805 research outputs found
Cytidine deaminase as a molecular target in cancer: an insight
Cancer is one of the leading causes of death globally. Although more than 400 varieties of cancer have been reported, based on cell lines, still the actual reason of all types of cancer is not very clear. Several internal and external factors have been identified and the study is ongoing. Up to now about 73 proteins have been identified that are capable to influence directly various phases of cancer including mutation, cell proliferation, invasion, angiogenesis, and metastasis. Cytidine deaminase is one of the important proteins that is responsible for various types of cancer that includes gastric, liver, biliary tract, bladder, breast, pancreatic ductal adenocarcinoma (PDAC) and so on. Two excellent inhibitors of cytidine deaminase are commercially available. A brief overview is presented in this advanced review. Any omission is completely unintentional
Structural stability of invasion graphs for generalized Lotka--Volterra systems
In this paper we study in detail the structure of the global attractor for a
generalized Lotka-Volterra system with Volterra--Lyapunov stable structural
matrix. We provide the full characterization of this structure and we show that
it coincides with the invasion graph as recently introduced in [15]. We also
study the stability of the structure with respect to the perturbation of the
problem parameters. This allows us to introduce a definition of structural
stability in Ecology in coherence with the classical mathematical concept where
there exists a detailed geometrical structure, governing the transient and
asymptotic dynamics, which is robust under perturbation.Comment: Declaration on the lack of competing interest has been adde
The effect of mineral and organic nutrient input on yields and nitrogen balances in western Kenya
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Agriculture, Ecosystems & Environment 214 (2015): 10-20, doi:10.1016/j.agee.2015.08.006.Soil fertility declines constrain crop productivity on smallholder farms in sub-Saharan Africa. Government and non-government organizations promote the use of mineral fertilizer and improved seed varieties to redress nutrient depletion and increase crop yields. Similarly, rotational cropping with nitrogen (N)-fixing legume cover crops or trees is promoted to improve soil fertility and crop yields. We examined maize grain yields and partial N balances on 24 smallholder maize farms in western Kenya, where interventions have increased access to agricultural inputs and rotational legume technologies. On these farms, mineral fertilizer inputs ranged from 0 to 161 kg N ha-1 (mean = 48 kg N ha-1), and maize grain yields ranged from 1-7 tons ha-1 (mean = 3.4 t ha-1). Partial N balances ranged from large losses (-112 kg N ha-1) to large gains (93 kg N ha-1)with a mean of -3 kg N ha-1. Maize grain yields increased significantly with N inputs (from fertilizer and legumes) in 2012 but not in 2013 when rainfall was lower. Nitrogen inputs of 40 kg N ha-1 were required to produce 3 tons of maize ha-1. N balances varied both among farms and between years, highlighting the importance of tracking inputs and outputs on multiple farms over multiple years before drawing conclusions about nutrient management, soil fertility outcomes and food security. The addition of N from legume rotations was a strong predictor of grain yields and positive N balances in lower-yielding farms in both years. This suggested that legume rotations may be particularly important for buffering yields from climate variability and maintaining N balances in low rainfall years.This research was funded by an Earth Institute at Columbia University Cross-Cutting Initiative Grant, a National Science Foundation PIRE grant (IIA-0968211), and by the Bill and Melinda Gates Foundation (Gates Special Initiative Grant)
A Quantização da Gravitação em 3D com Constante Cosmológica Positiva.
Foi mostrado por Bonzon e Livine que a gravitação em 2+1 dimensões com constante cosmológica contém uma ambiguidade que depende de um parâmetro γ do tipo BarberoImmirzi que se tenha na gravitação 4D. Baseados neste fato mostramos que, no caso > 0, a teoria Lorentziana pode ser parcialmente reduzida, através de uma fixação de calibre apropriada, à uma teoria de ChernSimons com grupo de
calibre SU(2). Revisamos então a já conhecida estrategia de quantização da teoria de ChernSimons no contexto da quantização de laços para o caso de um espaço com a topologia de um cilindro. Finalmente construÃmos um observável quântico que, embora tenha um espectro não trivial no nÃvel quântico, corresponde a uma
quantidade que classicamente é nula
Stellar ArAr reactions and their effect on light neutron-rich nuclide synthesis
The ArAr ( = 35 d) and
ArAr (269 y) reactions were studied for the first time
with a quasi-Maxwellian ( keV) neutron flux for Maxwellian Average
Cross Section (MACS) measurements at stellar energies. Gas samples were
irradiated at the high-intensity Soreq applied research accelerator
facility-liquid-lithium target neutron source and the Ar/Ar and
Ar/Ar ratios in the activated samples were determined by
accelerator mass spectrometry at the ATLAS facility (Argonne National
Laboratory). The Ar activity was also measured by low-level counting at
the University of Bern. Experimental MACS of Ar and Ar, corrected
to the standard 30 keV thermal energy, are 1.9(3) mb and 1.3(2) mb,
respectively, differing from the theoretical and evaluated values published to
date by up to an order of magnitude. The neutron capture cross sections of
Ar are relevant to the stellar nucleosynthesis of light neutron-rich
nuclides; the two experimental values are shown to affect the calculated mass
fraction of nuclides in the region A=36-48 during the weak -process. The new
production cross sections have implications also for the use of Ar and
Ar as environmental tracers in the atmosphere and hydrosphere.Comment: 18 pages + Supp. Mat. (13 pages) Accepted for publication in Phys.
Rev. Let
Sarcomas de partes blandas. Análisis de 42 casos
El objetivo de este estudio es valorar el pronóstico a largo plazo de una serie de pacientes tratados en nuestro hospital en relación con diversos factores clÃnicos, diagnósticos y terapéuticos que podrÃan condicionarlo. Se revisaron 123 pacientes tratado por tumores malignos de partes blandas entre los años 1979 y 1999, de estos solo 42 cumplieron las caracterÃsticas para incluirles en nuestro estudio. Se valoró su evolución teniendo en cuenta las variables pronosticas identificadas en trabajos previamente publicados y nuestra propia experiencia y se realizó el estudio estadÃstico de las mismas. En el análisis estadÃstico del estudio se utilizó el programa SPSS versión 8.0WIN y se realizó el análisis de supervivencia mediante el método de Kaplan-Meier. El tiempo de supervivencia total descrito según este método para el total de los casos estudiados presenta una mediana de 33 meses con un error estándar de 8 y un intervalo de confianza del 95% de (17,49), el tiempo libre de enfermedad presenta una mediana de 9 meses con un error estándar de 2 y un intervalo de confianza del 95% de (6,12) y el tiempo de aparición de metástasis presenta una mediana de 26 meses con un error estándar de 5 y un intervalo de confianza del 95% de (17,35). A su vez se realizó el análisis bivariante de las múltiples variables pronosticas. El gran número de variables y la dispersión de la muestra hacen aconsejable estudios multicéntricos prospectivos más numerosos para obtener conclusiones definitivas sobre este tipo de tumores.The aim of this study is to evaluate the long-term prognosis of a series of patients treated in our hospital with regard to various clinical, diagnostic and therapeutic factors. A total of 123 patients who had been treated for malignant soft tissue tumours between 1979 and 1999 were reviewed. Of these, only 42 fulfilled the requirements to be included in our study. The outcome was evaluated taking into account prognostic variables identified in previously published studies and our own experience, and a statistical study of these factors as carried out with the Kaplan-Meier survival analysis method. The total survival time for all the cases studied was 33+8 (median + SE) months with a 95% confidence interval of 17.49 months. The time free of illness was 9+2 (median + SE) months with a 95% confidence interval of 6.12 months. The time-period until metastasis appeared was 26+5 (median + SE) months with a 95% confidence interval of 17.35 months. At the same time, the bivariant analysis of the many prognostic variables was performed. The high number of variables and the dispersion of the sample group suggest that it would be advisable to carry out more prospective, multicentric studies to reach definitive conclusions about this type of tumour
A world of cobenefits : solving the global nitrogen challenge
Houlton, Benjamin Z. University of California. John Muir Institute of the Environment. Davis, CA, USA.Houlton, Benjamin Z. University of California. Department of Land, Air and Water Resources. Davis, CA, USA.Almaraz, Maya. University of California. Department of Land, Air and Water Resources. Davis, CA, USA.Aneja, Viney. North Carolina State University at Raleigh. Department of Marine, Earth, and Atmospheric Sciences. Raleigh, NC, USA.Austin, Amy T. Universidad de Buenos Aires. Facultad de AgronomÃa. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Austin, Amy T. CONICET – Universidad de Buenos Aires. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA). Buenos Aires, Argentina.Bai, Edith. Chinese Academy of Sciences. Institute of Applied Ecology. CAS Key Laboratory of Forest Ecology and Management. Shenyang, China.Bai, Edith. Northeast Normal University. School of Geographical Sciences. Changchun, China.Cassman, Kenneth. University of Nebraska – Lincoln. Department of Agronomy and Horticulture. Lincoln. NE, USA.Compton, Jana E. Environmental Protection Agency. Western Ecology Division. Washington, DC, USA.Davidson, Eric A. University of Maryland Center for Environmental Science. Appalachian Laboratory. Cambridge, MD, USA.865-872Nitrogen is a critical component of the economy, food security, and planetary health. Many of the world's sustainability targets hinge on global nitrogen solutions, which, in turn, contribute lasting benefits for (i) world hunger; (ii) soil, air, and water quality; (iii) climate change mitigation; and (iv) biodiversity conservation. Balancing the projected rise in agricultural nitrogen demands while achieving these 21st century ideals will require policies to coordinate solutions among technologies, consumer choice, and socioeconomic transformation
The first direct measurement of ¹²C (¹²C,n) ²³Mg at stellar energies
Neutrons produced by the carbon fusion reaction ¹²C(¹²C,n)²³Mg play an important role in stellar nucleosynthesis. However, past studies have shown large discrepancies between experimental data and theory, leading to an uncertain cross section extrapolation at astrophysical energies. We present the first direct measurement that extends deep into the astrophysical energy range along with a new and improved extrapolation technique based on experimental data from the mirror reaction ¹²C(¹²C,p)²³Na. The new reaction rate has been determined with a well-defined uncertainty that exceeds the precision required by astrophysics models. Using our constrained rate, we find that ¹²C(¹²C,n)²³Mg is crucial to the production of Na and Al in Pop-III Pair Instability Supernovae. It also plays a non-negligible role in the production of weak s-process elements as well as in the production of the important galacti
Effect of microencapsulated phenolic compound extracts of Maclura tinctoria (L.) Steud on growth performance and humoral immunity markers of white leg shrimp (Litopenaeus vannamei, Boone, 1931) juveniles
Aim of study: The effect of microencapsulated phenolic compound extracts of Maclura tinctoria (MTBE) on growth performance and humoral immunity markers of the white leg shrimp Litopenaeus vannamei juveniles (0.5 ± 0.2 g initial weight) was studied.Area of study: M. tinctoria was collected from Hampolol, Campeche, and Arroyo del Agua, Culiacan, Sinaloa, Mexico.Material and methods: Three MTBE inclusions (0.5, 1, and 2.5 g MTBE/kg, Purina®) were compared with a control commercial feed (Purina®) during 30 days. Nine phenolic acids, nine flavonols, four dihydro-flavonoids, four flavones, and seven unidentified phenolic compounds were determined fin the MTBE using a Perkin Elmer® HPLC chromatograph and diode array-detection.Main results: The mean concentrations of total phenolic compounds, total flavonoid compounds, and condensed tannins were 198.05 ± 5.59 mg gallic acid equivalent (GAE) g-1 dw, 78.57 ± 1.80 quercetin equivalent g-1, and 28.32 ± 0.33 mg epicatechin equivalent g-1, respectively. The ferric reducing antioxidant power and the total antioxidant capacity, respectively, averaged 28.32 mg GAE mL-1 and 10.9 mg ascorbic acid equivalent mL-1. Survival, weight gain, and specific growth rate of L. vannamei were similar among the experimental diets. The dietary inclusion of MTBE at 0.5 g/kg of food showed significant higher (p < 0.05) plasma hemocyte lysate protein (1.35 ± 0.055 µg mL-1), prophenoloxidase (0.47 ± 0.15, Abs. 492 nm), and superoxide anion (O2.-) activity (0.21 ± 0.07, Abs. 630 nm).Research highlights: The supplementation of MTBE at 0.5 g/kg of food could be considered as a potential alternative additive for L. vannamei diet in the juvenile production, since it improved the response of the humoral immunity markers at post larval life stages, when cultivated shrimp are more susceptible to be infected by pathogens
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