794 research outputs found
Tuning paramagnetic spin-excitations of single adatoms
Around 50 years ago, Doniach [Proc. Phys. Soc. 91, 86 (1967)] predicted the
existence of paramagnons in nearly ferromagnetic materials, recently measured
in bulk Pd [Phys. Rev. Lett. 105, 027207 (2010)]. Here we predict the analogous
effect for single adatoms, namely paramagnetic spin-excitations (PSE). Based on
time-dependent density functional theory, we demonstrate that these overdamped
excitations acquire a well-defined peak structure in the meV energy region when
the adatom's Stoner criterion for magnetism is close to the critical point. In
addition, our calculations reveal a subtle tunability and enhancement of PSE by
external magnetic fields, exceeding by far the response of bulk paramagnons and
even featuring the atomic version of a quantum phase transition. We further
demonstrate how PSE can be detected as moving steps in the
signal of state-of-the-art inelastic scanning tunneling spectroscopy, opening a
potential route for experimentally accessing fundamental electronic properties
of non-magnetic adatoms, such as the Stoner parameter.Comment: 6 pages, 3 figure
Introduction to the AdS/CFT correspondence
This is a pedagogical introduction to the AdS/CFT correspondence, based on
lectures delivered by the author at the third IDPASC school. Starting with the
conceptual basis of the holographic dualities, the subject is developed
emphasizing some concrete topics, which are discussed in detail. A very brief
introduction to string theory is provided, containing the minimal ingredients
to understand the origin of the AdS/CFT duality. Other topics covered are the
holographic calculation of correlation functions, quark-antiquark potentials
and transport coefficients.Comment: 64 pages, 12 figures;v2: minor improvements;v3: references adde
Información molecular vs información genealógica en la gestión de poblaciones
Tanto en el campo de la conservación como en el de la mejora genética, se han propuesto diversos métodos para gestionar una población controlando la pérdida de diversidad genética. En poblaciones no subdivididas, el método aceptado es determinar la contribución de cada posible padre (i.e., el número de descendientes que cada individuo deja a la siguiente generación), minimizando el parentesco global de los padres ponderado por estas contribuciones (Meuwissen, 1997; Grundy et al., 1998; Fernández et al., 2003). Los coeficientes de parentesco se obtienen normalmente de la genealogÃa, y en dicho caso, se optimiza el parentesco global genealógico. Sin embargo, la información genealógica no está siempre disponible, en cuyo caso se pueden usar marcadores moleculares para calcular el parentesco molecular o estimar el parentesco genealógico (Toro et al., 2009). AsÃ, cuando no se dispone de genealogÃas, se puede minimizar el parentesco molecular global o el parentesco global genealógico estimado con los marcadores. Fernández et al. (2005) estudiaron mediante simulaciones la capacidad de la información molecular de reemplazar a la información genealógica, y concluyeron que el uso exclusivo de información molecular era claramente insuficiente. En dicho estudio, los autores se basaron en un número limitado de marcadores microsatélites, del orden de decenas. En la actualidad, gracias a los métodos de secuenciación de última generación, disponemos de miles de marcadores de tipo SNP, lo que hace necesaria una revisión de aquellas investigaciones que concluÃan que la utilidad de la información molecular era limitada e inferior a la genealógica. En este estudio, reevaluamos vÃa simulaciones la capacidad de la información genómica de reemplazar a la información genealógica para mantener diversidad genética en programas de conservación, usando un número de SNPs en lÃnea con los datos actualmente disponible
Consumer Awareness on Labeled Food Products in Digos City, Philippines
Food label information assists consumers to better understand the nutritional value of the food. This study was conducted to determine the consumer awareness on labeled food products. There were 115 respondents interviewed while shopping at various shopping stores in Digos City. An exploratory and descriptive design method was used and data was analyzed using a cross-tabulation method and chi-square test. Results show that the most frequently referred labeling information are the expiry date and list of ingredients. Consumers were motivated to read labeling information because they are health conscious and want to know characteristics of the food. High level of awareness on food labeling information was observed among female respondents. Furthermore, consumers’ awareness of the information on the food labels is not determined by age, level of education, type of occupation, and gender. The level of education, gender, and type of occupation affect the extent of consumers’ knowledge about the importance of food labeling. It was found that the high extent of knowledge was observed among respondents who had college education. On the other hand, respondents within the 31-to-40-year-old age bracket and those who attained college degree perceived food labeling as very important. Furthermore, the consumers’ perception on the importance of food labeling information is affected by age, level of education, and type of occupation. Steps should be taken to improve food labeling, especially the labeling style, to provide clear, readable information, as well as develop consumer guidelines on purchasing labeled food products
Optimizing the creation of base populations for aquaculture breeding programs using phenotypic and genomic data and its consequences on genetic progress
The success of an aquaculture breeding program critically depends on the way in which the base population of breeders is constructed since all the genetic variability for the traits included originally in the breeding goal as well as those to be included in the future is contained in the initial founders. Traditionally, base populations were created from a number of wild strains by sampling equal numbers from each strain. However, for some aquaculture species improved strains are already available and, therefore, mean phenotypic values for economically important traits can be used as a criterion to optimize the sampling when creating base populations. Also, the increasing availability of genome-wide genotype information in aquaculture species could help to refine the estimation of relationships within and between candidate strains and, thus, to optimize the percentage of individuals to be sampled from each strain. This study explores the advantages of using phenotypic and genome-wide information when constructing base populations for aquaculture breeding programs in terms of initial and subsequent trait performance and genetic diversity level. Results show that a compromise solution between diversity and performance can be found when creating base populations. Up to 6% higher levels of phenotypic performance can be achieved at the same level of global diversity in the base population by optimizing the selection of breeders instead of sampling equal numbers from each strain. The higher performance observed in the base population persisted during 10 generations of phenotypic selection applied in the subsequent breeding program
Patterns of gauge symmetry in the background field method
The correlation functions of Yang-Mills theories formulated in the background
field method satisfy linear Slavnov-Taylor identities, which are naive
generalizations of simple tree level relations, with no deformations
originating from the ghost sector of the theory. In recent years, a stronger
version of these identities has been found to hold at the level of the
background gluon self-energy, whose transversality is enforced separately for
each special block of diagrams contributing to the gluon Schwinger-Dyson
equation. In the present work we demonstrate by means of explicit calculations
that the same distinct realization of the Slavnov-Taylor identity persists in
the case of the background three-gluon vertex. The analysis is carried out at
the level of the exact Schwinger-Dyson equation for this vertex, with no
truncations or simplifying assumptions. The demonstration entails the
contraction of individual vertex diagrams by the relevant momentum, which
activates Slavnov-Taylor identities of vertices and multi-particle kernels
nested inside these graphs; the final result emerges by virtue of a multitude
of extensive cancellations, without the need of performing explicit
integrations. In addition, we point out that background Ward identities amount
to replacing derivatives of propagators by zero-momentum background-gluon
insertions, in exact analogy to standard properties of Abelian gauge theories.
Finally, certain potential applications of these results are briefly discussed.Comment: 35 pages, 9 figure
Testing Supergravity Grand Unification at Future Accelerator and Underground Experiments
The full parameter space of supergravity grand unified theory with
type proton decay is analysed using renormalization
group induced electroweak symmetry breaking under the restrictions that the
universal scalar mass and gluino mass are TeV (no extreme fine
tuning) and the Higgs triplet mass obeys . Future proton
decay experiments at SuperKamiokande or ICARUS can reach a sensitivity for the
mode of yr allowing a number of
predictions concerning the SUSY mass spectrum. Thus either the decay mode will be seen at these experiments or a
chargino of mass GeV will exist and hence be observable
at LEP2. Further, if yr,
then either the light Higgs has mass GeV or GeV i.e. either the light Higgs or the light chargino (or both) would be
observable at LEP2. Thus, the combination of future accelerator and future
underground experiments allow for strong experimental tests of this theory.Comment: 7 figures available upon request, CTP-TAMU-32/93, NUB-TH-3066/93 and
SSCL-Preprint-44
Lean Production Model Aligned with Organizational Culture to Reduce Order Fulfillment Issues in Micro- and Small-sized Textile Businesses in Peru
This paper proposes an optimization model aimed at increasing production capabilities at a small-sized textile business dedicated to manufacturing polo shirts, while reducing order fulfillment issues, including incomplete orders and late deliveries. Hence, an assessment identified downtimes from unnecessary transportation travel, time spent looking for materials, and excessive losses due to cutting fabric errors. In this light, the study focused on selecting adaptable tools, such as 5S, Plant Layout, and Method Study, which may help improve production capabilities and address these situations. However, to guarantee that the objectives set forth are being met, the organizational culture must also be identified and improved so that it may serve as the foundation for the optimization model. Then, the proposed model will be validated to determine whether the selected operating tools supported by the strengthening of organization culture contribute to increasing production
- …