2,050 research outputs found
Improving Monolithic Perovskite Silicon Tandem Solar Cells From an Optical Viewpoint
Perovskite silicon tandem solar cells are the most promising concept for a future photovoltaic technology. We report on recent progress from an optical viewpoint and disucss how we achieved more than 25 device efficienc
Challenges to the development of antigen-specific breast cancer vaccines
Continued progress in the development of antigen-specific breast cancer vaccines depends on the identification of appropriate target antigens, the establishment of effective immunization strategies, and the ability to circumvent immune escape mechanisms. Methods such as T cell epitope cloning and serological expression cloning (SEREX) have led to the identification of a number target antigens expressed in breast cancer. Improved immunization strategies, such as using dendritic cells to present tumor-associated antigens to T lymphocytes, have been shown to induce antigen-specific T cell responses in vivo and, in some cases, objective clinical responses. An outcome of successful tumor immunity is the evolution of antigen-loss tumor variants. The development of a polyvalent breast cancer vaccine, directed against a panel of tumor-associated antigens, may counteract this form of immune escape
Determination of the charge carrier compensation mechanism in Te-doped GaAs by scanning tunneling microscopy.
We identified the charge carrier compensation mechanism in Te-doped GaAs with atomically resolved scanning tunneling microscopy. Three types of defects were found: tellurium donors (Te-As), Ga vacancies (V-Ga), and Ga vacancy-donor complexes (V-Ga-Te-As). We show quantitatively that the compensation in Te-doped bulk GaAs is exclusively caused by vacancy-donor complexes in contrast to Si-doped GaAs. This is explained with the Fermi-level effect as the universal mechanism leading to Ga vacancy formation in n-doped GaAs, and a Coulomb interaction leading to the formation of the complexes. The quantification of the carrier compensation yields a -3e charge state of V-Ga in bulk GaAs. (C) 2003 American Institute of Physics
Internal kinematics of spiral galaxies in distant clusters III. Velocity fields from FORS2/MXU spectroscopy
(Abridged) We study the impact of cluster environment on the evolution of
spiral galaxies by examining their structure and kinematics. Rather than
two-dimensional rotation curves, we observe complete velocity fields by placing
three adjacent and parallel FORS2 MXU slits on each object, yielding several
emission and absorption lines. The gas velocity fields are reconstructed and
decomposed into circular rotation and irregular motions using kinemetry. To
quantify irregularities in the gas kinematics, we define three parameters:
sigma_{PA} (standard deviation of the kinematic position angle), Delta phi (the
average misalignment between kinematic and photometric position angles) and
k_{3,5} (squared sum of the higher order Fourier terms). Using local,
undistorted galaxies from SINGS, these can be used to establish the regularity
of the gas velocity fields. Here we present the analysis of 22 distant galaxies
in the MS0451.6-0305 field with 11 members at z=0.54. In this sample we find
both field (4 out of 8) and cluster (3 out of 4) galaxies with velocity fields
that are both irregular and asymmetric. We show that these fractions are
underestimates of the actual number of galaxies with irregular velocity fields.
The values of the (ir)regularity parameters for cluster galaxies are not very
different from those of the field galaxies, implying that there are isolated
field galaxies that are as distorted as the cluster members. None of the
deviations in our small sample correlate with photometric/structural properties
like luminosity or disk scale length in a significant way.
Our 3D-spectroscopic method successfully maps the velocity field of distant
galaxies, enabling the importance and efficiency of cluster specific
interactions to be assessed quantitatively.Comment: accepted for publication in A&A, high resolution version available at
http://www.astro.rug.nl/~kutdemir/papers
Повышение урожайности в АПК с учетом инноваций и других факторов
В статье подняты актуальные вопросы продовольственной безопасности страны при существующих санкциях. Трудности импортозамещения рассмотрены в рамках российского агропромышленного комплекса (АПК). Обозначены существующие проблемы в сельскохозяйственном секторе экономике и предложены пути их преодоления. Исследованы направления инноваций в сельском хозяйстве, эффективные технологии в АПК, а также факторы, сдерживающие их внедрение в производство. Даны рекомендации доведения инноваций до производства.The article raised topical issues of food security of the country under existing sanctions. Difficulties of import substitution were considered within the framework of the Russian agroindustrial complex (AIC). The article identified the existing problems in the agricultural sector of the economy and proposed ways to overcome them. The directions of innovations in agriculture, effective technologies in the agroindustrial complex, as well as the factors that inhibit their introduction into production are studied. There are given recommendations for bringing innovations to production
Biophysically motivated efficient estimation of the spatially isotropic R*2 component from a single gradient‐recalled echo measurement
Purpose
To propose and validate an efficient method, based on a biophysically motivated signal model, for removing the orientation‐dependent part of R*2 using a single gradient‐recalled echo (GRE) measurement.
Methods
The proposed method utilized a temporal second‐order approximation of the hollow‐cylinder‐fiber model, in which the parameter describing the linear signal decay corresponded to the orientation‐independent part of R*2. The estimated parameters were compared to the classical, mono‐exponential decay model for R*2 in a sample of an ex vivo human optic chiasm (OC). The OC was measured at 16 distinct orientations relative to the external magnetic field using GRE at 7T. To show that the proposed signal model can remove the orientation dependence of R*2, it was compared to the established phenomenological method for separating R*2 into orientation‐dependent and ‐independent parts.
Results
Using the phenomenological method on the classical signal model, the well‐known separation of R*2 into orientation‐dependent and ‐independent parts was verified. For the proposed model, no significant orientation dependence in the linear signal decay parameter was observed.
Conclusions
Since the proposed second‐order model features orientation‐dependent and ‐independent components at distinct temporal orders, it can be used to remove the orientation dependence of R*2 using only a single GRE measurement
Discovery of an Optical Jet in the BL Lac Object 3C 371
We have detected an optical jet in the BL Lac object 3C 371 that coincides
with the radio jet in this object in the central few kpc. The most notable
feature is a bright optical knot 3 arcsec (4 kpc) from the nucleus that occurs
at the location where the jet apparently changes its direction by ~30 degrees.
The radio, near-infrared and optical observations of this knot are consistent
with a single power-law spectrum with a radio-optical spectral index alpha =
-0.81. One possible scenario for the observed turn is that the jet is
interacting with the material in the bridge connecting 3C 371 to nearby
galaxies and the pressure gradient is deflecting the jet significantly.Comment: 11 pages, LaTeX, 4 figures (1 eps, 3 gifs), accepted for publication
in ApJ Letter
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