402 research outputs found
Ab initio analysis of the x-ray absorption spectrum of the myoglobin-carbon monoxide complex: Structure and vibrations
We present a comparison between Fe K-edge x-ray absorption spectra of
carbonmonoxy-myoglobin and its simulation based on density-functional theory
determination of the structure and vibrations and spectral simulation with
multiple-scattering theory. An excellent comparison is obtained for the main
part of the molecular structure without any structural fitting parameters. The
geometry of the CO ligand is reliably determined using a synergic approach to
data analysis. The methodology underlying this approach is expected to be
especially useful in similar situations in which high-resolution data for
structure and vibrations are available.Comment: 13 pages, 3 figure
Flexible Lipid Bilayers in Implicit Solvent
A minimalist simulation model for lipid bilayers is presented. Each lipid is
represented by a flexible chain of beads in implicit solvent. The hydrophobic
effect is mimicked through an intermolecular pair potential localized at the
``water''/hydrocarbon tail interface. This potential guarantees realistic
interfacial tensions for lipids in a bilayer geometry. Lipids self assemble
into bilayer structures that display fluidity and elastic properties consistent
with experimental model membrane systems. Varying molecular flexibility allows
for tuning of elastic moduli and area/molecule over a range of values seen in
experimental systems.Comment: 5 pages, 5 figure
ESPACIOS, TRADICIONES Y CAMBIOS EN CONCHUCOS. Ecos desde la Escuela de etnografía del Proyecto “Antonio Raimondi”, Ancash Perú
Este volumen nace con dos finalidades precisas. La primera, dar a conocer los trabajos de investigación etnográfica que un grupo de nueve estudiantes de la Universidad de Bologna (Italia) y otro de la Pontificia Universidad Católica del Perú han desarrollado en la provincia de Huari, Ancash, Perú, durante seis años, entre 2003 y 2008 en el marco del Proyecto Arqueológico y Antropológico “Antonio Raimondi”. La segunda finalidad es realizar la difusión de las únicas miradas etnográficas que hasta hoy se han producido sobre la región Conchucos.
Otro objetivo, más teórico y más implícito, es desplegar a lo largo del camino de la lectura de los casos etnográficos, una visión processual y dinamista de la escritura etnográfica y de la especulación antropológica, procedente de una manera precisa de hacer trabajo de campo. Los artículos aquí propuestos presentan, mediante varios estilos y diferentes acercamientos, una realidad sociocultural en movimiento, en constante cambio. Construyendo cuadros de varios aspectos sociales, políticos y culturales de la provincia de Huari, los autores delinean un escenario en proceso en el cual diferentes actores, ámbitos y dinámicas socioculturales se interrelacionan, participando de maneras diferents en la transformación
Fauna de Lepidoptera associada a plantas lactíferas do cerrado
Nine lactiferous plants of five families were examined for caterpillars in a 4 ha cerrado sensu stricto (savanna-like vegetation) area of the University of Brasília Experimental Farm (DF, Brazil), from August 1995 to May 1997. In 5,540 censuses, less than 5% of the plants hosted caterpillars. All the caterpillars found, a total of 55 species in 15 families were reared under laboratory conditions. Pyralidae, Geometridae, Elachistidae, Megalopygidae, and Limacodidae were the richest caterpillar families recorded. Of the 55 species, more than 40% were polyphagous, feeding on different host plant families, while 21 were considered rare species with less than four records during the study period. The species' rareness did not permit any analysis of diet breadth. The presence of latex in the host plants seems to affect both the proportion of host plants with caterpillars (abundance) and the caterpillar species richness. The habit of eating plants that characteristically produce latex occurs in several distantly-related lepidopteran families. The results support the argument that specific behaviors to circumvent plant latex defense may have arisen independently many times in the Lepidoptera.Nove espécies de cinco famílias de plantas hospedeiras lactíferas foram examinadas, a procura de lagartas, em uma área de cerca de 4 ha de cerrado sensu stricto na Fazenda Água Limpa da Universidade de Brasília, DF, Brasil, de agosto de 1995 a maio de 1997. Foram realizados 5.540 censos e em menos de 5% das plantas hospedeiras foram encontradas lagartas. Todas as lagartas encontradas foram criadas em condições de laboratório. No laboratório emergiram 55 espécies de 15 famílias de Lepidoptera. As famílias mais comuns foram Pyralidae, Geometridae, Elachistidae, Megalopygidae e Limacodidae. Do total de 55 espécies mais de 40% são certamente polífagas. Entretanto, 21 espécies podem ser consideradas raras com menos de quatro ocorrências, o que impede uma análise de dieta. De um modo geral a presença de látex nas plantas hospedeiras parece afetar a abundância e a riqueza de espécies de Lepidoptera. Espécies de Lepidoptera de famílias distantes filogeneticamente foram encontradas alimentando-se dessas plantas lactíferas, o que corrobora a sugestão de que comportamentos específicos desenvolvidos para alimentar-se de plantas com látex tenham evoluido várias vezes entre os lepidópteros
Therapeutic androgen receptor ligands
In the past several years, the concept of tissue-selective nuclear receptor ligands has emerged. This concept has come to fruition with estrogens, with the successful marketing of drugs such as raloxifene. The discovery of raloxifene and other selective estrogen receptor modulators (SERMs) has raised the possibility of generating selective compounds for other pathways, including androgens (that is, selective androgen receptor modulators, or SARMs)
Prevalence and type distribution of human papillomavirus infection in women from North Sardinia, Italy
<p>Abstract</p> <p>Background</p> <p>Human papillomavirus (HPV) has been associated with several disorders of the genital tract, skin and oropharynx. The aims of our study were to evaluate the prevalence of HPV infection in women between 15 and 54 years of age in North Sardinia, Italy, to identify the prevalence of High Risk - Human papillomaviruses (HR-HPV) genotypes and to establish a correlation between molecular and cytological results.</p> <p>Methods</p> <p>From 2007 to 2009 we consecutively enrolled women aged 15-54 years admitted to public and private outpatient settings. All the participants filled in a questionnaire about the socio-cultural state, sexual activity and awareness about HPV. 323 cervical specimens were tested for HPV-DNA and HPV genotypes with INNO-LiPA HPV Genotyping CE Amp kit. Samples showing positivity to some HPV genotypes were re-tested using "in house" quantitative Real-Time PCR assays.</p> <p>Results</p> <p>Overall HPV-DNA positivity was detected in 35.9% of the women. The prevalence of HR-HPV infection among HPV positive samples was 93.1% with a specific prevalence of HPV 16, 51, 31, 53 and 18 of 54.3%, 37.9%, 10.3%, 6.9% and 5.2%, respectively. Co-infection with any HPV, HR-HPV, LR-HPV and HR/LR-HPV type was 18.3%, 14.9%, 0.9% and 2.5%, respectively; HPV 16/51 co-infection was detected in 64.6% of the HR-HPV co-infection group. The most frequent HPV-genotypes detected were 16 (32.5%) and 51 (22.7%). Among the 57 patients harboring mono-infection the most prevalent HPV genotypes were 16 (38.6%) and 31(10.5%). A multivariate analysis identified a statistical significant association between HPV infection and age and between HPV infection and previous sexual transmitted diseases. A statistically significant association between cytological cervical lesions and generic HPV exposure was identified.</p> <p>Conclusions</p> <p>To our knowledge, this is the first survey evaluating the prevalence of HPV infection in Northern Sardinia and drawing attention to the unusual high proportion of genotype HPV 51. Given the recent implementation of a widespread immunization program with vaccines not containing HPV 51, it has been relevant to prove the high prevalence of this HPV genotype from the start of the vaccination campaign, in order to avoid in the future attributing to the vaccination program a possible selection effect (HPV replacement).</p
Multi-Particle Collision Dynamics -- a Particle-Based Mesoscale Simulation Approach to the Hydrodynamics of Complex Fluids
In this review, we describe and analyze a mesoscale simulation method for
fluid flow, which was introduced by Malevanets and Kapral in 1999, and is now
called multi-particle collision dynamics (MPC) or stochastic rotation dynamics
(SRD). The method consists of alternating streaming and collision steps in an
ensemble of point particles. The multi-particle collisions are performed by
grouping particles in collision cells, and mass, momentum, and energy are
locally conserved. This simulation technique captures both full hydrodynamic
interactions and thermal fluctuations. The first part of the review begins with
a description of several widely used MPC algorithms and then discusses
important features of the original SRD algorithm and frequently used
variations. Two complementary approaches for deriving the hydrodynamic
equations and evaluating the transport coefficients are reviewed. It is then
shown how MPC algorithms can be generalized to model non-ideal fluids, and
binary mixtures with a consolute point. The importance of angular-momentum
conservation for systems like phase-separated liquids with different
viscosities is discussed. The second part of the review describes a number of
recent applications of MPC algorithms to study colloid and polymer dynamics,
the behavior of vesicles and cells in hydrodynamic flows, and the dynamics of
viscoelastic fluids
An Inka Offering at Yayno (North Highlands, Peru): Objects, Subjects and Gifts in the Ancient Andes
While Marcel Mauss's landmark essay on The Gift has been vital in social anthropology, inspiring a vast and influential secondary literature, the gift has been much less prominent in archaeological interpretation. This study considers evidence for an ancient Andean gift economy, a system of reciprocal exchanges focused on making people and ensuring group social relations, rather than accumulating wealth/capital. Excavations at Yayno (north highlands, Ancash, Peru) revealed two features dating to the time of the Inkas: 1) a slab-lined cist burial; and 2) an offering deposit containing abundant long-distance trade and sumptuary items. Besides its mountaintop location, the burial's intrusive character and foreign items indicate that the offerings were made to propitiate the place, ruins and their divine aspect. This essay studies the reciprocal acts that led to the offerings, comparing them to gifting patterns in Inka human sacrifices known as capac hucha. The key actors in the exchange were children, divinities, Inka bureaucrats, local leaders and state subjects
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