Papers by Gabriel Navarro
PLoS ONE, 2012
Background: Human African trypanosomiasis (HAT) is an infectious disease with a large global heal... more Background: Human African trypanosomiasis (HAT) is an infectious disease with a large global health burden occurring primarily in Central and Eastern Africa. Most current treatments have poor blood brain barrier (BBB) penetration, which prevent them from targeting the most lethal stage of the infection. In addition, current therapeutics suffer from a variety of limitations ranging from serious side effects to difficulties with treatment administration. Therefore it is of crucial importance to find new treatments that are safe, affordable, and effective against both sub-species of Trypanosoma brucei. Methods: Semi-synthetic derivatization of the fungally-derived natural product merulin A (1) has led to the discovery of new development candidates for the protozoan parasite T. brucei, the causative agent of HAT. Creation of an initial SAR library based around the merulin scaffold revealed several key features required for activity, including the endoperoxide bridge, as well as one position suitable for further derivatization. Subsequent synthesis of a 20-membered analogue library, guided by the addition of acyl groups that improve the drug-like properties of the merulin A core, resulted in the development of compound 12 with an IC 50 of 60 nM against T. brucei, and a selectivity index greater than 300-fold against HeLa and immortalized glial cells. Significance: We report the semi-synthetic optimization of the merulin class of endoperoxide natural products as development candidates against T. brucei. We have identified compounds with low nM antiparasitic activities and high selectivity indices against HeLa cells. These compounds can be produced economically in large quantities via a one step derivatization from the microbial fermentation broth isolate, making them encouraging lead candidates for further development.
Transactions of the American Mathematical Society, 2009
The Ito-Michler theorem asserts that if no irreducible character of a finite group G has degree d... more The Ito-Michler theorem asserts that if no irreducible character of a finite group G has degree divisible by some given prime p, then a Sylow p-subgroup of G is both normal and abelian. In this paper we relax the hypothesis, and we assume that there is at exactly one multiple of p that occurs as the degree of an irreducible character of G. We show that in this situation, a Sylow p-subgroup of G is almost normal in G, and it is almost abelian.
Transactions of the American Mathematical Society, 2007
We prove that a finite group G G has two rational-valued irreducible characters if and only if it... more We prove that a finite group G G has two rational-valued irreducible characters if and only if it has two rational conjugacy classes, and determine the structure of any such group. Along the way we also prove a conjecture of Gow stating that any finite group of even order has a non-trivial rational-valued irreducible character of odd degree.
Mathematische Zeitschrift, 1995
Let G be an M-group, let S be a subnormal subgroup of G, and let H be a Hall subgroup of S. If th... more Let G be an M-group, let S be a subnormal subgroup of G, and let H be a Hall subgroup of S. If the character γ ∈ Irr(H) is primitive, then γ(1) is a power of 2. Furthermore, if |G : S| is odd, then γ(1) = 1.
Journal of Pure and Applied Algebra, 2008
If p is a prime number and G is a finite group, we show that G has an irreducible complex charact... more If p is a prime number and G is a finite group, we show that G has an irreducible complex character of degree not divisible by p with values in the cyclotomic field Q p .
Journal of Pure and Applied Algebra, 2007
We apply the theory of localization for tame and wild coalgebras in order to prove the following ... more We apply the theory of localization for tame and wild coalgebras in order to prove the following theorem: "Let Q be an acyclic quiver. Then any tame admissible subcoalgebra of KQ is the path coalgebra of a quiver with relations".
Journal of Marine Systems, 2014
Journal of Group Theory, 2009
Let F be a subfield of the complex numbers. An element x of a finite group G is called an F-eleme... more Let F be a subfield of the complex numbers. An element x of a finite group G is called an F-element in G if wðxÞ A F for every character w of G. We show that G has a unique largest normal subgroup N containing no nonidentity F-elements of G. Also, the canonical homomorphism G ! G=N defines a bijection from the set of classes of F-elements of G to the set of classes of F-elements of G=N.
Journal of Algebra, 2009
We prove that in a finite group of odd order, the number of irreducible quadratic characters is t... more We prove that in a finite group of odd order, the number of irreducible quadratic characters is the number of quadratic conjugacy classes.
Journal of Algebra, 2008
If G is a p-solvable finite group, P is a self-normalizing Sylow psubgroup of G with derived subg... more If G is a p-solvable finite group, P is a self-normalizing Sylow psubgroup of G with derived subgroup P , and Ψ is the sum of all the irreducible characters of G of degree not divisible by p, then we prove that the integer Ψ (P zP) is divisible by |P | for all z ∈ G.
Israel Journal of Mathematics, 1999
If H is a subgroup of a finite group G and γ ∈ Irr(H) induces irreducibly up to G, we prove that,... more If H is a subgroup of a finite group G and γ ∈ Irr(H) induces irreducibly up to G, we prove that, under certain odd hypothesis, F(G)F(H) is a nilpotent subgroup of G.
Israel Journal of Mathematics, 2008
Global Biogeochemical Cycles, 2013
Deep chlorophyll maxima (DCMs) are widespread features of oceans. In temperate regions, DCMs are ... more Deep chlorophyll maxima (DCMs) are widespread features of oceans. In temperate regions, DCMs are commonly associated with isopycnal surfaces that frequently move over a wide vertical range. This general association between DCMs and isopycnals remains unexplained by present theories, and we show here that it emerges from the seasonal history of the water column. Analysis of the formation of more than 9000 seasonal DCMs throughout the world's oceans consistently locates the vertical position of spring/summer DCMs in temperate seas at the density of the previous winter mixed layer, independently of this density value and future depth. These results indicate that DCM formation cannot be understood without hysteresis by solely considering the instantaneous response of phytoplankton to vertical gradients in physical and chemical fields. Present theories for DCM formation cannot explain why spring and summer DCMs are systematically found at a density equal to that of the previous mixed layer where a bloom has occurred. Rather than reacting to instantaneous physical forcing, the results indicate that DCMs operate as self-preserving biological structures that are associated with particular isopycnals because of their capacity to modify the physicochemical environment. Combined with remote sensors to measure salinity and temperature in the surface ocean, this new understanding of DCM dynamics has the potential to improve the quantification of three-dimensional primary production via satellites. This significant enhancement of the representation of oceanic biological processes can also allow increasingly realistic predictions of future biogeochemical scenarios in a warming ocean.
Frontiers of Mathematics in China, 2013
We make a first approach to the representation theory of the wedge product of coalgebras by means... more We make a first approach to the representation theory of the wedge product of coalgebras by means of the description of its valued Gabriel quiver. Then we define semiprime coalgebras and study its category of comodules by the use of localization techniques. In particular, we prove that, whether its Gabriel quiver is locally finite, any monomial semiprime fc-tame coalgebra is string. We also prove a weaker version of Eisenbud-Griffith theorem for coalgebras, namely, any hereditary semiprime strictly quasi-finite coalgebra is serial.
Estuarine, Coastal and Shelf Science, 2009
... Diego Macías a , Gabriel Navarro b , Ana Bartual a , Fidel Echevarría a , c and I. Emma Huert... more ... Diego Macías a , Gabriel Navarro b , Ana Bartual a , Fidel Echevarría a , c and I. Emma Huertas b , Corresponding Author Contact Information , E ... 713 pH meter equipped with a combined glass electrode, calibrated following the protocol described by Del Valls and Dickson (1998 ...
Deep Sea Research Part II: Topical Studies in Oceanography, 2006
Upward velocities have been diagnosed through the development of an approach based on remotely se... more Upward velocities have been diagnosed through the development of an approach based on remotely sensed daily images of both chlorophyll and temperature at the ocean surface in the Gulf of Ca´diz. This novel approach allows to the detection of areas with vigorous vertical velocities (w), through the generation of a calculation algorithm built from the simple Lagrangian model of phytoplankton growth that occurs during the shoaling of deep waters to surface. The fast initial evolution of chlorophyll and temperature in surface limits the implementation of the algorithm to high upward velocities. Assuming this limitation, the values of w diagnosed have been found to be coherent with independent estimations based on diffusive and advective inputs of nitrogen into the euphotic zone in the area. The new production resulting from vertical advection of nitrogen during a regular upwelling event in the basin was more than two orders of magnitude greater than that maintained by vertical diffusion. According to our calculations the maintenance of vertical advection for 1 week under upwelling conditions could support new production equivalent to that due to residual vertical mixing during about half a year under conditions of stratification.
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Papers by Gabriel Navarro