2,543 research outputs found
Decisiones óptimas de las empresas frente a las regulaciones medioambientales
En este trabajo se describen, por un lado, los diferentes instrumentos de
política ambiental que el sector público ha de imponer a las empresas para
alcanzar unos objetivos determinados, sin olvidar el necesario control del
regulador para comprobar la aplicación y cumplimiento de dicho instrumento. El
más importante es el impuesto pigouviano, con el que se consigue un nivel de
emisiones que permiten que el beneficio marginal de contaminar se iguale al
daño marginal de contaminar, obteniendo un óptimo social o primer óptimo. Si
no se puede alcanzar, se busca un impuesto con el que se consiga un nivel de
emisiones distinto al óptimo pero eficiente, en términos de un
coste mínimo para la sociedad, segundo óptimo. Por otro lado, se analiza el
comportamiento de una empresa a la que el regulador impone un límite de
emisiones que, en caso de ser superado, implicará una multa para la empresa.
Se distinguen dos tipos de multa, dependiendo de si ésta aumenta con el
exceso de emisiones de forma lineal o cuadrática. Para cada tipo de multa se
obtiene el óptimo privado de emisiones, minimizando los costes de las
empresas. Es posible fijar el nivel de intensidad para cada tipo de multa que
consigue que el óptimo privado sea igual al óptimo social, permitiendo así
alcanzar el máximo beneficio para la sociedad.Departamento de Economía AplicadaGrado en Administración y Dirección de Empresa
-adic quotient sets
For , the question of when is dense in the positive real numbers has been examined by
many authors over the years. In contrast, the -adic setting is largely
unexplored. We investigate conditions under which is dense in the
-adic numbers. Techniques from elementary, algebraic, and analytic number
theory are employed in this endeavor. We also pose many open questions that
should be of general interest.Comment: 24 page
Evolution of the progenitors of SNe 1993J and 2011dh revealed through late time radio and X-ray studies
We perform hydrodynamical simulations of the interaction between supernova
(SN) ejecta and circumstellar medium (CSM) for SN 1993J and SN 2011dh, and
calculate the radio and X-ray emissions expected from the shocked gas at late
epochs (). Considering the ejecta structure from multi-group radiation
hydrodynamics simulation, we find that the observed rapid drop in radio and
X-ray light curves of SN 1993J at 3000 days can be due to a change in the
mass-loss rate () around 6500 years prior to the explosion of the
SN. The exact epoch scales inversely with the assumed wind velocity of . The progenitor of this SN very likely belonged to a binary
system, where, during its evolution, the primary had transferred material to
the secondary. It is argued in the paper that the change in can happen
because of a change in the mass accretion efficiency () of the companion
star. It is possible that before years
prior to the explosion, was high, thus the CSM was tenuous, which causes
the late time downturn in fluxes. In the case of SN 2011dh, the late time
evolution is found to be consistent with a wind medium with . It is difficult from
our analysis to predict whether the progenitor of this SN had a binary
companion, however, if future observations show similar decrease in radio and
X-ray fluxes, then that would give strong support to a scenario where both SNe
had undergone similar kind of binary evolution before explosion.Comment: 13 pages, 10 figures; Accepted for publication in Ap
Energy & Carbon Neutral NYC
In 2016, the world\u27s leading countries signed the Paris Agreement which focused on reducing anthropogenic climate change on the planet. On May 2019, New York State and New York City declared its own ambitious goals aimed at decarbonizing the city and restricting the state’s energy use to relying completely on renewables.
Some of these goals specifically target infrastructure in the city since estimates cite buildings as accounting for nearly 70% of New York’s energy use. The main law of New York’s Climate Policy, Local Law 97, requires all buildings over 25,000 sq ft to reduce their CO2 footprint by 40% by 2030 and by 80% by 2050. It also mandates increasing the efficiency of buildings based on the Energy Star rating system. While very ambitious and a step in the right direction for New York, some critics have voiced concern over the comprehensiveness of the Energy Star rating system, how carbon dioxide emissions are calculated and what means and methods building owners will take in order to comply with the law. The legislation will become legally binding in 2024 and owners with buildings meeting the legal requirement will need to move quickly in order ensure their properties meet benchmarks
Modules for Experiments in Stellar Astrophysics (MESA): Convective Boundaries, Element Diffusion, and Massive Star Explosions
We update the capabilities of the software instrument Modules for Experiments
in Stellar Astrophysics (MESA) and enhance its ease of use and availability.
Our new approach to locating convective boundaries is consistent with the
physics of convection, and yields reliable values of the convective core mass
during both hydrogen and helium burning phases. Stars with
become white dwarfs and cool to the point where the electrons are degenerate
and the ions are strongly coupled, a realm now available to study with MESA due
to improved treatments of element diffusion, latent heat release, and blending
of equations of state. Studies of the final fates of massive stars are extended
in MESA by our addition of an approximate Riemann solver that captures shocks
and conserves energy to high accuracy during dynamic epochs. We also introduce
a 1D capability for modeling the effects of Rayleigh-Taylor instabilities that,
in combination with the coupling to a public version of the STELLA radiation
transfer instrument, creates new avenues for exploring Type II supernovae
properties. These capabilities are exhibited with exploratory models of
pair-instability supernova, pulsational pair-instability supernova, and the
formation of stellar mass black holes. The applicability of MESA is now widened
by the capability of importing multi-dimensional hydrodynamic models into MESA.
We close by introducing software modules for handling floating point exceptions
and stellar model optimization, and four new software tools -- MESAWeb,
MESA-Docker, pyMESA, and mesastar.org -- to enhance MESA's education and
research impact.Comment: 64 pages, 61 figures; Accepted to AAS Journal
The WW-HECT protein Smurf2 interacts with the Docking Protein NEDD9/HEF1 for Aurora A activation
The multi-functional adaptor protein NEDD9/HEF1/Cas-L regulates cell motility, invasion and cell cycle progression, and plays key roles in cancer progression and metastasis. NEDD9 is localized to the centrosome and is required for activation of Aurora A kinase in mitosis. Here we demonstrate that the HECT-WW protein Smurf2 physically associates with NEDD9 and is required for the stability of NEDD9 protein. Smurf2 depletion results in a marked decrease in NEDD9 protein levels, by facilitating polyubiquitination and proteasomal degradation of NEDD9. Conversely, forced overexpression of Smurf2 results in upregulation of endogenous NEDD9 protein, confirming the role for Smurf2 in NEDD9 stability. Cells with Smurf2 depletion fail to activate Aurora A at the G2/M boundary, leading to a marked delay in mitotic entry. These observations suggest that the stable complex of Smurf2 and NEDD9 is required for timely entry into mitosis via Aurora A activation
A review of transformative strategies for climate mitigation by grasslands
Grasslands can significantly contribute to climate mitigation. However, recent trends indicate that human activities have switched their net cooling effect to a warming effect due to management intensification and land conversion. This indicates an urgent need for strategies directed to mitigate climate warming while enhancing productivity and efficiency in the use of land and natural (nutrients, water) resources. Here, we examine the potential of four innovative strategies to slow climate change including: 1) Adaptive multi-paddock grazing that consists of mimicking how ancestral herds roamed the Earth; 2) Agrivoltaics that consists of simultaneously producing food and energy from solar panels on the same land area; 3) Agroforestry with a reverse phenology tree species, Faidherbia (Acacia) albida, that has the unique trait of being photosynthetically active when intercropped herbaceous plants are dormant; and, 4) Enhanced Weathering, a negative emission technology that removes atmospheric CO2 from the atmosphere. Further, we speculate about potential unknown consequences of these different management strategies and identify gaps in knowledge. We find that all these strategies could promote at least some of the following benefits of grasslands: CO2 sequestration, non-CO2 GHG mitigation, productivity, resilience to climate change, and an efficient use of natural resources. However, there are obstacles to be overcome. Mechanistic assessment of the ecological, environmental, and socio-economic consequences of adopting these strategies at large scale are urgently needed to fully assess the potential of grasslands to provide food, energy and environmental security
Investigation of Cross-Reactivity of Anti-Ephrin-B2 Antibody to Other Ephrin-B Members in an Immunohistochemical Study in a Cohort of Oral Squamous Cell Carcinoma
Ephrin-B1,-B2 and -B3 proteins share a high degree of sequence similarity. Investigation of these proteins as putative prognostic markers in human cancers including oral squamous cell carcinoma (OSCC) has been limited by challenges in generating specific antibodies against them. The current study examined the reactivity of a polyclonal anti-human ephrin-B2 antibody (HPA008999) against ephrin-B proteins and investigated the prognostic significance of immunoreactivity of the same antibody at different intra-tumor sites in OSCC specimens. By amino acid sequence comparison, immunocytochemistry and Western blot analysis on cell lysates and precipitates from HEK-293T cells transfected with EFNB1, EFNB2, or EFNB3 expression constructs, we demonstrated that HPA008999 reacted to all ephrin-B proteins. Using immunohistochemistry (IHC) with the HPA008999 antibody in a cohort (n = 131) of OSCC, we showed high immunoreactivity at the tumor center, but not at the tumor invading front, was significantly associated with worse 5-year overall survival probabilities. In conclusion, the HPA008999 antibody reacted to all ephrin-B proteins and the immunoreactivity at the tumor center might be useful as a prognostic marker in OSCC. These data underscore the need for the investigation of antibodies for cross-reactivity to similar protein members for obtaining reliable and meaningful results in IHC based biomarker studies.publishedVersio
Investigation of Cross-Reactivity of Anti-Ephrin-B2 Antibody to Other Ephrin-B Members in an Immunohistochemical Study in a Cohort of Oral Squamous Cell Carcinoma
Ephrin-B1,-B2 and -B3 proteins share a high degree of sequence similarity. Investigation of these proteins as putative prognostic markers in human cancers including oral squamous cell carcinoma (OSCC) has been limited by challenges in generating specific antibodies against them. The current study examined the reactivity of a polyclonal anti-human ephrin-B2 antibody (HPA008999) against ephrin-B proteins and investigated the prognostic significance of immunoreactivity of the same antibody at different intra-tumor sites in OSCC specimens. By amino acid sequence comparison, immunocytochemistry and Western blot analysis on cell lysates and precipitates from HEK-293T cells transfected with EFNB1, EFNB2, or EFNB3 expression constructs, we demonstrated that HPA008999 reacted to all ephrin-B proteins. Using immunohistochemistry (IHC) with the HPA008999 antibody in a cohort (n = 131) of OSCC, we showed high immunoreactivity at the tumor center, but not at the tumor invading front, was significantly associated with worse 5-year overall survival probabilities. In conclusion, the HPA008999 antibody reacted to all ephrin-B proteins and the immunoreactivity at the tumor center might be useful as a prognostic marker in OSCC. These data underscore the need for the investigation of antibodies for cross-reactivity to similar protein members for obtaining reliable and meaningful results in IHC based biomarker studies.publishedVersio
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