641 research outputs found
Thermodynamic limit of random partitions and dispersionless Toda hierarchy
We study the thermodynamic limit of random partition models for the instanton
sum of 4D and 5D supersymmetric U(1) gauge theories deformed by some physical
observables. The physical observables correspond to external potentials in the
statistical model. The partition function is reformulated in terms of the
density function of Maya diagrams. The thermodynamic limit is governed by a
limit shape of Young diagrams associated with dominant terms in the partition
function. The limit shape is characterized by a variational problem, which is
further converted to a scalar-valued Riemann-Hilbert problem. This
Riemann-Hilbert problem is solved with the aid of a complex curve, which may be
thought of as the Seiberg-Witten curve of the deformed U(1) gauge theory. This
solution of the Riemann-Hilbert problem is identified with a special solution
of the dispersionless Toda hierarchy that satisfies a pair of generalized
string equations. The generalized string equations for the 5D gauge theory are
shown to be related to hidden symmetries of the statistical model. The
prepotential and the Seiberg-Witten differential are also considered.Comment: latex2e using amsmath,amssymb,amsthm packages, 55 pages, no figure;
(v2) typos correcte
Brane cosmology with a bulk scalar field
We consider ``cosmologically symmetric'' (i.e. solutions with homogeneity and
isotropy along three spatial dimensions) five-dimensional spacetimes with a
scalar field and a three-brane representing our universe. We write Einstein's
equations in a conformal gauge, using light-cone coordinates. We obtain
explicit solutions: a. assuming proportionality between the scalar field and
the logarithm of the (bulk) scale factor; b. assuming separable solutions. We
then discuss the cosmology in the brane nduced by these solutions.Comment: 24 pages, Latex, no figur
Antibacterial activity in the hemolymph of the catarina scallop Argopecten ventricosus
We conducted a search for antibacterial peptide like activity in hemolymph of Argopecten ventricosus. Pre-purification of peptides was done by reverse phase HPLC. Hemolymph acidic supernatant was loaded into a column packed with C18 matrix. Stepwise elutions were performed with 5, 50, 80, and 100 % acetonitrile (ACN) in 0.05 % trifluoroacetic acid (TFA) over 550 min at a flow rate of 0.2 ml/min. Absorbance was monitored at 280 nm. Eluted fractions were concentrated under vacuum. Vibrio alginolyticus 138-2 was used as a model to test fractions. Growth inhibition zone were observed at 5 and 50 % ACN. This is the first report of antimicrobial peptide-like activity in hemolymph of a pectinid species
Fluctuating brane in a dilatonic bulk
We consider a cosmological brane moving in a static five-dimensional bulk
spacetime endowed with a scalar field whose potential is exponential. After
studying various cosmological behaviours for the homogeneous background, we
investigate the fluctuations of the brane that leave spacetime unaffected. A
single mode embodies these fluctuations and obeys a wave equation which we
study for bouncing and ever-expanding branes.Comment: 17 pages, 7 figures, revte
Tuberculosis-Related Deaths within a Well-Functioning DOTS Control Program
To describe the molecular epidemiology of tuberculosis (TB)-related deaths in a well-managed program in a low-HIV area, we analyzed data from a cohort of 454 pulmonary TB patients recruited between March 1995 and October 2000 in southern Mexico. Patients who were sputum acid-fast bacillus smear positive underwent clinical and mycobacteriologic evaluation (isolation, identification, drug-susceptibility testing, and IS6110-based genotyping and spoligotyping) and received treatment from the local directly observed treatment strategy (DOTS) program. After an average of 2.3 years of follow-up, death was higher for clustered cases (28.6 vs. 7%, p=0.01). Cox analysis revealed that TB-related mortality hazard ratios included treatment default (8.9), multidrug resistance (5.7), recently transmitted TB (4.1), weight loss (3.9), and having less than 6 years of formal education (2). In this community, TB is associated with high mortality rates
Hot air treatment decreases chlorophyll catabolism during postharvest senescence of broccoli (Brassica oleracea L. var. italica) heads
A hot air treatment was applied to broccoli (Brassica oleracea L. var. italica) florets and its effect on chlorophyll catabolism during postharvest senescence was analyzed. Florets were treated at 48°C for 3 h and then placed in darkness at 20°C. During storage, the yellowing of florets occurred simultaneously with a decrease in chlorophylls and an increase in pheophytins. Heat treatment delayed the appearance of yellowing by 2-3 days and a similar extension of shelf-life could be inferred. Also, the treatment delayed the onset of chlorophyll catabolism and slowed both the rate of chlorophyll a degradation and pheophytin accumulation. No effect on chlorophyll b degradation was found. Chlorophyllase and Mg-dechelatase activities increased from the first day of storage in untreated florets, whereas peroxidase-linked chlorophyll bleaching activity increased from day 3. In heat-treated florets, chlorophyllase activity did not increase until day 2 and then increased at lower rate than in controls. Mg-dechelatase and peroxidase-linked chlorophyll bleaching activities were similar in treated and control florets during the first 2 days of storage, but thereafter the activity of both enzymes was lower in heat-treated samples. In conclusion, a treatment at 48°C for 3 h delayed chlorophyll a catabolism in broccoli during postharvest senescence and decreased the activities of chlorophyllase, Mg-dechelatase and peroxidase, three of the enzymes probably involved in chlorophyll degradation in plants. © 2006 Society of Chemical Industry.Fil: Costa, M.lorenza. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Civello, Pedro Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Chaves, Alicia Raquel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Martinez, Gustavo Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentin
Time variation of the fine structure constant in the early universe and the Bekenstein model
We calculate bounds on the variation of the fine structure constant at the
time of primordial nucleosynthesis and at the time of neutral hydrogen
formation. We use these bounds and other bounds from the late universe to test
Bekenstein model. We modify the Kawano code, CAMB and CosmoMC in order to
include the possible variation of the fine structure constant. We use
observational primordial abundances of \De, \He and \Li, recent data from
the Cosmic Microwave Background and the 2dFGRS power spectrum, to obtain bounds
on the variation of . We calculate a piecewise solution to the scalar
field equation of Bekenstein model in two different regimes; i) matter and
radiation, ii) matter and cosmological constant. We match both solutions with
appropriate boundary conditions. We perform a statistical analysis using the
bounds obtained from the early universe and other bounds from the late universe
to constrain the free parameters of the model. Results are consistent with no
variation of in the early universe. Limits on are
inconsistent with the scale length of the theory being larger than Planck
scale. In order to fit all observational and experimental data, the assumption
implied in Bekenstein's model has to be relaxed.Comment: 13 pages, 8 figures,version accepted to be published in Astronomy and
Astrophysic
Fitness Ranking of Individual Mutants Drives Patterns of Epistatic Interactions in HIV-1
This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
OPTIMIZACIÓN PARAMÉTRICA MULTI-OBJETIVO DE CICLOS DE POTENCIA RANKINE, UTILIZANDO TÉCNICAS DE DISEÑO DE EXPERIMENTOS DE TAGUCHI (MULTI-OBJECTIVE PARAMETRICOPTIMIZATION OF RANKINE POWER CYCLES, USING TAGUCHI EXPERIMENT DESIGN TECHNIQUES)
ResumenEn el presente trabajo se planteó optimizar los ciclos de potencia Rankine (simple, recalentado, regenerativo) variando los parámetros de operación más significativos del ciclo, según las fuentes literarias que se consultaron. Con el objetivo de poder mejorar sus características de calidad que en este caso de estudio son la eficiencia y la destrucción de exergía del ciclo. Primero se realizaron los modelos matemáticos de los tres diferentes ciclos Rankine. Enseguida se obtuvieron las combinaciones de los parámetros de los ciclos, usando un diseño de experimentos con un enfoque de Taguchi, en donde se seleccionó un arreglo ortogonal L9 (34). El cual cumple con la necesidad de cubrir tres factores a tres niveles y un número mínimo de siete experimentos. Posteriormente al tener la combinación de los parámetros se insertaron en el software Engineering equation solver (EES) para hacer la simulación de los sistemas con cada combinación obtenida y ver el comportamiento de la eficiencia y la destrucción de energía a los tres ciclos. Al tener los resultados del comportamiento de cada combinación se analizó el diseño de Taguchi para obtener la mejor combinación de parámetros para aumentar la eficiencia y disminuir la destrucción de exergía. Al tener los parámetros de optimización se realizó un experimento de confirmación donde en los tres casos de los ciclos Rankine se obtuvo un aumento en los parámetros de calidad. respecto a los parámetros iniciales del ciclo.Palabra(s) Clave: ANOVA, optimización, Rankine, Taguchi. AbstractIn the present work it was proposed to optimize Rankine power cycles (simple, reheated, regenerative) by varying the most significant operating parameters of the cycle, according to the literary sources that were consulted. With the aim of improving its quality characteristics, which in this case study are the efficiency and destruction of exergy of the cycle. First the mathematical models of the three different Rankine cycles were made. Next, the combinations of the cycle parameters were obtained, using an experiment design with a Taguchi approach, where an orthogonal arrangement L9 (34) was selected. Which meets the need to cover three factors at three levels and a minimum number of seven experiments. Subsequently, having the combination of the parameters, they were inserted into the Engineering equation solver (EES) software to simulate the systems with each combination obtained and see the performance of efficiency and the destruction of energy at three cycles. Having the results of the behavior of each combination, Taguchi's design was analyzed to obtain the best combination of parameters to increase efficiency and decrease the destruction of exergy. Having the optimization parameters, a confirmation experiment was carried out where in the three cases of the Rankine cycles an increase in the quality parameters was obtained. regarding the initial parameters of the cycle.Keywords: ANOVA, optimization, Rankine, Taguchi
Mannose-modified hyaluronic acid nanocapsules for the targeting of tumor-associated macrophages
Tumor-associated macrophages (TAMs), a class of immune cells that play a key role in tumor immunosuppression, are recognized as important targets to improve cancer prognosis and treatment. Consequently, the engineering of drug delivery nanocarriers that can reach TAMs has acquired special relevance. This work describes the development and biological evaluation of a panel of hyaluronic acid (HA) nanocapsules (NCs), with different compositions and prepared by different techniques, designed to target macrophages. The results showed that plain HA NCs did not significantly influence the polarization of M0 and M2-like macrophages towards an M1-like pro-inflammatory phenotype; however, the chemical functionalization of HA with mannose (HA-Man) led to a significant increase of NCs uptake by M2 macrophages in vitro and to an improved biodistribution in a MN/MNCA1 fibrosarcoma mouse model with high infiltration of TAMs. These functionalized HA-Man NCs showed a higher accumulation in the tumor compared to non-modified HA NCs. Finally, the pre-administration of the liposomal liver occupying agent Nanoprimer™ further increased the accumulation of the HA-Man NCs in the tumor. This work highlights the promise shown by the HA-Man NCs to target TAMs and thus provides new options for the development of nanomedicine and immunotherapy-based cancer treatmentsOpen Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by the 2^2-INTRATARGET project (A20/00028) funded by the ISCIII under the umbrella of the ERA NET EuroNanoMed GA N 723770 of the EU Horizon 2020 Research and Innovation Programme. This work was also supported by the Xunta de Galicia (ED431C 2018/30, and “Centro singular de investigación de Galicia” accreditation 2019 − 2022, ED431G2019/03), and the European Union (European Regional Development Fund-ERDF)S
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