214 research outputs found
Influence of climate change and human activities on the organic and inorganic composition of peat during the ‘Little Ice Age’ (El Payo mire, W Spain)
Acknowledgements We are grateful to Ana Moreno, Mariano Barriendos and Gerardo Benito who kindly provided us data included in Figure 5a. We also want to thank the two anonymous reviewers for their constructive comments. Funding This work was funded by the projects HAR2013-43701-P (Spanish Economy and Competitiveness Ministry) and CGL2010-20672 (Spanish Ministry of Science and Innovation). This research was also partially developed with Xunta de Galicia funding (grants R2014/001 and GPC2014/009). N Silva-Sánchez is currently supported by an FPU pre-doctoral grant (AP2010-3264) funded by the Spanish Government.Peer reviewedPostprin
On the Rees-Sciama effect: maps and statistics
Small maps of the Rees-Sciama (RS) effect are simulated by using an
appropriate N-body code and a certain ray-tracing procedure. A method designed
for the statistical analysis of cosmic microwave background (CMB) maps is
applied to study the resulting simulations. These techniques, recently proposed
--by our team-- to consider lens deformations of the CMB, are adapted to deal
with the RS effect. This effect and the deviations from Gaussianity associated
to it seem to be too small to be detected in the near future. This conclusion
follows from our estimation of both the RS angular power spectrum and the RS
reduced n-direction correlation functions for n<7.Comment: 11 pages, 13 figures, to appear in MNRA
Microwave background anisotropies and non-linear structures II. Numerical computations
A new method for modelling spherically symmetric inhomogeneities is applied
to the formation of clusters in an expanding Universe. We impose simple initial
velocity and density perturbations of finite extent and we investigate the
subsequent evolution of the density field. Photon paths are also calculated,
allowing a detailed consideration of gravitational lensing effects and
microwave background anisotropies induced by the cluster. We apply the method
to modelling high-redshift clusters and, in particular, we consider the
reported microwave decrement observed towards the quasar pair PC1643+4631 A&B.
We also consider the effect on the primordial microwave background power
spectrum due to gravitational lensing by a population of massive high-redshift
clusters.Comment: 15 pages, 23 figures; Monthly Notices of the Royal Astronomical
Society (MNRAS), in pres
Microwave Background Anisotropies and Nonlinear Structures I. Improved Theoretical Models
A new method is proposed for modelling spherically symmetric inhomogeneities
in the Universe. The inhomogeneities have finite size and are compensated, so
they do not exert any measurable gravitational force beyond their boundary. The
region exterior to the perturbation is represented by a
Friedmann-Robertson-Walker (FRW) Universe, which we use to study the anisotropy
in the cosmic microwave background (CMB) induced by the cluster. All
calculations are performed in a single, global coordinate system, with
nonlinear gravitational effects fully incorporated. An advantage of the gauge
choices employed here is that the resultant equations are essentially Newtonian
in form. Examination of the problem of specifying initial data shows that the
new model presented here has many advantages over `Swiss cheese' and other
models. Numerical implementation of the equations derived here is described in
a subsequent paper.Comment: 10 pages, 4 figures; Monthly Notices of the Royal Astronomical
Society (MNRAS), in pres
Stoichiometric and irreversible cysteine-selective protein modification using carbonylacrylic reagents
Maleimides remain the reagents of choice for the preparation of therapeutic and imaging protein conjugates despite the known instability of the resulting products that undergo thiol-exchange reactions . Here we present the rational design of carbonylacrylic reagents for chemoselective cysteine bioconjugation. These reagents undergo rapid thiol Michael-addition under biocompatible conditions in stoichiometric amounts. When using carbonylacrylic reagents equipped with PEG or fluorophore moieties, this method enables access to protein and antibody conjugates precisely modified at pre-determined sites. Importantly, the conjugates formed are resistant to degradation in plasma and are biologically functional, as demonstrated by the selective imaging and detection of apoptotic and HER2+ cells, respectively. The straightforward preparation, stoichiometric use and exquisite cysteine selectivity of the carbonylacrylic reagents combined with the stability of the products and the availability of biologically relevant cysteine-tagged proteins make this method suitable for the routine preparation of chemically defined conjugates for applications.FAPESP (Grant IDs: 2012/22274-2; BEPE 2015/07509-1, 2013/25504-1), Xunta de Galicia, FCT Portugal (FCT Investigator, SFRH/BPD/103172/2014 Postdoctoral fellowship, SFRH/BD/111556/2015 PhD Studentship), European Union (Marie-Sklodowska Curie ITN Protein Conjugates), Engineering and Physical Sciences Research Council, MECD (‘Salvador Madariaga’ mobility grant PRX15/00638), MINECO (CTQ2015-70524-R, RYC-2013-14706 ), Royal Society, European Research Council Starting Grant (TagIt
Microwave background anisotropies due to non-linear structures in open and Lambda universes
A new method arising from a gauge-theoretic approach to general relativity is
applied to the formation of clusters in an expanding universe. The three
cosmological models (Omega_0=1, Omega_Lambda=0), (Omega_0=0.3,
Omega_Lambda=0.7), (Omega_0=0.3, Omega_Lambda=0) are considered, which extends
our previous application (Lasenby et al. 1999
-"http://xxx.soton.ac.uk/abs/astro-ph/9810123"-, Dabrowski et al. 1999
-"http://xxx.soton.ac.uk/abs/astro-ph/9810149"-). A simple initial velocity and
density perturbation of finite extent is imposed at the epoch z=1000 and we
investigate the subsequent evolution of the density and velocity fields for
clusters observed at redshifts z=1, z=2 and z=3. Photon geodesics and redshifts
are also calculated so that the Cosmic Microwave Background (CMB) anisotropies
due to collapsing clusters can be estimated. We find that the central CMB
temperature decrement is slightly stronger and extends to larger angular scales
in the non-zero Omega_Lambda case. This effect is strongly enhanced in the open
case. Gravitational lensing effects are also considered and we apply our model
to the reported microwave decrement observed towards the quasar pair PC
1643+4631 A & B.Comment: 9 pages, 9 figures. Submitted to Monthly Notices of the Royal
Astronomical Society (MNRAS
Enhanced Permeability and Binding Activity of Isobutylene-Grafted Peptides.
We present a new peptide-macrocyclization strategy with an isobutylene graft. The reaction is mild and proceeds rapidly and efficiently both for linear and cyclic peptides. The resulting isobutylene-grafted peptides possess improved passive membrane permeability due to the shielding of the polar backbone of the amides, as demonstrated by NMR spectroscopy and molecular dynamics simulations. The isobutylene-stapled structures are fully stable in human plasma and in the presence of glutathione. This strategy can be applied to bioactive cyclic peptides such as somatostatin. Importantly, we found that structural preorganization forced by the isobutylene graft leads to a significant improvement in binding. The combined advantages of directness, selectivity, and smallness could allow application to peptide macrocyclization based on this attachment of the isobutylene graft
First record of the alien pest Rhaponticum repens (Compositae) in the Iberian Peninsula
First record of the alien pest Rhaponticum repens (Compositae) in the Iberian Peninsula.- Rhaponticum repens is reported for the first time for the flora of the Iberian Peninsula. The species is native from Central Asia and has become invasive in Argentina, Canada, Europe and the USA. It was detected for the first time in abandoned fields from Vilablareix, near the city of Girona (Catalonia, Spain) and in the valley of the Vinalopó in Alicante (Valencia, Spain), where it was collected as early as in 1959 but misdentified. Molecular data, based on nrDNA region ITS, suggest that the reported populations may be closely related to plants from the United States. Due to the extremely noxious character of the species and the possible relationship of Spanish plants with the invasive American populations, some kind of monitoring is recommended.Rhaponticum repens (Compositae), una nueva planta alóctona para la Península Ibérica.- Se cita por primera vez la especie Rhaponticum repens para la flora de la Península Ibérica. Rhaponticum repens es una especie nativa de Asia central que actúa como invasora en diversos países como Argentina, Canadá o los Estados Unidos. Se ha encontrado por primera vez en campos de cultivo abandonados en el pueblo de Vilablareix, cerca de la ciudad de Girona (Cataluña, España) y en el valle del Vinalopó (Valencia, España), donde fue recolectada y mal identificada en 1959. Los datos moleculares, obtenidos a partir de la región ITS del nrDNA, sugieren que estas poblaciones podrían estar relacionadas con plantas invasoras de Estados Unidos. Debido al carácter extremadamente invasor de la especie, y a su posible origen secundario a partir de las poblaciones norteamericanas, se recomienda el seguimiento de estas poblacione
Assisted Diagnosis of Parkinsonism Based on the Striatal Morphology
Parkinsonism is a clinical syndrome characterized by the progressive loss of striatal dopamine. Its diagnosis
is usually corroborated by neuroimaging data such as DaTSCAN neuroimages that allow visualizing
the possible dopamine deficiency. During the last decade, a number of computer systems have been
proposed to automatically analyze DaTSCAN neuroimages, eliminating the subjectivity inherent to the
visual examination of the data. In this work, we propose a computer system based on machine learning
to separate Parkinsonian patients and control subjects using the size and shape of the striatal region,
modeled from DaTSCAN data. First, an algorithm based on adaptative thresholding is used to parcel
the striatum. This region is then divided into two according to the brain hemisphere division and characterized
with 152 measures, extracted from the volume and its three possible 2-dimensional projections.
Afterwards, the Bhattacharyya distance is used to discard the least discriminative measures and, finally,
the neuroimage category is estimated by means of a Support Vector Machine classifier. This method was
evaluated using a dataset with 189 DaTSCAN neuroimages, obtaining an accuracy rate over 94%. This
rate outperforms those obtained by previous approaches that use the intensity of each striatal voxel as
a feature.This work was supported by the MINECO/
FEDER under the TEC2015-64718-R project, the
Ministry of Economy, Innovation, Science and
Employment of the Junta de Andaluc´ıa under the
P11-TIC-7103 Excellence Project and the Vicerectorate
of Research and Knowledge Transfer of the
University of Granada
Deciphering the Non-Equivalence of Serine and Threonine O-Glycosylation Points: Implications for Molecular Recognition of the Tn Antigen by an anti-MUC1 Antibody
© 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. The structural features of MUC1-like glycopeptides bearing the Tn antigen (α-O-GalNAc-Ser/Thr) in complex with an anti MUC-1 antibody are reported at atomic resolution. For the α-O-GalNAc-Ser derivative, the glycosidic linkage adopts a high-energy conformation, barely populated in the free state. This unusual structure (also observed in an α-S-GalNAc-Cys mimic) is stabilized by hydrogen bonds between the peptidic fragment and the sugar. The selection of a particular peptide structure by the antibody is thus propagated to the carbohydrate through carbohydrate/peptide contacts, which force a change in the orientation of the sugar moiety. This seems to be unfeasible in the α-O-GalNAc-Thr glycopeptide owing to the more limited flexibility of the side chain imposed by the methyl group. Our data demonstrate the non-equivalence of Ser and Thr O-glycosylation points in molecular recognition processes. These features provide insight into the occurrence in nature of the APDTRP epitope for anti-MUC1 antibodies.Peer Reviewe
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