3,284 research outputs found
Potenciar la experiencia y habilidades frente a problemas prácticos en las clases de laboratorio de “Flotabilidad y Estabilidad”
En este trabajo se presentan las medidas adoptadas en las prácticas de la asignatura “Flotabilidad y Estabilidad”, del grado de “Arquitectura Naval” de la UPM, para potenciar la capacidad de los alumnos de enfrentarse a problemas prácticos y para entender la casuística que ellos involucran (necesidad de planificación, manejo de herramientas, etc.). En concreto, se describen: a) Una actividad complementaria, introducida en el curso 2019/2020, que involucra la realización de un experimento con un barco real; b) La adaptación de las prácticas a formato no presencial en el curso 2020/2021. Este cambio de formato, consecuencia de la situación de pandemia, tiene en principio un efecto negativo en cuanto al objetivo que se persigue. Para tratar de minimizarlo, se introdujo un nuevo concepto de práctica en la que los alumnos realizaron un experimento casero, devolviendo así el aspecto práctico a la actividad, a pesar de la no presencialidad. En este artículo se evalúa la efectividad de las medidas implementadas en cuanto al cumplimento del objetivo de mejorar la capacidad de los alumnos de enfrentar problemas prácticos, así como de otros objetivos que se buscan con las prácticas. El artículo se cierra con conclusiones y propuestas de trabajo futuro
Crossover from spin accumulation into interface states to spin injection in the germanium conduction band
Electrical spin injection into semiconductors paves the way for exploring new
phenomena in the area of spin physics and new generations of spintronic
devices. However the exact role of interface states in spin injection mechanism
from a magnetic tunnel junction into a semiconductor is still under debate. In
this letter, we demonstrate a clear transition from spin accumulation into
interface states to spin injection in the conduction band of -Ge. We observe
spin signal amplification at low temperature due to spin accumulation into
interface states followed by a clear transition towards spin injection in the
conduction band from 200 K up to room temperature. In this regime, the spin
signal is reduced down to a value compatible with spin diffusion model. More
interestingly, we demonstrate in this regime a significant modulation of the
spin signal by spin pumping generated by ferromagnetic resonance and also by
applying a back-gate voltage which are clear manifestations of spin current and
accumulation in the germanium conduction band.Comment: 5 pages, 4 figure
Tunable mechanical resonator with aluminum nitride piezoelectric
The electromechanical response of piezoelectrically-actuated AlN micromachined bridge resonators has been characterized using laser interferometry and electrical admittance measurements. We compare the response of microbridges with different dimensions and buckling (induced by the initial residual stress of the layers). The resonance frequencies are in good agreement with numerical simulations of the electromechanical behavior of the structures. We show that it is possible to perform a rough tuning of the resonance frequencies by allowing a determined amount of builtin stress in the microbridge during its fabrication. Once the resonator is made, a DC bias added to the AC excitation signal allows to fine-tune the frequency. Our microbridges yield a tuning factor of around 88 Hz/V for a 500 ?m-long microbridge
Carbon and Oxygen Galactic Gradients: Observational Values from HII Region Recombination Lines
We present results of deep echelle spectrophotometry of eight Galactic HII
regions located at Galactocentric distances between 6.3 and 10.4 kpc. The data
have been taken with the Very Large Telescope (VLT) Ultraviolet Echelle
Spectrograph (UVES) in the 3100 to 10360 A range. We have derived C++ and O++
abundances from recombination lines for all the objects, as well as O+
abundances from this kind of lines for three of the nebulae. The intensity of
recombination lines is almost independent of the assumed electron temperature
as well as of the possible presence of spatial temperature variations or
fluctuations inside the nebulae. These data allow the determination of the
gas-phase C and O abundance gradients of the Galactic disk, of paramount
importance for chemical evolution models. This is the first time the C gradient
is derived from such a large number of HII regions and for such a wide range of
Galactocentric distances. Abundance gradients are found of the form
log(O/H) = -0.0440.010 dex kpc^-1, log(C/H) =
-0.1030.018 dex kpc^-1, and log(C/O) = -0.0580.018 dex
kpc^-1.Comment: 13 pages, 2 tables, 2 figures. Published in ApJ Letters, 618, L9
Structural signatures of water-soluble organic aerosols in contrasting environments in South America and Western Europe
This study describes and compares the key structural units present in water-soluble organic carbon (WSOC) fraction of atmospheric aerosols collected in different South American (Colombia – Medellín and Bogotá, Peru – Lima, Argentina – Buenos Aires, and Brazil – Rio de Janeiro, São Paulo, and Porto Velho, during moderate (MBB) and intense (IBB) biomass burning) and Western European (Portugal – Aveiro and Lisbon) locations. Proton nuclear magnetic resonance (1H NMR) spectroscopy was employed to assess the relative distribution of non-exchangeable proton functional groups in aerosol WSOC of diverse origin, for the first time to the authors’ knowledge in South America. The relative contribution of the proton functional groups was in the order H-C > H–C–C= > H-C-O > Ar-H, except in Porto Velho during MBB, Medellín, Bogotá, and Buenos Aires, for which the relative contribution of H-C-O was higher than that of H-C-C=. The 1H NMR source attribution confirmed differences in aging processes or regional sources between the two geographic regions, allowing the differentiation between urban combustion-related aerosol and biological particles. The aerosol WSOC in Aveiro, Lisbon, and Rio de Janeiro during summer are more oxidized than those from the remaining locations, indicating the predominance of secondary organic aerosols. Fresh emissions, namely of smoke particles, becomes important during winter in Aveiro and São Paulo, and in Porto Velho during IBB. The biosphere is an important source altering the chemical composition of aerosol WSOC in South America locations. The source attribution in Medellín, Bogotá, Buenos Aires, and Lima confirmed the mixed contributions of biological material, secondary formation, as well as urban and biomass burning emissions. Overall, the information and knowledge acquired in this study provide important diagnostic tools for future studies aiming at understanding the water-soluble organic aerosol problem, their sources and impact at a wider geographic scale.Fil: Duarte, Regina M.B.O.. Universidade de Aveiro; PortugalFil: Matos, João T.V.. Universidade de Aveiro; PortugalFil: Paula, Andreia S.. Universidade de Aveiro; PortugalFil: Lopes, Sónia P.. Universidade de Aveiro; PortugalFil: Pereira, Guilherme. Universidade de Sao Paulo; BrasilFil: Vasconcellos, Pérola. Universidade de Sao Paulo; BrasilFil: Gioda, Adriana. Universidade Federal do Rio de Janeiro; BrasilFil: Carreira, Renato. Universidade Federal do Rio de Janeiro; BrasilFil: Silva, Artur M.S.. Universidade de Aveiro; PortugalFil: Duarte, Armando C.. Universidade de Aveiro; PortugalFil: Smichowski, Patricia Nora. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rojas, Nestor. Universidad Nacional de Colombia; ColombiaFil: Sanchez Ccoyllo, Odon. No especifíca
EP05.02-003 Durvalumab after Chemoradiotherapy (CRT) in Unresectable Stage III NSCLC. Comparative Study of Two Cohorts in the Real-World Setting
[EN] Introduction: Durvalumab is the new standard of care for unresectable
locally advanced NSCLC, with PD-L1 _1% and who did not
have progression after CRT treatment in the European Union. Our
study compares the effectiveness and the frequency of radiation
pneumonitis in patients treated with concurrent CRT with or without
durvalumab consolidation during the same period in real clinical
practice. Methods: A single-center retrospective study. 71 treated
patients with unresectable stage III NSCLC were included between
March 2018 and December 2021, 37 with CRT followed by durvalumab
and 34 with CRT alone. Real-world progression-free survival
(rwPFS) and real-world overall survival (rwOS) were calculated since
the date of the end CRT. Propensity score matching (PSM) 1:1 was
used to account for differences in baseline characteristics. Results:
Median age was 67 years (range 46-82). 25.4% of the patients were
_75 years old. 78.9% were men and 53.5% former smokers. 54.9%
had squamous histology and 28%, 51% and 21% stage IIIA, IIIB and
IIIC disease, respectively. The most used scheme was carboplatinpaclitaxel
(43.7%), receiving induction chemotherapy in up to 54.9%
of patients. 73.2% received between 60-66 Gy doses of radiotherapy.
Median time from end of CRT to onset durvalumab was 44 days
(range 13-120) with a median of 14 infusions (range 6-27). Of the
34 patients without durvalumab treatment, the expression PD-L1
<1% (58.8%) was the most frequent cause for rejecting consolidation
therapy. After PSM analysis, patients distributions were well
balanced. With a median follow-up of 19.7 months (range 1.4-36.6);
median rw-PFS was 9.3 months (95% CI, 5-13.5) without durvalumab
and 17 months (95% CI, 11-22.9) with durvalumab (p¼0.013).
Median rw-OS was 19.3 months (95% CI, 3.8-34.8) without durvalumab
and 29.9 months (95% CI, 23.3-36.6) with durvalumab
(p¼0.241) with a rw-OS% at 6, 18 and 24 months of 90%, 62% and
49% vs 100%, 86% and 74%, respectively. The rate of radiation
pneumonitis was more frequent with durvalumab consolidation
(56.8% against 44.1%), (p¼0.346), especially within 3 months after
CRT. G3 pneumonitis was only observed in the consolidation therapy.
Conclusions: Our results demonstrate the effectiveness of
durvalumab consolidation after CRT in real-world patients with
unresectable stage III NSCLC. Further sample and longer follow-up
are required to obtain more accurate results. Active surveillance and
appropriate management for radiation pneumonitis are needed, in
especially in candidates for consolidation treatmentS
EP05.02-002 Who Benefits More of Durvalumab after Chemoradiotherapy (CRT) in Real-World Patients with Locally Advanced Non-Small-Cell Lung Cancer (NSCLC)?
[EN] Introduction: Durvalumab received EMA approval as consolidation
therapy (CT) for unresectable stage III NSCLC with PD-L1 _1% and
who did not have progression after CRT. Our objective was to analyze
in real clinical practice the effectiveness of durvalumab and explore the
clinical factors that may be associated with the benefit from CT.
Methods: Retrospective study was made at Hospital of Leon (Spain),
including 37 patients with locally advanced NSCLC treated with durvalumab
after CRT treatment between March 2018 and october 2021
(40.5% patients were included in the durvalumab early access program).
The neutrophil-to-lymphocyte ratio (NLR) could identified after
CRT as a factor that may be benefit from durvalumab. Results: Median
age was 67 years (range 46-82 years). 40.5% of patients were _70
years old. 78.4% were male and 51.4% smokers. 54% had non-squamous
histology. PD-L1 expression was <1% in 5% and not available in
8% patients. 2.7% ROS1 rearrangements, 5.4% KRAS mutations and
not available in 43.2% patients. Stage IIIA, IIIB, IIIC disease were
24.3%, 54.1% and 21.6%, respectively. Median time from end of CRT to
onset durvalumab was 44 days (range 13-120 days). Overall median CT
duration was 214.8 days (range 69-399 days) with a median of 14
infusions (range 6-27 infusions). With a median follow up of 19.7
months (range 1.4-34.9 months); 67.6% had stopped CT: 37.8% due to
completing treatment, 16.2% disease progression, 10.8% adverse event
and 2.7% due to COVID19 infection. Median real-world progressionfree
survival (rwPFS) was 17 months (95% CI, 11-23). Median realworld
overall survival (rwOS) was 29.9 months (95% CI, 23.3-36.6). %
rwOS at 6, 18 and 24 months were 100%, 86.9% and 74.5%, respectively.
For patients with post-CRT NLR not exceeding the cohort median
value of 6, receipt of durvalumab was associated with an improvement
in rwOS (median not reached vs 25.7 months; p¼0.025). 56.8% patients
had any grade of radiation pneumonitis (median time from CRT
start: 119 days [range 36-241 days]). Of these, 19% patients developed
worsening of radiation pneumonitis with durvalumab. 54,1% developed
immune-mediated toxicity, mostly G1-2 (85.1%). Conclusions:
Our results demonstrate the effectiveness of durvalumab consolidation
in this patients population in a real-life setting. We identified low NLR
after CRT as a potentially predictive factor for the benefit of CT in
locally advanced NSCLC.S
Ultrafast spin-currents and charge conversion at \u3ci\u3e3d-5d\u3c/i\u3e interfaces probed by time-domain terahertz spectroscopy
Spintronic structures are extensively investigated for their spin-orbit torque properties, required for magnetic commutation functionalities. Current progress in these materials is dependent on the interface engineering for the optimization of spin transmission. Here, we advance the analysis of ultrafast spin-charge conversion phenomena at ferromagnetic-Transition metal interfaces due to their inverse spin-Hall effect properties. In particular, the intrinsic inverse spin-Hall effect of Pt-based systems and extrinsic inverse spin-Hall effect of Au:W and Au:Ta in NiFe/Au:(W,Ta) bilayers are investigated. The spin-charge conversion is probed by complementary techniques-ultrafast THz time-domain spectroscopy in the dynamic regime for THz pulse emission and ferromagnetic resonance spin-pumping measurements in the GHz regime in the steady state-to determine the role played by the material properties, resistivities, spin transmission at metallic interfaces, and spin-flip rates. These measurements show the correspondence between the THz time-domain spectroscopy and ferromagnetic spin-pumping for the different set of samples in term of the spin mixing conductance. The latter quantity is a critical parameter, determining the strength of the THz emission from spintronic interfaces. This is further supported by ab initio calculations, simulations, and analysis of the spin-diffusion and spin-relaxation of carriers within the multilayers in the time domain, permitting one to determine the main trends and the role of spin transmission at interfaces. This work illustrates that time-domain spectroscopy for spin-based THz emission is a powerful technique to probe spin-dynamics at active spintronic interfaces and to extract key material properties for spin-charge conversion
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