Papers by Jose Luis Cortes
Physics Letters B, 1997
We show that it is possible to find an extension of the matter content of the standard model with... more We show that it is possible to find an extension of the matter content of the standard model with a unification of gauge and Yukawa couplings reproducing their known values. The perturbative renormalizability of the model with a single coupling and the requirement to accomodate the known properties of the standard model fix the masses and couplings of the additional particles. The implications on the parameters of the standard model are discussed.
Physical Review D, 2005
The possibility of a modification of special relativity with an invariant energy scale playing th... more The possibility of a modification of special relativity with an invariant energy scale playing the role of a minimum energy is explored. Consistency with the equivalence of different inertial frames is obtained by an appropriate choice of a non-linear action of the Lorentz group on momentum space. Limits on the low energy cutoff from tests of Einstein's theory and possible ways to measure the new energy scale are discussed.
Physical Review D, 1996
The technique of extended dualization developed in this paper is used to bosonize quantized fermi... more The technique of extended dualization developed in this paper is used to bosonize quantized fermion systems in arbitrary dimension $D$ in the low energy regime. In its original (minimal) form, dualization is restricted to models wherein it is possible to define a dynamical quantized conserved charge. We generalize the usual dualization prescription to include systems with dynamical non--conserved quantum currents. Bosonization based on this extended dualization requires the introduction of an additional rank $0$ (scalar) field together with the usual antisymmetric tensor field of rank $(D-2)$. Our generalized dualization prescription permits one to clearly distinguish the arbitrariness in the bosonization from the arbitrariness in the quantization of the system. We study the bosonization of four--fermion interactions with large mass in arbitrary dimension. First, we observe that dualization permits one to formally bosonize these models by invoking the bosonization of the free massive Dirac fermion and adding some extra model--dependent bosonic terms. Secondly, we explore the potential of extended dualization by considering the particular case of \underbar{chiral} four--fermion interactions. Here minimal dualization is inadequate for calculating the extra bosonic terms. We demonstrate the utility of extended dualization by successfully completing the bosonization of this chiral model. Finally, we consider two examples in two dimensions which illuminate the utility of using extended dualization by showing how quantization ambiguities in a fermionic theory propagate into the bosonized version. An explicit parametrization of the quantization ambiguities of the chiral current in the Chiral Schwinger model is obtained. Similarly, for the sine--Gordon interaction in the massive Thirring model the quantization
Journal of The American Academy of Dermatology, 2007
Cell therapy and regenerative medicine are potentially two of the most exciting aspects of the no... more Cell therapy and regenerative medicine are potentially two of the most exciting aspects of the novel therapeutic methods currently under development. However, these treatments present a number of important biosafety issues, like the possible transmission of microorganisms to the recipients. The most common potential form of contamination in these cell products is by bacteria (including Mycoplasma), yeast and fungi. In our study, 32 stem cell lines and feeder cell lines were analysed. There were 19 contaminated cell passages (12%). The main contaminants were gram positive cocci and Mycoplasma species, followed by gram negative rods and gram positive rods. The Mycoplasma contamination rate was 4%. Stem cell banks and other research centres aim to screen all processed stem cell lines for these microorganisms, and to assure that no contaminants are introduced in the banking procedures. It is a standard part of current good practice in stem cell banks to carry out routine microbiological controls of the stem cell lines and to work in a controlled environment to reduce the probability of contamination in the final product.
Nuclear Physics B, 1992
Using the Zaragoza proposal for lattice chiral gauge fermions, the S, U and \Delta\rho parameters... more Using the Zaragoza proposal for lattice chiral gauge fermions, the S, U and \Delta\rho parameters have been calculated at one loop. It is shown that the continuum values for these quantities can be reproduced without requiring explicit fine tuning of counterterms. Furthermore, fermion fields doubling is not necessary. To the best of our knowledge, the Zaragoza proposal is the only scheme which has these properties. A necessary (although not sufficient) symmetry is found to support the calculations. Previous results for some of these parameters in other lattice chiral regularizations are revisited in the light of this symmetry.
Cell stem cell, Jan 7, 2007
Applied Microbiology and Biotechnology, 2006
The processing of stem cell lines for application in human therapy requires a physical environmen... more The processing of stem cell lines for application in human therapy requires a physical environment in which air quality (i.e., the number of airborne particles) is controlled to minimize risk of contamination. The processing facility should be constructed and operated to minimise the introduction, generation and retention of particles and microorganisms. A formal program of environmental monitoring should be maintained in each stem cell bank to specify and assess key factors and their influence on the microbiological quality of the process and product. This program should assure the manipulation of cells involved in the derivation of stem cell lines and their culture under established limits for airborne particles and for microbial contamination of the air and surfaces. Environmental monitoring should also address the regulatory requirements in the countries in which the cells will be used. The monitoring programme will depend on local conditions in each processing centre or cell bank. Each centre will need to evaluate its specific needs and establish appropriate monitoring procedures which should not become intrusive to the extent that they might compromise the quality of the cell banks or products.
Physical Review D, 1997
A general discussion of the renormalization of the quantum theory of a scalar field as an effecti... more A general discussion of the renormalization of the quantum theory of a scalar field as an effective field theory is presented. The renormalization group equations in a mass-independent renormalization scheme allow us to identify the possibility to go beyond the renormalizable φ 4 theory without losing its predictive power. It is shown that there is a minimal extension with just one additional free parameter (the mass scale of the effective theory expansion) and some of its properties are discussed.
Journal of High Energy Physics, 2003
Generalizing the noncommutative harmonic oscillator construction, we propose a new extension of q... more Generalizing the noncommutative harmonic oscillator construction, we propose a new extension of quantum field theory based on the concept of "noncommutative fields". Our description permits to break the usual particle-antiparticle degeneracy at the dispersion relation level and introduces naturally an ultraviolet and an infrared cutoff. Phenomenological bounds for these new energy scales are given.
Physics Letters B, 1998
A generalization to any dimension of the fermion field transformation which allows to derive the ... more A generalization to any dimension of the fermion field transformation which allows to derive the solution of the massless Schwinger model in the path integral framework is identified. New arguments based on this transformation for a Nambu-Jona-Lasinio (NJL) like model as the low energy limit of a gauge theory in dimension greater than two are presented. Our result supports the spontaneous chiral symmetry breaking picture conjectured by Nambu many years ago and the link between QCD, NJL and chiral models.
Physical Review D, 1996
The technique of extended dualization developed in this paper is used to bosonize quantized fermi... more The technique of extended dualization developed in this paper is used to bosonize quantized fermion systems in arbitrary dimension D in the low energy regime. In its original (minimal) form, dualization is restricted to models wherein it is possible to define a dynamical quantized conserved charge. We generalize the usual dualization prescription to include systems with dynamical non-conserved quantum currents.
Role of the embryology laboratory in the human embryonic stem cell line derivation process
Cytotechnology, 2006
With the introduction of regenerative medicine and cell therapy programmes by means of human embr... more With the introduction of regenerative medicine and cell therapy programmes by means of human embryonic stem cells (hESC), several research centres have begun projects of derivation of hESC lines. In some stem cell banks, such as the Andalusian Stem Cell Bank, the law also permits the creation of these cell lines. Therefore, the recovery of cryopreserved embryos, their culture and the subsequent derivation to hESC lines requires a suitable embryology laboratory and specialized and highly qualified staff. Moreover, new techniques, from therapeutic nuclear transfer, need this type of laboratory and staff, too. Several International Associations have drawn up some guidelines for laboratories where embryos are manipulated and they reflect the physical space, the staff and the equipment needed in these kinds of laboratories. Nevertheless, we can see that these guidelines do not distinguish between IVF laboratories and other laboratories that obtain hESC lines, so it would be convenient to make a distinction. Following these guidelines, we have tried to draw up concurrent aspects applicable to areas of embryology within stem cell banks. So, the design and the specific implementation programmes for these areas and other research centres with this area but which do not use IVF techniques is vital to develop embryonic cell lines in optimum conditions for future therapeutic applications, although maybe it is rather premature to standardize this type of research.
Integrative and Comparative Biology, 1985
SYNOPSIS. The secretion of neurohormones from the crustacean X-organ -sinus gland system is contr... more SYNOPSIS. The secretion of neurohormones from the crustacean X-organ -sinus gland system is controlled by environmental influences, light being the most conspicuous. Two sets of photoreceptors appear to mediate the influence of light on neurosecretion based on intracellular recordings from X-organ neurons and estimations of hormone release. Extra-retinal photoreceptors can initiate neurohormonal release from the eyestalk.
Mesenchymal stem cells facilitate the derivation of human embryonic stem cells from cryopreserved poor-quality embryos
Human Reproduction, 2009
Human embryonic stem cells (hESCs) have opened up a new area of research in biomedicine. The effi... more Human embryonic stem cells (hESCs) have opened up a new area of research in biomedicine. The efficiency of hESC derivation from frozen poor-quality embryos is low and normally achieved by plating embryos on mouse or human foreskin feeders (HFFs). We attempted to optimize embryo survival and hESC derivation. Three conditions were tested on frozen poor-quality embryos: (i) embryo treatment with the Rho-associated kinase (ROCK) inhibitor, Y-27632; (ii) use of human mesenchymal stem cells (hMSCs) as feeders; and (iii) laser drilling (LD) for inner cell mass (ICM) isolation. Two hundred and nineteen thawed embryos were randomly treated with (n = 110) or without (n = 109) 10 microM Y-27632. Surviving embryos that developed to blastocyst stage (n = 50) were randomly co-cultured on HFFs (n = 21) or hMSCs (n = 29). ICM isolation was either by whole-blastocyst culture (WBC) or WBC plus LD. Embryo survival was 52% higher with Y-27632. hMSCs appeared to facilitate ICM outgrowth and hESC derivation: three hESC lines were derived on hMSCs (10.3% efficiency) whereas no hESC line was derived on HFFs. ROCK inhibition and ICM isolation method did not affect hESC efficiency. The lines derived on hMSCs (AND-1, -2, -3) were characterized and showed typical hESC morphology, euploidy, surface marker and transcription factor expression and multilineage developmental potential. The hESC lines have been stable for over 38 passages on hMSCs. Our data suggest that Y-27632 increases post-thaw embryo survival and that hMSCs may facilitate the efficiency of hESC derivation from frozen poor-quality embryos.
Applied Microbiology and Biotechnology, 2005
The transplant of cells of human origin is an increasingly complex sector of medicine which entai... more The transplant of cells of human origin is an increasingly complex sector of medicine which entails great opportunities for the treatment of a range of diseases. Stem cell banks should assure the quality, traceability and safety of cultures for transplantation and must implement an effective programme to prevent contamination of the final product. In donors, the presence of infectious micro-organisms, like human immunodeficiency virus, hepatitis B virus, hepatitis C virus and human T cell lymphotrophic virus, should be evaluated in addition to the possibility of other new infectious agents (e.g. transmissible spongiform encephalopathies and severe acute respiratory syndrome). The introduction of the nucleic acid amplification can avoid the window period of these viral infections. Contamination from the laboratory environment can be achieved by routine screening for bacteria, fungi, yeast and mycoplasma by European pharmacopoeia tests. Fastidious micro-organisms, and an adventitious or endogenous virus, is a well-known fact that will also have to be considered for processes involving in vitro culture of stem cells. It is also a standard part of current good practice in stem cell banks to carry out routine environmental microbiological monitoring of the cleanrooms where the cell cultures and their products are prepared. The risk of viral contamination from products of animal origin, like bovine serum and mouse fibroblasts as a “feeder layer” for the development of embryonic cell lines, should also be considered. Stem cell lines should be tested for prion particles and a virus of animal origin that assure an acceptable quality.
Fertility and Sterility, 2009
Cytotechnology, 2007
With the introduction of regenerative medicine and cell therapy programmes by means of human embr... more With the introduction of regenerative medicine and cell therapy programmes by means of human embryonic stem cells (hESC), several research centres have begun projects of derivation of hESC lines. In some stem cell banks, such as the Andalusian Stem Cell Bank, the law also permits the creation of these cell lines. Therefore, the recovery of cryopreserved embryos, their culture and the subsequent derivation to hESC lines requires a suitable embryology laboratory and specialized and highly qualified staff. Moreover, new techniques, from therapeutic nuclear transfer, need this type of laboratory and staff, too. Several International Associations have drawn up some guidelines for laboratories where embryos are manipulated and they reflect the physical space, the staff and the equipment needed in these kinds of laboratories. Nevertheless, we can see that these guidelines do not distinguish between IVF laboratories and other laboratories that obtain hESC lines, so it would be convenient to make a distinction. Following these guidelines, we have tried to draw up concurrent aspects applicable to areas of embryology within stem cell banks. So, the design and the specific implementation programmes for these areas and other research centres with this area but which do not use IVF techniques is vital to develop embryonic cell lines in optimum conditions for future therapeutic applications, although maybe it is rather premature to standardize this type of research.
Cell Biology International, 2007
Cell therapy and regenerative medicine are potentially two of the most exciting aspects of the no... more Cell therapy and regenerative medicine are potentially two of the most exciting aspects of the novel therapeutic methods currently under development. However, these treatments present a number of important biosafety issues, like the possible transmission of microorganisms to the recipients. The most common potential form of contamination in these cell products is by bacteria (including Mycoplasma), yeast and fungi. In our study, 32 stem cell lines and feeder cell lines were analysed. There were 19 contaminated cell passages (12%). The main contaminants were gram positive cocci and Mycoplasma species, followed by gram negative rods and gram positive rods. The Mycoplasma contamination rate was 4%. Stem cell banks and other research centres aim to screen all processed stem cell lines for these microorganisms, and to assure that no contaminants are introduced in the banking procedures. It is a standard part of current good practice in stem cell banks to carry out routine microbiological controls of the stem cell lines and to work in a controlled environment to reduce the probability of contamination in the final product. Ó
A model-independent formulation of anyons as spinning particles is presented. The general propert... more A model-independent formulation of anyons as spinning particles is presented. The general properties of the classical theory of (2+1)-dimensional relativistic fractional spin particles and some properties of their quantum theory are investigated. The relationship between all the known approaches to anyons as spinning particles is established. Some widespread misleading notions on the general properties of (2+1)-dimensional anyons are removed.
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Papers by Jose Luis Cortes