541 research outputs found
Collision between a dark soliton and a linear wave in an optical fiber
We report an experimental observation of the collision between a linear wave
propagating in the anomalous dispersion region of an optical fiber and a dark
soliton located in the normal dispersion region. This interaction results in
the emission of a new frequency component whose wavelength can be predicted
using phase-matching arguments. The measured efficiency of this process shows a
strong dependency with the soliton grayness and the linear wave wavelength, and
is in a good agreement with theory and numerical simulations.Comment: 10 pages, 6 figures, 1 annex
Muon calibration of the ASTRI-Horn telescope: preliminary results
Astri-Horn is a Small-Sized Telescope (SST) for very-high energy gamma-ray
astronomy installed in Italy at the INAF "M.C. Fracastoro" observing station
(Mt. Etna, Sicily). The ASTRI-Horn telescope is characterized by a dual-mirror
optical system and a curved focal surface covered by SiPM sensors managed by a
innovative fast front-end electronics. Dedicated studies were performed to
verify the feasibility of the calibration through muons on the relatively small
size of the primary mirror (~4 m diameter), as in the case of larger Cherenkov
telescopes. A number of tests were performed using simulations of the
atmospheric showers with the CORSIKA package and of the telescope response with
a dedicated simulator. In this contribution we present a preliminary analysis
of muon events detected by ASTRI-Horn during the regular scientific data taking
performed in December 2018 and March 2019. These muon events validate the
results obtained with the simulations and definitively confirm the feasibility
of calibrating the ASTRI-Horn SST telescope with muons.Comment: Proceedings of the 36th International Cosmic Ray Conference, Madison,
Wisconsin, USA, 24 July-1 August 201
Status and Plans for the Array Control and Data Acquisition System of the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) is the next-generation atmospheric
Cherenkov gamma-ray observatory. CTA will consist of two installations, one in
the northern, and the other in the southern hemisphere, containing tens of
telescopes of different sizes. The CTA performance requirements and the
inherent complexity associated with the operation, control and monitoring of
such a large distributed multi-telescope array leads to new challenges in the
field of the gamma-ray astronomy. The ACTL (array control and data acquisition)
system will consist of the hardware and software that is necessary to control
and monitor the CTA arrays, as well as to time-stamp, read-out, filter and
store -at aggregated rates of few GB/s- the scientific data. The ACTL system
must be flexible enough to permit the simultaneous automatic operation of
multiple sub-arrays of telescopes with a minimum personnel effort on site. One
of the challenges of the system is to provide a reliable integration of the
control of a large and heterogeneous set of devices. Moreover, the system is
required to be ready to adapt the observation schedule, on timescales of a few
tens of seconds, to account for changing environmental conditions or to
prioritize incoming scientific alerts from time-critical transient phenomena
such as gamma ray bursts. This contribution provides a summary of the main
design choices and plans for building the ACTL system.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
Towards Minimal Barcodes
In the setting of persistent homology computation, a useful tool is the persistence barcode representation in which pairs of birth and death times of homology classes are encoded in the form of intervals. Starting from a polyhedral complex K (an object subdivided into cells which are polytopes) and an initial order of the set of vertices, we are concerned with the general problem of searching for filters (an order of the rest of the cells) that provide a minimal barcode representation in the sense of having minimal number of “k-significant” intervals, which correspond to homology classes with life-times longer than a fixed number k. As a first step, in this paper we provide an algorithm for computing such a filter for k = 1 on the Hasse diagram of the poset of faces of K
Endocrine-responsive lobular carcinoma of the breast: features associated with risk of late distant recurrence
BACKGROUND:
Invasive lobular carcinomas (ILCs) account for 10-15% of all breast cancers. They are characterized by an elevated endocrine responsiveness and by a long lasting risk of relapse over time. Here we report for the first time an analysis of clinical and pathological features associated with the risk of late distant recurrence in ILCs.
PATIENTS AND METHODS:
We retrospectively analyzed all consecutive patients with hormone receptor-positive ILC operated at the European Institute of Oncology (EIO) between June 1994 and December 2010 and scheduled to receive at least 5\u2009years of endocrine treatment. The aim was to identify clinical and pathological variables that provide prognostic information in the period beginning 5\u2009years after definitive surgery. The cumulative incidence of distant metastases (CI-DM) from 5\u2009years after surgery was the prospectively defined primary endpoint.
RESULTS:
One thousand eight hundred seventy-two patients fulfilled the inclusion criteria. The median follow-up was 8.7\u2009years. Increased tumor size and positive nodal status were significantly associated with higher risk of late distant recurrence, but nodal status had a significant lower prognostic value in late follow-up period (DM-HR, 3.21; 95% CI, 2.06-5.01) as compared with the first 5\u2009years of follow-up (DM-HR, 9.55; 95% CI, 5.64-16.2; heterogeneity p value 0.002). Elevated Ki-67 labeling index (LI) retained a significant and independent prognostic value even after the first 5\u2009years from surgery (DM-HR, 1.81; 95% CI 1.19-2.75), and it also stratified the prognosis of ILC patients subgrouped according to lymph node status. A combined score, obtained integrating the previously validated Clinical Treatment Score post 5\u2009years (CTS5) and Ki-67 LI, had a strong association with the risk of late distant recurrence of ILCs.
CONCLUSION:
We identified factors associated with the risk of late distant recurrence in ER-positive ILCs and developed a simple prognostic score, based on data that are readily available, which warrants further validation
Extended formulations from communication protocols in output-efficient time
Deterministic protocols are well-known tools to obtain extended formulations,
with many applications to polytopes arising in combinatorial optimization.
Although constructive, those tools are not output-efficient, since the time
needed to produce the extended formulation also depends on the number of rows
of the slack matrix (hence, on the exact description in the original space). We
give general sufficient conditions under which those tools can be implemented
as to be output-efficient, showing applications to e.g.~Yannakakis' extended
formulation for the stable set polytope of perfect graphs, for which, to the
best of our knowledge, an efficient construction was previously not known. For
specific classes of polytopes, we give also a direct, efficient construction of
extended formulations arising from protocols. Finally, we deal with extended
formulations coming from unambiguous non-deterministic protocols
Expected performance of the ASTRI-SST-2M telescope prototype
ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) is an
Italian flagship project pursued by INAF (Istituto Nazionale di Astrofisica)
strictly linked to the development of the Cherenkov Telescope Array, CTA.
Primary goal of the ASTRI program is the design and production of an end-to-end
prototype of a Small Size Telescope for the CTA sub-array devoted to the
highest gamma-ray energy region. The prototype, named ASTRI SST-2M, will be
tested on field in Italy during 2014. This telescope will be the first
Cherenkov telescope adopting the double reflection layout in a
Schwarzschild-Couder configuration with a tessellated primary mirror and a
monolithic secondary mirror. The collected light will be focused on a compact
and light-weight camera based on silicon photo-multipliers covering a 9.6 deg
full field of view. Detailed Monte Carlo simulations have been performed to
estimate the performance of the planned telescope. The results regarding its
energy threshold, sensitivity and angular resolution are shown and discussed.Comment: In Proceedings of the 33rd International Cosmic Ray Conference
(ICRC2013), Rio de Janeiro (Brazil). All CTA contributions at arXiv:1307.223
Endogenous Nmnat2 Is an Essential Survival Factor for Maintenance of Healthy Axons
We conclude that endogenous Nmnat2 prevents spontaneous degeneration of healthy axons and propose that, when present, the more long-lived, functionally related WldS protein substitutes for Nmnat2 loss after axon injury. Endogenous Nmnat2 represents an exciting new therapeutic target for axonal disorders
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