220 research outputs found
Estimation of protein folding probability from equilibrium simulations
The assumption that similar structures have similar folding probabilities
() leads naturally to a procedure to evaluate for every
snapshot saved along an equilibrium folding-unfolding trajectory of a
structured peptide or protein. The procedure utilizes a structurally
homogeneous clustering and does not require any additional simulation. It can
be used to detect multiple folding pathways as shown for a three-stranded
antiparallel -sheet peptide investigated by implicit solvent molecular
dynamics simulations.Comment: 7 pages, 4 figures, supplemetary material
New approach of fragment charge correlations in 129Xe+(nat)Sn central collisions
A previous analysis of the charge (Z) correlations in the
plane for Xe+Sn central collisions at 32 MeV/u has shown an enhancement in the
production of equally sized fragments (low ) which was interpreted as
an evidence for spinodal decomposition. However the signal is weak and rises
the question of the estimation of the uncorrelated yield. After a critical
analysis of its robustness, we propose in this paper a new technique to build
the uncorrelated yield in the charge correlation function. The application of
this method to Xe+Sn central collision data at 32, 39, 45 and 50 MeV/u does not
show any particular enhancement of the correlation function in any
bin.Comment: 23 pages, 9 figures, revised version with an added figure and minor
changes. To appear in Nuclear Physics
Evaluation of lung flute in sputum samples for molecular analysis of lung cancer
BACKGROUND: Molecular analysis of sputum provides a promising approach for lung cancer diagnosis, yet is limited by the difficulty in collecting the specimens from individuals who can’t spontaneously expectorate sputum. Lung Flute is a small self-powered audio device that can induce sputum by generating sound waves and vibrating in the airways of the lungs. Here we propose to evaluate the usefulness of Lung Flute for sputum sampling to assist diagnosis of lung cancer. METHODS: Forty-three stage I lung cancer patients and 47 cancer-free individuals who couldn’t spontaneously cough sputum were instructed to use Lung Flute for sputum sampling. Expressions of two microRNAs, miRs-31 and 210, were determined in the specimens by qRT-PCR. The results were compared with sputum cytology. RESULTS: Sputum was easily collected from 39 of 43 (90.7%) lung cancer patients and 42 of 47 (89.4%) controls with volume ranges from 1 to 5 ml (median, 2.6 ml). The specimens had less than 4% oral squamous cells, indicating that sputum was obtained from low respiratory tract. Expressions of miRs-31 and 210 in sputum were considerably higher in cancer patients than cancer-free individuals (8.990 vs. 4.514; 0.6847 vs. 0.3317; all P <0.001). Combined use of the two miRNAs produced a significantly higher sensitivity (61.5% vs. 35.9%, P = 0.002) and a slightly lower specificity (90.5% vs. 95.2%, p = 0.03) compared with cytology for lung cancer diagnosis. CONCLUSION: Lung Flute could potentially be useful in convenient and efficient collection of sputum for molecular diagnosis of lung cancer
Freeze-out volume in multifragmentation - dynamical simulations
Stochastic mean-field simulations for multifragmenting sources at the same
excitation energy per nucleon have been performed. The freeze-out volume, a
concept which needs to be precisely defined in this dynamical approach, was
shown to increase as a function of three parameters: freeze-out instant,
fragment multiplicity and system size.Comment: Submitted to Eur. Phys. J. A - march 200
Evidence for Spinodal Decomposition in Nuclear Multifragmentation
Multifragmentation of a ``fused system'' was observed for central collisions
between 32 MeV/nucleon 129Xe and natSn. Most of the resulting charged products
were well identified thanks to the high performances of the INDRA 4pi array.
Experimental higher-order charge correlations for fragments show a weak but non
ambiguous enhancement of events with nearly equal-sized fragments. Supported by
dynamical calculations in which spinodal decomposition is simulated, this
observed enhancement is interpreted as a ``fossil'' signal of spinodal
instabilities in finite nuclear systems.Comment: 4 pages, 4 figures, to be published in Phys. Rev. Letter
Primer Acuerdo Nacional de Referentes para la Prevención de las Complicaciones y del Diagnóstico y Tratamiento de la Toxoplasmosis
El presente trabajo es un relato de experiencia de la reunión realizada en la ciudad de Alta Gracia, Córdoba, donde se llevo cabo el “1er Acuerdo Nacional de Referentes para la Prevención de las Complicaciones y del Diagnóstico y Tratamiento de la Toxoplasmosis”. Se discutieron conocimientos validados por la literatura científica como base para propuestas racionales de diagnóstico.
Los objetivos del acuerdo fueron: discutir y reflexionar sobre las prácticas y diagnóstico de la Toxoplasmosis en el sistema público nacional, consensuar y proponer un algoritmo de diagnóstico para el sistema público, analizar la brecha entre el nivel de conocimiento y la aplicación de practicas y procedimientos en la población general y en los grupos de riesgo, discutir y proponer actividades destinadas a identificar el riesgo de transmisión vertical con el fin de proponer estrategias de tamizaje adecuados a la prevalencia nacional, proponer actividades para reducir la brecha conocimiento/aplicación de ese conocimiento en un marco de equidad.
Los profesionales referentes acordaron la firma del Acta de Alta Gracia que contempla para la red pública de atención médica el diagnóstico de Toxoplasmosis con equidad, calidad, acceso a metodologías complejas, cooperación y asesoría técnica y disponibilidad oportuna de insumos en casos de emergencias jurisdiccionales
Multifragmentation of a very heavy nuclear system (II): bulk properties and spinodal decomposition
The properties of fragments and light charged particles emitted in
multifragmentation of single sources formed in central 36AMeV Gd+U collisions
are reviewed. Most of the products are isotropically distributed in the
reaction c.m. Fragment kinetic energies reveal the onset of radial collective
energy. A bulk effect is experimentally evidenced from the similarity of the
charge distribution with that from the lighter 32AMeV Xe+Sn system. Spinodal
decomposition of finite nuclear matter exhibits the same property in simulated
central collisions for the two systems, and appears therefore as a possible
mechanism at the origin of multifragmentation in this incident energy domain.Comment: 28 pages including 14 figures; submitted to Nucl. Phys.
Mechanical and chemical spinodal instabilities in finite quantum systems
Self consistent quantum approaches are used to study the instabilities of
finite nuclear systems. The frequencies of multipole density fluctuations are
determined as a function of dilution and temperature, for several isotopes. The
spinodal region of the phase diagrams is determined and it appears that
instabilities are reduced by finite size effects. The role of surface and
volume instabilities is discussed. It is indicated that the important chemical
effects associated with mechanical disruption may lead to isospin
fractionation.Comment: 4 pages, 4 figure
Fragment size correlations in finite systems - application to nuclear multifragmentation
We present a new method for the calculation of fragment size correlations in
a discrete finite system in which correlations explicitly due to the finite
extent of the system are suppressed. To this end, we introduce a combinatorial
model, which describes the fragmentation of a finite system as a sequence of
independent random emissions of fragments. The sequence is accepted when the
sum of the sizes is equal to the total size. The parameters of the model, which
may be used to calculate all partition probabilities, are the intrinsic
probabilities associated with the fragments. Any fragment size correlation
function can be built by calculating the ratio between the partition
probabilities in the data sample (resulting from an experiment or from a Monte
Carlo simulation) and the 'independent emission' model partition probabilities.
This technique is applied to charge correlations introduced by Moretto and
collaborators. It is shown that the percolation and the nuclear statistical
multifragmentaion model ({\sc smm}) are almost independent emission models
whereas the nuclear spinodal decomposition model ({\sc bob}) shows strong
correlations corresponding to the break-up of the hot dilute nucleus into
nearly equal size fragments
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