6,923 research outputs found
Anti-programmed cell death protein-1/ligand-1 therapy in different cancers.
Immunologic checkpoint blockade with antibodies against the programmed cell death protein-1 (PD-1) or its ligand (PD-L1) is an effective method for reversing cancer immunosuppression and thereby promoting immune responses against several cancer types. Anti-PD-1 and anti-PD-L1 antibodies have resulted in long-term responses with minimal side effects in significant numbers of patients with melanoma, lung, kidney, bladder and triple-negative breast cancer, as well as in chemotherapy-refractory Hodgkin disease. There is already evidence from at least one randomised trial that anti-PD-1 therapy is superior to chemotherapy in the treatment of patients with metastatic melanoma, and two anti-PD-1 antibodies, pembrolizumab and nivolumab, have been approved by the US Food and Drug Administration for the treatment of patients previously treated for metastatic melanoma. It is anticipated that approvals by drug regulatory bodies will be forthcoming in several cancers in the next months
Characteristics and dynamics of surfzone transverse finger bars
Patches of transverse finger bars have been identified in the surf zone of Noordwijk
beach (Netherlands). They consisted of three to nine elongated accumulations of sand
attached to the low-tide shoreline. The bars extended up to 50 m into the inner surf zone,
had an oblique orientation with respect to the shore-normal, and were quasiregularly
spaced in the alongshore direction.Postprint (published version
Photospheric activity, rotation and magnetic interaction in LHS 6343 A
Context. The Kepler mission has recently discovered a brown dwarf companion
transiting one member of the M4V+M5V visual binary system LHS 6343 AB with an
orbital period of 12.71 days. Aims. The particular interest of this transiting
system lies in the synchronicity between the transits of the brown dwarf C
component and the main modulation observed in the light curve, which is assumed
to be caused by rotating starspots on the A component. We model the activity of
this star by deriving maps of the active regions that allow us to study stellar
rotation and the possible interaction with the brown dwarf companion. Methods.
An average transit profile was derived, and the photometric perturbations due
to spots occulted during transits are removed to derive more precise transit
parameters. We applied a maximum entropy spot model to fit the out-of-transit
optical modulation as observed by Kepler during an uninterrupted interval of
500 days. It assumes that stellar active regions consist of cool spots and
bright faculae whose visibility is modulated by stellar rotation. Results.
Thanks to the extended photometric time series, we refine the determination of
the transit parameters and find evidence of spots that are occulted by the
brown dwarf during its transits. The modelling of the out-of-transit light
curve of LHS 6343 A reveals several starspots rotating with a slightly longer
period than the orbital period of the brown dwarf, i.e., 13.13 +- 0.02 days. No
signature attributable to differential rotation is observed. We find evidence
of a persistent active longitude on the M dwarf preceding the sub- companion
point by 100 deg and lasting for at least 500 days. This can be relevant for
understanding how magnetic interaction works in low-mass binary and star-planet
systems.Comment: 14 pages, 16 figure
Doppler-beaming in the Kepler light curve of LHS 6343 A
Context. Kepler observations revealed a brown dwarf eclipsing the M-type star
LHS 6343 A with a period of 12.71 days. In addition, an out-of-eclipse light
modulation with the same period and a relative semi-amplitude of 2 x 10^-4 was
observed showing an almost constant phase lag to the eclipses produced by the
brown dwarf. In a previous work, we concluded that this was due to the light
modulation induced by photospheric active regions in LHS 6343 A. Aims. In the
present work, we prove that most of the out-of-eclipse light modulation is
caused by the Doppler-beaming induced by the orbital motion of the primary
star. Methods. We introduce a model of the Doppler-beaming for an eccentric
orbit and also considered the ellipsoidal effect. The data were fitted using a
Bayesian approach implemented through a Monte Carlo Markov chain method. Model
residuals were analysed by searching for periodicities using a Lomb-Scargle
periodogram. Results. For the first seven quarters of Kepler observations and
the orbit previously derived from the radial velocity measurements, we show
that the light modulation of the system outside eclipses is dominated by the
Doppler-beaming effect. A period search performed on the residuals shows a
significant periodicity of 42.5 +- 3.2 days with a false-alarm probability of 5
x 10^-4, probably associated with the rotational modulation of the primary
component.Comment: 6 pages, 7 figure
Current Challenges in Financing Agricultural Cooperatives
Agricultural, Cooperatives, Finance, Agribusiness, L10, L23, L16, Q13,
A possible black hole in the gamma-ray microquasar LS 5039
The population of high energy and very high energy gamma-ray sources,
detected with EGRET and the new generation of ground-based Cherenkov
telescopes, conforms a reduced but physically important sample. Most of these
sources are extragalactic (e.g., blazars), while among the galactic ones there
are pulsars and SN remnants. The microquasar LS 5039, previously proposed to be
associated with an EGRET source by Paredes et al. (2000), has recently been
detected at TeV energies, confirming that microquasars should be regarded as a
class of high energy gamma-ray sources. To model and understand how the
energetic photons are produced and escape from LS 5039 it is crucial to unveil
the nature of the compact object, which remains unknown. Here we present new
intermediate-dispersion spectroscopy of this source which, combined with values
reported in the literature, provides an orbital period of 3.90603+/-0.00017 d,
a mass function f(M)=0.0053+/-0.0009 M_sun, and an eccentricity e=0.35+/-0.04.
Atmosphere model fitting to the spectrum of the optical companion, together
with our new distance estimate of d=2.5+/-0.1 kpc, yields R_opt=9.3+0.7-0.6
R_sun, log (L_opt/L_sun)=5.26+/-0.06, and M_opt=22.9+3.4-2.9 M_sun. These,
combined with our dynamical solution and the assumption of
pseudo-synchronization, yield an inclination i=24.9+/-2.8 degree and a compact
object mass M_X=3.7+1.3-1.0 M_sun. This is above neutron star masses for most
of the standard equations of state and, therefore, we propose that the compact
object in LS 5039 is a black hole. We finally discuss about the implications of
our orbital solution and new parameters of the binary system on the CNO
products, the accretion/ejection energetic balance, the SN explosion scenario,
and the behaviour of the TeV emission with the new orbital period.Comment: 10 pages, 8 figures. Accepted for publication in MNRAS. Minor changes
according to referee repor
A census of Oph candidate members from Gaia DR2
The Ophiuchus cloud complex is one of the best laboratories to study the
earlier stages of the stellar and protoplanetary disc evolution. The wealth of
accurate astrometric measurements contained in the Gaia Data Release 2 can be
used to update the census of Ophiuchus member candidates. We seek to find
potential new members of Ophiuchus and identify those surrounded by a
circumstellar disc. We constructed a control sample composed of 188 bona fide
Ophiuchus members. Using this sample as a reference we applied three different
density-based machine learning clustering algorithms (DBSCAN, OPTICS, and
HDBSCAN) to a sample drawn from the Gaia catalogue centred on the Ophiuchus
cloud. The clustering analysis was applied in the five astrometric dimensions
defined by the three-dimensional Cartesian space and the proper motions in
right ascension and declination. The three clustering algorithms systematically
identify a similar set of candidate members in a main cluster with astrometric
properties consistent with those of the control sample. The increased
flexibility of the OPTICS and HDBSCAN algorithms enable these methods to
identify a secondary cluster. We constructed a common sample containing 391
member candidates including 166 new objects, which have not yet been discussed
in the literature. By combining the Gaia data with 2MASS and WISE photometry,
we built the spectral energy distributions from 0.5 to 22\microm for a subset
of 48 objects and found a total of 41 discs, including 11 Class II and 1 Class
III new discs. Density-based clustering algorithms are a promising tool to
identify candidate members of star forming regions in large astrometric
databases. If confirmed, the candidate members discussed in this work would
represent an increment of roughly 40% of the current census of Ophiuchus.Comment: A&A, Accepted. Abridged abstrac
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