1,228 research outputs found
New insight on the Sivers transverse momentum dependent distribution function
Polarised Semi-Inclusive Deep Inelastic Scattering (SIDIS) processes allow to
study Transverse Momentum Dependent partonic distributions (TMDs), which reveal
a non trivial three dimensional internal structure of the hadrons in momentum
space. One of the most representative of the TMDs is the so-called Sivers
function that describes the distribution of unpolarized quarks inside a
transversely polarized proton. We present a novel extraction of the Sivers
distribution functions from the most recent experimental data of HERMES and
COMPASS experiments. Using suitable parametrizations, within the TMD
factorization scheme, and a simple fitting strategy, we also perform a
preliminary exploration of the role of the proton sea quarks.Comment: Talk delivered by M. Boglione at SPIN2010, September 27-October 2,
2010, Juelich, Germany. Left panel of Fig. 5 replace
Research in the general area of non-linear dynamical systems Final report, 8 Jun. 1965 - 8 Jun. 1967
Nonlinear dynamical systems research on systems stability, invariance principles, Liapunov functions, and Volterra and functional integral equation
Partly burnt runaway stellar remnants from peculiar thermonuclear supernovae
We report the discovery of three stars that, along with the prototype
LP40-365, form a distinct class of chemically peculiar runaway stars that are
the survivors of thermonuclear explosions. Spectroscopy of the four confirmed
LP 40-365 stars finds ONe-dominated atmospheres enriched with remarkably
similar amounts of nuclear ashes of partial O- and Si-burning. Kinematic
evidence is consistent with ejection from a binary supernova progenitor; at
least two stars have rest-frame velocities indicating they are unbound to the
Galaxy. With masses and radii ranging between 0.20-0.28 Msun and 0.16-0.60
Rsun, respectively, we speculate these inflated white dwarfs are the partly
burnt remnants of either peculiar Type Iax or electron-capture supernovae.
Adopting supernova rates from the literature, we estimate that ~20 LP40-365
stars brighter than 19 mag should be detectable within 2 kpc from the Sun at
the end of the Gaia mission. We suggest that as they cool, these stars will
evolve in their spectroscopic appearance, and eventually become peculiar O-rich
white dwarfs. Finally, we stress that the discovery of new LP40-365 stars will
be useful to further constrain their evolution, supplying key boundary
conditions to the modelling of explosion mechanisms, supernova rates, and
nucleosynthetic yields of peculiar thermonuclear explosions.Comment: 22 pages, 14 figures, 6 tables. Accepted for publication on MNRA
Single cell imaging of nuclear architecture changes
This is the final version. Available from Frontiers Media via the DOI in this record.Data and materials availability: Data obtained in this work are available upon request.The dynamic architecture of chromatin, the macromolecular complex comprised primarily of
DNA and histones, is vital for eukaryotic cell growth. Chemical and conformational changes to
chromatin are important markers of functional and developmental processes in cells. However,
chromatin architecture regulation has not yet been fully elucidated. Therefore, novel approaches
to assessing chromatin changes at the single-cell level are required. Here we report the use of
FTIR imaging and microfluidic cell-stretcher chips to assess changes to chromatin architecture
and its effect on the mechanical properties of the nucleus in immune cells. FTIR imaging enables
label-free chemical imaging with subcellular resolution. By optimizing the FTIR methodology
and couple it with cell segmentation analysis approach, we have identified key spectral changes
corresponding to changes in DNA levels and chromatin conformation at the single cell level. By
further manipulating live single cells using pressure-driven microfluidics, we found that
chromatin decondensation – either during general transcriptional activation or during specific
immune cell maturation – can ultimately lead to nuclear auxeticity which is a new biological
phenomenon recently identified. Taken together our findings demonstrate the tight and,
potentially bilateral, link between extra-cellular mechanotransduction and intra-cellular nuclear
architecture.Engineering and Physical Sciences Research Council (EPSRC)Biotechnology and Biological Sciences Research Council (BBSRC)Academy of Medical SciencesRoyal Societ
Complete devil's staircase and crystal--superfluid transitions in a dipolar XXZ spin chain: A trapped ion quantum simulation
Systems with long-range interactions show a variety of intriguing properties:
they typically accommodate many meta-stable states, they can give rise to
spontaneous formation of supersolids, and they can lead to counterintuitive
thermodynamic behavior. However, the increased complexity that comes with
long-range interactions strongly hinders theoretical studies. This makes a
quantum simulator for long-range models highly desirable. Here, we show that a
chain of trapped ions can be used to quantum simulate a one-dimensional model
of hard-core bosons with dipolar off-site interaction and tunneling, equivalent
to a dipolar XXZ spin-1/2 chain. We explore the rich phase diagram of this
model in detail, employing perturbative mean-field theory, exact
diagonalization, and quasiexact numerical techniques (density-matrix
renormalization group and infinite time evolving block decimation). We find
that the complete devil's staircase -- an infinite sequence of crystal states
existing at vanishing tunneling -- spreads to a succession of lobes similar to
the Mott-lobes found in Bose--Hubbard models. Investigating the melting of
these crystal states at increased tunneling, we do not find (contrary to
similar two-dimensional models) clear indications of supersolid behavior in the
region around the melting transition. However, we find that inside the
insulating lobes there are quasi-long range (algebraic) correlations, opposed
to models with nearest-neighbor tunneling which show exponential decay of
correlations
Alleghenian Deformation, Sedimentation, and Metamorphism in Southeastern Massachusetts and Rhode Island
Guidebook for field trips to the Boston area and vicinity : 68th annual meeting, New England Intercollegiate Geological Conference, October 8-10, 1976: Trip F-
Desempenho do cultivo da berinjela em plantio direto submetida a diferentes lâminas de irrigação.
Este estudo foi conduzido no municĂpio de SeropĂ©dica, RJ, com o objetivo de se determinar, em cultivo
orgânico e sistema de plantio direto, a produtividade da cultura da berinjela sob diferentes lâminas de
irrigação e sistemas de cultivo (consorciada com leguminosa e solteira). O delineamento experimental
adotado foi o de blocos ao acaso, no esquema de parcela subdividida com quatro repetições
caracterizando, na parcela, os tratamentos equivalentes à lâmina de irrigação (40; 70; 100 e 120% ETc)
e, na subparcela, os sistemas de cultivo consorciado com feijĂŁo caupi e solteiro. Ambos os sistemas de
cultivo nĂŁo influenciaram a produtividade final da berinjela; no entanto, considerando as diferentes
lâminas, a maior produtividade comercial foi de 65,41 Mg ha-1, obtida para uma lâmina total de 690,04
mm (106,8% ETc). A menor lâmina aplicada resultou em qualidade inferior dos frutos em relação à s
maiores lâminas, sendo a taxa de descarte dos frutos de 3 e 14%, respectivamente, para a maior e a
menor lâmina
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