271 research outputs found
Effect of Disorder and Notches on Crack Roughness
We analyze the effect of disorder and notches on crack roughness in two
dimensions. Our simulation results based on large system sizes and extensive
statistical sampling indicate that the crack surface exhibits a universal local
roughness of and is independent of the initial notch size
and disorder in breaking thresholds. The global roughness exponent scales as
and is also independent of material disorder. Furthermore, we
note that the statistical distribution of crack profile height fluctuations is
also independent of material disorder and is described by a Gaussian
distribution, albeit deviations are observed in the tails.Comment: 6 pages, 6 figure
Measuring functional renormalization group fixed-point functions for pinned manifolds
Exact numerical minimization of interface energies is used to test the
functional renormalization group (FRG) analysis for interfaces pinned by
quenched disorder. The fixed-point function R(u) (the correlator of the
coarse-grained disorder) is computed. In dimensions D=d+1, a linear cusp in
R''(u) is confirmed for random bond (d=1,2,3), random field (d=0,2,3), and
periodic (d=2,3) disorders. The functional shocks that lead to this cusp are
seen. Small, but significant, deviations from 1-loop FRG results are compared
to 2-loop corrections. The cross-correlation for two copies of disorder is
compared with a recent FRG study of chaos.Comment: 4 pages, 4 figure
Clinical and Molecular Features of Ewing Sarcoma in a Patient with Triple-X Syndrome
A case of Ewing sarcoma in a 16-year-old girl with 47 XXXc karyotype is reporte
Congenital infiltrating lipoma of the upper limb in a patient with von Willebrand disease
Infiltrating lipoma is a rare variety of lipoma, characterized by an infiltration of the adipose tissue of the muscles. Infiltrating lipomas are usually classified in two groups: intermuscular infiltrating lipoma and intramuscular infiltrating lipoma. Most are acquired, and they usually appear in middle-aged individuals. Exceptionally, they are congenital. In such cases they are not related to other diseases. We report an 8-year-old boy with a congenital infiltrating lipoma of the upper limb and von Willebrand disease. Both diseases are linked to an alteration in chromosome 12, but this clinical association seems to be random rather than causal
Insuficiencia respiratoria neonatal asociada a mutación en el gen de la proteína C del surfactante
La insuficiencia respiratoria en el recién nacido a término
durante las primeras semanas de vida extrauterina
es una situación poco frecuente. Entre sus causas se incluyen
las enfermedades difusas del intersticio pulmonar, un
grupo heterogéneo de enfermedades, la mayoría idiopáticas,
caracterizadas por infiltrados difusos, alteraciones
funcionales de tipo restrictivo y afectación del intercambio
gaseoso. Una forma de enfermedad pulmonar intersticial
que puede afectar a lactantes, niños o adultos jóvenes
es la que se asocia al déficit congénito de proteínas B o C
del surfactante pulmonar. En estos casos los procesos inflamatorios
que evolucionan hacia la fibrosis pulmonar están
precedidos por la acumulación de material proteináceo
en el alvéolo.
Se indagó la presencia de mutaciones en los genes de
las proteínas B y C del surfactante en una familia española
en la cual dos lactantes presentaron insuficiencia
respiratoria progresiva desde el nacimiento, con alteraciones
radiológicas y anatomopatológicas compatibles
con enfermedad del intersticio pulmonar, y el padre
refería historia de problemas respiratorios desde la infancia.
Se encontró que los dos hermanos de esta familia afectados
por la enfermedad presentaban una expresión anómala
del precursor de la proteína C del surfactante y concentraciones
muy bajas de proteína madura. Se describe
además una mutación nueva en el gen que codifica la proteína
C del surfactante y que cosegrega con la enfermedad
en esta familia
Morphology of two dimensional fracture surface
We consider the morphology of two dimensional cracks observed in experimental
results obtained from paper samples and compare these results with the
numerical simulations of the random fuse model (RFM). We demonstrate that the
data obey multiscaling at small scales but cross over to self-affine scaling at
larger scales. Next, we show that the roughness exponent of the random fuse
model is recovered by a simpler model that produces a connected crack, while a
directed crack yields a different result, close to a random walk. We discuss
the multiscaling behavior of all these models.Comment: slightly revise
Ewing Family Tumors: Potential Prognostic Value of Reverse-Transcriptase Polymerase Chain Reaction Detection of Minimal Residual Disease in Peripheral Blood Samples
In more than 95% of patients, the Ewing family of tumors (ET) has chimeric
transcripts caused by fusion of the EWS gene to either FLI1 or ERG. The presence
of specific EWS-FLI1 or EWS-ERG transcripts in peripheral blood (PB) samples of
patients being treated for ET was prospectively evaluated, and these data were
correlated to their clinical status. The authors studied 113 PB samples from 28
patients with ET. Treatment included chemotherapy, radiotherapy, and surgical
excision of tumor after induction therapy. PB samples were taken prospectively at
least 2 weeks after resection of tumor. Nested reverse-transcriptase polymerase
chain reaction (RT-PCR) followed by Southern blot was performed in all samples.
Resected tumors were reviewed for the degree of response to chemotherapy and
volume. Seventy-seven PB samples from 28 patients had EWS-FLI1/ERG transcripts.
In 11 patients, PB samples became negative with treatment, and, in 5 of them, the
samples remained negative throughout the study. Samples taken during progression
were always positive and, in 4 patients, became positive before progression was
clinically evident. All patients with transcripts other than EWS-FLI1 type 1 (n =
3) died from tumor progression. This is a sensitive assay to monitor circulating
tumor cells in Ewing tumors. The preliminary data suggest that progression is
preceded by positive samples and may be related to specific transcript types
Size effects in statistical fracture
We review statistical theories and numerical methods employed to consider the
sample size dependence of the failure strength distribution of disordered
materials. We first overview the analytical predictions of extreme value
statistics and fiber bundle models and discuss their limitations. Next, we
review energetic and geometric approaches to fracture size effects for
specimens with a flaw. Finally, we overview the numerical simulations of
lattice models and compare with theoretical models.Comment: review article 19 pages, 5 figure
Characterization of human mesenchymal stem cells from Ewing sarcoma patients. Pathogenetic implications
Ewing Sarcoma (EWS) is a mesenchymal-derived tumor that generally arises in bone and soft tissue. Intensive research regarding the pathogenesis of EWS has been insufficient to pinpoint the early events of Ewing sarcomagenesis. However, the Mesenchymal Stem Cell (MSC) is currently accepted as the most probable cell of origin
Crack Roughness in the 2D Random Threshold Beam Model
We study the scaling of two-dimensional crack roughness using large scale
beam lattice systems. Our results indicate that the crack roughness obtained
using beam lattice systems does not exhibit anomalous scaling in sharp contrast
to the simulation results obtained using scalar fuse lattices. The local and
global roughness exponents ( and , respectively) are equal
to each other, and the two-dimensional crack roughness exponent is estimated to
be . Removal of overhangs (jumps) in the
crack profiles eliminates even the minute differences between the local and
global roughness exponents. Furthermore, removing these jumps in the crack
profile completely eliminates the multiscaling observed in other studies. We
find that the probability density distribution of the
height differences of the crack profile
obtained after removing the jumps in the profiles follows a Gaussian
distribution even for small window sizes ().Comment: 8 pages, 6 figure
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