positive opinions recorded during this experience, the first experiment with a "psycho-theatrical approach" developed in a CME course in our country, suggest the benefit of implementing nonconventional, educational approaches in a multidisciplinary discussion of the patient-physician relationship in transplantation medicine.

Making a movie on kidney transplantation: a medical school graduation thesis to explain kidney transplantation from students to students.

The aim of this study was to report on the production and the opinions of a video movie on transplantation and organ donation. The video was developed by a medical school student with the help of the students and teachers of a high school for applied arts. For this task, the making of the video was included in the high school program of the participating class. The students were tutored by their photography teacher. The video movie lasts about 50 minutes. Each "scene" lasts no more than 5 minutes, to avoid reducing the attention level. The choice of a nonmedical frame helped to have some moments to digest the technical information and to stress the importance of the patient-physician relationship. The video was employed as a part of small-group lessons in the nephrology course. A semistructured anonymous questionnaire gathered the opinion of 65 students at the end of the lessons. Student satisfaction was high; the median score was the highest (8, range 6 to 10) for the lesson based upon the movie, as compared with the conventional ones on chronic kidney disease or dialysis (7, range 5 to 10). As far as the authors know, this is the first experiment of a multimedia approach, dedicated to medical and nonmedical targets, developed as a graduation thesis in an Italian Medical School. In conclusion, the positive opinions of the students, who highly appreciated the peer-developed message, may suggest implementing such nonconventional educational approaches to support human resources and enthusiasm for kidney transplantation among the new generations.

EPO or not-EPO? An evidence based informed consent.

BACKGROUND: Informed consent is crucial in therapeutic choices; however, the forms presented to patients are often locally developed and information may not be homogeneous. OBJECTIVE: To prepare an evidence-based model for informed consent, applied in the case of erythropoietin therapy (EPO) as a teaching tool for medical students. METHODS: Methodological tools of Evidence-Based Medicine (EBM) were developed within the EBM Course in the Medical School of Torino, Italy, as problem solving and patient information tools (5th year students work in small groups under the supervision of statisticians, epidemiologists and experts of internal medicine--nephrology in this case). RESULTS: Methodological and ethical problems were identified: in the pre-dialysis field, evidence from randomized clinical trials (RCT) is scant; how to use evidence gathered in dialysis? How to deal with implementation? How with the mass media? Do we need to discuss the drug choice with the patients? How to deal with rare and severe side effects?). The "evidence" was searched for on Medline/Embase, by using key-words and free terms. About 680 papers were retrieved and screened. Forms available on the Internet were retrieved and a general scheme was drawn: it included 5 areas: title, aim and targets (patients and family physicians); search strategies and updating; pros and cons of therapy; alternative options; open questions. CONCLUSIONS: EBM may offer valuable tools for systematically approaching patient information; the inclusion of this kind of exercise in the Medical School EBM courses may help enhance the awareness of future physicians of the correct communication with patients.

Maintenance of residual renal function 10 years after the start of hemodialysis: the advantage of tailored schedules?

Maintenance of residual renal clearance is a clinical advantage, protecting against the long-term effects of uremia: although demonstrated in peritoneal dialysis, the strategies in hemodialysis are less clear. This case suggests that dialysis schedules individualized on the basis of renal clearances may help preserve residual function. SB is a 58 year-old male who started dialysis in emergency (creatinine 30.7 mg/dL) in 1993. He had a history of gout, small shrunken kidneys and moderate hypertension. The clinical diagnosis was vasculointerstitial nephropathy. Eighteen months after starting hemodialysis on a conventional thrice weekly schedule, the patient was switched to 2 sessions/week (creatinine clearance increased to 6 ml/min). Thereafter, clearances were checked in alternate months and treatment was tailored to an equivalent renal clearance > or =12 ml/min (1-2 sessions, 2-3.30 hours/week). Ten years after beginning dialysis, he is on a twice weekly schedule (3.30 hours), is normotensive, works full-time and does not want to go on a transplant waiting list.

Opinions on renal transplantation and organ donation in high school students in two large northern (Torino) and southern (Napoli) Italian cities.

UNLABELLED: Organ shortage for transplantation has focused attention on educational interventions. Italy is a nonhomogenous country whose cultural and economic differences are reflected in the health-care system: dialysis is mainly public in the north versus private in the south; and transplantation rates display a wide range from 3.4 to 37.8 per million people in 2002. The aim of the present study was to analyze the opinions of population of high school students (last two years) in two large cities: northern (Torino) and southern (Napoli) Italy, as a knowledge base for a randomized controlled trial on the efficacy of educational interventions on renal replacement therapy and organ donation, targeted to high school students. METHODS: This preliminary study included eight public high schools that completed a first and anonymous semistructured questionnaire. Five hundred and eighty nine questionnaires were retrieved in Torino and 539 in Napoli. In both cities most students answered that they would give a kidney to a brother, sister, or partner needing dialysis (Torino: yes 80.6%; no 2.2%, uncertain-blank 17.2%; Napoli: yes 86.1%, no 1.1%; uncertain-blank 12.8%). Only 36.3% of the students in Torino and 37.7% in Napoli answered that they would consent to organ donation, if they had to choose for a strict relative with brain death. Opposition was 28% in Torino and 23.7% in Napoli; 35.7% in Torino and 38.6% in Napoli were blank-uncertain. These data underline the need for detailed information on the opinions of the overall population as basis for tailored educational campaigns.

Efficacy of an educational program on dialysis, renal transplantation, and organ donation on the opinions of high school students: a randomized controlled trial.

AIM: Organ shortage is a rate-limiting factor for transplantation. The aim of this study was to evaluate the impact of an educational program targeted to high school students on opinions concerning organ donation. METHODS: Sixteen public high schools in Torino, Italy, were randomized (2001 to 2002) as interventions (n = 8) or controls (n = 8). Intervention was composed of first questionnaire, first lesson (one to two classes; 2 hours, by a trained nephrology fellow); second lesson (all classes together; coordinated by a nephrologist, with patients and trainees); second questionnaire. Control included questionnaires. Statistical analysis compared the opinions in the questionnaires after stratification for age, sex, and type of school. RESULTS: Fourteen schools completed the program (seven interventions: 937 first and 808 second questionnaires; controls: 739 and 659). Television (82.5%) and newspapers (43.2%) were the main sources of information; knowledge on renal transplantation (grafts feasible per patient, average duration) was low; only 12.2% of the students gave correct answers. The opinions on living donation were highly positive (76.8%) with no difference in control, intervention schools, first and second questionnaires, according to sex, age, or type of school. The opinions on cadaveric transplantation were affected by the educational intervention with a drop in negative answers (from 33.7% to 16%), with an increase in positive (from 31.5% to 42.9%) and in uncertain ones (from 34.8% to 41.1%) among the intervention schools; 98% of the students appreciated the program. CONCLUSION: The positive effect on student opinions suggests the need to develop educational approaches as a part of our routine clinical work.

How many organs should one patient receive? The ethics of transplantation in the medical school.

BACKGROUND: Interest in the humanities in the medical school is growing; while several medical schools, mainly of Anglo-Saxon background, have developed dedicated courses, the experience in Italy is limited. METHODS: Since the academic year 2000 to 2001, a discussion of ethical problems was implemented in the nephrology course (fourth year of the Medical School of Torino, Italy; overall 6 years). In 2002 to 2003, a case entitled "Retransplantation of Multiple Organs (Prog Transplant 2002)" was discussed in 2 hours of small-group tutorial teaching: a boy received a renal graft at age 5, failed at age 7 due to recurrent glomerulonephritis, required a heart-kidney graft at age 11, and a second heart-kidney graft at 17. Student opinions were gathered by anonymous semistructured questionnaires at the beginning of the lessons as a basis for discussion. RESULTS: Following the lessons all students returned the questionnaires (n = 104). In the absence of competition for allocation, retransplantation was approved by 76.2%, unacceptable for 1% (22.9% uncertain-blank). With a waiting list of 10 patients, the opinions changed: 32.4% approved transplantation, 6.7% didn't approve it, 60.9% were uncertain. A theoretical categorization into deontological or utilitaristic approaches favored the first (41.9% vs 26.7%), with a high prevalence of blank-uncertain (31.5%); 21.9% of the students would change their opinion was that study head of the Transplant Department. CONCLUSION: Ethical aspects of the medical profession have been discussed with interest by medical school students; the high prevalence of uncertain answers and requests to develop specific tools underline the importance of this educational approach.

Kidney vending: opinions of the medical school students on this controversial issue.

BACKGROUND: In this era of globalization, in which different cultural and economic barriers are progressively abated, in the context of the development of rapid information networks such as the Internet, physicians are increasingly challenged by clinical and ethical questions. Kidney vending, banned in some countries, legal or tolerated in others, may be the prototype of the ethical aspects of health-care globalization. METHODS: To test the interest and the opinions of medical school students, a simulated case was proposed to students attending a seminar within the nephrology course fourth year of the Medical School of Torino, san Luigi): an Italian patient comes to the nephrologist's office asking for advice on the possibility to legally buy a kidney in a foreign country. The 43 students attending the lesson answered a semistructured questionnaire (15 boys, 28 girls, of median age 23 years). Attendance was within the usual standards (50 students inscribed per year). From the clinical point of view, 11.6% were favorable to kidney vending, 51.2% were contrary, 37.2% were uncertain. From the ethical point of view, no student was pro, 81.4% were contrary, and 18.6% were uncertain. The open comments underline the importance of patient self-determination and of informed consent. Similar opinions were recorded in a nonstructured question: "What should physician's attitude be, in the face of a choice he/she doesn't share?" CONCLUSION: Students' uncertainties and doubts underline the need to discuss ethical scenarios in the clinical teachings of the medical school.

To give or to receive? Opinions of teenagers on kidney donation.

BACKGROUND: The attitude toward living donation varies widely in the world, for economic and cultural reasons. In Italy, as in other Mediterranean settings, the role of living kidney donation is minor. AIM: To analyze the reasons for this attitude, we gathered data in a general population sample of high school students in a large northern Italian industrial city (Torino, about 900,000 inhabitants). METHODS: Semistructured questionnaires (n = 1676), gathered in 2001 to 2002 in 14 high schools, in the context of an educational program on dialysis, renal transplantation, and organ donation, were analyzed presumably reflecting opinions gathered before the educational intervention. RESULTS: Most students, in the case of a close relative or partner needing dialysis, answer that they would donate a kidney (yes: 78.2%, no: 2.9%, uncertain-blank: 18.9%); receiving a living donor kidney is felt as disturbing: only 57.5% of the students would accept it (no: 5.9%, uncertain-blank: 36.6%), mainly because of fear of long-term problems for the donor. Donation from an older to a younger person is seen more positively than vice versa. CONCLUSION: In our settings, the attitude of the teenagers on living donation is positive; however, while "giving" is positively seen, the presence of unresolved fears is witnessed by the lower acceptance of the idea of "taking." These data suggest to focus on the risks of kidney donation in educational campaigns and in patient-physician information. The positive attitude shared by the teenagers supports the working hypothesis that lack of information is one of the determinants of the low living donor transplantation rate in our area.

Preparation of candidates for renal transplantation: cost analysis.

While the costs of renal transplantation are lower than those of dialysis, little is known about the costs of managing the waiting list. We performed a cost analysis of admission and clinical management of a waiting list for renal and pancreas-kidney transplantation. Admission to the waiting list included (1) renal graft from cadaver: minimum cost Euros () 1784.56 for men < 55 years, maximum 2127.85 for women >/= 55 years; (2) pancreas-kidney transplantation: minimum 2475.50 for men, maximum 2540.10 for women >/= 35 years. Check of suitability state on waiting list after 2 and 5 years: minimum 1400.15 for men >/= 55 years (check every 2 years), maximum 1467.07 for women >/=40, <55 years (every 5 years). The differences are related to the imaging techniques: from 43.90 (Doppler ultrasonography) to 283.28 (coronary angiography). Maintenance of the waiting list: minimum cost 1885.21 in the first year and 3187.02 in the (fifth year) for men < 55 years; maximum 2228.50 (first year) and 5116.70 (fifth year) for women >/= 55 years. These results show different costs for recipients on the basis of sex and age ranges, due to the different requirements for imaging tests such as cardiac scintiscan at age >/= 55 years) and economic charges that increase with age. Reduced waiting times allow lowered total costs. This evaluation allowed us to calculate for our region (Piemonte, Northern Italy), the management costs of the patients presently on our waiting list (369 patients at December 31, 2002) from preparation to transplantation as 959,179.18.

Preemptive pancreas-kidney transplantation: multidisciplinary follow-up starts too late.

BACKGROUND: Preemptive pancreas-kidney transplantation is increasingly considered at early stages of nephropathy in type 1 diabetics. A multidisciplinary approach is required, but referral to the nephrologist is often delayed. OBJECTIVE: To analyze the referral pattern of type 1 diabetics to a dedicated nephrology unit and to test the prevalence of indications for pancreas-kidney transplantation in this population, according to early preemptive criteria (creatinine >/= 2 mg/dL and/or nephrotic syndrome). PATIENTS AND METHODS: The setting of study was the first Italian Nephrology Outpatient Unit dedicated to diabetics during 1991 to 2002. The main biochemical and clinical parameters were analyzed at referral. RESULTS: Ninety type 1 diabetics underwent at least one nephrological visit during the period; 85 had data at referral. The referral pattern was stable: 1991 to June 1996 [22 men, 24 women of median age 36 (18 to 65) years; diabetological follow-up 18.0 (3 to 37) years] and July 1996 to March 2002 [26 men, 18 women median age 40 (18 to 65); diabetological follow-up 21.5 (11 to 36) years]. The main biochemical data at referral were superimposable: serum creatinine: 1.2 (0.6 to 3.2) versus 1.3 (0.6 to 7) mg/dL; proteinuria: 0.9 (0 to 11) versus 1.01 (0.05 to 12.3) g/24 hours. Diabetes follow-up was greater in July 1996 to March 2002 [18 (3 to 37) versus 21.5 (11 to 36) years] suggesting an effect of improvements in diabetic care. At referral 76.6% were macroproteinuric 85.6% had signs of end-organ damage other than nephropathy; and 30.6% had indications for pancreas-kidney grafting (creatinine >/= 2 mg/dL: n = 6 cases; nephrotic syndrome: n = 10; or both n = 10). CONCLUSIONS: One new frontier of transplantation is the need for early multidisciplinary evaluation of type 1 diabetic patients.

Complete reversal of the nephrotic syndrome after preemptive pancreas-kidney transplantation: a case report.

BACKGROUND: Nephrotic syndrome due to diabetic nephropathy is presently considered an indication for pancreas-kidney transplantation even in the absence of severe renal failure. Reversal of the nephrotic syndrome has been reported, but the mechanisms of this effect are unclear. AIM: To describe the renal morphofunctional pattern and the pattern of proteinuria before and after preemptive pancreas-kidney transplantation. METHODS: Methods included quantitative and qualitative assessment of proteinuria as well as renal ultrasound and scintiscan. CASE REPORT: A 42-year-old woman with type 1 diabetes since age 24 had widespread end-organ damage. Renal biopsy (2001) showed a mainly nodular pattern of diabetic nephropathy. Following referral (1999), her serum creatinine ranged from 1.6 to 2.2 mg/dL, with nephrotic range proteinuria (glomerular nonselective, tubular complete). Renal scintiscan revealed bilateral, symmetric, well-perfused kidneys. The functional data before pancreas-kidney graft (February 2003) were: serum creatinine 1.6 mg/dL, creatinine clearance 58 mL/min, serum albumin 2.6 g/dL, proteinuria 9.1 g/d. At hospital discharge (March 2003), the creatinine was 1.2 mg/dL, the creatinine clearance 97 mL/min, the proteinuria 0.676 g/d. Two months later, the creatinine was 1.2 mg/dL and proteinuria 0.421 g/d. A renal scintiscan demonstrated the functional prevalence of the grafted kidney (77% of total function), with vital, almost completely excluded native kidneys (functional contribution, 11.5% each). Proteinuria, ranging from 0.3 to 0.6 g/d, showed a physiological pattern. CONCLUSIONS: Functional exclusion of the native kidneys by renal scintiscan gives morphological support to reversal of the nephrotic syndrome.