Does Sb2Se3 Admit Nonstoichiometric Conditions? How Modifying the Overall Se Content Affects the Structural, Optical, and Optoelectronic Properties of Sb2Se3 Thin Films.

Sb2Se3 is a quasi-one-dimensional (1D) semiconductor, which has shown great promise in photovoltaics. However, its performance is currently limited by a high Voc deficit. Therefore, it is necessary to explore new strategies to minimize the formation of intrinsic defects and thus unlock the absorber's whole potential. It has been reported that tuning the Se/Sb relative content could enable a selective control of the defects. Furthermore, recent experimental evidence has shown that moderate Se excess enhances the photovoltaic performance; however, it is not yet clear whether this excess has been incorporated into the structure. In this work, a series of Sb2Se3 thin films have been prepared imposing different nominal compositions (from Sb-rich to Se-rich) and then have been thoroughly characterized using compositional, structural, and optical analysis techniques. Hence, it is shown that Sb2Se3 does not allow an extended range of nonstoichiometric conditions. Instead, any Sb or Se excesses are compensated in the form of secondary phases. Also, a correlation has been found between operating under Se-rich conditions and an improvement in the crystalline orientation, which is likely related to the formation of a MoSe2 phase in the back interface. Finally, this study shows new utilities of Raman, X-ray diffraction, and photothermal deflection spectroscopy combination techniques to examine the structural properties of Sb2Se3, especially how well-oriented the material is.

Controlling the Anionic Ratio and Gradient in Kesterite Technology.

Accurate anionic control during the formation of chalcogenide solid solutions is fundamental for tuning the physicochemical properties of this class of materials. Compositional grading is the key aspect of band gap engineering and is especially valuable at the device interfaces for an optimum band alignment, for controlling interface defects and recombination and for optimizing the formation of carrier-selective contacts. However, a simple and reliable technique that allows standardizing anionic compositional profiles is currently missing for kesterites and the feasibility of achieving a compositional gradient remains a challenging task. This work aims at addressing these issues by a simple and innovative technique. It basically consists of first preparing a pure sulfide absorber with a specific thickness followed by the synthesis of a pure selenide part of complementary thickness on top of it. Specifically, the technique is applied to the synthesis of Cu2ZnSn(S,Se)4 and Cu2ZnGe(S,Se)4 kesterite absorbers, and a series of characterizations are performed to understand the anionic redistribution within the absorbers. For identical processing conditions, different Se incorporation dynamics is identified for Sn- and Ge-based kesterites, leading to a homogeneous or graded composition in depth. It is first demonstrated that for Sn-based kesterite the anionic composition can be perfectly controlled through the thicknesses ratio of the sulfide and selenide absorber parts. Then, it is demonstrated that for Ge-based kesterite an anionic (Se-S) gradient is obtained and that by adjusting the processing conditions the composition at the back side can be finely tuned. This technique represents an innovative approach that will help to improve the compositional reproducibility and determine a band gap grading strategy pathway for kesterites. Furthermore, due to its simplicity and reliability, the proposed methodology could be extended to other chalcogenide materials.

Measuring the Impacts of Extra-Musical Elements in Guitar Music Playing: A Pilot Study.

Philosophers, composers, and musicians have long argued whether instrumental music finds meaning in its formal structure and musical content (Hanslick, 1986) or through reference to extra-musical elements, like narratives, emotions, or memories (Meyer, 1956). While the use of extra-musical elements appears grounded in individual musicians' priorities for performance and teaching (Héroux, 2018), the impact of emotional indications on expressivity has not previously been studied in a large-scale experiment. The aim of this pilot study was to construct the methodology for a larger project to study the impact of the use of extra-musical elements on the sound results of guitarists. We asked guitar students to record one short newly composed piece, Evocation 1, according to the following conditions: (A) in a non-expressive manner, (B) according to the notated musical indications, and (C) with the addition of suggested contextual and emotional extra-musical elements to the musical instructions. We asked two expert guitarists to evaluate the level of expressiveness for conditions B and C and conducted interviews with participants to collect data on the experimental process to refine protocol. To more objectively measure manifestations of objectivity from the recorded performances, we extracted data from each recording about pitch, dynamics, and timing, as well as expressive dynamic deviations. The impact of both recording conditions and the expertise level of performers on the quality of this audio data led us to change the analysis design from a comparative design (with other participants) to a self-comparative design (each participant with himself) for the larger study.

Prognostic Factors for Inguinal Lymph Node Involvement and Tumor Recurrence in Squamous Cell Carcinoma of the Penis / Factores pronósticos de compromiso ganglionar inguinal y recaída tumoral en carcinoma escamocelular de pene

Zoom Image Abstract Introduction Penile carcinoma is an aggressive disease with catastrophic consequences that frequently lead to death. Therefore, further knowledge on the prognostic factors that can help identify patients in need of more aggressive treatments becomes essential. Objective To identify the prognostic factors for lymph node (LN) involvement and tumor recurrence in patients diagnosed with squamous cell carcinoma of the penis (SCCP). Methods A retrospective cohort study was conducted. Patients diagnosed and treated for SCCP at Instituto Nacional de Cancerología between 2008 and 2015 were included in the sample. Cases in which no information on recurrence was available for the follow-up were excluded, as well as patients with no initial pathology and those getting penile reconstructions after cancer. Relevant data was retrieved from the medical records of each patient, and a descriptive analysis was performed. Subsequently, this data was used to apply a logistic regression model to determine the potential clinical and histopathological prognostic factors. Results A total of 104 patients were included in the present study. The average age of the sample was 59 years, while the follow-up averaged 24 months per patient. Inguinal lymphadenectomy was performed on 61 patients (59%) during the follow-up. The logistic regression model showed that lymphovascular invasion (odds ratio [OR]: 6.7; 95% confidence interval [95%CI]: 1.2­35) and poor tumor differentiation (OR: 17; 95%CI: 3.2­92) were associated with tumor recurrence. Likewise, the lymphadenectomy procedures showed that lymphovascular invasion was associated with LN involvement (OR: 3.3; 95%CI: 1.1­10). Conclusion Lymphovascular invasion was the strongest prognostic factor observed in our sample, aiding in the prediction of inguinal LN involvement and tumor recurrence in SCCP patients

Introduccion El cáncer de pene es una enfermedad agresiva con consecuencias catastróficas que frecuentemente llevan a la muerte. Por lo tanto, es esencial un mayor conocimiento sobre los factores pronósticos que pueden ayudar a identificar a los pacientes que necesitan tratamientos más agresivos. Objetivo Identificar los factores pronósticos patológicos de compromiso ganglionar inguinal y recaída tumoral en pacientes con carcinoma escamocelular de pene. Métodos Se realizó un estudio de cohorte retrospectivo. Se incluyeron en la muestra pacientes diagnosticados y tratados por carcinoma escamocelular de pene (SCCP) en el Instituto Nacional de Cancerología entre 2008 y 2015. Los casos en los que no había información sobre la recurrencia en el seguimiento fueron excluidos, así como los pacientes sin patología inicial y aquellos que reciben reconstrucciones del pene después del cáncer. Se recuperaron los datos relevantes de los registros médicos de cada paciente, y una descripción fue realizada. Posteriormente, estos datos se utilizaron para aplicar un modelo de regresión logística para determinar los posibles factores pronósticos clínicos e histopatológicos. Resultados Un total de 104 pacientes fueron incluidos en el estudio. La edad promedio de la muestra fue de 59 años, mientras que el seguimiento promedió fue de 24 meses por paciente. La linfadenectomía inguinal se realizó en 61 pacientes (59%) durante el seguimiento. El modelo de regresión logística mostró que la invasión linfovascular (odds ratio [OR]: 6,7; intervalo de confianza del 95% [IC 95%]: 1,2­35) y la pobre diferenciación tumoral (OR: 17; IC 95%: 3,2­92) se asociaron con recurrencia tumoral. Así mismo, los procedimientos de linfadenectomía mostraron que la invasión linfovascular se asoció con afectación de LN. (OR: 3,3; IC 95%: 1,1-10). Conclusión La invasión linfovascular es el factor pronóstico independiente más importante que se asocia de manera independiente con compromiso ganglionar inguinal positivo y recaída tumoral.

Automatic Assessment of Tone Quality in Violin Music Performance.

The automatic assessment of music performance has become an area of increasing interest due to the growing number of technology-enhanced music learning systems. In most of these systems, the assessment of musical performance is based on pitch and onset accuracy, but very few pay attention to other important aspects of performance, such as sound quality or timbre. This is particularly true in violin education, where the quality of timbre plays a significant role in the assessment of musical performances. However, obtaining quantifiable criteria for the assessment of timbre quality is challenging, as it relies on consensus among the subjective interpretations of experts. We present an approach to assess the quality of timbre in violin performances using machine learning techniques. We collected audio recordings of several tone qualities and performed perceptual tests to find correlations among different timbre dimensions. We processed the audio recordings to extract acoustic features for training tone-quality models. Correlations among the extracted features were analyzed and feature information for discriminating different timbre qualities were investigated. A real-time feedback system designed for pedagogical use was implemented in which users can train their own timbre models to assess and receive feedback on their performances.

Phrase-Level Modeling of Expression in Violin Performances.

Background: Expression is a key skill in music performance, and one that is difficult to address in music lessons. Computational models that learn from expert performances can help providing suggestions and feedback to students. Aim: We propose and analyze an approach to modeling variations in dynamics and note onset timing for solo violin pieces with the purpose of facilitating expressive performance learning in new pieces, for which no reference performance is available. Method: The method generates phrase-level predictions based on musical score information on the assumption that expressiveness is idiomatic, and thus influenced by similar-sounding melodies. Predictions were evaluated numerically using three different datasets and against note-level machine-learning models, and also perceptually by listeners, who were presented to synthesized versions of musical excerpts, and asked to choose the most human-sounding one. Some of the presented excerpts were synthesized to reflect the variations in dynamics and timing predicted by the model, whereas others were shaped to reflect the dynamics and timing of an actual expert performance, and a third group was presented with no expressive variations. Results: surprisingly, none of the three synthesized versions was consistently selected as human-like nor preferred with statistical significance by listeners. Possible interpretations of these results include the fact that the melodies might have been impossible to interpret outside their musical context, or that expressive features that were left out of the modeling such as note articulation and vibrato are, in fact, essential to the perception of expression in violin performance. Positive feedback by some listeners toward the modeled melodies in a blind setting indicate that the modeling approach was capable of generating appropriate renditions at least for a subset of the data. Numerically, performance in phrase-level suffers a small degradation if compared to note-level, but produces predictions easier to interpret visually, thus more useful in a pedagogical setting.

Progress and Perspectives of Thin Film Kesterite Photovoltaic Technology: A Critical Review.

The latest progress and future perspectives of thin film photovoltaic kesterite technology are reviewed herein. Kesterite is currently the most promising emerging fully inorganic thin film photovoltaic technology based on critical raw-material-free and sustainable solutions. The positioning of kesterites in the frame of the emerging inorganic solar cells is first addressed, and the recent history of this family of materials briefly described. A review of the fast progress achieved earlier this decade is presented, toward the relative slowdown in the recent years partly explained by the large open-circuit voltage (VOC ) deficit recurrently observed even in the best solar cell devices in the literature. Then, through a comparison with the close cousin Cu(In,Ga)Se2 technology, doping and alloying strategies are proposed as critical for enhancing the conversion efficiency of kesterite. In the second section herein, intrinsic and extrinsic doping, as well as alloying strategies are reviewed, presenting the most relevant and recent results, and proposing possible pathways for future implementation. In the last section, a review on technological applications of kesterite is presented, going beyond conventional photovoltaic devices, and demonstrating their suitability as potential candidates in advanced tandem concepts, photocatalysis, thermoelectric, gas sensing, etc.

Continuous-wave laser annealing of metallic layers for CuInSe2 solar cell applications: effect of preheating treatment on grain growth.

Ultra-fast thermal annealing of semiconductor materials using a laser can be revolutionary for short processing times and low manufacturing costs. Here we investigate Cu-In-Se thin films as precursors for CuInSe2 semiconductor absorber layers via laser annealing. The reaction mechanism of laser annealed metal stacks is revealed by measuring ex situ X-ray diffractograms, Raman spectra and composition. It is shown that the formation of CuInSe2 occurs via the formation of Cu x Se/In x Se y binary phases as in conventional annealing routes, despite the entirely different annealing time scale. Pre-alloying the Cu and In metals prior to laser annealing significantly enhances the selenisation reaction rate. Laser annealing for six seconds approaches a near phase-pure material, which exhibits similar crystalline quality to the reference material annealed for ninety minutes in a tube furnace. The estimated quasi Fermi level splitting deficit for the laser annealed material is only 60 meV lower than the reference sample, which implies a high optoelectronic quality.

Turning Earth Abundant Kesterite-Based Solar Cells Into Efficient Protected Water-Splitting Photocathodes.

CZTS/Se kesterite-based solar cells have been protected by conformal atomic layer deposition (ALD)-deposited TiO2 demonstrating its feasibility as powerful photocathodes for water splitting in highly acidic conditions (pH < 1), achieving stability with no detected degradation and with current density levels similar to photovoltaic productivities. The ALD has allowed low deposition temperatures of 200 °C for TiO2, preventing significant variations to the kesterite structure and CdS heterojunction, except for the pure-sulfide stoichiometry, which was studied by Raman spectroscopy. The measured photocurrent at 0 V vs reversible hydrogen electrode, 37 mA·cm-2, is the highest reported to date, and the associated half-cell solar-to-hydrogen efficiency reached 7%, being amongst the largest presented for kesterite-based photocathodes, corroborating the possibility of using them as abundant low-cost alternative photoabsorbers as their efficiencies are improved toward those of chalcopyrites. An electrical circuit has been proposed to model the photocathode, which comprises the photon absorption, charge transfer through the protective layer, and catalytic performance, which paves the way to the design of highly efficient photoelectrodes.

Improved quantum efficiency models of CZTSe: GE nanolayer solar cells with a linear electric field.

We fabricated and characterized CZTSe:Ge nanolayer (<10 nm) thin film solar cells to quantitatively demonstrate an exact analytical model of quantum efficiency for Ge doped CZTSe devices. The linear electric field model is developed with the incomplete gamma function of the quantum efficiency as compared to the empirical data at forward bias conditions. This model is characterized with a consistent set of parameters from a series of measurements and the literature. Using the analytical modelling method, the carrier collection profile in the absorber is calculated and closely fitted by the developed mathematical expressions to identify the carrier dynamics during the quantum efficiency measurement of the device. The analytical calculation is compared with the measured quantum efficiency data at various bias conditions.

Optical modeling and optimizations of Cu2ZnSnSe4 solar cells using the modified transfer matrix method.

The fast and computationally inexpensive Modified Transfer Matrix Method (MTM) is employed to simulate the optical response of kesterite Cu2ZnSnSe4 solar cells. This method can partially take into account the scattering effects due to roughness at the interfaces between the layers of the stack. We analyzed the optical behavior of the whole cell structure by varying the thickness of the TCO layer (iZnO + ITO) between 50 and 1200 nm and the buffer CdS layer between 0 and 100 nm. We propose optimal combinations of the TCO/CdS thicknesses that can locally maximize the device photocurrent. We provide experimental data that qualitatively confirm our theoretical predictions.

Impact of Na Dynamics at the Cu2ZnSn(S,Se)4/CdS Interface During Post Low Temperature Treatment of Absorbers.

Cu2SnZn(S,Se)4 (CZTSSe) solar cells based on earth abundant and nontoxic elements currently achieve efficiencies exceeding 12%. It has been reported that, to obtain high efficiency devices, a post thermal treatment of absorbers or devices at temperatures ranging between 150 and 400 °C (post low temperature treatment, PLTT) is advisable. Recent findings point toward a beneficial passivation of grain boundaries with SnOx or Cu-depleted surface and grain boundaries during the PLTT process, but no investigation regarding alkali doping is available, even though alkali dynamics, especially Na, are systematically reported to be crucial within the field. In this work, CZTSSe absorbers were subjected to the PLTT process under different temperatures, and solar cells were completed. We found surprisingly behavior in which efficiency decreased to nearly 0% at 200 °C during the PLTT process, being recovered or even improved at temperatures above 300 °C. This unusual behavior correlates well with the Na dynamics in the devices, especially with the in-depth distribution of Na in the active CZTSSe/CdS interface region, indicating the key importance of Na spatial distribution on device properties. We present an innovative model for Na dynamics supported by theoretical calculations and additional specially designed experiments to explain this behavior. After optimization of the PLTT process, a Se-rich CZTSSe solar cell with 8.3% efficiency was achieved.

A Machine Learning Approach to Discover Rules for Expressive Performance Actions in Jazz Guitar Music.

Expert musicians introduce expression in their performances by manipulating sound properties such as timing, energy, pitch, and timbre. Here, we present a data driven computational approach to induce expressive performance rule models for note duration, onset, energy, and ornamentation transformations in jazz guitar music. We extract high-level features from a set of 16 commercial audio recordings (and corresponding music scores) of jazz guitarist Grant Green in order to characterize the expression in the pieces. We apply machine learning techniques to the resulting features to learn expressive performance rule models. We (1) quantitatively evaluate the accuracy of the induced models, (2) analyse the relative importance of the considered musical features, (3) discuss some of the learnt expressive performance rules in the context of previous work, and (4) assess their generailty. The accuracies of the induced predictive models is significantly above base-line levels indicating that the audio performances and the musical features extracted contain sufficient information to automatically learn informative expressive performance patterns. Feature analysis shows that the most important musical features for predicting expressive transformations are note duration, pitch, metrical strength, phrase position, Narmour structure, and tempo and key of the piece. Similarities and differences between the induced expressive rules and the rules reported in the literature were found. Differences may be due to the fact that most previously studied performance data has consisted of classical music recordings. Finally, the rules' performer specificity/generality is assessed by applying the induced rules to performances of the same pieces performed by two other professional jazz guitar players. Results show a consistency in the ornamentation patterns between Grant Green and the other two musicians, which may be interpreted as a good indicator for generality of the ornamentation rules.

Musical neurofeedback for treating depression in elderly people.

We introduce a new neurofeedback approach, which allows users to manipulate expressive parameters in music performances using their emotional state, and we present the results of a pilot clinical experiment applying the approach to alleviate depression in elderly people. Ten adults (9 female and 1 male, mean = 84, SD = 5.8) with normal hearing participated in the neurofeedback study consisting of 10 sessions (2 sessions per week) of 15 min each. EEG data was acquired using the Emotiv EPOC EEG device. In all sessions, subjects were asked to sit in a comfortable chair facing two loudspeakers, to close their eyes, and to avoid moving during the experiment. Participants listened to music pieces preselected according to their music preferences, and were encouraged to increase the loudness and tempo of the pieces, based on their arousal and valence levels. The neurofeedback system was tuned so that increased arousal, computed as beta to alpha activity ratio in the frontal cortex corresponded to increased loudness, and increased valence, computed as relative frontal alpha activity in the right lobe compared to the left lobe, corresponded to increased tempo. Pre and post evaluation of six participants was performed using the BDI depression test, showing an average improvement of 17.2% (1.3) in their BDI scores at the end of the study. In addition, an analysis of the collected EEG data of the participants showed a significant decrease of relative alpha activity in their left frontal lobe (p = 0.00008), which may be interpreted as an improvement of their depression condition.