Erratum: Ubiquitous Non-Majorana Zero-Bias Conductance Peaks in Nanowire Devices [Phys. Rev. Lett. 123, 107703 (2019)].

This corrects the article DOI: 10.1103/PhysRevLett.123.107703.

Parity-preserving and magnetic field-resilient superconductivity in InSb nanowires with Sn shells.

Improving materials used to make qubits is crucial to further progress in quantum information processing. Of particular interest are semiconductor-superconductor heterostructures that are expected to form the basis of topological quantum computing. We grew semiconductor indium antimonide nanowires that were coated with shells of tin of uniform thickness. No interdiffusion was observed at the interface between Sn and InSb. Tunnel junctions were prepared by in situ shadowing. Despite the lack of lattice matching between Sn and InSb, a 15-nanometer-thick shell of tin was found to induce a hard superconducting gap, with superconductivity persisting in magnetic field up to 4 teslas. A small island of Sn-InSb exhibits the two-electron charging effect. These findings suggest a less restrictive approach to fabricating superconducting and topological quantum circuits.

Ubiquitous Non-Majorana Zero-Bias Conductance Peaks in Nanowire Devices.

We perform tunneling measurements on indium antimonide nanowire-superconductor hybrid devices fabricated for the studies of Majorana bound states. At finite magnetic field, resonances that strongly resemble Majorana bound states, including zero-bias pinning, become common to the point of ubiquity. Since Majorana bound states are predicted in only a limited parameter range in nanowire devices, we seek an alternative explanation for the observed zero-bias peaks. With the help of a self-consistent Poission-Schrödinger multiband model developed in parallel, we identify several families of trivial subgap states that overlap and interact, giving rise to a crowded spectrum near zero energy and zero-bias conductance peaks in experiments. These findings advance the search for Majorana bound states through improved understanding of broader phenomena found in superconductor-semiconductor systems.

Effect of Bias on the Response of GaN Axial p-n Junction Single-Nanowire Photodetectors.

We present a comprehensive study of the performance of GaN single-nanowire photodetectors containing an axial p-n junction. The electrical contact to the p region of the diode is made by including a p+/n+ tunnel junction as cap structure, which allows the use of the same metal scheme to contact both ends of the nanowire. Single-nanowire devices present the rectifying current-voltage characteristic of a p-n diode but their photovoltaic response to ultraviolet radiation scales sublinearly with the incident optical power. This behavior is attributed to the dominant role of surface states. Nevertheless, when the junction is reverse biased, the role of the surface becomes negligible in comparison to the drift of photogenerated carriers in the depletion region. Therefore, the responsivity increases by about 3 orders of magnitude and the photocurrent scales linearly with the excitation. These reverse-biased nanowires display decay times in the range of ∼10 µs, limited by the resistor-capacitor time constant of the setup. Their ultraviolet/visible contrast of several orders of magnitude is suitable for applications requiring high spectral selectivity. When the junction is forward biased, the device behaves as a GaN photoconductor with an increase of the responsivity at the price of a degradation of the time response. The presence of leakage current in some of the wires can be modeled as a shunt resistance which reacts to the radiation as a photoconductor and can dominate the response of the wire even under reverse bias.

Shot-Noise-Limited Nanomechanical Detection and Radiation Pressure Backaction from an Electron Beam.

Detecting nanomechanical motion has become an important challenge in science and technology. Recently, electromechanical coupling to focused electron beams has emerged as a promising method adapted to ultralow scale systems. However the fundamental measurement processes associated with such complex interaction remain to be explored. Here we report a highly sensitive detection of the Brownian motion of µm-long semiconductor nanowires (InAs). The measurement imprecision is found to be set by the shot noise of the secondary electrons generated along the electromechanical interaction. By carefully analyzing the nanoelectromechanical dynamics, we demonstrate the existence of a radial backaction process that we identify as originating from the momentum exchange between the electron beam and the nanomechanical device, which is also known as radiation pressure.

Mirage Andreev Spectra Generated by Mesoscopic Leads in Nanowire Quantum Dots.

We study transport mediated by Andreev bound states formed in InSb nanowire quantum dots. Two kinds of superconducting source and drain contacts are used: epitaxial Al/InSb devices exhibit a doubling of tunneling resonances, while, in NbTiN/InSb devices, Andreev spectra of the dot appear to be replicated multiple times at increasing source-drain bias voltages. In both devices, a mirage of a crowded spectrum is created. To describe the observations a model is developed that combines the effects of a soft induced gap and of additional Andreev bound states both in the quantum dot and in the finite regions of the nanowire adjacent to the quantum dot. Understanding of Andreev spectroscopy is important for the correct interpretation of Majorana experiments done on the same structures.

Ultra-low threshold polariton lasing at room temperature in a GaN membrane microcavity with a zero-dimensional trap.

Polariton lasers are coherent light sources based on the condensation of exciton-polaritons in semiconductor microcavities, which occurs either in the kinetic or thermodynamic (Bose-Einstein) regime. Besides their fundamental interest, polariton lasers have the potential of extremely low operating thresholds. Here, we demonstrate ultra-low threshold polariton lasing at room temperature, using an all-dielectric, GaN membrane-based microcavity, with a spontaneously-formed zero-dimensional trap. The microcavity is fabricated using an innovative method, which involves photo-electrochemical etching of an InGaN sacrificial layer and allows for the incorporation of optimally-grown GaN active quantum wells inside a cavity with atomically-smooth surfaces. The resulting structure presents near-theoretical Q-factors and pronounced strong-coupling effects, with a record-high Rabi splitting of 64 meV at room-temperature. Polariton lasing is observed at threshold carrier densities 2.5 orders of magnitude lower than the exciton saturation density. Above threshold, angle-resolved emission spectra reveal an ordered pattern in k-space, attributed to polariton condensation at discrete levels of a single confinement site. This confinement mechanism along with the high material and optical quality of the microcavity, accounts for the enhanced performance of our polariton laser, and pave the way for further developments in the area of robust room temperature polaritonic devices.

Focused parathyroidectomy without intraoperative parathormone testing is safe after pre-operative localization with 18F-Fluorocholine PET/CT.

A focused surgical approach based on pre-operative localization replaced the classical four-gland exploration in patients with primary hyperparathyroidism (PHP). Sestamibi scanning and ultrasound are most often used localization modalities with reported sensitivity of 54-100% for identification of single gland disease. The aim of this study was to analyze the results of pre-operative localization with 18F-Fluorocholine PET/CT (FCh-PET) in patients with PHP. A retrospective review of 151 patients with PHP who underwent surgery after pre-operative localization with FCh-PET was performed. Only a focused parathyroidectomy without ioPTH testing had been done in patients with single adenoma on FCh-PET. Primary outcome was operative failure, defined as persistent PHP. According to pre-operative FCh-PET 126 (83,4%) patients had single adenoma, 22 (14,5%) multiglandular disease and the test was negative in only two patients. Intraoperative failure experienced 4/126 patients (3,3%) with single adenoma. Removed parathyroid glands were normal in three and hyperplastic in one patient with intraoperative failure. A limited bilateral neck exploration with ioPTH testing was used in 14/22 patients with double adenoma and a classical four-gland exploration without ioPTH testing was used in 8/22 patients with more than two pathological glands according to pre-operative FCh-PET. Intraoperative failure experienced 2/22 patients (9,1%). In two patients with negative FCh-PET a classical four-gland exploration without ioPTH testing was used and one experienced intraoperative failure. A preoperative localization with FCh-PET is a reliable test in patients with PHP. Patients with a single adenoma on FCh-PET can safely undergo a focused parathyroidectomy without ioPTH testing.

Residual melanoma after an excisional biopsy is an independent prognostic factor for local recurrence and overall survival.

UNLABELLED: The aim of this study was to evaluate the effect of a residual melanoma after an excisional biopsy on prognosis of patients with cutaneous melanoma. PATIENTS AND METHODS: Between 2000 and 2007 sentinel lymph node biopsy with wide reexcision of a primary melanoma site was successfully performed in 692 patients (315 male and 377 female; mean age 55.7 years) at the Institute of Oncology Ljubljana, Slovenia. Clinicopathological data of all patients were extracted from a prospective institutional melanoma database and the frequency of local recurrences and survival were compared between patients with residual melanoma and those without it. For a statistical analysis univariate and multivariate analyses were used. RESULTS: Only 25 (3.6%) patients had a residual melanoma. There was no difference in mean tumor thickness (3.9 and 2.8 mm) and ulceration (40% and 34%) of the primary melanoma between patients with and without residual melanoma. However, a number of local recurrences (16% versus 2.7%) and a number of metastases in sentinel lymph nodes (44% versus 22%) were significantly higher and a 5-year survival was significantly lower (64% versus 87.5%) in patients with residual melanoma. Breslow thickness, ulceration, positive SLNB and residual melanoma were independent prognostic factors for overall survival. CONCLUSIONS: Residual melanoma is very rare after an excisional biopsy of the primary melanoma. However, when present it indicates a higher probability of local recurrence and a worse overall survival.

Geographical distribution of Slovenian BRCA1/2 families according to family origin: implications for genetic screening.

Knowledge of the geographical distribution of highly recurrent mutations may be useful for efficient screening in cancer families. Since the cloning of the BRCA1/2 genes, it is known that the wide spectrum of deleterious mutations shows high ethnic and geographic heterogeneity. In this study, we have tested probands from 582 breast/ovarian cancer families and positioned all 156 BRCA1/2 families on the map according to the family origin. We observed that high-risk families with the same recurrent mutation present a typical geographical distribution and that different recurrent mutations may show different distribution patterns. We then evaluated the genetic screening implications of this heterogeneous prevalence of the most recurrent mutations found [300T>G(c.181T>G), 1806C>T(c.1687C>T), 969ins7(c.844_850dupTCATTAC), 5382insC(c.5266dupC), 235G>A(c.116G>A) in BRCA1 and IVS16-2A>G(c.7806-2A>G) in BRCA2]. On the basis of these results, specific testing procedures for new incident cases may be offered according to their family origins and, according to the information regarding clusters revealed in this study, the individuals (especially those at low risk), originating from regions with clusters, might be screened preferentially for cluster mutations and analysis may be simplified according to the family origin.

BRCA1/2 status and clinicopathologic characteristics of patients with double primary breast and ovarian cancer.

The aim of the study was to analyse the results of BRCA1/2 testing in a group of patients with double primary breast and ovarian cancer (DPBOC) in Slovenia. Additionally, the family history and the clinicopathologic characteristics of BRCA1/2 mutation positive and negative patients with DPBOC were analysed, comparing them to a group of untested patients with DPBOC. For these groups of patients, survival analysis was also performed. From the 52 patients who were invited to genetic counselling and testing, 20 responded positively (38% compliance). BRCA1/2 mutations were found in 60% (12/20): 45% BRCA1 and 15% BRCA2 (9 and 3 patients, respectively). There was significantly higher grade of ovarian cancer and significantly higher rate of multiple primary breast cancer in BRCA1/2 positive group. Additionaly, there was a trend towards higher rate of first-degree family history of breast cancer, a trend towards higher stage of ovarian cancer, and a trend towards breast cancer being the first cancer in BRCA1/2 positive group. According to survival analysis, the tested group was not a representative sample of the larger untested group (of 51 patients), so we estimate that the rate of BRCA1/2 mutations in DPBOC patients is probably less than 60%.

Pre-operative ultrasound with a 12-15 MHz linear probe reliably differentiates between melanoma thicker and thinner than 1 mm.

BACKGROUND: Pre-operative determination of primary melanoma thickness could be a tool to identify those patients who could be treated with radical primary tumour excision and sentinel lymph node biopsy in a single procedure. An excellent correlation between sonographic and histological measurement of maximal tumour thickness has been achieved using 20-MHz transducers. OBJECTIVE: To show that widely available high resolution ultrasound with 12-15 MHz linear probe could also reliably assess the thickness of primary melanoma. METHODS: Sixty-nine patients underwent ultrasound evaluation of 70 clinically and dermoscopically suspicious pigmented skin lesions before surgical excision. RESULTS: The sensitivity, specificity, positive and negative predictive values of ultrasound to detect melanoma > 1 mm were 92%, 92%, 95% and 81% respectively. The correlation between ultrasound and histological tumour thickness was very good [Pearson's correlating index 0.823 (P < 0.001)]. Mean difference between sonographic and histological measurements was 0.045 mm with limits of agreement estimated at -1.4 and +1.49, and a bias between two methods 45 microm. CONCLUSION: Ultrasound examination with a 12-15 MHz linear transducer can reliably differentiate primary melanoma > 1 mm from those

Aggressiveness of therapy and prognosis of patients with Hürthle cell papillary thyroid carcinoma.

Hürthle cell papillary thyroid carcinoma (HCPTC) has been studied separately from other types of thyroid carcinoma in relatively few studies. The aim of our study was to determine the factors associated with the survival of patients with HCPTC in Slovenia, an iodine-deficient region. A total of 1552 patients with thyroid carcinoma were seen at our institute during the period of 1976-2003; of them, 42 patients (33 females, 9 males; age 10-85 years, median 56.5 years) had histopathologically verified HCPTC. The data on the patients' gender, age, disease history, extent of disease, morphologic characteristics, therapy, locoregional control, disease-free interval, and survival were collected. The statistical correlation between possible prognostic factors and the disease-free interval and survival was analyzed by chi2 test and log rank analysis. The tumor diameter ranged from 1 to 9 cm (median, 3 cm). Extrathyroid tumor growth was found in 19 patients, lymph node metastases in 13 patients, and distant metastases in 2 patients. Primary treatment consisted of total or near-total thyroidectomy (39 patients), lobectomy (2 patients), radioiodine ablation of the thyroid remnant (37 patients), external irradiation (14 patients), and chemotherapy (3 patients). Locoregional recurrence was diagnosed in four patients, and dissemination in 1 patient during the follow-up period of 0.75-20 years (median, 5.5 years). Three patients died of thyroid carcinoma during the follow-up period. The 5-year and 10-year survivals were 94% and 87%, respectively. The 5-year and 10-year disease-free intervals were 93% and 81%, respectively. The factors correlated with the survival were: age, extrathyroid tumor growth, primary tumor stage, and regional and distant metastases. Although extrathyroidal tumor growth was found in 45% of the patients with HCPTC, our patients had a favorable prognosis. Long-term survival and locoregional control of disease are likely after the radical tumor resection, radioiodine ablation of the thyroid remnant, and external irradiation.

Prognostic significance of tyrosinase mRNA detected by nested RT-PCR in patients with malignant melanoma.

The aim of this study was to evaluate the role of tyrosinase mRNA appearance in blood of malignant melanoma (MM) patients, especially with advanced stages, for predicting the disease progression, and consequently the survival. The tyrosinase mRNA was measured by nested RT-PCR in peripheral venous blood samples obtained from 86 patients (53 male and 33 female) with mainly stage III and IV MM. The data were analyzed using standard methods for survival analysis and logistic regression. Tyrosinase was negative in the MM patients with the disease stage I or II, positive tyrosinase was in 11/50 patients with stage III and in 5/22 patients with stage IV. Systemic metastases developed in 14/16 patients with positive tyrosinase and in 41/70 with negative tyrosinase. The 3-year survival was 8% and 28% among the patients with positive and the patients with negative tyrosinase, respectively. The log rank test showed statistically significant better survival of tyrosinase negative patients when compared to tyrosinase positive patients (p=0.039). Multivariate analysis using logistic regression indicated tyrosinase to be a statistically significant prognostic factor for the survival of MM patients after controlling for Breslow and ulceration values (p=0.006). Positive tyrosinase in peripheral venous blood is statistically significant, and more importantly independent negative predictor of survival.

The reliability and accuracy of intraoperative imprint cytology of sentinel lymph nodes in breast cancer.

OBJECTIVE: Sentinel lymph node (SLN) biopsy is a new component of the surgical treatment of breast cancer that accurately predicts axillary status. In this study the authors evaluated the accuracy of intraoperative imprint cytology (IC) in comparison with definitive histologic evaluation of SLN in breast cancer patients. METHODS: A total 413 women with breast carcinoma and clinically negative axillary nodes underwent breast surgery and SLN biopsy. Mapping of SLN involved injection of (99m)Technecium labelled human albumin nanocolloid particles and Patent Blue dye. At the Department of Pathology, SLNs were bisected along its major axis. Both halves were imprinted 2-4 times on the slides and immediate staining with Hemacolor (Merck Germany) was performed for intraoperative examination. Imprint node negative women underwent no further surgery, while node positive women proceeded to full axillary clearance. Histological analysis of the SLN involved serial sectioning of the whole node with H&E and immunostaining for cytokeratin. RESULTS: Definitive histology revealed metastases (pN+) in 159/413 patients (38.5%): 69 (16.7%) macro metastases, 57 (13.8%) micro metastases, and 33 (8%) women with only isolated IHC positive cells or positive cell groups smaller than 0.2 mm (pNO sn+). The other 254 women had negative SLN biopsy. Imprint cytology detected 54/69 macro metastases, and 4/57 micro metastases. In the group with negative SLN (254), 2 cases were ''false positives''. CONCLUSIONS: Imprint of SLN biopsy can identify a negative axilla with high accuracy (specificity 99.2%). Overall sensitivity is only 36.5%, but macrometastases are detected in 77% which is important for performing ALDN in one session with operation of primary tumour.

Radioguided occult lesion localization (ROLL) of the nonpalpable breast lesions.

Standard localization techniques of the nonpalpable breast lesions (guide wire, carbon, skin marking) have several disadvantages. Radioguided occult lesion localization (ROLL) was recently proposed as a better alternative resulting in wider surgical margins and lower average specimen weight. The aim of our study was to compare ROLL to our previously published series of the standard guidewire localization, performed at the Institute of Oncology Ljubljana. ROLL was performed in 110 nonpalpable breast lesions. Human serum albumin macroaggregats, marked with 1.8-5.5 MBq 99mTc was injected in the nonpalpable lesion. During surgery the radioactive breast tissue was excised using hand held gamma probe. Nonpalpable breast lesions were excised in all 110 patients. The definitive histology revealed 32 invasive carcinomas, 19 DCIS, 5 LCIS in and 54 benign breast lesions. Mean specimen weight was 40 g which is less in comparison to 53 g of the guidewire series (p=0.002). Surgical margins were clear in 36/51 (70%) invasive breast cancer or DCIS patients and close or involved in 15/51 (30%) patients. Compared to the guidewire series, where 41/92 (44%) margins were clear and 51/92 (56%) were close or involved, the difference was statistically significant (p=0.005). ROLL proved to be superior to guidewire localization in our series, allowing excision of the nonpalpable breast lesion with wider surgical margins despite lower average specimen weight.

Role of imprint cytology in the intraoperative evaluation of sentinel lymph nodes for malignant melanoma.

Controversy exists over the utility of different methods for intra-operative sentinel lymph node (SLN) evaluation in patients with malignant melanoma (MM). The aim of this study was to evaluate the role of intra-operative imprint cytology (IC) in patients with MM. 215 SLNs from 99 patients with MM were examined by IC and results compared with the results of permanent sections. 24 patients had MM deposits in their SLNs and this was confirmed by histological examination. Intraoperative IC was positive in 11 of these patients (46% sensitivity). In addition, there were three false-positive IC diagnoses (79% positive predictive value); one of these was due to contamination during the sectioning of the SLN. The specificity and the negative predictive values of the IC were 96 and 85%, respectively. IC is a valuable method of intra-operative SLN evaluation which can spare approximately half of the patients with clinically occult regional metastases from a second surgical procedure. However, special care must be taken to avoid false-positive results due to contamination.

Medullary thyroid carcinoma. Genetic screening and prophylactic thyroidectomies.

Medullary thyroid cancer is a rare, neuroendocrine, tumor. It arises from parafollicular or C-cells with the ability to produce and secrete different bioactive substances like calcitonin (TC) and CEA (1-5) TC is ideal tumor marker in early diagnosis, in patents' follow up and in evaluation of their treatment. TC determinations after ca/pentagastrine stimulation test give us even more accurate results and the procedure is used for biochemical family screening. MTC occurs as a sporadic tumor or in hereditary settings MEN 2A, MEN 2B and FMCT. Germ/line point mutations in RET proto/onkogene are responsible for tumor arise and inheritance of settings. Genetic screening provides information of these RET mutations in family members even before pathologic changes occur. These individuals with MEN 2A, 2B and FMCT characteristic RET mutations are almost certain to acquire MTC (95% penetrance) in their lives and are candidates for preventive total thyroidectomy (TT), with or without central neck dissection (CND). Surgery is still the treatment of choice for MTC and only C-cell hyperplasia and early stage of MTC can be cured. Prophylactic thyroid surgery eliminates the possibility of MTC but doesn't influence appearance of other diseases (PHEO, HPTH) of MEN 2 syndromes.

Breast biopsy with wire localization: factors influencing complete excision of nonpalpable carcinoma.

Our aim was to find out the factors influencing the complete excision of nonpalpable carcinoma. During a 2-year period, 215 patients (median age 55 years) underwent biopsy after wire localization of 222 nonpalpable breast lesions. Mammographic, surgical and pathological factors were correlated with the outcome of surgery using contingence tables in SPSS statistical software. A total of 96 carcinomas were diagnosed: 38 in situ and 58 invasive carcinomas. Surgical margins were clear in 43, close in 20 and involved in 33 cases. Factors correlated with clear surgical margins are mammographically spicular lesion, cytologically proven carcinoma, excision of more than 50 g of tissue, carcinoma smaller than 10 mm, invasive carcinoma without in situ component, and unicentric ductal carcinoma in situ ( p<0.05). Complete excision of multifocal in situ carcinoma or invasive carcinoma with extensive in situ component, which are diagnosed on mammogram as suspicious microcalcifications, remains a puzzling surgical task.