Abstract
All known small solar system bodies have diameters between a few meters and a few thousands of kilometers. Based on the collisional evolution of solar system bodies, a larger number of ...asteroids with diameters down to ∼2 m is thought to exist. As all solar system bodies, small bodies can be passive sources of high-energy gamma-rays, produced by the interaction of energetic cosmic rays impinging on their surfaces. Since the majority of known asteroids are in orbits between Mars and Jupiter (in a region known as the Main Belt), we expect them to produce a diffuse emission close to the ecliptic plane. In this work, we have studied the gamma-ray emission coming from the ecliptic using the data collected by the Large Area Telescope (LAT) onboard the Fermi satellite. We have fit the results with simulations of the gamma-ray intensity at the source level (calculated with the software
FLUKA
) to constrain the small solar system bodies population. Finally, we have proposed a model describing the distribution of asteroid sizes and we have used the LAT data to constrain the gamma-ray emission expected from this model and, in turn, on the model itself.
The Sonic Hedgehog (Hh) signal transduction pathway plays a critical role in many developmental processes and, when deregulated, may contribute to several cancers, including basal cell carcinoma, ...medulloblastoma, colorectal, prostate, and pancreatic cancer. In recent years, several Hh inhibitors have been developed, mainly acting on the Smo receptor. However, drug resistance due to Smo mutations or non-canonical Hh pathway activation highlights the need to identify further mechanisms of Hh pathway modulation. Among these, deacetylation of the Hh transcription factor Gli1 by the histone deacetylase HDAC1 increases Hh activity. On the other end, the KCASH family of oncosuppressors binds HDAC1, leading to its ubiquitination and subsequent proteasomal degradation, leaving Gli1 acetylated and not active.
It was recently demonstrated that the potassium channel containing protein KCTD15 is able to interact with KCASH2 protein and stabilize it, enhancing its effect on HDAC1 and Hh pathway.
KCTD15 and KCTD1 proteins share a high homology and are clustered in a specific KCTD subfamily. We characterize here KCTD1 role on the Hh pathway. Therefore, we demonstrated KCTD1 interaction with KCASH1 and KCASH2 proteins, and its role in their stabilization by reducing their ubiquitination and proteasome-mediated degradation. Consequently, KCTD1 expression reduces HDAC1 protein levels and Hh/Gli1 activity, inhibiting Hh dependent cell proliferation in Hh tumour cells. Furthermore, analysis of expression data on publicly available databases indicates that KCTD1 expression is reduced in Hh dependent MB samples, compared to normal cerebella, suggesting that KCTD1 may represent a new putative target for therapeutic approaches against Hh-dependent tumour.
A light tracker based on scintillating fibers with SiPM readout Mazziotta, M.N.; Altomare, C.; Bissaldi, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2022, Letnik:
1039
Journal Article
Recenzirano
We have developed a novel light tracker based on plastic scintillating fiber arrays readout with Silicon Photomultipliers (SiPMs). The tracker consists of multiple planes, with the fibers in each ...plane oriented perpendicularly to those in the adjacent plane, in order to allow 3D track reconstruction. The fibers in each plane have round cross sections, with a diameter of 500μm, and are arranged in two staggered layers in a close-packed configuration. The fibers are readout by means of SiPM arrays with a 250μm strip pitch placed at one of their ends. Scintillating fibers allow a reduced material budget while providing a good spatial resolution and a fast response. This design is therefore suitable to track low-energy particles, such as the lowest energy cosmic rays or the electrons produced in Compton scatterings of gamma rays with energies down to 100 keV. We have built a detector prototype, equipped with Hamamatsu 128-channel SiPM arrays, readout with 32-channel PETIROC2A front-end ASICs. These ASICs are controlled by a custom data acquisition system board equipped with Xilinx Kintex-7 FPGA with self-triggering capabilities. The prototype has been tested with particle beams, cosmic rays and radioactive sources. The tracker design will be presented and performance of the prototype will be discussed.
A compact, light scintillating fiber tracker with SiPM readout Pillera, R.; Altomare, C.; Bissaldi, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
March 2023, 2023-03-00, Letnik:
1048
Journal Article
Recenzirano
We present the concept of a novel compact and light tracker based on arrays of plastic scintillating fibers readout with Silicon Photomultipliers (SiPMs). The tracker will be composed of multiple ...planes, with the fibers in each plane oriented perpendicularly to those in the adjacent planes. Each plane will consist of two staggered layers of fibers, having a round cross section with 500 μm diameter and arranged in a close packed configuration. Scintillation photons produced in the fibers will be collected by SiPM arrays with 250 μm strip pitch located at one end of the fibers. This configuration will ensure an accurate spatial resolution and a fast response, while keeping a reduced material budget. Hence, this detector will be suitable to track low energy particles and will be able to efficiently detect the Compton scattered electrons produced by gamma rays with energies down to 100 keV. We built a reduced scale tracker prototype, using Hamamatsu 128 channel SiPM arrays and 32 channel PETIROC2A front end ASICs readout. The latter are controlled by a custom data acquisition board with self triggering capabilities. We tested this prototype with cosmic rays, radioactive sources and accelerated particle beams.
After large galaxies merge, their central supermassive black holes are expected to form binary systems. Their orbital motion should generate a gravitational wave background (GWB) at nanohertz ...frequencies. Searches for this background use pulsar timing arrays, which perform long-term monitoring of millisecond pulsars at radio wavelengths. We used 12.5 years of Fermi Large Area Telescope data to form a gamma-ray pulsar timing array. Results from 35 bright gamma-ray pulsars place a 95% credible limit on the GWB characteristic strain of 1.0 × 10
at a frequency of 1 year
. The sensitivity is expected to scale with
, the observing time span, as Formula: see text. This direct measurement provides an independent probe of the GWB while offering a check on radio noise models.
Abstract
We present an incremental version (4FGL-DR3, for Data Release 3) of the fourth Fermi Large Area Telescope (LAT) catalog of
γ
-ray sources. Based on the first 12 years of science data in the ...energy range from 50 MeV to 1 TeV, it contains 6658 sources. The analysis improves on that used for the 4FGL catalog over eight years of data: more sources are fit with curved spectra, we introduce a more robust spectral parameterization for pulsars, and we extend the spectral points to 1 TeV. The spectral parameters, spectral energy distributions, and associations are updated for all sources. Light curves are rebuilt for all sources with 1 yr intervals (not 2 month intervals). Among the 5064 original 4FGL sources, 16 were deleted, 112 are formally below the detection threshold over 12 yr (but are kept in the list), while 74 are newly associated, 10 have an improved association, and seven associations were withdrawn. Pulsars are split explicitly between young and millisecond pulsars. Pulsars and binaries newly detected in LAT sources, as well as more than 100 newly classified blazars, are reported. We add three extended sources and 1607 new point sources, mostly just above the detection threshold, among which eight are considered identified, and 699 have a plausible counterpart at other wavelengths. We discuss the degree-scale residuals to the global sky model and clusters of soft unassociated point sources close to the Galactic plane, which are possibly related to limitations of the interstellar emission model and missing extended sources.
Delayed closure of the anterior fontanelle is often associated with significant disease entities. Range of normal closure of the anterior fontanelle is 4 to 26 months. Increased intracranial ...pressure, hypothyroidism, and skeletal anomalies are common etiologic factors. History, physical examination, and diagnostic testing rule out most disorders. Once these disorders have been ruled out, it is important for the physician to realize that a persistent open anterior fontanelle beyond the accepted ranges of closure can be a normal outlier.
