421 research outputs found
Utilization of photon orbital angular momentum in the low-frequency radio domain
We show numerically that vector antenna arrays can generate radio beams which
exhibit spin and orbital angular momentum characteristics similar to those of
helical Laguerre-Gauss laser beams in paraxial optics. For low frequencies (< 1
GHz), digital techniques can be used to coherently measure the instantaneous,
local field vectors and to manipulate them in software. This opens up for new
types of experiments that go beyond those currently possible to perform in
optics, for information-rich radio physics applications such as radio
astronomy, and for novel wireless communication concepts.Comment: 4 pages, 5 figures. Changed title, identical to the paper published
in PR
Neurofilament light chain: a specific serum biomarker of axonal damage severity in rat models of Chemotherapy-Induced Peripheral Neurotoxicity
Chemotherapy-Induced Peripheral Neurotoxicity (CIPN) is a severe and long-lasting side effect of anticancer therapy, which can severely impair patients’ quality of life. It is a sensory and length-dependent neuropathy, which predominantly affects large myelinated fibers. Easy and reliable monitoring of CIPN in patients is still an unmet clinical need. Since increasing clinical evidence supports the potential use of neurofilament light chain (NfL) as a biomarker of axonal injury, in this study we measured serum NfL levels in animals chronically treated with cisplatin (CDDP) and paclitaxel (PTX), two antineoplastic drugs with different neuronal targets. Wistar rats were treated with CDDP (2 mg/kg i.p. twice/week for 4 weeks) or PTX (10 mg/kg i.v. once/week for 4 weeks). Repeated serum NfL quantification was obtained using the Single Molecule Array (Simoa) technology. The onset and progression of peripheral neurotoxicity were evaluated through neurophysiology, morphological assessments and intraepidermal nerve fibers density quantification. Our results showed that serum NfL measurements correlated with the severity of axonal damage. In fact, both treatments induced serum NfL increase, but higher levels were evidenced in PTX-treated animals, compared with CDDP-treated rats, affected by a milder neurotoxicity. Notably, also the timing of the NfL level increase was associated with the severity of morphological and functional alterations of axonal structure. Therefore, NfL could be a useful biomarker for axonal damage in order to follow the onset and severity of axonal degeneration and possibly limit the occurrence of serious PNS disease
Anti-tumor efficacy assessment of the sigma receptor pan modulator RC-106. A promising therapeutic tool for pancreatic cancer
Introduction: Pancreatic cancer (PC) is one of the most lethal tumor worldwide, with no prognosis improvement over the past 20-years. The silent progressive nature of this neoplasia hampers the early diagnosis, and the surgical resection of the tumor, thus chemotherapy remains the only available therapeutic option. Sigma receptors (SRs) are a class of receptors proposed as new cancer therapeutic targets due to their over-expression in tumor cells and their involvement in cancer biology. The main localization of these receptors strongly suggests their potential role in ER unfolded protein response (ER-UPR), a condition frequently occurring in several pathological settings, including cancer. Our group has recently identified RC-106, a novel pan-SR modulator with good in vitro antiproliferative activities toward a panel of different cancer cell lines. In the present study, we investigated the in vitro properties and pharmacological profile of RC-106 in PC cell lines with the aim to identify a potential lead candidate for the treatment of this tumor. Methods: Pancreatic cancer cell lines Panc-1, Capan-1, and Capan-2 have been used in all experiments. S1R and TMEM97/S2R expression in PC cell lines was quantified by Real-Time qRT-PCR and Western Blot experiments. MTS assay was used to assess the antiproliferative effect of RC-106. The apoptotic properties of RC-106 was evaluated by TUNEL and caspase activation assays. GRP78/BiP, ATF4, and CHOP was quantified to evaluate ER-UPR. Proteasome activity was investigated by a specific fluorescent-based assay. Scratch wound healing assay was used to asses RC-106 effect on cell migration. In addition, we delineated the in vivo pharmacokinetic profile and pancreas distribution of RC-106 in male CD-1 mice. Results: Panc-1, Capan-1, and Capan-2 express both SRs. RC-106 exerts an antiproliferative and pro-apoptotic effect in all examined cell lines. Cells exposure to RC-106 induces the increase of the expression of ER-UPR related proteins, and the inhibition of proteasome activity. Moreover, RC-106 is able to decrease PC cell lines motility. The in vivo results show that RC-106 is more concentrated in pancreas than plasma. Conclusion: Overall, our data evidenced that the pan-SR modulator RC-106 is an optimal candidate for in vivo studies in animal models of PC
A Kinematic Link between Boxy Bulges, Stellar Bars, and Nuclear Activity in NGC 3079 & NGC 4388
We present direct kinematic evidence for bar streaming motions in two active
galaxies with boxy stellar bulges. The Hawaii Imaging Fabry-Perot
Interferometer was used on the Canada-France-Hawaii 3.6-m telescope and the
University of Hawaii 2.2-m telescope to derive the two-dimensional velocity
field of the line-emitting gas in the disks of the Sc galaxy NGC 3079 and the
Sb galaxy NGC 4388. In contrast to previous work based on long-slit data, the
detection of the bar potential from the Fabry-Perot data does not rely on the
existence of inner Lindblad resonances or strong bar-induced shocks. Simple
kinematic models which approximate the intrinsic gas orbits as nonintersecting,
inclined elliptical annuli that conserve angular momentum characterize the
observed velocity fields. Box-shaped bulges in both NGC 3079 and NGC 4388 are
confirmed using new near-infrared images to reduce dust obscuration.
Morphological analysis of starlight in these galaxies is combined with the gas
kinematics derived from the Fabry-Perot spectra to test evolutionary models of
stellar bars that involve transitory boxy bulges, and to quantify the
importance of such bars in fueling active nuclei. Our data support the
evolutionary bar models, but fail to prove convincingly that the stellar bars
in NGC 3079 and NGC 4388 directly trigger or sustain the nuclear activity.
(abridged)Comment: 31 pages, 18 figures, Latex, requires aaspp4.sty. Accepted for the
Astronomical Journal (November issue
Reliable detection and characterization of low-frequency polarized sources in the LOFAR M51 field
The new generation of broad-band radio continuum surveys will provide large
data sets with polarization information. New algorithms need to be developed to
extract reliable catalogs of linearly polarized sources that can be used to
characterize those sources and produce a dense rotation measure (RM) grid to
probe magneto-ionized structures along the line of sight via Faraday rotation.
The aim of the paper is to develop a computationally efficient and rigorously
defined source-finding algorithm for linearly polarized sources. We used a
calibrated data set from the LOw Frequency ARray (LOFAR) at 150 MHz centered on
the nearby galaxy M51 to search for polarized background sources. With a new
imaging software, we re-imaged the field at a resolution of 18''x15'' and
cataloged a total of about 3000 continuum sources within 2.5 degrees of the
center of M51. We made small Stokes Q and U images centered on each source
brighter than 100 mJy in total intensity (201 sources) and used RM synthesis to
create corresponding Faraday cubes that were analyzed individually. For each
source, the noise distribution function was determined from a subset of
measurements at high Faraday depths where no polarization is expected; the
peaks in polarized intensity in the Faraday spectrum were identified and the
p-value of each source was calculated. Finally, the false discovery rate method
was applied to the list of p-values to produce a list of polarized sources and
quantify the reliability of the detections. We also analyzed sources fainter
than 100 mJy but that were reported as polarized in the literature at at least
another radio frequency. Of the 201 sources that were searched for
polarization, 6 polarized sources were detected confidently (with a false
discovery rate of 5 percent). This corresponds to a number density of 1
polarized source per 3.3 square degrees, or 0.3 source/square degree.
[Abridged]Comment: 17 pages, 11 figures, accepted for publication in A&
The LOFAR Tied-Array All-Sky Survey: Timing of 35 radio pulsars and an overview of the properties of the LOFAR pulsar discoveries
The LOFAR Tied-Array All-Sky Survey (LOTAAS) is the most sensitive untargeted
radio pulsar survey performed at low radio frequencies (119--151\,MHz) to date
and has discovered 76 new radio pulsars, among which the 23.5-s pulsar
J0250+5854, up until recently the slowest-spinning radio pulsar known. Here, we
report on the timing solutions of 35 pulsars discovered by LOTAAS, which
include a nulling pulsar and a mildly recycled pulsar, and thereby complete the
full timing analysis of the LOTAAS pulsar discoveries. We give an overview of
the findings from the full LOTAAS sample of 76 pulsars, discussing their pulse
profiles, radio spectra and timing parameters. We found that the pulse profiles
of some of the pulsars show profile variations in time or frequency and while
some pulsars show signs of scattering, a large majority display no pulse
broadening. The LOTAAS discoveries have on average steeper radio spectra and
have longer spin periods () as well as lower spin-down rates
() compared to the known pulsar population. We discuss the cause of
these differences, and attribute them to a combination of selection effects of
the LOTAAS survey as well as previous pulsar surveys, though can not rule out
that older pulsars tend to have steeper radio spectra.Comment: Accepted to Astronomy & Astrophysic
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